POWER DROOP COMPENSATION FOR DC POWER SOURCING EQUIPMENT

Abstract

A power droop handling device (400) for controlling DC electrical power delivery from an external power sourcing equipment (PSE, 402) to an external electrical load device (404) in response to the PSE receiving a predetermined maintain-power-signature pulse from the load device, wherein the power droop handling device comprises a droop sensor unit (406) configured to receive power-delivery information regarding DC electrical power delivery from the PSE to the load device and to provide a droop warning signal indicative of a power-droop condition, and a control unit (408) configured to output, in response to the droop warning signal, a maintain-operation signal to the PSE instructing the PSE to maintain the power delivery to the electrical load device for a predetermined time span, regardless of whether or not the maintain-power-signature pulse is detected during this time span.

Claims

1. A power droop handling device for controlling DC electrical power delivery from an external power sourcing equipment to an external electrical load device, the power being delivered in response to the power sourcing equipment receiving from the electrical load device a predetermined maintain-power-signature pulse that is repeated according to a repetition rule, the power droop handling device comprising: a droop sensor unit configured to receive power-delivery information regarding DC electrical power delivery from the external power sourcing equipment to the external electrical load device, and to provide, based on the received power-delivery information, a droop warning signal indicative of a power-droop condition defined by a power amount to be delivered from the power sourcing equipment to the load device falling below a predetermined power threshold value; and a control unit configured to receive the droop warning signal, and, in response to receiving the droop warning signal, to output a maintain-operation signal to the external power sourcing equipment, the maintain-operation signal instructing the power sourcing equipment to maintain the power delivery to the electrical load device for a predetermined time span, regardless of whether or not the maintain-power-signature pulse is detected during this time span.

2. The power droop handling device of claim 1, comprising a power sensor unit configured to be connected with the power sourcing equipment, to determine a power amount currently delivered from the power sourcing equipment to the load device and to provide to the droop sensor unit the power-delivery information as a power signal indicative of the power amount currently delivered from the power sourcing equipment to the load device.

3. The power droop handling device of claim 1, wherein the droop sensor unit further comprises a data analysis unit which is configured to receive the power-delivery information in the form of power control data that is exchanged or to be exchanged between the external power sourcing equipment and the external electrical load device, the power control data being indicative of an operational status or instruction regarding power delivery from the power-sourcing equipment to the electrical load device; and determine or forecast an occurrence of the power-droop condition based on the received power control data.

4. The power droop handling device of claim 1, wherein the maintain-operation signal is further indicative of an instruction to the power sourcing equipment to request the load device to provide the maintain-power-signature pulse with a an increased power.

5. A power sourcing equipment for delivering DC electrical power to at least one external electrical load device, in response to detecting a predetermined maintain-power-signature pulse from the electrical load device, the power sourcing equipment comprising: a power unit, configured to provide the DC electrical power; an interface unit comprising at least one connection port, which is connected with the power unit and configured to output the electrical power to the external electrical load device, and to receive the maintain-power-signature pulse from the electrical load device; at least one power droop handling device of claim 1, which is connected with the power unit for sensing the power amount delivered from the power sourcing equipment to the load device; and a power sourcing control unit, which is connected with the interface unit and which is configured to discontinue the power delivery to the electrical load device upon establishing a missing-pulse condition in which a respective maintain-power-signature pulse expected according to the repetition rule has not been received, and upon additionally receiving the maintain-operation signal from the power droop handling device under the missing-pulse condition, to temporarily maintain the power delivery to the electrical load device for a predetermined time span.

6. The power sourcing equipment of claim 5, wherein the power sourcing control unit is configured, upon receiving the maintain-operation signal from the power droop handling device, to pause a detection of the maintain-power-signature pulse for the predetermined time span

7. The power sourcing equipment of claim 5, wherein the sourcing control unit is configured, upon receiving the maintain-operation signal from the power droop handling device, to disregard any detected maintain-power-signature pulse for the predetermined time span.

8. The power sourcing equipment of claim 5, wherein the power sourcing control unit is configured to return to normal power delivery upon establishing that the missing-pulse condition has ended.

9. The power sourcing equipment of claim 5, wherein the power sourcing control unit is configured, in case a missing-pulse condition ends before the time span has lapsed, to initialize a second time span upon establishing a reoccurrence of the missing-pulse condition during the time span.

10. The power sourcing equipment of claim 5, wherein the power sourcing control unit further comprises a timing unit, which is configured to determine and store a duration of an established missing-pulse condition, and to determine an extension of the time span in dependence on the stored duration.

11. The power sourcing equipment of claim 10, wherein the timing unit is further configured to initialize monitoring the time span upon receiving the maintain-operation-signal; stop monitoring the time span upon establishing that the missing-pulse condition has ended before the time span has lapsed; discontinue the power delivery to the electrical load device when the time span has lapsed without discontinuation of the missing-pulse condition.

12. The power sourcing equipment of claim 5, comprising the power droop handling device as an internal unit within a housing of the power sourcing equipment.

13. An electrical arrangement comprising a power sourcing equipment according to claim 5, wherein the interface unit has at least two connection ports; a power droop handling device that is connected to the power sourcing equipment through a first connection port of the at least two connection ports; and an electrical load device that is connected to the power sourcing equipment through a second connection port of the at least two connection ports.

14. A droop handling method for controlling DC electrical power delivery from an external power sourcing equipment to an external electrical load device, the power being delivered in response to the power sourcing equipment receiving from the electrical load device a predetermined maintain-power-signature pulse that is repeated according to a repetition rule, the droop handling method comprising: receiving power-delivery information regarding DC electrical power delivery from the external power sourcing equipment to the external electrical load device, providing, based on the received power-delivery information, a droop warning signal indicative of a power-droop condition defined by a power amount to be delivered from the power sourcing equipment to the load device falling below a predetermined power threshold value; in response to the droop warning signal, providing a maintain-operation signal to the external power sourcing equipment, the maintain-operation signal instructing the power sourcing equipment to maintain the power delivery to the electrical load device for a predetermined time span, regardless of whether or not the maintain-power-signature pulse is detected during this time span.

15. A method for operating a power sourcing equipment in delivering DC electrical power to at least one external electrical load device in response to detecting a predetermined maintain-power-signature pulse from the electrical load device, the method comprising: providing the DC electrical power to the electrical load device; receiving the maintain-power-signature pulse from the electrical load device; performing a droop handling method according to claim 14; upon receiving the maintain-operation signal during performance of the droop handling method of claim 14 under a missing-pulse condition, in which a respective maintain-power-signature pulse expected according to the repetition rule has not been received, temporarily maintaining the power delivery to the electrical load device for a predetermined time span; and discontinuing the power delivery to the electrical load device upon establishing that the missing-pulse condition continues after the predetermined time span has lapsed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In the following drawings:

[0055] FIG. 1 and FIG. 2 show simplified circuit diagrams of an electrical load device,

[0056] FIG. 3 shows a simulation showing the effect of a power droop,

[0057] FIG. 4 shows a block diagram of an embodiment of a power droop handling device connected to an external power sourcing equipment and to an external electrical load device,

[0058] FIG. 5 shows a block diagram of an embodiment of a power sourcing equipment connected to electrical load devices,

[0059] FIG. 6 shows a block diagram of another embodiment of a power sourcing equipment connected to electrical load devices,

[0060] FIG. 7 shows a flow diagram of an embodiment of a droop handling method, and

[0061] FIG. 8 shows a flow diagram of an embodiment of a method for controlling DC electrical power delivery

DETAILED DESCRIPTION OF EMBODIMENTS

[0062] In powering systems, such as but not limited to, Power over Ethernet, where it is mandatory to remove electrical power if an electrical load device is unplugged from the power supply device/power sourcing equipment to avoid voltages being present at an open connector, a strategy commonly used is to configure the power sourcing equipment (PSE) to detect a maintain-power-signature pulse which is repeated according to a repetition rule. The detection of the expected MPS pulses is interpreted by the PSE as a sign that the electrical load device is connected to the system.

[0063] Following the example of Power over Ethernet, IEEE Standard 802.3-2005 section 33.2.10 sets the requirements for maintain-power-signature pulses. According to the IEEE Standard, as of 2015, power sourcing equipment must monitor a power port that is powered up for the presence of a MPS. The MPS has different power modes. For some electrical load devices, the MPS is defined to be 10 mA. This current is called IHold. This figure puts the lower bound power consumption (i.e. the power mode) at least on 50V*10 mA=500 mW. It was recognized that this lower bound limit was too high to achieve low standby, hence the standard also has the provision to duty cycle this current. The rule is that the IHold current only must be present for 75 ms out of every 325 ms period. This reduces the lower bound power consumption (i.e. the power mode) to approximately 115 mW. The 802.3bt amendment introduces two new types of electrical loads, namely Type 3 & Type 4, which are required to show the MPS for 7 ms out of every 300 ms period. When the MPS is absent, the PSE must discontinue supplying power to the power port.

[0064] In FIG. 1 and FIG. 2 simplified electrical load device circuit diagrams are shown. In FIG. 1 a maintain-power-signature (MPS) pulse generator 102 is positioned between a powered device (PD) interface comprising a hot swap FET 104 and a power sourcing equipment (PSE, not shown). In FIG. 2 an MPS pulse generator 202 is positioned between a PD interface comprising a hot swap FET 204 and a load 205.

[0065] The diagrams illustrate the underlying problem, namely the existence of undesirable current paths 106, 206 where the MPS is provided by the bulk capacitors 108 and 208, whereas in the desirable current paths 110, 210 the MPS is drawn from the PSE.

[0066] When the MPS, or another current based on a minimum current requirement, is at least partially not drawn from the power supply (e.g. PSE) then, when measured at the power supply side of the power distribution system (i.e. at the PSE), the minimum current requirement might not be met. Such a requirement is set to allow, for example a PSE, to detect if an electrical load device becomes unplugged from the cable. In such an event, the PSE must quickly remove the voltage to avoid voltages to be present on an open connector. In other words, the MPS is the minimum power signature an electrical load must draw from the power source to ensure that it remains powered. Short pulses such as the ones allowed for type 3 and 4 systems (required to show the MPS for 7 ms out of every 300 ms) are hard to detect on the PSE side and can even be masked in droop situations. Due to droop effects in the PSE power supply, the supplied voltage gets reduced and this mostly causes the rectifier diodes 112, 212 in the PD to isolate. In the undesirable current paths 106 and 206, the MPS pulse is provided the respective bulk capacitor 108 and 208. In the desirable current paths 110 and 210 the MPS current is drawn from the PSE. As reflected in the simplified circuits shown in FIG. 1 and FIG. 2, if the voltages at the input capacitors 114, 214 are higher than the PSE voltages (the reason for this being, for example, a power droop), the rectifier diodes 122, 124 will stop conducting and no MPS can flow into the PSE.

[0067] Such a power droop is shown in the simulation of FIG. 3. The PSE voltage 302 is shown, it transitions from 57V to 50V and back to 57V. Also shown is the voltage 304 over the bulk capacitor (e.g. 108, 208). The MPS current on the PD side is shown 306 as well as the current as observed by the PSE 308. While the pulses in 308 are filtered and reduced in amplitude during the period of high PSE voltage, they completely disappear after the voltage has dropped to 50V and only reappear later once the bulk capacitor has discharged sufficiently. The absence of detected MPS pulses caused by the voltage droop and not intentionally, may lead cause the PD to be accidentally turned off. Time span 310 approximately indicates the duration of the power droop, whereas time span 312 approximately indicates the time during which the MPS pulse 308 is not detected at the PSE. This time span 312 depends on the amount of voltage loss during the droop and on the capacitance value of the bulk capacitor.

[0068] FIG. 4, also in reference to FIG. 3, shows a power droop handling device 400 for controlling DC electrical power delivery from an external power sourcing equipment 402 to an external electrical load device 404. The power 302 is delivered in response to the power sourcing equipment receiving from the electrical load device a predetermined maintain-power-signature pulse 308 that is repeated according to a repetition rule. The power droop handling device comprises a droop sensor unit 406 configured to receive power-delivery information regarding DC electrical power delivery from the external power sourcing equipment to the external electrical load device, and to provide, based on the received power-delivery information, a droop warning signal indicative of a power-droop condition. A power-droop condition takes place when a certain power amount delivered or to be delivered from the power sourcing equipment to the load device falls or is going to fall below a predetermined power threshold value. Additionally it comprises a control unit 408 configured to receive the droop warning signal, and, in response to receiving the droop warning signal, to output a maintain-operation signal to the external power sourcing equipment. The maintain-operation signal instructs the power sourcing equipment to maintain the power delivery to the electrical load device for a predetermined time span, regardless of whether or not the maintain-power-signature pulse is detected during this time span. The time span is preferably longer than the time span 312 to avoid undesired discontinuation of the power supply.

[0069] FIG. 5 represents a block diagram of a power sourcing equipment 500 for delivering DC electrical power to a plurality of external electrical load devices 404.1, 404.2, 404.n in response to detecting a predetermined maintain-power-signature pulse (e.g. signal 308) from each respective electrical load device. The PSE comprises a power unit 502, configured to provide the DC electrical power to the load device. It also comprises an interface unit 504 comprising a plurality of connection ports 506.1, 506.2, 506.n. The interface unit is connected with the power unit and configured to output the electrical power to the external electrical load device, and to receive the maintain-power-signature pulse from the electrical load device. The connection between the PSE and an electrical load device is performed through a patch cable configured to transmit electrical power and operational instructions (i.e. power supply and connectivity data). The PSE further comprises a power droop handling device 508 according to this invention, which is connected with the power unit for sensing the power amount delivered from the power sourcing equipment to the load device and to the interface unit to receive power control data. The PSE also comprises a power sourcing control unit 510, which is connected with the interface unit and which is configured to discontinue the power delivery to the electrical load device upon establishing a missing-pulse condition in which a respective maintain-power-signature pulse expected according to the repetition rule has not been received, and upon additionally receiving the maintain-operation signal from the power droop handling device under the missing-pulse condition, to temporarily maintain the power delivery to the electrical load device for a predetermined time span.

[0070] In this example, the power sourcing control unit 510 detects the maintain-power-signature pulses from the plurality of load devices. The load devices are powered by the power unit 502, which is configured to provide the DC electrical power. The power droop handling device 508 is here configured to receive power-delivery information both in terms indicative of the power amount delivered from the PSE to the electrical load device and of an operational status or instruction regarding the power delivery, i.e. in form of power control data which is exchanged between the PSE and the load devices. The power droop handling device is therefore configured to detect a droop condition based on the amount of power being currently delivered to the electrical load devices and to forecast an imminent droop situation based on the actual power control data exchanged. For example, if due to an instability in the power unit, the power provided falls below a predetermined power threshold value, the droop handling device will output the maintain-operation signal to the power sourcing sensor unit, which would otherwise, upon establishing a missing-pulse condition, undesirably discontinue the power delivery to the electrical load device. The power droop handling device 508 is further configured to receive power control data exchanged between the PSE and the load devices. If the power droop handling device receives power control data from a plurality of load devices requesting to be switched on or otherwise to drastically change their operational status in a very short time span, it is configured to output the maintain-operation signal to the power sourcing unit, ensuring the delivery of power during a predetermined time span independently of the occurrence of a power droop situation.

[0071] FIG. 6 is a block diagram of another embodiment of a power sourcing equipment 600 comprising a power unit 502, an interface unit 504 with a plurality of connection ports 506.1 to 506.n. The PSE further comprises a power sourcing control unit 504. In this embodiment, a plurality of power droop handling devices 602.1, 602.n are connected to the connection ports 506.1 506.n and to the electrical load devices 404.1 and 404.n. The power droop handling devices receive through the connection port power delivery information in form of the power amount currently delivered to the load device which is connected to it. It also receives power delivery information in form of power control data that is exchanges or to be exchanged between the PSE and the electrical load device. The power droop handling devices are also connected with the power sourcing control unit 604 through the interface unit. The power sourcing control unit is able to discontinue or to maintain the power delivery according to the detection of the maintain-power-signature pulse from the electrical load devices (404.1, 404.n) and the maintain-operation signal from the respective power droop handling device (602.1, 602.n). The devices 404.1 to 404.n can be detached networked electrical consumers like routers, switches, printer spoolers, webcams, luminaries, fans, sensors, user interface devices such displays or switch panels, etc.

[0072] FIG. 7 represents a flow diagram describing a droop handling method 700 for controlling DC electrical power delivery from an external power sourcing equipment to an external electrical load device, the power being delivered in response to the power sourcing equipment receiving from the electrical load device a predetermined maintain-power-signature pulse that is repeated according to a repetition rule. The droop handling method 700 comprises receiving, in a first step 702, power-delivery information regarding DC electrical power delivery from the external power sourcing equipment to the external electrical load device. It then provides, in a step 704 and based on the received power-delivery information, a droop warning signal indicative of a power-droop condition defined by a power amount to be delivered from the power sourcing equipment to the load device falling below a predetermined power threshold value. Finally, and in response to the droop warning signal, it provides in a step 706 a maintain-operation signal to the external power sourcing equipment, the maintain-operation signal instructing the power sourcing equipment to maintain the power delivery to the electrical load device for a predetermined time span, regardless of whether or not the maintain-power-signature pulse is detected during this time span.

[0073] FIG. 8 represents a flow diagram describing a method 800 for operating a power sourcing equipment in delivering DC electrical power to at least one external electrical load device in response to detecting a predetermined maintain-power-signature pulse from the electrical load device. The method 800 comprises providing in a first step 802 the DC electrical power to the electrical load device, receiving, in a step 804 the maintain-power-signature pulse from the electrical load device, performing, in a step 806, a droop handling method 700 and upon receiving, in a step 808, the maintain-operation signal during performance of the droop handling method 700 under a missing-pulse condition, in which a respective maintain-power-signature pulse expected according to the repetition rule has not been received, temporarily maintaining the power delivery to the electrical load device for a predetermined time span, the method 800 finally discontinues, in a step 810, the power delivery to the electrical load device upon establishing that the missing-pulse condition continues after the predetermined time span has lapsed.

[0074] In summary thus, a power droop handling device for controlling DC electrical power delivery from an external power sourcing equipment (PSE) to an external electrical load device in response to the PSE receiving a predetermined maintain-power-signature pulse from the load device comprises a droop sensor unit configured to receive power-delivery information regarding DC electrical power delivery from the PSE to the load device and to provide a droop warning signal indicative of a power-droop condition, and a control unit configured to output, in response to the droop warning signal, a maintain-operation signal to the PSE instructing the PSE to maintain the power delivery to the electrical load device for a predetermined time span, regardless of whether or not the maintain-power-signature pulse is detected during this time span. Corresponding features are provided in a power sourcing equipment, an electrical arrangement, a power droop handling method and in a method for operating a power sourcing equipment.

[0075] While the present invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims.

[0076] In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality.

[0077] A single step or other units may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

[0078] Any reference signs in the claims should not be construed as limiting the scope.