Electronic Power Distribution Arrangement for Fusing Capacitive Loads

Abstract

An electronic power distribution arrangement is disclosed which includes an electrical line for supplying power to a capacitive load; a first electronic switch for fusing the capacitive load; a second electronic switch for precharging the capacitive load prior to switching through the first electronic switch; a resistor connected in series with the second switchable current path of the second electronic switch, the series connection being connected in parallel with the first switchable current path of the first electronic switch; and a controller. The controller is adapted to turn on the second electronic switch to precharge the capacitive load before turning on the first electronic switch to supply power to the capacitive load, and to turn on the first electronic switch only when a voltage across the resistor reaches a threshold value.

Claims

1. An electronic power distribution arrangement for fusing a capacitive load, the arrangement comprising: an electrical line configured to supply power to a capacitive load; a first electronic switch configured to fuse the capacitive load, the first electronic switch comprising a first switchable current path arranged between a first load terminal and a second load terminal of the first electronic switch, and wherein the electrical line is connected to the first load terminal of the first electronic switch, and wherein the second load terminal of the first electronic switch is connected to a power supply to supply power to the capacitive load; a second electronic switch configured to precharge the capacitive load prior to switching through the first electronic switch, the second electronic switch comprising a second switchable current path arranged between a first load terminal and a second load terminal of the second electronic switch, a resistor connected in series with the second switchable current path of the second electronic switch, a controller configured to control the first electronic switch and the second electronic switch, wherein the series connection of the resistor to the second electronic switch is connected in parallel with the first switchable current path of the first electronic switch; and wherein the controller is configured to turn on the second electronic switch to precharge the capacitive load before turning on the first electronic switch to supply power to the capacitive load, and to turn on the first electronic switch only when a voltage across the resistor reaches a threshold value.

2. The arrangement according to claim 1, wherein the controller is further configured to precharge the capacitive load via an electrical bypass path from the power supply via the second switchable current path of the second electronic switch and the resistor to the capacitive load.

3. The arrangement according to claim 1, wherein the threshold value of the voltage across the resistor is above a voltage that occurs when the capacitive load is short-circuited across the resistor.

4. The arrangement according to claim 1, wherein the controller is further configured to disable a short-circuit disconnection of the first electronic switch when the first electronic switch is switched through.

5. The arrangement according to claim 4, wherein the short circuit shutdown of the first electronic switch is configured to be implemented in the controller and is configured to shut down the first electronic switch when a current through the first switchable current path of the first electronic switch reaches a shutdown threshold.

6. The arrangement according to claim 5, wherein the controller is configured to allow a current flow through the first switchable current path that is above the turn-off threshold when the first electronic switch is turned on.

7. The arrangement according to claim 1, wherein the controller is further configured to detect the voltage across the resistor after a predetermined time has elapsed from when the second electronic switch is turned on.

8. The arrangement according to claim 1, wherein the controller is adapted to maintain the first electronic switch in the off state when the voltage across the resistor remains below the threshold voltage after the predetermined time has elapsed.

9. The arrangement according to claim 1, wherein the threshold value of the voltage is below a start-up voltage of a voltage regulator of the capacitive load.

10. The arrangement according to claim 1, wherein at least one of the first electronic switch and the second electronic switch comprises a MOSFET transistor.

11. The arrangement according to claim 1, wherein the controller comprises an application specific integrated circuit, ASIC, in particular an electrical fuse ASIC, eFASic.

12. The arrangement according to claim 1, wherein the controller is configured to control a connection of an on-board power supply voltage to the capacitive load based on a control of the first electronic switch and the second electronic switch.

13. An electronic power distribution arrangement for fusing a capacitive load, the arrangement comprising: an electrical line configured to supply power to a capacitive load; an electronic switch configured to fuse the capacitive load, the electronic switch further comprising a switchable current path arranged between a first load terminal and a second load terminal, and the electrical line arranged connected to the first load terminal, and the second load terminal arranged connectable to a power supply to provide power to the capacitive load; and a controller configured to control the electronic switch, wherein the controller comprises a short-circuit shutdown circuit configured to turn off the electronic switch when a current through the switchable current path of the electronic switch reaches a shutdown threshold and to turn on the electronic switch again after the shutdown, thereby gradually charging the capacitive load, and wherein the controller is configured to sense a voltage across the capacitive load and to turn on the electronic switch when the sensed voltage across the capacitive load reaches a threshold value.

14. The arrangement according to claim 13, wherein the controller is further configured to switch on the electronic switch again after a predetermined time after the switch-off threshold of the electronic switch has been reached.

15. The arrangement according to claim 13, wherein the threshold value of the voltage at the capacitive load is above a voltage at the capacitive load which occurs in the event of a short circuit at the capacitive load.

16. The arrangement according to claim 13, wherein the controller is configured to deactivate the short-circuit disconnection of the electronic switch when the electronic switch is switched through.

17. A method of fusing a capacitive load connected via an electrical line to an electronic power distribution arrangement, the method comprising the steps of: arranging a first electronic switch having a first switchable current path between a first load terminal and a second load terminal of the first electronic switch, wherein the electrical line is connected to the first load terminal of the first electronic switch, and wherein the second load terminal of the first electronic switch is connected to a power supply so as to provide power to the capacitive load; arranging a second electronic switch having a second switchable current path between a first load terminal and a second load terminal of the second electronic switch; connecting a resistor in series with the second switchable current path of the second electronic switch, wherein the series connection of the resistor with the second electronic switch is connected in parallel with the first switchable current path of the first electronic switch; turning on the second electronic switch to precharge the capacitive load before turning on the first electronic switch; detecting a voltage across the resistor; and turning on the first electronic switch when the sensed voltage across the resistor reaches a threshold value.

18. A method of fusing a capacitive load connected via an electrical line to an electronic power distribution arrangement, the method comprising the steps of: arranging an electronic switch having a switchable current path between a first load terminal and a second load terminal, wherein the electrical line is connected to the first load terminal, and wherein the second load terminal is connected to the power supply to provide power to the capacitive load; gradually turning off the first electronic switch when a current through the switchable current path of the electronic switch reaches a turn-off threshold, and turning the electronic switch back on after the turn-off to gradually charge the capacitive load; detecting a voltage across the capacitive load; and switching through the electronic switch when the detected voltage at the capacitive load reaches a threshold value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0062] As used throughout the present disclosure, unless specifically stated otherwise, the term “or” encompasses all possible combinations, except where infeasible. For example, the expression “A or B” shall mean A alone, B alone, or A and B together. If it is stated that a component includes “A, B, or C”, then, unless specifically stated otherwise or infeasible, the component may include A, or B, or C, or A and B, or A and C, or B and C, or A and B and C. Expressions such as “at least one of” do not necessarily modify an entirety of the following list and do not necessarily modify each member of the list, such that “at least one of “A, B, and C” should be understood as including only one of A, only one of B, only one of C, or any combination of A, B, and C.

[0063] In the following detailed description, reference is made to the accompanying drawings, which form a part hereof and in which are shown, by way of illustration, specific embodiments in which the invention may be carried out. It is understood that other embodiments may be used, and structural or logical changes may be made without departing from the concept of the present invention. Therefore, the following detailed description is not to be understood in a limiting sense. It is further understood that the features of the various embodiments described herein may be combined, unless otherwise specifically indicated.

[0064] The aspects and embodiments are described with reference to the drawings, where like reference signs generally refer to like elements. In the following description, for purposes of explanation, numerous specific details are set forth to provide a thorough understanding of one or more aspects of the invention. However, it may be apparent to one skilled in the art that one or more aspects or embodiments may be embodied with a lesser degree of specific detail. In other instances, known structures and elements are shown in schematic form to facilitate description of one or more aspects or embodiments. It will be understood that other embodiments may be used, and structural or logical changes may be made without departing from the concept of the present invention.

[0065] FIG. 1 depicts a schematic diagram of the current curve 10 when a capacitive load is connected to the on-board power supply with repeated connection of the electronic switch.

[0066] The current trace 10 shows a number of successive current ramps over time. In this example, eight successive current ramps are shown. The number can also typically be several hundred or thousand.

[0067] During the current switching process, also known as “inrush”, in which the load is switched to the on-board power supply, the load is immediately switched back on again after it has been switched off via the fast short-circuit disconnection. With each switching operation, a partial charge is loaded onto the capacity of the load. Thus, the voltage across the capacitor of the load slowly increases.

[0068] Smart FETs typically have such a mechanism, in which the capacitance of the load is gradually charged by steady reconnection to the capacitive load.

[0069] The current rise i(t) in the capacitive load shown in FIG. 1 is limited by the inductance of the lines. If the switch-off threshold of the MOSFET driver is reached, the MOSFET switches off. This is followed by an immediate restart. With each i(t) triangle, charge is applied to the capacitance and the voltage increases in steps.

[0070] FIG. 2 depicts a schematic diagram of the voltage curve 20 at the capacitive load when the capacitive load is connected to the vehicle electrical system voltage with repeated connection of the electronic switch, without hard switching after a threshold voltage is reached.

[0071] FIG. 2 further depicts how the voltage u(t) at the capacitive load increases with each switch-on, as shown in FIG. 1. At about 4.5V to 5.5V, the μcontroller of the load starts to ramp up because the start voltage of the voltage regulator is exceeded. At this moment, however, the capacitance is loaded by the μcontroller and the load itself. As a consequence, the voltage of the capacitance decreases. This can again fall below the operating voltage of the controller. Thus, depending on the behavior of the load, an unstable start-up of the load including the μcontroller can occur. The unstable start-up (brown-in) can lead to an unspecified behavior of the load and thus to errors which are difficult to identify, and which can also only occur sporadically.

[0072] FIG. 3 depicts a schematic diagram of an electronic power distribution arrangement 100 according to a first aspect of the disclosure.

[0073] The electronic power distribution arrangement 100 is for fusing a capacitive load 170. The electronic power distribution arrangement 100 includes an electrical line 110 for supplying power to the capacitive load 170; a first electronic switch 120 for fusing the capacitive load 170; a second electronic switch 130 for precharging the capacitive load 170; a resistor 160; and a controller 140.

[0074] The first electronic switch 120 has a first switchable current path 125 between a first load terminal 121 and a second load terminal 122 of the first electronic switch 120. The electrical line 110 is connected to the first load terminal 121 of the first electronic switch 120. The second load terminal 122 of the first electronic switch 120 is connectable to a power supply 150, such as the electrical system of an electrified vehicle, to supply power to the capacitive load 170.

[0075] The second electronic switch 130 is for precharging the capacitive load 170 prior to a switching through of the first electronic switch 120. The second electronic switch 130 includes a second switchable current path 135 between a first load terminal 131 and a second load terminal 132 of the second electronic switch 130.

[0076] The resistor 160 is connected in series with the second switchable current path 135 of the second electronic switch 130. The series connection of the resistor 160 to the second electronic switch 130 is connected in parallel with the first switchable current path 125 of the first electronic switch 120.

[0077] The controller 140 is used to control the first electronic switch 120 and the second electronic switch 130.

[0078] The controller 140 is configured to turn on the second electronic switch 130 to precharge the capacitive load 170 before turning on the first electronic switch 120 to supply power to the capacitive load 170, and to turn on the first electronic switch 120 only when a voltage across the resistor 160 reaches a threshold value.

[0079] For example, the controller 140 is configured to precharge the capacitive load 170 via an electrical bypass path from the power supply 150 through the second switchable current path 135 of the second electronic switch 130 and the resistor 160 to the capacitive load 170.

[0080] For example, the threshold voltage across the resistor 160 is above a voltage that occurs when the capacitive load 170 shorts across the resistor 160.

[0081] For example, the controller 140 is configured to disable a short circuit shutdown of the first electronic switch 120 when the first electronic switch 120 is switched through.

[0082] The short-circuit shutdown of the first electronic switch 120 is implemented in the controller 140, for example, and may be configured to shut down the first electronic switch 120 when a current through the first switchable current path 125 of the first electronic switch 120 reaches a shutdown threshold, for example, in accordance with the current and voltage waveforms shown above with respect to FIGS. 1 and 2.

[0083] The controller 140 may be configured to allow a current flow through the first switchable current path 125 that is above the shutdown threshold when the first electronic switch 120 is switched on, such as shown in FIG. 5A.

[0084] The controller 140 may be configured to sense the voltage across the resistor 160 after a predetermined time has elapsed from when the second electronic switch 130 is turned on.

[0085] The controller 140 may be configured to maintain the first electronic switch 120 in the off state when the voltage across the resistor 160 remains below the voltage threshold after the predetermined time has elapsed.

[0086] For example, the threshold voltage may be below a start-up voltage of a voltage regulator of the capacitive load 170.

[0087] In one embodiment of the electronic power distribution arrangement 100 shown in more detail in FIG. 4, the first electronic switch 120 and/or the second electronic switch 130 comprises a MOSFET transistor 220, 230.

[0088] In one embodiment of the electronic power distribution arrangement 100, shown in more detail in FIG. 4, the controller 140 comprises an application specific integrated circuit (ASIC), such as an electrical fuse ASIC, also referred to herein as eFASic 240.

[0089] For example, the controller 140 is configured to control a connection of an on-board power supply voltage to the capacitive load 170 based on a control of the first electronic switch 120 and the second electronic switch 130.

[0090] FIG. 4 further depicts a schematic diagram of an embodiment of the electronic power distribution arrangement 200 according to the first aspect of the disclosure.

[0091] The electronic power distribution arrangement 200 is for fusing a capacitive load 170. The electronic power distribution arrangement 100 includes an electrical line 110 for supplying power to the capacitive load 170; a first electronic switch 120 for fusing the capacitive load 170, implemented in this embodiment as a first MOSFET 220; a second electronic switch 130 for precharging the capacitive load 170, implemented in this embodiment as a second MOSFET 230; a resistor 160; and a controller 140.

[0092] The first electronic switch 120 has a first switchable current path 225, e.g., n-channel or p-channel of the first MOSFET, between a first load terminal 121, e.g., drain or source, and a second load terminal 122, e.g., source or drain of the first MOSFET 220. The electrical line 110 is connected to the first load terminal 121 of the first MOSFET 220. The second load terminal 122 of the first MOSFET 220 is connectable to a power supply 150, such as the electrical system of an electrified vehicle, to supply power to the capacitive load 170.

[0093] The second MOSFET 230 is used to precharge the capacitive load 170 prior to a turn-on of the first MOSFET 220. The second MOSFET 230 includes a second switchable current path 235, e.g., n-channel or p-channel of the second MOSFET 230, between a first load terminal 131, e.g., drain or source, and a second load terminal 132, e.g., source or drain, of the second MOSFET 230.

[0094] The resistor 160 is connected in series with the second switchable current path 235 of the second MOSFET 230. The series connection of the resistor 160 to the second MOSFET 230 is connected in parallel with the first switchable current path 125 of the first MOSFET 220.

[0095] The controller 140 is used to control the first MOSFET 220 and the second MOSFET 230.

[0096] The controller 140 is configured to turn on the second MOSFET 230 to precharge the capacitive load 170 before turning on the first MOSFET 220 to power the capacitive load 170, and to turn on the first MOSFET 220 only when a voltage across the resistor 160 reaches a threshold value.

[0097] In this embodiment, the controller comprises an EFASic 242, i.e., an Electronic Fuse ASIC device, i.e., an ASIC (application specific integrated circuit) that implements an electronic fuse. The EFASic 242 can control the first MOSFET 220 and the second MOSFET 230 accordingly.

[0098] FIG. 5A depicts a schematic diagram of the current waveform 500a at the capacitive load when the capacitive load is successfully connected via the electronic power distribution arrangement 200 without a short circuit in the load branch.

[0099] In the representation of FIG. 5A, a current limited by a resistor 160 of e.g., 1.5 ohms flows to the capacitive load 170 for a short test period 501, e.g., 2 ms (see FIG. 4). The thermal load of the resistor remains low, because of the only short switching on. Also, the ballast resistor of the transistor 230 can be selected accordingly small, e.g., Rdson=10 mOhm. After this test period 501 of e.g., 2 ms, the voltage at the load 170 can be measured via the driver 241 of the eFASic 240. The measurement time 502 or measurement period 502 for measuring the voltage across the load is shown in the current trace 500a. If this voltage is above OV, there is no short circuit of the load or the load circuit. The voltage threshold 510 to be reached in this process should be selected to be below the start-up voltage of the voltage regulators of the load 170, e.g., 2V, as shown in the voltage trace 500b. When this voltage threshold 510 of, for example, 2V is reached, the fast short circuit shutdown of the driver 241 is disabled. Thereafter, i.e., for the time 503 or activation time 503, the switching MOSFET 220 is driven through by the driver 241.

[0100] FIG. 5B depicts a schematic representation of the voltage characteristic 500b at the capacitive load for a successful connection of the capacitive load 170 via the electronic power distribution arrangement 200 without a short circuit in the load branch. The voltage waveform 500b and the corresponding current waveform 500a show the behavior with the described inrush control for a successful connection without a short circuit in the load branch. By means of the bypass branch via transistor 230 and resistor 160 (see FIG. 4), the capacitance of load 170 can be charged to a value corresponding to a voltage above voltage threshold 510 of, for example, 2V, since there is no short circuit which would prevent such charging of load 170. Thus, the fast overcurrent shutdown by the controller 240 can be disabled and the controller 240 can enable hard turn-on. In the current waveform 500a, the inrush current, or make-up current, rises to a high value that would otherwise have been prevented by the overcurrent shutdown, and the voltage rises rapidly to the on-board voltage of, for example, 12V, as shown in the voltage waveform 500b.

[0101] FIG. 6A depicts a schematic diagram of the current waveform 600a at the capacitive load when the capacitive load is switched on via the electronic power distribution arrangement 200 for a short circuit in the load branch or impermissibly low impedance of the load branch.

[0102] As described above for FIG. 4A, for a short test period 501, e.g., 2 ms, a current limited via the resistor 160 of e.g., 1.5 Ohm flows to the capacitive load 170 (see FIG. 4). After this test period 501 of e.g., 2 ms, the voltage at the load 170 can be measured via the driver 241 of the eFASic 240. The measurement time 502 for measuring the voltage at the load is shown in the current waveform 500a. If this voltage is below the previously described voltage threshold 510 of, for example, 2V, as shown in the voltage trace 600b, the controller 240 detects a short circuit in the load branch or an impermissibly low impedance of the load branch. Thus, the fast short-circuit disabling of the driver 241 is not disabled, but remains on, and in the following time interval 503 or the activation time 503, the switching MOSFET 220 is not driven through by the driver 241 but remains in the disabling state. Since no voltage builds up in the load branch due to the bypass charge, the switching transistor 220 is not hard cycled.

[0103] FIG. 6B depicts a schematic diagram of the voltage waveform 600b across the capacitive load when the capacitive load is connected across the electronic power distribution arrangement 200 for a short circuit in the load leg or impermissibly low impedance of the load leg.

[0104] The voltage waveform 600b and the corresponding current waveform 600a show the behavior in the described inrush control for a short circuit in the load branch or an impermissibly low impedance of the load branch. By using the bypass branch via transistor 230 and resistor 160 (see FIG. 4), the capacitance of load 170 can be charged to a value corresponding to a voltage above the voltage threshold 510 of, for example, 2V. However, since there is a short circuit, such charging of load 170 is prevented. Thus, the fast overcurrent shutdown by the controller 240 remains activated and a hard turn-on is prevented, which would result in an unstable condition due to the short circuit. In the current waveform 600a, the current remains at zero in the following time interval 510, as does the voltage in the voltage waveform 600b plot.

[0105] FIG. 7 depicts a schematic diagram of an electronic power distribution arrangement 700 according to a second aspect of the disclosure.

[0106] The electronic power distribution arrangement 700 is for fusing a capacitive load 170 and includes an electrical line 110 for supplying power to the capacitive load 170; an electronic switch 120 for fusing the capacitive load 170; and a controller 140 for controlling the electronic switch 120.

[0107] The electronic switch 120 includes a switchable current path 125 between a first load terminal 121 and a second load terminal 122. The electrical line 110 is connected to the first load terminal 121 and the second load terminal 122 is connectable to a power supply 150 to provide power to the capacitive load 170.

[0108] The controller 140 includes a short-circuit shutdown circuit configured to turn off the electronic switch 120 when a current through the switchable current path 125 of the electronic switch 120 reaches a shutdown threshold. The controller 140 is further configured to turn the electronic switch 120 back on after it is turned off, thereby charging the capacitive load 170 in a stepwise manner, for example, as shown by the voltage waveform in FIG. 2.

[0109] The controller 140 is configured to sense a voltage across the capacitive load 170 and to turn on the electronic switch 120 when the sensed voltage across the capacitive load 170 reaches a threshold value.

[0110] The controller 140 may be configured to turn the electronic switch 120 back on after a predetermined time after the electronic switch 120 reaches the turn-off threshold, thereby allowing the load 170 to be charged in stages.

[0111] The threshold voltage across capacitive load 170 may be selected to be above a voltage across capacitive load 170 that occurs when a short circuit occurs across capacitive load 170.

[0112] The controller 140 may be configured to disable the short circuit disconnect of the electronic switch 120 when the electronic switch 120 is cycled.

[0113] The behavior of the voltage waveform at the capacitive load is shown in FIG. 2. The voltage at the capacitive load 170 is gradually charged until a threshold value of, for example, 2V is reached, as described above for FIGS. 5A, 5B, 6A, and 6B. If this threshold is held for a subsequent measurement interval, it is detected that the capacitive load is not shorted. In this case, the short-circuit disconnect may be disabled and the controller 140 may enable a hard turn-on as described above with respect to FIGS. 5A, 5B, 6A, and 6B.

[0114] However, if this threshold cannot be maintained in the subsequent measurement interval, it is detected that the capacitive load is short-circuited. In this case, the short-circuit disconnection remains activated and the control 140 prevents the short-circuited capacitive load from being switched on and thus instabilities in the voltage and current curve.

[0115] FIG. 8 depicts a schematic diagram of a method 800 for fusing a capacitive load according to a third aspect of the disclosure.

[0116] The method 800 is for fusing a capacitive load 170 connected via an electrical line 110 to an electronic power distribution arrangement 100, as described above with respect to FIGS. 3 and 4. Such an electronic power distribution arrangement 100 comprises: a first electronic switch 120 having a first switchable current path between a first load terminal and a second load terminal of the first electronic switch, wherein the electrical line is connected to the first terminal of the first electronic switch, and wherein the second terminal of the first electronic switch is connected to a power supply 150 to provide power to the capacitive load 170; a second electronic switch 130 having a second switchable current path between a first load terminal and a second load terminal of the second electronic switch; a resistor 160 connected in series with the second switchable current path 135 of the second electronic switch 130, wherein the series connection of the resistor 160 to the second electronic switch 130 is connected in parallel with the first switchable current path 125 of the first electronic switch 120.

[0117] The method 800 comprises the steps of: turning on 801 the second electronic switch 130 to precharge the capacitive load 120 prior to turning on the first electronic switch 120, such as described above with respect to FIGS. 3 and 4; sensing 802 a voltage across the resistor, such as described above with respect to FIGS. 3 and 4; and turning on 803 the first electronic switch 120 when the sensed voltage across the resistor reaches a threshold value, such as described above with respect to FIGS. 3 and 4.

[0118] FIG. 9 depicts a schematic diagram of a method 900 for fusing a capacitive load according to a fourth aspect of the disclosure.

[0119] The method 900 is for fusing a capacitive load 170 connected via an electrical line 110 to an electronic power distribution arrangement 700, such as described above with respect to FIG. 7. This electronic power distribution arrangement 700 comprises: an electronic switch 120 having a switchable current path 125 between a first load terminal and a second load terminal, wherein the electrical line is connected to the first load terminal, and wherein the second load terminal is connected to the power supply to provide power to the capacitive load 170 as described above with respect to FIG. 7.

[0120] The method 900 comprises the steps of: incrementally turning off 901 the first electronic switch when a current through the switchable current path of the electronic switch reaches a turn-off threshold, and turning the electronic switch back on after the turn-off to incrementally charge the capacitive load, such as described above with respect to FIG. 7; sensing 902 a voltage across the capacitive load, such as described above with respect to FIG. 7; and turning on 903 the electronic switch when the sensed voltage across the capacitive load reaches a threshold, such as described above with respect to FIG. 7.

[0121] Further, a computer program including program code for executing methods 800, 900 in a controller, e.g., a controller 140 of an electronic power distribution arrangement 100, 200, 700 as described above with respect to FIGS. 3, 4, and 7, may be provided.

[0122] Some preferred embodiments of apparatus according to the invention have been disclosed above. The invention is not limited to the solutions explained above, but the innovative solutions can be applied in different ways within the limits set by the claims.