Patent Application
20220376935
The invention relates to a power-over-Ethernet system, in particular to a power-good detection device to be used in the system. Specifically, the present invention relates to a power-over-Ethernet system having a plurality of power source devices, and a dynamic power-good detection device used in such a system.
In a wired communication network, supplying electrical power to devices on the network through network cables is already a mature technology. For example, the Power-over-Ethernet (PoE) system, which is powered by the wiring of the Ethernet, has gradually become popular, due to its low installation costs and centralized power supply and power backup, and safety management. Currently most PoE systems follow the IEEE 802.3af-2003 standard, which is incorporated herein for reference.
The PoE system provides a scalable function, with which in the initial operation stage, the system can automatically or manually configure its power distribution to the limited number of ports in the system. As time passes, the system can also detect the power supply state automatically, and increase or decrease the number of communication ports to receive electrical power, based on the detection results in the power supply state. Each communication port is connectable by one power consuming device, to receive electrical power from the system.
There are methods to increase power supply in a PoE system. One of the methods is to use multiple power source devices or multiple groups of power supply. The plurality of power source devices is connected to one or more control elements in parallel, which control element then supplies or distributes the electrical power of the plural power source devices to individual power consuming devices in connection with the communication ports. Power source devices of non-PoE systems can also supply power to the PoE system, to increase its supplied power, as long as the sum of the PoE power and the non-PoE power can be distributed to one or more ports via the Ethernet wire/cables.
In a power supply system wherein a plurality of power source device is used, an important technical problem to be overcome is how to immediately stop supplying power to particular power consuming devices, i.e., to particular ports, when one or more of the plural power source devices shuts down or reduces its output power, in order to avoid the occurrence of overloading on the remaining supplied power. Further, in order to prevent impacts on the remaining power consuming devices due to a shutdown or low-power status, it is also necessary to stop supplying power to the particular power consuming devices immediately or within a very short time, usually within 20 ms, preferably within 2 ms. If the total power consumption of all the connected power consuming devices cannot be reduced within that period, the total system would just shut down.
The power distribution controller 202 receives the power-good state signal PGD1, PGD2, PGD3 of the power-good detection device 201, and generates a power supply control signal, such as EN1-EN8, according to a predetermined power supply policy, followed by sending them to the communication ports Port N1 to Port N8. The power supply control signal is usually a switch signal used to turn ON or OFF the port switches of individual communication ports Port N1 to Port N8. The predetermined power supply policy is usually a preset rule that determines which of the communication ports Port N1 to Port N8 should be turned ON or OFF, when one or more power source device fails. Therefore, when the power-good detection device 201 determines that the power supply state of any of the power source devices 101, 102, 103 changes, for example, when a failure occurs or when a failure is repaired, it generates a power-good state signal PGD1, PGD2, and PGD3 to reflect the change. When the power distribution controller 202 receives the power-good state signal of the power-good detection device 201, it generates the power supply control signal EN1-EN8 and sent it to the communication ports Port N1 to Port N8, to change the ON/OFF state of the specific communication port.
As shown in the figure, the p power state signals PG1, PG2, and PG3 are generated by the branch circuits of the power source devices 101, 102, and 103. The detection points of the power state signals PG1, PG2, and PG3 are between the resistor pairs R11 and R12, R21 and R22, and R31 and R32, respectively. Therefore, the power state signals PG1, PG2, and PG3 are voltage signals and their values are:
PG1_V=HVpwr_1×[R12/(R11+R12)]
PG2_V=HVpwr_2×[R22/(R21+R22)]
PG3_V=HVpwr_3×(R32/(R31+R32)] (1)
wherein HVpwr is the voltage value of the power source devices 101, 102, 103.
According to the IEEE 802.3af/at standard, the regular voltage range for a PoE power source device is 57V to 44V.
Under this regulation, if the regular voltage of the power supplied by a power source device is set to 57V, the threshold (power-good) voltage value of PG1_V, PG2_V, and PG3_V should be about 1.390V, assuming that R11, R21 and R31 are 200KΩ, and R12, R22 and R32 are 5KΩ.
57V×[5KΩ/(5KΩ+200KΩ)]=1.390V
In this case, the power-good detection device 201 must set a power-good threshold value of 55V; when the voltage of the supplied power is below 55V, the power-good detection device 201 shall determine it as “failure,” because a power crash would take place, whenever the supplied voltage of a power source device is over 2V below its regular voltage value. To determine correctly, the power-good threshold value of the power state signals shall be set to 1.341V (55V ×[5KΩ/(5kΩ+200KΩ)]=1.341V). All power state signals with a detected voltage value equal to or higher than 1.341V would be determined as “power-good” (normal), whereby a signal (power-good state signal) representing a “power-good” state, such as 1, will be generated; otherwise, a signal representing a “failure” state, such as 0, will be generated. The combination of the determination of the power-good detection device 201 forms a power-good state signal.
However, this threshold value of 1.341V will cause a wrong decision, when the regular voltage of one of the power source devices is HVpwr=44V. As described above, the regular voltage of some PoE power source devices can be as low as 44V, in which case the PG1_V, PG2_V, and PG3_V values would be 1.073V (44V ×[5KΩ/(5KΩ+200KΩ)]=1.073V). For such power source devices, only when their supplied voltage is lower than 42V can the power-good detection device determine it is in a failure state. When this happens, the PG1_V, PG2_V, and PG3_V value would be 1.024V (42V×[5KΩ/(5KΩ+200KΩ)]=1.024V). However, because the power-good threshold value for power source device 101 was set to 1.341V, all the times power source device 101 will be determined as failure, no matter whether its supplied voltage falls into the regular range of voltage or not. The power-good detection device described above violates the IEEE 802.3af/at standard, which requires all PoE system to accept power source devices with a supplied voltage within the range of 57V to 44V.
Since the power-good state of the power source device cannot be detected correctly, the power supply policy cannot be adopted correctly to shutoff the switches of the communication port in time. As a result, the entire system will shut down.
The conventional art has proposed several solutions to this technical problem.
US patent publication US 2007/283173A1 disclosed a “system and method for detecting faults in an Ethernet power supply system”. In a PoE device whose operating range is set to 33 to 57 volts, using a booster diode with a 28-volt ride-through characteristic can produce an allowable error range of about 5 volts. Therefore, false alarms of power failure event detection can be prevented. A preferred embodiment selects booster diodes with different ride-through characteristics to combine between the ride-through voltage and the operating voltage range to provide a smaller or larger margin. In addition, diode circuits can also be used to achieve ride-through characteristics. The diode circuit includes a plurality of increasing diodes in series, a plurality of standard diodes or any combination thereof, so as to improve the accuracy of power failure detection.
U.S. Pat. No. 9,769,090 B2 disclosed “adjusting the current limit threshold based on the power demand of the powered device in the system to provide power through the communication link”. The invention controls the current limit according to the power demand of the PD. A current limit comparison table is provided to store the current limit thresholds corresponding to various PD power requirements. The threshold control circuit finds the corresponding limit value in the current limit comparison table based on the power required by the PD. The threshold control circuit can be applied to a system containing multiple power source devices.
From the observation in the above known technologies, it is known that the industry is in need of a novel multi-power Ethernet power supply system power-good detection device, which can dynamically set the power-good detection threshold according to the regular voltage value of the power source devices.
The objective of the present invention is to provide a novel power-good detection device for a PoE system with multiple power source devices, which can dynamically set the power-good threshold value according to the specifications of the power source devices.
Another objective of the present invention is to provide a novel power-good detection device for a PoE system with multiple power source devices, which can correctly detect power failures and take appropriate measures in time.
The objective of the present invention is also to provide a PoE system with multiple power source devices with the above-mentioned power-good detection device.
According to the first aspect of the present invention, a power-good detection device for a PoE system with multiple power source devices is provided. The power-good detection device comprises:
a plurality of power state signal input terminals, each terminal to be electrically connected with at least one power source device, to receive a power state signal from the power source device; wherein the power state signal is preferably a voltage signal;
a power state detection circuit connected to the plurality of power state signal input terminals for receiving the power state signal and determining whether the power supply state of the corresponding power source device is in normal state, according to the power state signal; and
a power-good threshold generation circuit comprising a control signal input terminal for generating a power-good threshold value according to a control signal received at the control signal input terminal, and for providing the power-good threshold value to the power state detection circuit; wherein the power-good threshold value signal is preferably a voltage signal;
wherein, the power state detection circuit determines a power-good state of a power source device according to a corresponding power-good threshold value and generates a power-good state signal representing the determined power-good state. In a preferred embodiment of the present invention, the power-good state signal comprises a signal representing a normal status of a power source device and a signal representing failure status of a power source device.
In a particular preferred embodiment of the present invention, the power-good threshold generation circuit may include a programmable register and a digital-to-analog converter. The programmable register can generate a second control signal representing a threshold level and provide it to the digital-to-analog converter so that the digital-to-analog converter generates a corresponding power-good threshold value. In this embodiment, the threshold level may be one of 2, 4, 8, or 16 levels, or one of a multiple of 2 levels.
In addition, the input signal of the control signal input terminal can be provided to the control signal input terminal via any communication channel Applicable examples include any communication channel used in the conventional PoE system with multiple power source devices and can be an IIC bus, an EEPROM bus and so on.
In a specific preferred embodiment of the present invention, the power-good detection device may further comprise an optional encoding device connected to the back end of the power state detection circuit for converting the power supply state signal generated by the power state detection circuit into a code. The encoding device may also comprise a de-bounce circuit, to eliminate jitter noise in the power supply state signal.
In some preferred embodiments of the present invention, the power state detection circuit may comprise at least one comparator for generating a power-good state signal representing a normal or failure state of the power source devices according to a comparison result of the power-good threshold value and the input power state signal.
According to a second aspect, the present invention provides a PoE system with multiple power source devices, which comprises:
a plurality of power source devices;
a plurality of communication ports, each communication port to be connected by a power consuming device to establish a signal and power connection with the power consuming device; each communication port having a port switch to control a power supplied to the port;
a control device in connection with the plurality of power source devices and the plurality of communication ports via a network cable, to convert electrical power supplied by the respective power source device to electrical power usable by the power consuming device connected to each communication port, and to generate a power consumption control signal, to control power supplied to the communication port from the plurality of power source devices;
wherein the control device comprises one of the power-good detection devices for a PoE system with multiple power source devices described above; wherein the power-good detection device generates a power-good threshold value according to an input control signal and determines a power-good state according to the power-good threshold value, to generate a power-good state signal representing a normal or failure state of the plurality of power source devices; and
a power supply distribution controller for generating the power consumption control signal according to the power-good state signal.
Other objectives, features, and advantages of the present invention can be appreciated clearly from the detailed description of the preferred embodiments by referring to the drawings. It should be noted that the description of the embodiments of the present invention is only intended to illustrate the main technical content, features, and effects of the present invention, and is not intended to limit the scope of the present invention. It is obvious for the skilled persons in this industry to derive various changes and applications based on the description of the embodiments. As long as they do not depart from the scope of the attached patent claims, they are all within the scope of the present invention.
In the following, several embodiments of the PoE system with multiple power source devices and its power-good detection device of the present invention will be described by referring to the drawings, in order to demonstrate the technology, features and effects of the present invention.
As shown in
The power state signal input assembly 410 provides a plurality of power status signal input terminals. The embodiment shown in
In a preferred embodiment of the present invention, the power state signal may be a voltage signal. A method to implement such a voltage signal is shown in
The power state signal input terminals 411, 412, and 413 are conventional electrical connectors. It can also be a fixed contact, used to connect the power source devices 101, 102, 103, and introduce the power state signals PG1, PG2, PG3 of the power source devices 101, 102, 103 to the power state detection circuit 430.
The power state detection circuit 430 is connected to the plurality of power state signal input terminals 411, 412, 413 for receiving the power state signal PG1, PG2, and PG3, whereby to determine whether each corresponding power source device 101, 102, 103 is in normal operation, based on the power state signals PG1, PG2, and PG3. The result of the determination is output in the form of a power supply status signal PGD1, PGD2, PGD3. As shown in
Of course, other method to determine the power-good state of a power source device according to a threshold and to generate the power-good state signal PGD1, PGD2, PGD3 can also be applied to the present invention.
In order to dynamically adjusting the power-good threshold value, the power-good threshold generation circuit 420 provides a control signal input terminal 421 for receiving a first control signal from the external. The input terminal 421 can be any electrical connector, or an electrical contact, connected to any applicable signal channel to receive the first control signal. The signal channel can be any communication channel used in the conventional PoE system with multiple power source devices, such as an IIC bus, an EEPROM bus, etc. Other communication channels can also be used to provide the first control signal.
In a particularly preferred embodiment of the present invention, the power-good threshold generation circuit 420 may include a programmable register 422 and a digital-to-analog converter 423. The programmable register 422 can generate a second control signal representing a threshold level corresponding to the first control signal, and provide it to the digital-to-analog converter 423, so that the digital-to-analog converter 423 generates a corresponding power-good threshold value.
For example, the threshold level can be one of 2, 4, 8 or 16 levels, or one of a multiple of 2 levels. If a 16-level threshold is to be generated, the programmable register 422 can be a 4-bit programmable register, storing a value of from 0-15, representing the 16-level threshold. After receiving the second control signal, the programmable register 422 sends a corresponding numerical signal to the digital-to-analog converter 423, which can be also a 4-bit digital-to-analog converter, and generates a corresponding voltage according to the value of the level.
In detail, as mentioned earlier, the IEEE PoE standard stipulates that the regular range of power supply voltage HVpwr is 44V-57V. Accordingly, in the example shown in
(1.390V−1.073V)/16=0.317V/16=19.8 mV
The digital-to-analog converter 423 generates a threshold voltage of 1.073V+(0.0198V*N), wherein N is the value of the first control signal, and provides it to the comparators 431, 432, and 433.
Therefore, as long as a correct first control signal is generated according to the distribution of the regular operating voltage range of the power source devices 101, 102, 103 and provided to the power-good threshold generation circuit 420, the power-good detection device 400 can correctly determine the power-good state of the power source devices.
In this embodiment, a voltage signal is used as the threshold signal, mainly because the power state signal PG1, PG2, and PG3 is also a voltage signal. In other embodiments of the present invention, the threshold signal is not limited to a voltage signal.
In a specific preferred embodiment of the present invention, the power-good detection device 400 may further include an encoding device 440, connected to the back end of the power state detection circuit 430, to compile the power supply state signal PGD1, PGD2, PGD3 of the power state detection circuit 430 into a code. For example, if the power supply status signal PGD1, PGD2, PGD3 is 1, 1, 0, the encoding device 440 can generate a corresponding code of 1100 or 0110, to act as a control signal of the power distribution controller 202 of the PoE system with multiple power source devices. The encoding device may also include a de-bounce circuit (not shown) to eliminate jitter noise in the power supply state signal.
As mentioned above, by simply providing a power-good threshold generation circuit 420, such as that comprising a programmable register 422 and a digital-to-analog converter 423, the power-good detection device for a PoE system with multiple power source devices of the present invention can achieve correct determination of the power-good state of power source devices of various specifications.
The power-good detection device can be used in any known PoE system with multiple power source devices that comprises:
a plurality of power source devices;
a plurality of communication ports, each communication port to be connected by a power consuming device to establish a signal and power connection with the power consuming device; each communication port having a port switch to control a power supplied to the port;
a control device in connection with the plurality of power source devices and the plurality of communication ports via a network cable, to convert electrical power supplied by the respective power source device to electrical power usable by the power consuming device connected to each communication port, and to generate a power consumption control signal, to control power supplied to the communication port from the plurality of power source devices;
wherein the control device comprises one of the power-good detection devices described above; and
a power supply distribution controller for generating the power consumption control signal according to the power-good state signal.
| Number | Date | Country | Kind |
|---|---|---|---|
| 110118668 | May 2021 | TW | national |
