Apparatus and system for providing power to solid state lighting
09894730 ยท 2018-02-13
Assignee
Inventors
Cpc classification
H05B45/56
ELECTRICITY
H05B45/48
ELECTRICITY
International classification
Abstract
An apparatus and computer readable storage medium are disclosed for supplying power to a load such as a plurality of light emitting diodes. A representative apparatus comprises a primary module, a first secondary module couplable to a first load, and a second secondary module couplable to a second load. The primary module comprises a transformer having a transformer primary. The first secondary module comprises a first transformer secondary magnetically coupled to the transformer primary, and the second secondary module comprises a second transformer secondary magnetically coupled to the transformer primary, with the second secondary module couplable through the first or second load to the first secondary module.
Claims
1. A method of providing power to a plurality of light emitting diodes of a circuit, the method comprising: energizing a first secondary module and a second secondary module from a transformer of a primary module; energizing a first light emitting diode by the first secondary module, wherein the first light emitting diode is coupled in series with the first secondary module; and energizing a second light emitting diode by the second secondary module, wherein the second secondary module is coupled in series with the first light emitting diode and the second light emitting diode, and wherein the circuit is configured to flow a direct current from the second secondary module to the first secondary module and back to the second secondary module; wherein the first secondary module is configured to have a first voltage polarity, and wherein the first load is configured to have a second voltage polarity opposite the first voltage polarity.
2. The method of claim 1, further comprising: detecting a fault in the first secondary module or the first light emitting diode; and in response to the detected fault, flowing a bypass current around the first secondary module and the first light emitting diode from a third light emitting diode to the second secondary module.
3. The method of claim 2, wherein the detected fault comprises an open circuit.
4. The method of claim 2, further comprising: sensing a current level in at least one of the first or second secondary modules with a current sensor; and in response to the sensed current level, regulating a primary current in the primary module with a controller coupled to the current sensor and the primary module.
5. The method of claim 4, wherein the controller provides dimming of at least one of the first or second light emitting diodes by regulating the bypass current.
6. The method of claim 4, wherein the controller provides a pulse-width modulated signal to regulate the bypass circuit.
7. The method of claim 4, wherein the controller is optically coupled to the primary module.
8. The method of claim 1, wherein a resultant voltage of the first voltage polarity combined with the voltage of the second voltage polarity is substantially less than a magnitude of the first voltage polarity or the second voltage polarity.
9. The method of claim 1, wherein the second secondary module is configured to have a third voltage polarity, and wherein the second load is configured to have a fourth voltage polarity opposite the third voltage polarity.
10. The method of claim 9, wherein a resultant voltage of a combination of the first voltage polarity, the second voltage polarity, the third voltage polarity, and the fourth voltage polarity is substantially less than a magnitude of the first voltage polarity, the second voltage polarity, the third voltage polarity, or the fourth voltage polarity.
11. A method of providing power to a plurality of light emitting diodes, the method comprising: generating a first voltage across a first secondary module; generating a second voltage across a first light emitting diode, wherein the first light emitting diode is coupled in series with the first secondary module, and wherein the first and the second voltages have opposing polarities; generating a third voltage across a second secondary module, wherein the second secondary module is coupled in series with the first light emitting diode; generating a fourth voltage across a second light emitting diode, wherein the second light emitting diode is coupled in series with the second secondary module, and wherein the third and the fourth voltages have opposing polarities; and in response to a detected fault, routing a bypass current through a first bypass circuit coupled to the first secondary module to bypass the first secondary module and the first load.
12. The method of claim 11, wherein the bypass current is a first bypass current, the method further comprising, in response to the detected fault, routing a second bypass current through a second bypass circuit coupled to the second secondary module to bypass the second secondary module and the second load.
13. The method of claim 12, wherein each of the first bypass circuit and the second bypass circuit comprises a switch coupled in parallel with a diode.
14. The method of claim 12, wherein each of the first bypass circuit and the second bypass circuit comprises a zener diode.
15. The method of claim 12, further comprising dimming the first or second light emitting diodes by regulating the first or second bypass circuits.
16. The method of claim 11, wherein the bypass current is further routed to the second light emitting diode.
17. The method of claim 11, further comprising, in response to the detected fault, interrupting a current being provided from the first secondary module to the first light emitting diode.
18. The method of claim 11, wherein the detected fault is a short circuit or an open circuit.
19. The method of claim 11, further comprising: routing a current from the first secondary module to the first light emitting diode for a first predetermined on-time duration at a first frequency; and routing a current from the second secondary module to the second light emitting diode for a second predetermined on-time duration at a second frequency.
20. The method of claim 11, wherein a resultant voltage of the first voltage polarity combined with the second voltage polarity is substantially less than a magnitude of the first voltage polarity or the second voltage polarity.
21. The method of claim 11, wherein the first voltage polarity and the second voltage polarity substantially offset each other to provide a comparatively low resultant voltage level.
22. The method of claim 11, wherein a resultant voltage of the combined first voltage polarity, the second voltage polarity, the third voltage polarity, and the fourth voltage polarity is substantially less than a magnitude of the first voltage polarity, the second voltage polarity, the third voltage polarity, or the fourth voltage polarity.
Description
DESCRIPTION OF THE DRAWINGS
(1) The objects, features and advantages of the present disclosure will be more readily appreciated upon reference to the following when considered in conjunction with the accompanying drawings, wherein like reference numerals are used to identify identical components in the various views, and wherein reference numerals with alphabetic characters are utilized to identify additional types, instantiations or variations of a selected component embodiment in the various views, in which:
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DETAILED DESCRIPTION
(15) While the present disclosure illustrates embodiments in many different forms, there are shown in the drawings and will be described herein in detail specific exemplary embodiments thereof, with the understanding that the present disclosure is to be considered as an exemplification of the principles of the claimed subject matter and is not intended to limit the claimed subject matter to the specific embodiments illustrated. In this respect, before explaining at least one embodiment consistent with the present invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of components set forth above and below, illustrated in the drawings, or as described in the examples. Methods and apparatuses consistent with the present invention are capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract included below, are for the purposes of description and should not be regarded as limiting.
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(17) Primary module 515 is couplable to power source 110 and provides power to secondary modules 520. Power source 110 may provide, for example, AC, DC, chopped DC, or another form of power. In an exemplary embodiment, primary module 515 provides power in the form of magnetic energy via a transformer primary (also referred to as a primary winding) and each secondary module 520 receives the magnetic energy via a corresponding transformer secondary (also referred to as a secondary winding). Primary module 515 may comprise, for example and without limitation, an AC-to-DC converter, such as a rectifier, and a switch adapted to conduct or otherwise apply power in the form of a current or voltage to a transformer primary. The power applied to the transformer primary may comprise a power signal such as a sine wave, a square or rectangular wave, a series of pulses, etc. The power signal may vary, such as in terms of amplitude and/or wave shape, in response to a control signal from controller 125. Those having skill in the electronic arts will recognize that numerous techniques are available for providing power to a transformer primary, and that primary module 515 may have innumerable implementations and configurations, any and all of which are considered equivalent and within the scope of the present disclosure.
(18) In an exemplary embodiment, a first terminal of a first load 130.sub.1 is coupled to a first secondary module 520.sub.1 and a second terminal of first load 130.sub.1 is coupled to a second secondary module 520.sub.2. A first terminal of a second load 130.sub.2 is coupled to second secondary module 520.sub.2 and a second terminal of second load 130.sub.2 is coupled to a third secondary module 520.sub.3. Other loads 130 and secondary modules 520 are similarly coupled (i.e., each load is coupled to two (electrically adjacent) secondary modules) up through load 130.sub.N, where a first terminal of an N.sup.th load 130.sub.N is coupled to an N.sup.th secondary module 520.sub.N and a second terminal of N.sup.th load 130.sub.N is coupled to first secondary module 520.sub.1. Such an arrangement places secondary modules 520 and loads 130 in series, with a load between each pair of adjacent secondary modules 520. Such an arrangement may be referred to herein as an alternating series arrangement in two ways, with a secondary module 520 alternating with a load 130 in series, and as discussed below, with corresponding voltages across a secondary module 520 and a load 130 alternating in polarities. (The term adjacent may refer to sequential components in a series circuit. For example, secondary module 520.sub.N may be considered to be adjacent to secondary module 520.sub.N1 and secondary module 520.sub.1.) In an exemplary embodiment, secondary modules 520 and loads 130 are coupled in series so that current flows through a secondary module 520 and a load 130, then another secondary module 520 and a load 130, and so on, in a complete circuit.
(19) In an exemplary embodiment, the secondary modules 520 and loads 130 are arranged such that each output voltage level provided by a secondary module 520 is substantially compensated by a corresponding voltage drop across a corresponding load 130. For example, a voltage rise with a first voltage polarity, such as a positive voltage across first secondary module 520.sub.1 which provides power to first load 130.sub.1 is substantially offset by a corresponding voltage drop across the first load 130.sub.1 having a second, opposing voltage polarity, such as a negative voltage. A similar pattern holds for other secondary modules 520 and loads 130, wherein the voltage rises across each secondary module and then drops across each corresponding load, providing a resultant, overall voltage that is substantially less than the magnitude of the voltage rise or the voltage drop, and may even be relatively or substantially close to zero (depending upon whether the opposing voltage polarities are closely matched). As a result, overall voltage levels at the terminals of loads 130 remain within predetermined and comparatively lower limits. This novel feature of the present disclosure is discussed below in greater detail with reference to
(20) Controller 125 may be adapted to sense one or more parameters from one or more secondary modules 520 or loads 130. Sensed parameters, for example, may comprise a current level or a voltage level, such as a current level through or voltage level of one or more loads 130 or secondary modules 520. The sensed current or voltage level may be utilized by controller 125 and primary module 515 to directly or indirectly regulate current through loads 130, such as to provide substantially stable current levels or current levels at or near selected or predetermined values. For example, in response to a sensed parameter, the controller 125 may increase or decrease the current through the transformer primary of the primary module 515, and/or may separately modify current or voltage provided by a secondary module 520, such as by using the bypass circuitry discussed below (not separately illustrated in
(21) For example, and among other things, the controller 125 utilizes one or more sensed parameters, as feedback signals, to output a control signal to primary module 515, such as to regulate power levels to loads 130. The control signal may be utilized by primary module 515 to determine a power level to be provided to secondary modules 520. In an exemplary embodiment, the controller 125 may utilize a sensed parameter to cause primary module 515 to reduce the level of power or current provided to secondary modules 520 if current to loads 130 exceeds a first predetermined threshold or to increase the level of power or current provided to secondary modules 520 if current to loads 130 falls below a second predetermined threshold.
(22) Controller 125 may also be adapted to supply control signals to secondary modules 520 to independently adjust power or current levels to loads 130.sub.1, 130.sub.2, 130.sub.3, through 130.sub.N, such as for dimming or turning on or off one or more channels. In an exemplary embodiment, a temperature sensor (not separately illustrated in
(23) Secondary modules 520 may be configured to bypass or shunt current past one or more loads 130 in the event of one or more faults, such as short circuits or open circuits in one or more secondary modules 520 or loads 130. As illustrated in
(24) Controller 125 may comprise analog circuitry such as amplifiers, comparators, integrators, etc. and/or digital circuitry such as processors, memory, gates, A/D and D/A converters, etc. Those having skill in the electronic arts will recognize that numerous techniques are known for regulating power to one or more loads and that controller 125 may have innumerable implementations and configurations, any and all of which are considered equivalent and within the scope of the present disclosure.
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(26) Stated another way, the system 100A comprises a driver 115, a controller 125, a transformer 155, a sensor 165, a plurality of secondary power modules 140.sub.1, 140.sub.2, through 140.sub.N, and a plurality of loads 130.sub.1, 130.sub.2, through 130.sub.N. In exemplary embodiments, the system 100A may further comprise a plurality of bypass circuits 145.sub.1, 145.sub.2, through 145.sub.N. In exemplary embodiments, system 100A may further comprise an isolator 120 configured to, for example, electrically isolate the driver 115 from the controller 125. (AC and DC input voltages as referred to herein and within the scope of the present disclosure are discussed in greater detail below). In an exemplary embodiment, each power module 140.sub.1, 140.sub.2, through 140.sub.N comprises a corresponding transformer secondary (150.sub.1, 150.sub.2, through 150.sub.N), a corresponding rectifier (135.sub.1, 135.sub.2, through 135.sub.N), and a corresponding filter (195.sub.1, 195.sub.2, through 195.sub.N), respectively. In an alternative exemplary embodiment, filters 195 may be omitted or combined with rectifiers 135.
(27) As illustrated, loads 130 comprise a plurality of N individual loads 130.sub.1, 130.sub.2, through 130.sub.N. Components with a plurality of instantiations may be referenced herein collectively without subscripts or individually with subscripts. For example, loads 130 may be referred to equivalently as loads 130.sub.1, 130.sub.2, through 130.sub.N. Similar notation applies to power modules 140, secondaries 150, rectifiers 135, filters 195, bypass circuits 145, etc.
(28) In
(29) As illustrated, a power source 110 provides AC or DC power to driver 115. As mentioned above, such AC or DC power may be, for example, single phase or multiphase AC, DC or chopped DC power, such as from batteries or from an AC to DC converter, or any other form of electrical power. Driver 115 receives power from power source 110, converts received power to DC if appropriate, receives control signals from controller 125 (optionally via isolator 120), and provides a driving signal to primary 105. Driver 115 may, for example, provide a PWM (pulse width modulated) signal, and may use any of various modes of operation such as continuous conduction mode (CCM), discontinuous conduction mode (DCM), and critical conduction mode. Driver 115 may comprise one or more stages such as power conversion stages. Those having skill in the electronic arts will recognize that there are numerous methods for utilizing a controller 125 and a driver 115 for providing driving signals, any and all of which are considered equivalent and within the scope of the present disclosure.
(30) Transformer secondaries 150.sub.1, 150.sub.2, through 150.sub.N are coupled to and provide power to rectifiers 135.sub.1, 135.sub.2, through 135.sub.N, respectively. In an exemplary embodiment, rectifiers 135.sub.1, 135.sub.2, through 135.sub.N convert AC power from secondaries 150.sub.1, 150.sub.2, through 150.sub.N, respectively, into DC power. Filters 195.sub.1, 195.sub.2, through 195.sub.N smooth the DC power from rectifiers 135.sub.1, 135.sub.2, through 135.sub.N, respectively, to provide a relatively or comparatively stable DC power level.
(31) In the exemplary embodiment as illustrated in
(32) In an exemplary embodiment, a first terminal of a first load 130.sub.1 is coupled to a second terminal of a first power module 140.sub.1 and a second terminal of the first load 130.sub.1 is coupled to a first terminal of a second power module 140.sub.2. Other cells may be coupled similarly, i.e., a first terminal of K.sup.th load 130.sub.K, 1K<N, is coupled to a second terminal of K.sup.th power module 140.sub.K and a second terminal of K.sup.th load 130.sub.K is coupled to a first terminal of a K+1.sup.th power module 140.sub.K+1. In an exemplary embodiment, a first terminal of N.sup.th load 130.sub.N is coupled to a second terminal of N.sup.th power module 140.sub.N and a second terminal of N.sup.th load 130.sub.N is coupled to a first terminal of sensor 165. A second terminal of sensor 165 is coupled to a first terminal of first power module 140.sub.1. In an alternative embodiment (not illustrated in
(33) In an exemplary embodiment, a sensor 165 determines a sensed parameter such as a current level. Controller 125 receives the sensed parameter information or signal from sensor 165 and utilizes the sensed parameter information to provide one or more control signals (such as a series of control signals) for driver 115.
(34) While
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(36) In an exemplary embodiment, bypass circuits 145 provide a switchable current (or voltage) path around loads 130 and power modules 140. Bypass circuits 145 may be utilized to provide current flow in the event of detected faults or to provide a means for reducing or increasing current flow through individual loads 130, such as for light dimming and for turning individual loads 130 on or off. Bypass circuits 145 are described in further detail below.
(37) In an exemplary embodiment, current levels in power modules 140 and loads 130 may be substantially the same (since they are coupled in series), so current sensing and corresponding control may be accomplished with fewer components, compared to prior art multichannel LED drivers where power to individual channels is separately regulated for each channel. More particularly, in the exemplary embodiment illustrated in
(38) In an exemplary embodiment, as mentioned above, the power modules 140 (of the secondary modules 520) and loads 130 are arranged such that each output voltage level provided by a power module 140 (of a corresponding secondary module 520) is substantially compensated by a corresponding voltage drop across a corresponding load 130. For example, a voltage rise with a first voltage polarity, such as a positive voltage across first power module 140.sub.1 which provides power to first load 130.sub.1, is substantially offset by a corresponding voltage drop across the first load 130.sub.1 having a second, opposing voltage polarity, such as a negative voltage. A similar pattern holds for other power modules 140 and loads 130, wherein the voltage rises across each power module 140 and then drops across each corresponding load, providing a resultant, overall voltage that is substantially less than the magnitude of the voltage rise or the voltage drop, and may even be relatively or substantially close to zero (depending upon whether the opposing voltage polarities are closely matched). As a result, overall voltage levels at the terminals of loads 130 remain within predetermined and comparatively lower limits, as described above.
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(40) Each power module (140A.sub.1, 140A.sub.2, through 140A.sub.N) comprises a corresponding transformer secondary (150.sub.1, 150.sub.2, through 150.sub.N), a corresponding diode (225.sub.1, 225.sub.2, through 225.sub.N), and a corresponding capacitor (220.sub.1, 220.sub.2, through 220.sub.N), respectively. Each bypass circuit (145A.sub.1, 145A.sub.2, through 145A.sub.N) comprises a switch, illustrated as a silicon controlled rectifier (SCR) (230.sub.1, 230.sub.2, through 230.sub.N) and a voltage sensor, illustrated as a zener diode (235.sub.1, 235.sub.2, through 235.sub.N), respectively. Transformer 155 comprises primary 105 and a plurality of secondaries 150.sub.1, 150.sub.2, through 150.sub.N. Isolator 120A comprises a first optical isolator 210 and a second optical isolator 215. One skilled in the electronic arts will recognize that isolator 120A, illustrated in
(41) In
(42) In the following discussion, operation of power modules 140A will be described using power module 140A.sub.1 as an example. Operation of power modules 140A.sub.2 through 140A.sub.N is similar. As illustrated, power module 140A.sub.1 comprises a transformer secondary 150.sub.1, a diode 225.sub.1, and a capacitor 220.sub.1. The secondary 150.sub.1 provides power to diode 225.sub.1. Diode 225.sub.1 acts as a half-wave rectifier to provide DC power to a DC smoothing filter, illustrated as capacitor 220.sub.1. In
(43) As with
(44) As illustrated in
(45) More particularly, in an exemplary embodiment, as mentioned above, the power modules 140A and LEDs 170 (as loads 130) are arranged such that each output voltage level provided by a power module 140A (of a corresponding secondary module) is substantially compensated by a corresponding voltage drop across corresponding LEDs 170. For example, a voltage rise with a first voltage polarity, such as a positive voltage across first power module 140A.sub.1 which provides power to first LEDs 170.sub.1, is substantially offset by a corresponding voltage drop across the first LEDs 170.sub.1 having a second, opposing voltage polarity, such as a negative voltage. A similar pattern holds for other power modules 140A and LEDs 170, wherein the voltage rises across each power module 140A and then drops across each corresponding string of LEDs 170, providing a resultant, overall voltage that is substantially less than the magnitude of the voltage rise or the voltage drop, and may even be relatively or substantially close to zero (depending upon whether the opposing voltage polarities are closely matched). As a result, overall voltage levels at the terminals of LEDs 170 remain within predetermined and comparatively lower limits, as described above.
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(47) In the example illustrated in
(48) The third voltage level 27 for SECOND POWER MODULE shows the voltage rise (i.e., a third voltage polarity) across second power module 140A.sub.2. The fourth voltage level 28 for SECOND LOAD shows the subsequent voltage drop (i.e., a fourth voltage polarity) across the second LED string 170.sub.2 to a level relatively near zero. Such a pattern of voltage rising across power modules 140A and falling by approximately the same amount across LEDs 170 continues through to the fourth load, where the voltage level falls across the fourth load to a value relatively near zero (29). In other words, the voltage rise across power modules 140A may be approximately proportional to the voltage drop across LED strings 170, with the voltage level returning to a value relatively near or about zero volts after each voltage drop. The voltage map of
(49) Referring again to
(50) The operation of bypass circuits 145A in an exemplary embodiment is described utilizing an example of a first bypass circuit 145A.sub.1, a first power module 140A.sub.1, and a first LED string 170.sub.1. Operation of bypass circuits 145A.sub.2 through 145A.sub.N is similar. Transformer 155 provides power to diode 225.sub.1 via secondary 150.sub.1. Diode 225.sub.1 is configured as a half-wave rectifier and converts power from secondary 150.sub.1 to DC power. Capacitor 220.sub.1 acts as a filter to smooth the DC power and provide a relatively constant DC power level. As illustrated in
(51) An exemplary embodiment of the present invention provides continued operation for one or more channels in the event of any of several fault modes. An example of a first fault mode is where an LED string becomes substantially nonconducting. In an exemplary embodiment, if LED string 170.sub.1 becomes a relatively high impedance or open circuit (i.e. enters a state where it is substantially nonconducting), such as due to a failed LED or a broken connection, the voltage level across bypass circuit 145A.sub.1 may increase. The voltage level increase may be caused by current from other power modules 140A.sub.2, 140A.sub.3, etc., providing power to a relatively high impedance circuit comprising LED string 170.sub.1. When the voltage level across bypass circuit 145A.sub.1 reaches or exceeds a predetermined level, such as a threshold voltage, bypass circuit 145A.sub.1 detects a fault. (Other examples of detecting faults by comparing parameter values to thresholds are described below.) After the voltage level across bypass circuit 145A.sub.1 reaches or exceeds a predetermined level (such as a predetermined level determined, in part, by a threshold (or breakdown) voltage of zener diode 235.sub.1), zener diode 235.sub.1 conducts current into the gate of SCR 230.sub.1 and causes SCR 230.sub.1 to switch on (i.e. switch to a conducting state). With SCR 230.sub.1 switched on, SCR 230.sub.1 shunts current past power module 140A.sub.1 and LED string 170.sub.1 to other power modules 140A and LEDs 170. By thus shunting current around the open circuit (as an example of a detected fault), bypass circuit 145A.sub.1 provides an alternate path for current to flow to power modules 140A.sub.2 through 140A.sub.N and LEDs 170.sub.1 through 170.sub.2 in the event of an open circuit (or high impedance) condition in power module 140A.sub.1 or LED string 170.sub.1. Likewise, bypass circuits 145A.sub.2 through 145A.sub.N provide alternate current paths in the event of open circuit conditions in power modules 140A.sub.1 through 140A.sub.N or LED strings 170.sub.1 through 170.sub.N, respectively.
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(53) Returning to
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(55) Beginning with start step 600, a first power module 140A.sub.1 provides power to a first load, implemented as LED string 170.sub.1. In step 610, a bypass circuit 145A.sub.1 determines a first sensed parameter, such as a voltage level across the first power module 140A.sub.1 and the first load, LED string 170.sub.1. Typically, the first sensed parameter will be measured continuously or periodically (e.g., sampled), for ongoing use in a plurality of comparison steps. In step 615, the first sensed parameter is compared to a first threshold such as a first predetermined value substantially proportional to the breakdown voltage of the zener diode 235.sub.1, plus the gate voltage of SCR 230.sub.1 (the voltage applied to the gate that turns on SCR 230.sub.1). In step 620, when the value of the first sensed parameter is greater than or substantially equal to the first threshold, the method proceeds to step 625 and bypasses the detected fault (illustrated in two steps), where the first switch, SCR 230.sub.1 is turned on (step 625), for example by zener diode 235.sub.1 then to step 630, where due to the conducting SCR 230.sub.1, the bypass circuit 145A.sub.1 reroutes current around the first power module 140A.sub.1 and the first load, LED string 170.sub.1 and provides current to the second load, LED string 170.sub.2. In one embodiment of the present invention, the first switch may remain in an on state until power is removed from power modules 140A. As other faults may occur, following step 630, when the method is to continue (i.e., as long as input power is available to the converter), step 635, the method returns to step 610 for ongoing monitoring, and otherwise may end, return step 640. When the value of the first sensed parameter is not greater than or substantially equal to the first threshold in step 620, and also when the method is to continue in step 635, the method also returns to step 610.
(56) Referring again to
(57) An example of a third fault mode is where LED string 170.sub.1 substantially becomes a short circuit (i.e. is set to a relatively low impedance state). In an exemplary embodiment, if LED string 170.sub.1 substantially becomes a short circuit, LED string 170.sub.1 continues to conduct current, thus providing a path for current to flow to other channels. Power module 140A.sub.1 may continue to provide power, which may be utilized by other LED channels.
(58) An example of a fourth fault mode is where power module 140A.sub.1 becomes a short circuit (i.e. enters a relatively low impedance state), such as if power module 140A.sub.1 stops providing power or provides power at a reduced level, yet continues to conduct current. In an exemplary embodiment, current may continue to flow through power module 140A.sub.1 and LED string 170.sub.1. If the breakdown voltage of zener diode 235.sub.1 is set to a relatively high voltage level, such as a value greater than the operational forward voltage across LED string 170.sub.1, then zener diode 235.sub.1 and SCR 230.sub.1 may remain in a nonconducting state and LED string 170.sub.1 may continue to receive power. At least some of the power provided to LED string 170.sub.1 during this fourth fault mode may be provided by one or more of power modules 140A.sub.2 through 140A.sub.N. In such an exemplary embodiment, LED string 170.sub.1 may remain lit while its corresponding power module 140A.sub.1 fails, which is a significant improvement, compared to prior art where an LED channel may lose power if its corresponding power converter fails. In an alternative exemplary embodiment, the breakdown voltage of zener diode 235.sub.1 is set to a relatively low voltage level, such as significantly less than the operational forward voltage across LED string 170.sub.1. In this alternative exemplary embodiment, in the fourth fault mode, zener diode 235.sub.1 trips, triggering SCR 230.sub.1, which shunts current around power module 140A.sub.1 and LED string 170.sub.1.
(59) As described above, in the event of a fault in a representative power module 140A.sub.1 or LED string 170.sub.1, under the fault modes described herein, other LED strings (i.e., LED strings 170.sub.2, 170.sub.3, through 170.sub.N) may continue to receive power. This desirable feature, described herein with respect to power module 140A.sub.1, LED string 170.sub.1, and bypass circuit 145A.sub.1, as an example, may apply also to other LED strings 170.sub.2 through 170.sub.N and their corresponding bypass circuits 145A.sub.2 through 145A.sub.N and power modules 140A.sub.2 through 140A.sub.N, respectively. A fault in circuitry associated with one or more channels may tend to increase or decrease power levels in other channels. Controller 125A may compensate for such a power level change, such as by utilizing a sensed parameter from resistor 260 and adjusting a power output level from driver 115 to primary 105 to bring levels of power provided to LED strings 170 closer to selected or predetermined values using feedback and control methods known in the electronic arts.
(60) Continuing with
(61) A third output 360 and a fourth output 370 of controller 125A may be utilized to provide an over-voltage signal via optical isolator 215 to driver 115. An over-voltage condition may comprise, for example, a state where a voltage level across one or more components, such as LED strings 170 or power modules 140A, rises above a predetermined level. This predetermined level may, for example, correspond to a voltage level deemed to be unsafe or correspond to a condition where LEDs 170 may no longer be receiving useful amounts of power, in which case it may be desirable to discontinue providing power to power modules 140A. Such an over-voltage condition may cause current through resistor 260 to decrease, so voltage across resistor 260 may be utilized in determining an over-voltage condition. In an exemplary embodiment, the value of a sensed parameter such as LED current may be determined utilizing resistor 260 and compared to a predetermined threshold by controller 125A. If the value of the sensed parameter is less than the predetermined threshold, controller 125A may output an over-voltage signal (optionally via optical isolator 215) to driver 155, causing driver 115 to discontinue providing power to primary 105.
(62) In the exemplary embodiment illustrated in
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(64) Fuses 190 may be any of a wide variety of devices known to limit current or provide current protection, as known or becomes known to those having skill in the electronic arts, such as resettable fuses, non-resettable fuses, resistors, voltage dependent resistors such as varistors or metal oxide varistors, circuit breakers, thermal breakers such as bimetallic strips and other thermostats, thermistors, positive temperature coefficient (PTC) thermistors, polymeric positive temperature coefficient devices (PPTCs), switches, sensors, active current limiting circuitry, etc. Depending upon the selected embodiment, with the diacs 180 considered first switches, the fuses 190 may function as and be considered second switches in accordance with the present invention.
(65) Operation of power modules 140B, fuses 190, resistors 260, and bypass circuits 145B will be described herein utilizing power module 140B.sub.1, fuse 190.sub.1, resistor 260.sub.1, and bypass circuits 145B.sub.1 as examples. Operation of power modules 140B.sub.2 through 140B.sub.N, fuses 190.sub.2 through 190.sub.N, and bypass circuits 145B.sub.2 through 145.sub.N is similar. Power module 140B.sub.1 comprises a transformer secondary 150.sub.1, a first diode 240.sub.1, a second diode 245.sub.1, an inductor 250.sub.1, and a capacitor 220.sub.1. The transformer secondary 150.sub.1 provides power through first diode 240.sub.1 to inductor 250.sub.1. First diode 240.sub.1, second diode 245.sub.1, and inductor 250.sub.1 form a buck-based rectifier to convert power from secondary 150.sub.1 to DC. Inductor 250.sub.1 and a DC smoothing filter, illustrated as capacitor 220.sub.1, provide power to LED string 170.sub.1. As illustrated, bypass circuit 145B.sub.1 differs from the respective exemplary bypass circuit 145A.sub.1 in
(66) In an exemplary embodiment, operation of the topology illustrated in
(67) Controller 125B functions similarly to controller 125A, as described above, but is able to utilize additional signals from the additional sensors 260 to provide more fine-tuned control over the driver 115. Feedback signals from any of the sensors 260 may be utilized, for example, to control the voltage or current levels of the driver 115 (and/or transformer primary 105) and/or to control various switches (e.g., as illustrated separately in
(68)
(69) In step 650, a first parameter is determined, such as a voltage level across the bypass circuit 145B.sub.1 or other circuit parameter, such as by the bypass circuit 145B.sub.1 (comprising a first switch, such as an SCR 230.sub.1 or a diac 180.sub.1, and a first sensor, such as a zener diode 235.sub.1 or the diac 180.sub.1). In step 655, a second parameter is determined, such as current through the first corresponding load, LED string 170.sub.1, typically by a fuse 190.sub.1, functioning as both a second switch and a sensor. Typically, the first and second parameters will be measured continuously or periodically (e.g., sampled), for ongoing use in a plurality of comparison steps.
(70) In step 660, the magnitude of the first parameter (e.g., (1) the voltage level across bypass circuit 145B.sub.1 or (2) the voltage level across first power module 140B.sub.1, fuse 190.sub.1, and the first load, LED string 170.sub.1) is compared to a first threshold, such as the diac 180.sub.1 trip voltage. (The comparison in step 660 is a magnitude comparison, comparing the magnitude of the first parameter with the magnitude of the first threshold, since the polarities of the first parameter and the first threshold may be reversed.) If LED string 170.sub.1 becomes an open circuit or enters a relatively or substantially high impedance state, the voltage rise across power module 140B.sub.1 may be substantially greater than the (otherwise offsetting) voltage drop across LED string 170.sub.1, and the voltage level across bypass circuit 145B.sub.1 may be greater than or substantially equal to a first threshold, such as a diac 180.sub.1 trip voltage level. Similarly, if LED string 170.sub.1 becomes a short circuit or enters a relatively or substantially low impedance state, such that it no longer provides an offsetting voltage, the voltage rise across power module 140B.sub.1 may be substantially greater than the (otherwise offsetting) voltage drop across LED string 170.sub.1, and the voltage level across bypass circuit 145B.sub.1 may be greater than or substantially equal to a first threshold, such as a diac 180.sub.1 trip voltage level. Accordingly, in step 670, when the value of the first parameter is greater than or substantially equal to the first threshold, the method proceeds to step 680 and bypasses or reroutes current around the power module and corresponding load, e.g., reroutes current to a next power module and a next load. In exemplary embodiments, step 680 is accomplished by turning on a first switch (i.e., setting the first switch to a conducting state), such as SCR 230.sub.1 or diac 180.sub.1. In addition, in exemplary embodiments, the second switch (e.g., fuse 190, or other type of second switch) may be open circuited or otherwise rendered substantially non-conducting. When the value of the first parameter is not greater than or substantially equal to the first threshold, the method proceeds to step 685.
(71) It should be noted that, in the embodiments illustrated in
(72) Similarly, in step 665, the magnitude of the second parameter is compared to a second threshold, such as the rated current or break point of fuse 190.sub.1. If LED string 170.sub.1 becomes a short circuit or enters a relatively low impedance state (as with the third fault mode described above), power module 140B.sub.1 may provide a relatively high level of current through fuse 190.sub.1 that is greater than the second threshold. In step 675, when the magnitude (or value) of the second parameter is greater than or substantially equal to a second threshold, such a fuse 190.sub.1 or other similar device will become non-conducting or otherwise turn off, creating an open circuit, which will have the ultimate effect of bypassing or rerouting current around the power module and corresponding load, e.g., reroutes current to a next power module and a next load, step 680 (via steps 650, 660, 670 and 680 discussed above). More particularly, if the portion of the circuit having the LED string 170.sub.1 becomes an open circuit via a non-conducting fuse 190.sub.1 or enters a relatively or substantially high impedance state, the voltage rise across power module 140B.sub.1 may be substantially greater than the (otherwise offsetting) voltage drop across LED string 170.sub.1, and the voltage level across bypass circuit 145B.sub.1 may be greater than or substantially equal to a first threshold, such as a diac 180.sub.1 trip voltage level, which will reroute current as previously discussed. In an exemplary embodiment (not shown in
(73)
(74) The system and apparatus illustrated in
(75) Operation of bypass circuits 145C and power modules 140C in an exemplary embodiment will be described utilizing, as an example, a first bypass circuit 145C.sub.1, a first power module 140C.sub.1, and a first LED string 170.sub.1. Operation of other bypass circuits 145C.sub.2 through 145C.sub.N and power modules 140C.sub.2 through 140C.sub.N is similar. Secondary 150.sub.1, first diode 255.sub.1 and second diode 285.sub.1 form a full-wave, half-bridge rectifier and provide power to inductor 151.sub.1 and capacitor 220.sub.1, which in turn provide power to LED string 170.sub.1. SCR 230.sub.1 and zener diode 235.sub.1 provide a bypass function similar to that illustrated in
(76) With first switch 275.sub.1 in an off state and second switch 270.sub.1 in an on state, power module 140C.sub.1 provides power to LED string 170.sub.1. With first switch 275.sub.1 in an on state and second switch 270.sub.1 in an off state, power module 140C.sub.1 is disconnected from LED string 170.sub.1 and bypass circuit 145C.sub.1 shunts current around power module 140C.sub.1 and LED string 170.sub.1. Controller 125C may thus utilize first output signal 370.sub.1 to turn LED string 170.sub.1 off and on. Similarly, controller 125C may turn LED strings 170.sub.2 through 170.sub.N on and off independently via additional output signals on outputs 370.sub.2 through 370.sub.N, respectively. Such a capability may be utilized, for example, for controlling LED displays or lighting where it may be desired to turn individual LEDs or channels of LEDs on and off, entirely, periodically, or otherwise selectably. In an exemplary embodiment, controller 125C may also effectively reduce or increase the average power level provided to individual LED strings 170, such as for setting apparent brightness (as perceived by the human eye) to a selected or predetermined level (i.e., dimming), utilizing pulse wave modulation (PWM). By rapidly (relative to the response time of the human eye) turning individual LED channels 170 off and on and by adjusting the ratio of on time t.sub.ON to off time t.sub.OFF, the LED channels 170 may appear to independently dim or brighten in response to corresponding output signals on outputs 370.sub.1 through 370.sub.N from controller 125C. In addition, controller 125C may also increase or decrease the brightness, such as average brightness, of LED strings 170 as a group by providing signals to driver 115 adapted to cause driver 115 to increase or decrease the amount of power or current provided to primary 105.
(77) In another exemplary embodiment, a first load comprises at least one first LED 170.sub.1 having a first emission spectrum (such as an emission spectrum in the red, green, blue, white, yellow, amber, or other visible wavelengths), and a second load comprises at least one LED 170.sub.2 having a second emission spectrum. For example, a first LED may provide emission in the red visible spectrum, a second LED may provide emission in the green visible spectrum, and a third LED may provide emission in the blue visible spectrum, and so on. In such an exemplary embodiment, the controller 125C may be further adapted to regulate an output spectrum by regulating the first bypass circuit, or the second bypass circuit, or a third bypass circuit, such as by dimming or bypassing a corresponding LED string, to modify the overall emitted light spectrum, such as to increase or decrease corresponding portions of red, green, or blue emitted light, for example. This type of control may be utilized to provide any type of architectural or other ambient lighting effect.
(78)
(79) In step 720, a primary power or current level is determined, for example by controller 125C. The primary power or current level may, for example, be determined as a function of a general power setting such as average desired brightness, emission spectra (desired output color), which also may be averaged over LED channels 170 or total selected or predetermined output power for power modules 140C.sub.1, 140C.sub.2, through 140C.sub.N. In step 725, the determined primary power or current level is utilized to provide power to transformer primary 105.
(80) In step 730, a pulse width or a pulse on time t.sub.ON and off time t.sub.OFF are determined for each channel. The value of t.sub.ON and t.sub.OFF may be different for each channel. In an exemplary embodiment, t.sub.ON may be substantially proportional to the selected or predetermined brightness of the corresponding channel. The off time t.sub.OFF may be determined utilizing any of various methods such as determining t.sub.OFF to be substantially proportional to a predetermined pulse interval (i.e. the period of time between the start of two adjacent pulses) minus t.sub.ON. A pulse interval may, for example, be predetermined such that the action of LEDs 170 turning on and off is substantially imperceptible to the human eye.
(81) The perceived brightness of each channel may be substantially proportional to both the corresponding pulse width determined in step 730 for the corresponding channel and the primary power or current level determined in step 720. In an exemplary embodiment, each LED channel is turned on in step 735 for an on time t.sub.ON and turned off in step 740 for an off time t.sub.OFF. When the method is to continue, step 745, the method returns to step 715, and otherwise may end, return step 750.
(82)
(83) Power modules 140D.sub.1, 140D.sub.2, through 140D.sub.N comprise transformer secondaries 150.sub.1, 150.sub.2, through 150.sub.N, first diodes 410.sub.1, 410.sub.2, through 410.sub.N, second diodes 415.sub.1, 415.sub.2, through 415.sub.N, first inductors 430.sub.1, 430.sub.2, through 430.sub.N, and second inductors 435.sub.1, 435.sub.2, through 435.sub.N, respectively. Bypass circuits 145D.sub.1, 145D.sub.2, through 145D.sub.N comprise third diodes 420.sub.1, 420.sub.2, through 420.sub.N, diacs 180.sub.1, 180.sub.2, through 180.sub.N, and switches 275.sub.1, 275.sub.2, through 275.sub.N, respectively.
(84) Operation of bypass circuits 145D and power modules 140D in an exemplary embodiment is described utilizing, as an example, a first bypass circuit 145D.sub.1, a first power module 140D.sub.1, and a first LED string 170.sub.1. Operation of other bypass circuits 145D.sub.2 through 145D.sub.N and power modules 140D.sub.2 through 140D.sub.N is similar. Secondary 150.sub.1 provides power to a rectifier circuit, configured as a current doubler and comprising first diode 410.sub.1, second diode 415.sub.1, first inductor 430.sub.1, and second inductor 435.sub.1. The first power module 140D.sub.1 provides power to LED string 170.sub.1.
(85) Bypass circuit 145D.sub.1 comprises third diode 420.sub.1, diac 180.sub.1, and switch 275.sub.1. Third diode 420.sub.1 provides current bypass for power module 140D.sub.1, while diac 180.sub.1 and switch 275.sub.1 provide current bypass for LED string 170.sub.1. If LED string 170.sub.1 becomes an open or relatively high impedance circuit, a voltage level across diac 180.sub.1 may increase to a value greater than or substantially equal to a predetermined threshold, causing diac 180.sub.1 to trip and bypass (i.e., shunt current around) the LED string 170.sub.1. Third diode 420.sub.1 is coupled in parallel with power module 140D.sub.1 and may shunt current around power module 140D.sub.1 to LED string 170.sub.1 and to other channels in the event of a fault in power module 140D.sub.1. That LED string 170.sub.1 may continue to receive power despite a fault in the corresponding power module 140D.sub.1 is a significant advantage of exemplary embodiments of the present invention over prior art power converters. Third diode 420.sub.1 may be considered optional because, in various exemplary embodiments, other components in the rectifier circuit may shunt power past power module 140D.sub.1 in the event of a fault in power module 140D.sub.1. For example, if secondary 150.sub.1 becomes an open circuit, diode 410.sub.1 and inductor 430.sub.1 may provide a current path through power module 140D.sub.1. Third diode 420.sub.1, placed across a power module, may also be utilized in conjunction with alternate embodiments such as those illustrated in
(86) Switch 275.sub.1, placed in parallel with LED string 170.sub.1, may serve as a current shunt to substantially stop current flow through LED string 170.sub.1 and set LED string 170.sub.1 to an off state in response to a control signal on output 370.sub.1 of controller 125D, as previously discussed. Similarly, controller 125D may independently control LED strings 170.sub.2 through 170.sub.N by providing output signals (on outputs 370.sub.2 through 370.sub.N) to the respective gates of switches 275.sub.2 through 275.sub.N. Such control may be separate and independent or may be coordinated, such as for brightness control or architectural lighting effects. As with the exemplary embodiments illustrated in
(87)
(88) The controller 125 (including variations 125A, 125B, 125C, and 125D) may be any type of controller or processor, and may be embodied as any type of digital logic or analog circuitry or combination thereof or any other circuitry adapted to perform the functionality discussed herein. The controller (including variations) may have other or additional outputs and inputs to those described and illustrated herein, and all such variations are considered equivalent and within the scope of the present invention. Similarly, not all inputs and outputs may be utilized for a given embodiment of the present invention. As the term controller, processor or control logic block is used herein, a controller or processor or control logic block may include use of a single integrated circuit (IC), or may include use of a plurality of integrated circuits or other components connected, arranged or grouped together, such as controllers, microprocessors, digital signal processors (DSPs), parallel processors, multiple core processors, custom ICs, application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), adaptive computing ICs, associated memory (such as RAM, DRAM and ROM), discrete components, and other ICs and components. As a consequence, as used herein, the term controller, processor or control logic block should be understood to equivalently mean and include a single IC, or arrangement of custom ICs, ASICs, processors, microprocessors, controllers, FPGAs, adaptive computing ICs, or some other grouping of integrated circuits or electronic components which perform the functions discussed herein, with any associated memory, such as microprocessor memory or additional RAM, DRAM, SDRAM, SRAM, MRAM, ROM, PROM, FLASH, EPROM, or E.sup.2PROM. A controller or processor (such as controller 125, 125A, 125B, 125C, and 125D), with its associated memory, may be adapted or configured (via programming, FPGA interconnection, or hard-wiring) to perform the methodology of the invention, as discussed above and below. For example, the methodology may be programmed and stored, in a controller 125 and other equivalent components, as a set of program instructions or other code (or equivalent configuration or other program) for subsequent execution when the controller or processor is operative (i.e., powered on and functioning). Equivalently, the controller may be implemented in whole or part as FPGAs, digital logic such as registers and gates, custom ICs and/or ASICs, the FPGAs, digital logic such as registers and gates, custom ICs or ASICs, also may be designed, configured and/or hard-wired to implement the methodology of the invention. For example, the controller or processor may be implemented as an arrangement of controllers, microcontrollers, microprocessors, state machines, DSPs and/or ASICs, which are respectively programmed, designed, adapted or configured to implement the methodology of the invention.
(89) The controller 125 (and variations) may comprise memory, which may include a data repository (or database) and may be embodied in any number of forms, including within any computer or other machine-readable data storage medium, memory device or other storage or communication device for storage or communication of information, currently known or which becomes available in the future, including, but not limited to, a memory integrated circuit (IC), or memory portion of an integrated circuit (such as the resident memory within a controller or processor IC), whether volatile or non-volatile, whether removable or non-removable, including without limitation RAM, FLASH, DRAM, SDRAM, SRAM, MRAM, FeRAM, ROM, EPROM, or E.sup.2PROM, or any other form of memory device, such as a magnetic hard drive, an optical drive, a magnetic disk or tape drive, a hard disk drive, other machine-readable storage or memory media such as a floppy disk, a CDROM, a CD-RW, digital versatile disk (DVD) or other optical memory, or any other type of memory, storage medium, or data storage apparatus or circuit, which is known or which becomes known, depending upon the selected embodiment. In addition, such computer readable media includes any form of communication media, which embodies computer readable instructions, data structures, program modules or other data in a data signal or modulated signal. The memory may be adapted to store various look up tables, parameters, coefficients, other information and data, programs or instructions (of the software of the present invention), and other types of tables such as database tables.
(90) As indicated above, the controller may be programmed, using software and data structures, for example, to perform the methodology of the present disclosure. As a consequence, systems and methods may be embodied as software, which provides such programming or other instructions, such as a set of instructions and/or metadata embodied within a computer readable medium, discussed above. In addition, metadata may also be utilized to define the various data structures of a look up table or a database. Such software may be in the form of source or object code, by way of example and without limitation. Source code further may be compiled into some form of instructions or object code (including assembly language instructions or configuration information). The software, source code or metadata may be embodied as any type of code, such as C, C++, C#, SystemC, LISA, XML, Java, ECMAScript, JScript, Brew, SQL and its variations (e.g., SQL 99 or proprietary versions of SQL), DB2, Oracle, or any other type of programming language which performs the functionality discussed herein, including various hardware definition or hardware modeling languages (e.g., Verilog, VHDL, RTL) and resulting database files (e.g., GDSII). As a consequence, a construct, program construct, software construct or software, as used equivalently herein, means and refers to any programming language, of any kind, with any syntax or signatures, which provides or can be interpreted to provide the associated functionality or methodology specified (when instantiated or loaded into a processor or computer and executed, including the controller 125, for example).
(91) The software, metadata, or other source code and any resulting bit file (object code, database, or look up table) may be embodied within any tangible storage medium, such as any of the computer or other machine-readable data storage media, as computer-readable instructions, data structures, program modules or other data, such as discussed above, e.g., a floppy disk, a CDROM, a CD-RW, a DVD, a magnetic hard drive, an optical drive, or any other type of data storage apparatus or medium, as mentioned above.
(92) In some exemplary embodiments, control circuitry may be implemented using digital circuitry such as logic gates, memory registers, a digital processor such as a microprocessor or digital signal processor, I/O devices, memory, analog-to-digital converters, digital-to-analog converters, FPGAs, etc. In other exemplary embodiments, this control circuitry may be implemented in analog circuitry such as amplifiers, resistors, integrators, multipliers, error amplifiers, operational amplifiers, etc. For example, one or more parameters stored in digital memory may, in an analog implementation, be encoded as the value of a resistor or capacitor, the voltage of a zener diode or resistive voltage divider, or otherwise designed into a circuit. It is to be understood that embodiments illustrated as analog circuitry may alternatively be implemented with digital circuitry or with a mixture of analog and digital circuitry and that embodiments illustrated as digital circuitry may alternatively be implemented with analog circuitry or with a mixture of analog and digital circuitry within the scope of the present disclosure.
(93) Controller 125 executes methods of control as described in the exemplary embodiments. Methods of implementing, in software and/or logic, a digital form of the embodiments shown herein is well known by those skilled in the art. The controller 125 may comprise any type of digital or sequential logic for executing the methodologies and performing selected operations as discussed above and as further described below. For example, the controller 125 may be implemented as one or more finite state machines, various comparators, integrators, operational amplifiers, digital logic blocks, configurable logic blocks, or may be implemented to utilize an instruction set, and so on, as described herein.
(94) Switches illustrated and described herein, such as fuses 190 and switches shown in the Figures, are illustrated as SCRs, diacs, MOSFETs, diodes, fuses, etc., and may be implemented as any type of power switch, in addition to those illustrated, including without limitation a thyristor such as a diac, sidac, SCR, triac, or quadrac, a bipolar junction transistor, an insulated-gate bipolar transistor, a N-channel or P-channel MOSFET, a relay or other mechanical switch, a vacuum tube, various enhancement or depletion mode FETs, fuses, diodes, etc. A plurality of power switches may be utilized in the circuitry.
(95) Numerous advantages of the exemplary embodiments, for providing power to loads such as LEDs, are readily apparent. The exemplary embodiments provide power conversion for multiple channels of LEDs at comparatively low voltage levels. The exemplary embodiments provide an overall reduction in size, weight, and cost of the power converter by sharing components across channels. The exemplary embodiments provide increased reliability by providing continued operation of one or more channels in the event of faults. The exemplary embodiments further provide stable output power levels and compensate for factors such as temperature, component aging, and manufacturing tolerances. Exemplary embodiments provide independent control over individual channels such as dimming, emission spectra, and turning channels on or off.
(96) Although various methods, systems and apparatuses have been described with respect to specific embodiments thereof, these embodiments are merely illustrative and should not be considered restrictive in any manner. In the description herein, numerous specific details are provided, such as examples of electronic components, electronic and structural connections, materials, and structural variations, to provide a thorough understanding of embodiments disclosed. One skilled in the relevant art will recognize, however, that an embodiment can be practiced without one or more of the specific details, or with other apparatus, systems, assemblies, components, materials, parts, etc. In other instances, well-known structures, materials, or operations are not specifically shown or described in detail to avoid obscuring aspects of embodiments disclosed herein. In addition, the various Figures are not drawn to scale and should not be regarded as limiting.
(97) Reference throughout this specification to one embodiment, an embodiment, or a specific embodiment means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment and not necessarily in all embodiments, and further, are not necessarily referring to the same embodiment. Furthermore, the particular features, structures, or characteristics of any specific embodiment may be combined in any suitable manner and in any suitable combination with one or more other embodiments, including the use of selected features without corresponding use of other features. In addition, many modifications may be made to adapt a particular application, situation or material to the essential scope and spirit of the claimed subject matter. It is to be understood that other variations and modifications of the embodiments described and illustrated herein are possible in light of the teachings herein and are to be considered part of the spirit and scope of the appended claims.
(98) It will also be appreciated that one or more of the elements depicted in the Figures can be implemented in a more separate or integrated manner, or even removed or rendered inoperable in certain cases, as may be useful in accordance with a particular application. Integrally formed combinations of components are also within the scope of the claimed subject matter, particularly for embodiments in which a separation or combination of discrete components is unclear or indiscernible. In addition, use of the term coupled herein, including in its various forms such as coupling or couplable, means and includes any direct or indirect electrical, structural or magnetic coupling, connection or attachment, or adaptation or capability for such a direct or indirect electrical, structural or magnetic coupling, connection or attachment, including integrally formed components and components which are coupled via or through another component.
(99) As used herein for purposes of the claimed subject matter, the term LED and its plural form LEDs should be understood to include any electroluminescent diode or other type of carrier injection- or junction-based system which is capable of generating radiation in response to an electrical signal, including without limitation, various semiconductor- or carbon-based structures which emit light in response to a current or voltage, light emitting polymers, organic LEDs, and so on, including within the visible spectrum, or other spectra such as ultraviolet or infrared, of any bandwidth, or of any color or color temperature.
(100) Channels of LEDs may have the same or different numbers of LEDs. Channels of LEDs may be illustrated and described herein utilizing LED strings as exemplary embodiments, however it is to be understood that LED channels may comprise one or more LEDs in innumerable configurations such as a plurality of strings in series or parallel, arrays of LEDs, LEDs of various types and colors, and LEDs combined with other components such as diodes, resistors, fuses, positive temperature coefficient (PTC) fuses, sensors such as optical sensors or current sensors, switches, etc., any and all of which are considered equivalent and within the scope of the present disclosure. Although, in an exemplary embodiment, the power converter drives one or more LEDs, the converter may also be suitable for driving other linear and nonlinear loads such as computer or telephone equipment, lighting systems, radio transmitters or receivers, telephones, computer displays, motors, heaters, etc. Where reference is made herein to a load or group of LEDs, it is to be understood that a load (such as LEDs) may comprise a plurality of loads.
(101) In the foregoing description and in the Figures, sense resistors are shown in exemplary configurations and locations; however, those skilled in the art will recognize that other types and configurations of sensors may also be used and that sensors may be placed in other locations. Alternate sensor configurations and placements are within the scope of the present disclosure.
(102) It is to be understood in discussing fault modes that the terms short circuit and open circuit are used herein as examples of types of component failures. The term short circuit may include partial short circuit conditions where impedance or voltage drops to a level lower than normal (i.e., absent faults) operational level, such as below a predetermined threshold. The term open circuit may include partial open circuit conditions where impedance or voltage increases to a level higher than during normal operation, such as above another predetermined threshold.
(103) As used herein, the term DC denotes both fluctuating DC (such as is obtained from rectified AC), chopped DC, and constant voltage DC, such as is obtained from a battery, voltage regulator, or power filtered with a capacitor. As used herein, the term AC denotes any form of alternating current, such as single phase or multiphase, with any waveform (sinusoidal, sine squared, rectified sinusoidal, square, rectangular, triangular, sawtooth, irregular, etc.), and with any DC offset and may include any variation such as chopped or forward- or reverse-phase modulated alternating current, such as from a dimmer switch.
(104) In the foregoing description of illustrative embodiments and in attached figures where diodes are shown, it is to be understood that synchronous diodes or synchronous rectifiers (for example relays or MOSFETs or other transistors switched off and on by a control signal) or other types of diodes may be used in place of standard diodes within the scope of the present disclosure. Exemplary embodiments presented here typically generate positive voltages with respect to ground potential; however, the teachings of the present disclosure apply also to power converters that generate positive and/or negative voltages, where mixed or complementary topologies may be constructed, such as by reversing the polarity of semiconductors and other polarized components or by swapping positive and negative terminals on power modules, bypass circuits, loads, etc.
(105) Furthermore, any signal arrows in the drawings/Figures should be considered only exemplary, and not limiting, unless otherwise specifically noted. Combinations of components of steps will also be considered within the scope of the present disclosure, particularly where the ability to separate or combine is clear or foreseeable. The disjunctive term or, as used herein and throughout the claims that follow, is generally intended to mean and/or, having both conjunctive and disjunctive meanings (and is not confined to an exclusive or meaning), unless otherwise indicated. As used in the description herein and throughout the claims that follow, a, an, and the include plural references unless the context clearly dictates otherwise. Also as used in the description herein and throughout the claims that follow, the meaning of in includes in and on unless the context clearly dictates otherwise.
(106) The foregoing description of illustrated embodiments, including what is described in the summary or in the abstract, is not intended to be exhaustive or to limit the claimed subject matter to the precise forms disclosed herein. From the foregoing, it will be observed that numerous variations, modifications and substitutions are intended and may be effected without departing from the spirit and scope of the novel concepts described here. It is to be understood that no limitation with respect to the specific methods and apparatus illustrated herein is intended or should be inferred. It is, of course, intended to cover by the appended claims all such modifications as fall within the scope of the claims.