WO2017114265A1 - 以太网供电方法及供电设备与受电设备 - Google Patents

以太网供电方法及供电设备与受电设备 Download PDF

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Publication number
WO2017114265A1
WO2017114265A1 PCT/CN2016/111338 CN2016111338W WO2017114265A1 WO 2017114265 A1 WO2017114265 A1 WO 2017114265A1 CN 2016111338 W CN2016111338 W CN 2016111338W WO 2017114265 A1 WO2017114265 A1 WO 2017114265A1
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Prior art keywords
power
power supply
pairs
pse
powered
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PCT/CN2016/111338
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English (en)
French (fr)
Inventor
付世勇
庄艳
威廉 迪亚布瓦埃勒
郭金娥
胡寅力
华睿
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华为技术有限公司
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Publication of WO2017114265A1 publication Critical patent/WO2017114265A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/02—Details
    • H04L12/10—Current supply arrangements

Definitions

  • the present application relates to the field of communications, and in particular, to a power over Ethernet method, a power supply device, and a power receiving device.
  • PoE Power over Ethernet
  • the power sourcing equipment (PSE) is connected to the powered device (PD) via an Ethernet cable.
  • the Ethernet cable can be a twisted pair cable (English: twisted pair cable). Each Ethernet twisted pair typically includes four pairs (wire pairs). When powered by Power over Ethernet, the PSE can power the PD in two pairs.
  • the supply current on each pair is formed by the PD according to its own power demand, when the PD is in an idle state, the supply current on the twisted pair is correspondingly small due to the small PD power requirement. If the supply current on the twisted pair is less than the predetermined value for a long time, the PSE will stop supplying power to the PD. To prevent the PSE from stopping to supply power to the PD when the PD is in the idle state, the PD can be powered from the PSE by maintaining the power feature (MPS) when it is in the idle state. The PD is pumped from the PSE in MPS mode to maintain the power supply between the PSE and the PD.
  • MPS power feature
  • the MPS mode refers to that the PD extracts a current from the PSE for at least 75 milliseconds (ms) and greater than 10 milliamps (mA) every predetermined time interval, wherein the predetermined duration is usually less than 250 ms. If the PD is not pumped for a predetermined period of time or the pumping current is less than 10 mA, the PSE stops supplying power to the PD.
  • the PSE only uses two pairs of wires to power the PD, which cannot meet the power consumption requirements of the PD. So the PSE starts using four pairs to power the PD.
  • the four pairs can be divided into two twisted pairs, each of which includes two pairs.
  • the PSE uses four pairs of wires to power the PD at the same time, the PD draws power from the two twisted pairs. Since the two twisted pairs are connected in parallel, the current of each of the two twisted pairs is approximately half of the total current. If the PD draws less than 20 mA from the PSE in MPS mode, the current per twisted pair is less than 10 mA. Since the current of each twisted pair does not meet the MPS requirements, the PSE will stop supplying power to the PD.
  • the present application provides a power over Ethernet method and a PSE and a PD to solve the problem that when the power is supplied to the PD by using four pairs, the actual current in the pair does not meet the requirement of maintaining the power supply between the PSE and the PD.
  • the problem that caused the PD to lose power
  • the present application provides a power over Ethernet method, the method comprising: a power supply device powering a single powered device connected to the Ethernet port with four pairs of one Ethernet port; the power supply device Detecting an output power of the Ethernet port to obtain a first output power; when the first output power is lower than a first predetermined power, the power supply device uses two pairs of the four pairs of wires Powered by the powered device.
  • the power supply device can only supply two pairs of wires to power the powered device when the power demand of the powered device is small, so that the sustaining current formed by the powered device pumping power from the power supply device in the MPS mode only exists in the power supply device.
  • the two pairs are paired to avoid the problem that the power receiving device is powered down because the actual current in the pair does not reach the requirement of maintaining the power supply state between the power supply device and the power receiving device.
  • the method further includes: The power supply device sends a first power supply mode notification to the power receiving device, where the first power supply mode notification is used to indicate that the power supply device will use the two wire pairs to supply power to the power receiving device.
  • the power supply device can notify the power receiving device that the power supply device uses two pairs of wires to supply power to the powered device in advance, so that the powered device can clearly know that the power supply device will use two pairs as the powered device. powered by.
  • the first power supply mode notification is a specified bit in a power type-length-value TLV via a medium related interface; or
  • the first power supply mode notification is a power supply mode TLV.
  • the power supply device can send a first power supply mode notification by using an existing communication mode between the power supply device and the power receiving device.
  • the method further includes: using the two line pairs During the power supply of the powered device, the power supply device detects the output power of the Ethernet port to obtain a second output power; when the second output power is higher than the second predetermined power, the power supply device uses The four line pairs supply power to the powered device, wherein the second predetermined power is greater than or equal to the first predetermined power.
  • the power supply device can change the power supply to the powered device by using two pairs of wires, and change the power supply to the powered device by using four wire pairs, thereby meeting the power consumption requirements of the powered device.
  • the method before the powering the power receiving device by using the four line pairs, the method further includes: the power supply device The power receiving device sends a second power supply mode notification, where the second power supply mode notification is used to instruct the power supply device to use the four wire pairs to supply power to the power receiving device.
  • the power supply device can inform the power receiving device that the power supply device uses four wire pairs to supply power to the power receiving device in advance, so that the power receiving device can clearly know that the power supply device will use four wire pairs as the power receiving device. powered by.
  • the second power supply mode notification is that the specified bit in the type-length-value TLV is powered via the medium related interface; or The second power supply mode is notified as a power supply mode TLV.
  • the power supply device can send a second power supply mode notification by using an existing communication mode between the power supply device and the power receiving device.
  • the present application further provides another method for powering over a power supply, the method comprising: powering a device to draw power from a power supply device with four wire pairs; the power receiving device will use four wire pairs from the The power of the power-supply device is reduced to below the first predetermined power, so that the power supply device uses the two pairs of the four pairs to supply power to the powered device; the powered device is used in the MPS mode The two pairs of wires are pumped from the power supply device to maintain a power supply state between the power receiving device and the power supply device.
  • the power supply device can only supply two pairs of wires to power the powered device when the power demand of the powered device is small, so that the sustaining current formed by the powered device pumping power from the power supply device in the MPS mode only exists in the power supply device.
  • the two pairs are paired to avoid the problem that the power receiving device is powered down because the actual current in the pair does not reach the requirement of maintaining the power supply state between the power supply device and the power receiving device.
  • the method further includes: the powered device increases a power drawn from the power supply device to a second predetermined power or higher
  • the power supply device uses the four wire pairs to supply power to the power receiving device, wherein the second predetermined power is greater than or equal to the first predetermined power; when the predetermined condition is met, the power receiving device uses four The pair draws power from the power supply device according to the power demand.
  • the power supply device can change the power supply to the powered device by using two pairs of wires, and change the power supply to the powered device by using four wire pairs, thereby meeting the power consumption requirements of the powered device.
  • the power receiving device extracts from the power supply device by using the two wire pairs in an MPS manner Maintaining the power supply state between the power receiving device and the power supply device includes: receiving, by the power receiving device, the first power supply mode notification by the power receiving device, where the first power supply mode notification is used to indicate the power supply The device will use the two wire pairs to supply power to the power receiving device; after receiving the first power supply mode notification, the power receiving device extracts from the power supply device by using the two wire pairs in an MPS manner. The power supply maintains a power supply state between the power receiving device and the power supply device.
  • the power supply device can notify the power receiving device that the power supply device uses two wire pairs to supply power to the power receiving device in advance, so that the power receiving device can clearly know that the power supply device will use two wire pairs to supply power to the power receiving device.
  • the power receiving device is configured to draw power from the power supply device by using four pairs of wires, including: the powered device in use In the process of pumping power from the power supply device, the receiving the power receiving device sends a second power supply mode notification, where the second power supply mode notification is used to indicate that the power supply device will use the four lines Supplying power to the power receiving device; after receiving the second power supply mode notification, the power receiving device draws power from the power supply device by using the two wire pairs.
  • the power supply device can inform the power receiving device that the power supply device uses four wire pairs to supply power to the power receiving device in advance, so that the power receiving device can clearly know that the power supply device will use four wire pairs as the power receiving device. powered by.
  • the application further provides a power supply device
  • the power supply device includes: a power supply circuit and an Ethernet port;
  • the Ethernet port includes four wire pairs, wherein the four wire pairs and a single power receiving The power supply circuit is connected to the Ethernet port;
  • the power supply circuit is configured to supply power to the power receiving device by using the four line pairs, and detect an output power of the Ethernet port to obtain a first And outputting power, and when the first output power is lower than the first predetermined power, powering the powered device with two of the four pairs.
  • the power supply device can only supply two pairs of wires to power the powered device when the power demand of the powered device is small, so that the sustaining current formed by the powered device pumping power from the power supply device in the MPS mode only exists in the power supply device.
  • the two pairs are paired to avoid the problem that the power receiving device is powered down because the actual current in the pair does not reach the requirement of maintaining the power supply state between the power supply device and the power receiving device.
  • the PSE further includes: a processor, configured to send, by using the Ethernet port, a first power supply mode notification to the power receiving device, where A power supply mode notification is used to indicate that the power supply device will use the two wire pairs to supply power to the power receiving device.
  • the power supply circuit includes a PSE chip, a switch circuit, and a power source; a circuit is coupled to the Ethernet port and supplies power to the four line pairs of the Ethernet port; the PSE chip is configured to detect an output power of the Ethernet port to obtain a first output power, and When the first output power is lower than the first predetermined power, the switching circuit is controlled to cause the power supply to supply power to two of the four line pairs.
  • the power supply circuit includes a PSE chip and a power source; and the power source is connected to the PSE chip, And supplying power to the PSE chip; the PSE chip is connected to the Ethernet port; the PSE chip is configured to supply power to the powered device by using the four line pairs, and detect an output of the Ethernet port Power to obtain a first output power, and in said When the first output power is lower than the first predetermined power, power is supplied to the power receiving device by two of the four line pairs.
  • the power supply circuit is further configured to detect the Ethernet port Outputting power to obtain a second output power; and powering the powered device with the four line pairs when the second output power is higher than a second predetermined power.
  • the power supply device can change the power supply to the powered device by using two pairs of wires, and change the power supply to the powered device by using four wire pairs, thereby meeting the power consumption requirements of the powered device.
  • the processor is further configured to send, by using the Ethernet port, a second power supply mode to the power receiving device
  • the second power supply mode notification is used to instruct the power supply device to use the four wire pairs to supply power to the power receiving device.
  • the application further provides a PD, where the PD includes: a power receiving circuit and an Ethernet port; the Ethernet port includes four wire pairs, wherein the four wire pairs are connected to the power supply device;
  • the power receiving circuit is connected to the Ethernet port; the power receiving circuit is configured to draw power from the power supply device by using four wire pairs; in the process of pumping power from the power supply device by using four wire pairs Reducing power drawn from the power supply device to below a first predetermined power, so that the power supply device supplies power to the powered device using two of the four pairs; using MPS
  • the two wire pairs are powered from the power supply device to maintain a power supply state between the power receiving device and the power supply device.
  • the power receiving circuit is further configured to increase a power drawn from the power supply device to a second predetermined power or higher to enable the power supply
  • the device uses the four wire pairs to power the powered device, wherein the second predetermined power is greater than or equal to the first predetermined power; and power is drawn from the powering device with four wire pairs.
  • the power supply device can only supply two pairs of wires to power the powered device when the power demand of the powered device is small, so that the powered device is powered by the MPS mode.
  • the holding current formed by the pumping of the device exists only in the two pairs, so as to avoid the fact that the actual current in the pair does not reach the requirement of maintaining the power supply state between the power supply device and the power receiving device, resulting in the power receiving device.
  • FIG. 1 is a flow chart of an embodiment of a method for powering a power supply of the present application
  • FIG. 2 is a schematic structural diagram of an embodiment of a PSE according to the present application.
  • FIG. 3 is a schematic structural diagram of an embodiment of a PD of the present application.
  • the PSE can supply power to the PD through an Ethernet line that conforms to the Electronic Industries Alliance/Telecommunications Industry Association (EIA/TIA) T568A standard or the EIA/TIA T568B standard.
  • EIA/TIA Electronic Industries Alliance/Telecommunications Industry Association
  • the Ethernet cable is a twisted pair cable conforming to the EIA/TIA 568B standard
  • the four wire pairs included in the Ethernet cable can be divided into two twisted pair groups.
  • the orange-orange-orange pair and the green-white-blue pair in the Ethernet cable can be used as a twisted pair; and the blue-white-green pair and the brown-white-brown pair in the Ethernet cable are used as another A twisted pair.
  • the following two pairs of orange-orange-orange pair and green-white-blue line pair are referred to as the first twisted pair; and the blue-white-green pair and the brown-white-brown pair are two lines.
  • the pair is called the second twisted pair.
  • the PSE may supply power to the PD only through two pairs included in the first twisted pair or two pairs included in the second twisted pair, or may simultaneously pass the first twisted pair and the second twisted pair
  • the four pairs included include powering the PD.
  • FIG. 1 is a flowchart of an embodiment of an Ethernet method according to the present application, where the method includes the following steps:
  • step 101 the power supply device supplies power to a single power receiving device connected to the Ethernet port by using four wire pairs of one Ethernet port, and the power receiving device draws power from the power supply device by using four wire pairs.
  • the PD When the PD is connected to an Ethernet port of the PSE through an Ethernet cable, after the PSE is started, the PD can be powered by two twisted pairs in the Ethernet cable connected to the Ethernet port, that is, after the PSE is started. At the same time, the four pairs are used to power the PD, and the PD is pumped from the PSE with four pairs.
  • Step 102 The power supply device detects an output power of the Ethernet port to obtain a first output power.
  • the PSE can detect the output power of the Ethernet port to obtain the first output power.
  • the first output power may be equal to the power that the PD draws from the PSE with two twisted pairs and the power that is lost during power transmission through the Ethernet line.
  • Step 103 if the first output power is lower than the first predetermined power because the power receiving device reduces the power drawn from the power supply device, the power supply device uses two of the four wire pairs. Powering the powered device.
  • the first predetermined power may be set as needed, and may be greater than or equal to the output power of the PSE when the PD is powered by four line pairs and meets the minimum current required by the MPS.
  • the first predetermined power is generally less than the PSE through one The maximum power supply that the twisted pair can provide when powering the PD. For example, when the total current of the PD when pumping through four pairs is 20 mA, the total current of the two twisted pairs is 20 mA, and the current of at least one of the strands is greater than or equal to 10 mA, which satisfies the minimum current required by the MPS.
  • the PSE output power is 0.96 watts (w)
  • the first predetermined power can be between 0.96 and 30 watts. If the supply voltage is 54V, the first predetermined power may be between 1.08w and 30w. Therefore, the first predetermined power may be about 1 w.
  • the PD may first reduce the power drawn from the PSE to below a first predetermined power, thereby causing the first output The power is lower than the first predetermined power, and when the first output power is lower than the first predetermined power, the PSE may determine that the PD may need to maintain a power supply state between the PSE and the PD.
  • the manner in which the PD reduces the power drawn from the power supply device may be various.
  • the PD may reduce the pumping power below a first preset power and continuously draw power from the PSE.
  • the PD may reduce the power drawn from the power supply device to a third preset power, and continuously draw power from the PSE at a third preset power. Wherein the third power is less than the first predetermined power.
  • the PD may also draw power directly from the PSE in an MPS manner, so that the first output power detected by the PSE is lower than the first predetermined power.
  • the PSE may not immediately stop powering the PD, but retain the station.
  • One of the two twisted pairs is powered by the powered device so that the PD can be powered in MPS mode.
  • the PD is powered off.
  • the PSE can reserve any twisted pair to supply power to the PD. For example, the PSE can stop using the first twisted pair to power the PD, but only the second twisted pair to power the PD. It can also stop using the second twisted pair to power the PD, leaving only the first twist.
  • the line group supplies power to the PD. And determining that the power supply device supplies power to the power receiving device by using two of the four wire pairs. When the PSE stops using a twisted pair to power the PD, the potential difference between the PSE and the PD on the two pairs included in the twisted pair is removed.
  • the PSE can reserve one of the two twisted pair groups to supply power to the PD according to a preset rule.
  • the PSE can also choose which twisted pair to reserve for the PD.
  • the PSE may send a first power mode notification to the powered device to indicate which twisted pair group the PSE will use to power the PD.
  • the PSE can use the type-length-value in the LLDP data unit (LLDPDU) in the process of communicating with the Link Layer Discovery Protocol (LLDP).
  • LLDPDU LLDP data unit
  • TLV Link Layer Discovery Protocol
  • the PSE may send the first power mode notification to the PD by using a specified bit in a Power via MDI TLV.
  • the PSE may add a designated byte for indicating the twisted pair used for power supply in the Power via MDI TLV, indicating the twisted pair used to power the PD by a different value of the specified byte.
  • the value of the specified byte is 1, it indicates that the PSE will power the PD with the first twisted pair.
  • the value of the specified byte is 2, it indicates that the PSE will supply power to the PD with the second twisted pair.
  • the value of the specified byte is 3, it indicates that the PSE will power the PD with two twisted pairs.
  • a value of 0 indicates that the power supply mode is unchanged or the power supply mode is unknown.
  • the meaning of the value 4 to the value 255 is reserved for subsequent use for other purposes.
  • the PSE can also use the reserved bits in the Power via MDI TLV to indicate the twisted pair used to power the PD, indicating different twisted pairs by different values of reserved bits.
  • the PSE may also send a power model TLV to the PD during the LLDP negotiation with the PD.
  • the power model TLV can be used to indicate the twisted pair used by the PSE to power the PD.
  • the different values of the power model TLV indicate the different twisted pairs used to power the PD.
  • the power model TLV may be one byte in length. When the first bit of the power model TLV is 1, it means that the PSE will use two twisted pairs to supply power to the PD. When the first bit of the power model TLV is 0, it indicates that the PSE will use the predetermined twisted pair to supply power to the PD, wherein the predetermined twisted pair may be the first twisted pair or the second. Twisted pair.
  • the PSE can be used after the output power is less than the first predetermined power for a predetermined period of time.
  • a twisted pair of wires supplies power to the PD.
  • Step 104 The power receiving device extracts power from the power supply device by using the two wire pairs in an MPS manner to maintain a power supply state between the power receiving device and the power supply device.
  • the PD can continue to draw power from the PSE with the twisted pair or from the twisted pair in MPS mode.
  • the current in the two pairs of the twisted pair is the total current that the PD draws from the PSE. If the PD is pumped from the PSE in MPS mode, only the pumping current exists in the two pairs included in the twisted pair. When the total current drawn by the PD from the PSE is greater than 10 mA, the twisted pair The current in the two pairs included will also be greater than 10 mA, so that the current in the two pairs included in the twisted pair can meet the MPS requirements, thus maintaining the power supply between the PSE and the PD.
  • the PSE Since in the process of powering the powered device with the two pairs, the PSE only reserves one twisted pair to power the PD, so the PD can only draw power from the PSE through two pairs, so in the PD
  • the MPS mode is pumped from the PSE, the actual current can reach the requirement of maintaining the power supply state between the PSE and the PD in the two pairs used to power the PD, so that the PD can be prevented from being powered down when it is in the idle state.
  • the powered device does not draw power from the PSE in MPS mode, for example, the powered device stops pumping, the PSE stops supplying power to the PD.
  • the power receiving device draws current from the power supply device in MPS mode. It exists only in two pairs, so as to avoid the problem that the actual power in the pair does not reach the requirement of maintaining the power supply state between the power supply device and the power receiving device, resulting in power failure of the power receiving device.
  • the PD When the PD enters the active state from the idle state, the PD can draw power from the PSE according to its own power requirement. Since the PD is in an idle state, the PSE retains only two pairs of twisted pairs to power the PD. In order to avoid the problem that the power supply process of the PSE exceeds the power supply capability of the PSE when using a twisted pair power supply, the PSE can resume the use of two twisted pairs when the PD enters the active state from idle state. Wire pair, powering the PD.
  • the method may further include:
  • Step 105 In a process in which the power supply device uses two wire pairs to supply power to the power receiving device, the power supply device detects an output power of the Ethernet port to obtain a second output power.
  • the PSE can detect the output power of the Ethernet port to obtain a second output power.
  • the second output power may be equal to the power that the PD draws from the PSE with one twisted pair and the power that is lost during power transmission through the Ethernet line.
  • the process in which the power supply device uses two pairs of wires to supply power to the powered device may include a process in which the PD is powered by the PD in two MPs by the MPS, or may be included in the PD by the two pairs.
  • the process of pumping power from the PD may include a process in which the PD is powered by the PD in two MPs by the MPS, or may be included in the PD by the two pairs. The process of pumping power from the PD.
  • Step 106 If the power output device raises the power drawn from the power supply device, so that the second output power is higher than the second predetermined power, the power supply device uses the four wire pairs as the power receiving device. powered by.
  • the PD may first increase the power drawn from the PSE to a second predetermined power or higher, so that the PSE can know that the PD is about to enter an active state from an idle state.
  • the second predetermined power is greater than or equal to the first predetermined power, and is less than or equal to the maximum power that the PSE can provide when powering the PD through a twisted pair.
  • the second predetermined power is less than the actual power demand of the PD when it is in operation.
  • the line group power supply is frequently switched between using two twisted pair power supplies, and the second predetermined power may be greater than the first predetermined power. For example, when the first predetermined power is 1w, the second predetermined power may be 2w.
  • Increasing the power drawn by the PD from the PSE to a second predetermined power may cause the output power of the Ethernet port, that is, the second output power, to be higher than the second predetermined power. If the second output power is higher than the second predetermined power, it indicates that the PD is to be converted from an idle state to an active state. To ensure power supply efficiency and power supply capability, the PSE may resume using the four line pairs for the received Electrical equipment is powered.
  • one or more predetermined conditions may be preset.
  • the second output power is higher than the second predetermined power, and when the predetermined condition is met, the PSE resumes using the four line pairs to power the PD.
  • the predetermined condition may be that the second output power does not change within a predetermined length of time.
  • the PSE may resume powering the PD using four line pairs when the second output power is higher than the second predetermined power and has not changed within a predetermined length of time.
  • the second output power may be considered to have not changed within the predetermined length of time.
  • the PSE may further send a second power supply mode notification to the power receiving device, and the second power supply mode notification is used to indicate that the power supply device is to use the four wire pairs. Powered by the powered device.
  • the second power supply mode notification may be sent by the PSE to the power receiving device through a designated bit of the Power-via-MDI TLV or a power model TLV.
  • the PSE may further monitor the output power from the Ethernet port to obtain a first output power, and at the first output power being lower than the first
  • the power supply device supplies power to the powered device with two of the four pairs.
  • the PD can draw power from the PSE with four pairs according to its own power requirements.
  • the power requirement of the PD may be greater than the second predetermined power, or may be less than or equal to the second predetermined power.
  • the power demand is 40W.
  • the PD may first use a double.
  • the power of the stranded group from the PSE is increased to 15W; when the PSE is switched to use two twisted pairs to power the PSE, the PD can increase the power drawn from the PSE to 40W.
  • 15W and 40W are examples, and other power values may be used in actual use.
  • the PSE can restore the power supply of the PD by using two twisted pairs when the power requirement of the PD is high, thereby improving the power supply efficiency and meeting the power requirement of the PD.
  • FIG. 2 is a schematic structural diagram of an embodiment of a PSE according to the present application. Among them, the portion indicated by the broken line is an optional part. The PSE may also not include the connection relationship between the circuits and circuits included in the broken line portion.
  • the PSE may include: a power supply circuit 201 and an Ethernet port 202; the Ethernet port 202 includes four wire pairs, wherein the four wire pairs are connected to a single power receiving device;
  • the power supply circuit 201 is connected to the Ethernet port 202.
  • the power supply circuit 201 is configured to supply power to the power receiving device by using the four line pairs, and detect an output power of the Ethernet port 202 to obtain a first output. Power, and when the first output power is lower than the first predetermined power, powering the powered device with two of the four pairs.
  • the power supply circuit 201 is further configured to detect an output power of the Ethernet port 202 to obtain a second output power; and when the second output power is higher than a second predetermined power, use the fourth The pair of wires supplies power to the powered device.
  • the power supply device can change the power supply to the powered device by using two pairs of wires, and change the power supply to the powered device by using four wire pairs, thereby meeting the power consumption requirements of the powered device.
  • the power supply circuit 201 includes a PSE chip and a power source. As shown by the solid line in FIG. 2, the power supply is connected to the PSE chip and supplies power to the PSE chip.
  • FIG. 2 shows an alternative configuration of the power supply circuit 201 in broken lines. In this configuration, the PSE chip controls the power supply to power the Ethernet port. The PSE chip can also directly supply power to the Ethernet port. In this case, the structure of the power supply circuit 201 is relatively simple, and no schematic diagram is provided.
  • the PSE chip directly powers the Ethernet port, the PSE chip is connected to the Ethernet port 202 (not shown).
  • the PSE chip is configured to supply power to the power receiving device by using the four wire pairs, detecting an output power of the Ethernet port 202 to obtain a first output power, and the first output power is lower than the first output power At a predetermined power, power is supplied to the powered device using two of the four pairs.
  • the PSE chip may be further configured to detect an output power of the Ethernet port 202 to obtain a first output power, and when the second output power is higher than a second predetermined power, use the four lines to face The four pairs are powered.
  • the power supply circuit 201 further includes a switching circuit. As shown by the broken line portion in FIG. 2, the power source is connected to the Ethernet port 202 via the switch circuit, and supplies power to the four line pairs of the Ethernet port 202; the PSE chip is used Detecting the output power of the Ethernet port 202 to obtain a first output power, and when the first output power is lower than the first predetermined power, controlling the switch circuit to cause the power supply to the four lines Power the two pairs in the pair.
  • the PSE chip may be further configured to detect an output power of the Ethernet port 202 to obtain a second output power, and when the second output power is higher than a second predetermined power, control the switch circuit to The power supply supplies power to the four line pairs.
  • the switching circuit can include two switches, each of which can be controlled by the PSE chip.
  • one of the switches is used to control circuit continuity between the first twisted pair and the power source, and the other switch is used to control circuit continuity between the second twisted pair and the power supply.
  • one of the switches is a main switch for controlling circuit continuity between the two twisted pairs and the power source, and the other switch is only for individually controlling one of the two twisted pairs and the power supply. The circuit is switched on and off.
  • the switch may be a metal-oxide-semiconductor field-effect transistor (English: metal-oxide-semiconductor field-effect transistor, MOSFET), or other devices with switching functions, such as a junction field effect transistor (English: junction) Gate field-effect transistor (abbreviation: JFET) or bipolar junction transistor (abbreviation: BJT).
  • MOSFET metal-oxide-semiconductor field-effect transistor
  • JFET Gate field-effect transistor
  • BJT bipolar junction transistor
  • the PSE may further include: a processor, configured to send, by using the Ethernet port 202, a first power supply mode notification to the power receiving device, where the first power supply mode notification is used to indicate the power supply device The two line pairs will be used to power the powered device.
  • the processor may be further configured to send, by using the Ethernet port 202, a second power supply mode notification to the power receiving device, where the second power supply mode notification is used to indicate that the power supply device is to use the four lines Powering the powered device.
  • FIG. 3 it is a schematic structural diagram of an embodiment of a PD of the present application.
  • the PD includes a power receiving circuit 301 and an Ethernet port 302.
  • the Ethernet port 302 includes four wire pairs, wherein the four wire pairs are connected to a power supply device; the power receiving circuit 301 is connected to the Ethernet port 302; and the power receiving circuit 301 is used for Four pairs of wires are pumped from the power supply device; in the process of pumping power from the power supply device with four wire pairs, the power drawn from the power supply device is reduced to below a first predetermined power, so that The power supply device uses the two pairs of the four pairs to supply power to the powered device; the two pairs of wires are pumped from the power supply device in an MPS manner to maintain the powered device and the device The power supply status between the power supply devices.
  • the power receiving circuit 301 is further configured to increase power drawn from the power supply device to a second predetermined power or higher, so that the power supply device uses the four wire pairs to receive the power The device is powered, wherein the second predetermined power is greater than or equal to the first predetermined power; and the power is extracted from the power supply device by four wire pairs.
  • the power receiving circuit may include a PD chip, a DC conversion circuit, etc., so that each circuit element can be powered according to the requirements of each circuit component in the PD.
  • the technical solution in the present application may be embodied in the form of a software product, which may be stored in a storage medium, such as a read only memory (ROM), a random access memory (RAM), a magnetic disk, an optical disk, etc., including several fingers.
  • a storage medium such as a read only memory (ROM), a random access memory (RAM), a magnetic disk, an optical disk, etc., including several fingers.
  • the method is described to enable a computer device (which may be a personal computer, server, or network device, etc.) to perform various embodiments of the present application or portions of the embodiments.

Abstract

公开了以太网供电方法及供电设备与受电设备。所述方法可以包括：供电设备用一个以太网端口的四个线对为连接到以太网端口的单个受电设备供电；供电设备检测以太网端口的输出功率以得到第一输出功率；在第一输出功率低于第一预定功率时，供电设备用四个线对中的两个线对为受电设备供电。采用本申请所公开的以太网供电方法及供电设备与受电设备，供电设备可以在受电设备的功率需求较小时，仅保留两个线对为受电设备供电，使受电设备以MPS方式从供电设备抽电所形成的维持电流只存在于两个线对之中，从而避免因线对中的实际电流达不到维持供电设备与受电设备之间持续处于供电状态的要求而导致受电设备掉电的问题。

Description

以太网供电方法及供电设备与受电设备
本申请要求于2015年12月31日提交中国专利局、申请号为201511026074.3、发明名称为“以太网供电方法及供电设备与受电设备”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及通信领域，尤其涉及以太网供电方法及供电设备与受电设备。
背景技术
以太网供电(英文：Power over Ethernet，PoE)是一种在以太网线(英文：Ethernet cable)上随着数据传输电力(英文：electrical power)的技术。供电设备(英文：power sourcing equipment，PSE)通过以太网线与受电设备(英文：powered device，PD)连接。其中，以太网线可以为双绞线(英文：twisted pair cable)。每一条以太网双绞线一般包括四个线对(英文：wire pairs)。在采用以太网供电时，PSE可以以两个线对为PD供电。
由于各个线对上的供电电流由PD根据自身的功率需求抽电形成，因此当PD处于空闲状态时，由于PD功率需求较小，双绞线组上的供电电流相应也会较小。如果双绞线组上的供电电流长时间小于预定值，PSE就会停止为PD供电。为避免PD在处于空闲状态时出现PSE停止为PD供电的情况，PD在处于空闲状态时，可以通过维持功率特征(英文：Maintain Power Signature，MPS)方式从PSE抽电。PD以MPS方式从PSE抽电可以维持PSE与PD之间持续处于供电状态。MPS方式是指PD每间隔预定时长，从PSE抽取一个持续至少75毫秒(ms)且大于10毫安(mA)的电流，其中，所述预定时长通常小于250ms。如果PD超出预定时间未抽电或者抽电电流小于10mA，PSE停止为PD供电。
随着技术的发展，PSE仅采用两个线对为PD供电已经无法满足PD的功耗需求。因此PSE开始使用四个线对为PD供电。在采用四个线对为PD供电时，可以将四个线对划分为两个双绞线组，其中每一个双绞线组包括两个线对。当PSE同时采用四个线对为PD供电时，PD从两个双绞线组抽电。由于两个双绞线组并联，每个两个双绞线组的电流大约为总电流的一半。如果PD以MPS方式从PSE抽电的电流小于20mA，则每个双绞线组的电流小于10mA。由于每一个双绞线组的电流都不满足MPS要求，PSE会停止为PD供电。
发明内容
本申请提供了以太网供电方法及PSE与PD，以解决在采用四个线对为PD供电时，因线对中的实际电流达不到维持PSE与PD之间持续处于供电状态的要求，而导致PD掉电的问题。
第一方面，本申请提供了一种以太网供电方法，该方法包括：供电设备用一个以太网端口的四个线对为连接到所述以太网端口的单个受电设备供电；所述供电设备检测所述以太网端口的输出功率以得到第一输出功率；在所述第一输出功率低于第一预定功率时，所述供电设备用所述四个线对中的两个线对为所述受电设备供电。采用此实现方式，供电设备可以在受电设备的功率需求较小时，仅保留两个线对为受电设备供电，使受电设备以MPS方式从供电设备抽电所形成的维持电流只存在于两个线对之中，从而避免因线对中的实际电流达不到维持供电设备与受电设备之间持续处于供电状态的要求而导致受电设备掉电的问题。
结合第一方面，在第一方面第一种可能的实现方式中，在所述供电设备用所述四个线对中的两个线对为所述受电设备供电之前，还包括：所述供电设备向所述受电设备发送第一供电方式通知，所述第一供电方式通知用于指示所述供电设备将使用所述两个线对为所述受电设备供电。采用此实现方式，供电设备可以预先将供电设备使用两个线对为受电设备的供电的情况告知受电设备，从而使受电设备能够明确获知供电设备将使用两个线对为受电设备供电。
结合第一方面第一种可能的实现方式，在第一方面第二种可能的实现方式中，所述第一供电方式通知为经由介质相关接口供电类型-长度-值TLV中的指定比特；或，所述第一供电方式通知为供电方式TLV。采用此实现方式，供电设备可以利用供电设备与受电设备之间的现有通信方式发第一供电方式通知。
结合第一方面或第一方面第一或二种可能的实现方式其中任意一种，在第一方面第三种可能的实现方式中，所述方法还包括：在用所述两个线对为所述受电设备供电的过程中，所述供电设备检测所述以太网端口的输出功率以得到第二输出功率；在所述第二输出功率高于第二预定功率时，所述供电设备用所述四个线对为所述受电设备供电，其中，所述第二预定功率大于或等于所述第一预定功率。采用此实现方式，供电设备可以从使用两个线对为受电设备的供电，改变为使用四个线对为受电设备供电，从而可以满足受电设备的功耗需求。
结合第一方面第三种可能的实现方式，在第一方面第四种可能的实现方式中，在用所述四个线对为所述受电设备供电之前，还包括：所述供电设备向所述受电设备发送第二供电方式通知，所述第二供电方式通知用于指示所述供电设备将用所述四个线对为所述受电设备供电。采用此实现方式，供电设备可以预先将供电设备使用四个线对为受电设备的供电的情况告知受电设备，从而使受电设备能够明确获知供电设备将使用四个线对为受电设备供电。
结合第一方面第四种可能的实现方式，在第一方面第五种可能的实现方式中，所述第二供电方式通知为经由介质相关接口供电类型-长度-值TLV中的指定比特；或所述第二供电方式通知为供电方式TLV。采用此实现方式，供电设备可以利用供电设备与受电设备之间的现有通信方式发第二供电方式通知。
第二方面，本申请还提供了另一种以太网供电方法，所述方法包括：受电设备用四个线对从供电设备抽电；所述受电设备将用四个线对从所述供电设备抽电的功率降低至第一预定功率以下，以使所述供电设备使用所述四个线对中的两个线对为所述受电设备供电；所述受电设备以MPS方式用所述两个线对从所述供电设备抽电维持所述受电设备与所述供电设备之间的供电状态。采用此实现方式，供电设备可以在受电设备的功率需求较小时，仅保留两个线对为受电设备供电，使受电设备以MPS方式从供电设备抽电所形成的维持电流只存在于两个线对之中，从而避免因线对中的实际电流达不到维持供电设备与受电设备之间持续处于供电状态的要求而导致受电设备掉电的问题。
结合第二方面，在第二方面第一种可能的实现方式中，所述方法还包括：所述受电设备将从所述供电设备抽电的功率提高至第二预定功率以上，以使所述供电设备使用所述四个线对为所述受电设备供电，其中，所述第二预定功率大于或等于所述第一预定功率；在符合预定条件时，所述受电设备用四个线对按照功率需求从供电设备抽电。采用此实现方式，供电设备可以从使用两个线对为受电设备的供电，改变为使用四个线对为受电设备供电，从而可以满足受电设备的功耗需求。
结合第二方面或第二方面第一种可能的实现方式，在第二方面第二种可能的实现方式中，所述受电设备以MPS方式用所述两个线对从所述供电设备抽电维持所述受电设备与所述供电设备之间的供电状态包括：所述受电设备接收所述受电设备发送第一供电方式通知，所述第一供电方式通知用于指示所述供电设备将使用所述两个线对为所述受电设备供电；在接收到所述第一供电方式通知后，所述受电设备以MPS方式用所述两个线对从所述供电设备抽电维持所述受电设备与所述供电设备之间的供电状态。采用此实现 方式，供电设备可以预先将供电设备使用两个线对为受电设备的供电的情况告知受电设备，从而使受电设备能够明确获知供电设备将使用两个线对为受电设备供电。
结合第二方面第二种可能的实现方式，在第二方面第三种可能的实现方式中，所述受电设备用四个线对从供电设备抽电包括：所述受电设备在用所述两个线对从所述供电设备抽电的过程中，接收所述受电设备发送第二供电方式通知，所述第二供电方式通知用于指示所述供电设备将使用所述四个线对为所述受电设备供电；在接收到所述第二供电方式通知后，所述受电设备用所述两个线对从所述供电设备抽电。采用此实现方式，供电设备可以预先将供电设备使用四个线对为受电设备的供电的情况告知受电设备，从而使受电设备能够明确获知供电设备将使用四个线对为受电设备供电。
第三方面，本申请还提供了一种供电设备，所述供电设备包括：供电电路及以太网端口；所述以太网端口包括四个线对，其中，所述四个线对与单个受电设备连接；所述供电电路和所述以太网端口连接；所述供电电路，用于用所述四个线对为所述受电设备供电，检测所述以太网端口的输出功率以得到第一输出功率，以及在所述第一输出功率低于第一预定功率时，用所述四个线对中的两个线对为所述受电设备供电。采用此实现方式，供电设备可以在受电设备的功率需求较小时，仅保留两个线对为受电设备供电，使受电设备以MPS方式从供电设备抽电所形成的维持电流只存在于两个线对之中，从而避免因线对中的实际电流达不到维持供电设备与受电设备之间持续处于供电状态的要求而导致受电设备掉电的问题。
结合第三方面在第三方面第一种可能的实现方式中，所述PSE还包括：处理器，用于通过所述以太网端口向所述受电设备发送第一供电方式通知，所述第一供电方式通知用于指示所述供电设备将使用所述两个线对为所述受电设备供电。
结合第三方面或第三方面第一种可能的实现方式，在第三方面第二种可能的实现方式中，所述供电电路，包括PSE芯片、开关电路与电源；所述电源经由所述开关电路和所述以太网端口连接，并向所述以太网端口的所述四个线对供电；所述PSE芯片，用于检测所述以太网端口的输出功率以得到第一输出功率，以及在所述第一输出功率低于第一预定功率时，控制所述开关电路以使所述电源向所述四个线对中的两个线对供电。
结合第三方面或第三方面第一种可能的实现方式，在第三方面第三种可能的实现方式中，所述供电电路，包括PSE芯片与电源；所述电源和所述PSE芯片连接，并向所述PSE芯片供电；所述PSE芯片和所述以太网端口连接；所述PSE芯片，用于用所述四个线对为所述受电设备供电，检测所述以太网端口的输出功率以得到第一输出功率，以及在所述 第一输出功率低于第一预定功率时，用所述四个线对中的两个线对为所述受电设备供电。
结合第三方面或第三方面第一至三种可能的实现方式其中任意一种，在第三方面第四种可能的实现方式中，所述供电电路，还用于检测所述以太网端口的输出功率以得到第二输出功率；以及在所述第二输出功率高于第二预定功率时，用所述四个线对为所述受电设备供电。采用此实现方式，供电设备可以从使用两个线对为受电设备的供电，改变为使用四个线对为受电设备供电，从而可以满足受电设备的功耗需求。
结合第三方面第四种可能的实现方式，在第三方面第五种可能的实现方式中，所述处理器，还用于通过所述以太网端口向所述受电设备发送第二供电方式通知，所述第二供电方式通知用于指示所述供电设备将使用所述四个线对为所述受电设备供电。
第四方面，本申请还提供了一种PD，所述PD包括：受电电路及以太网端口；所述以太网端口包括四个线对，其中，所述四个线对与供电设备连接；所述受电电路和所述以太网端口连接；所述受电电路，用于用四个线对从所述供电设备抽电；在用四个线对从所述供电设备抽电的过程中，将从所述供电设备抽电的功率降低至第一预定功率以下，以使所述供电设备使用所述四个线对中的两个线对为所述受电设备供电；以MPS方式用所述两个线对从所述供电设备抽电以维持所述受电设备与所述供电设备之间的供电状态。
结合第四方面，在第四方面第一种可能的实现方式中，所述受电电路，还用于将从所述供电设备抽电的功率提高至第二预定功率以上，以使所述供电设备使用所述四个线对为所述受电设备供电，其中，所述第二预定功率大于或等于所述第一预定功率；用四个线对从供电设备抽电。
采用本申请所提用的方法及供电设备与受电设备，供电设备可以在受电设备的功率需求较小时，仅保留两个线对为受电设备供电，使受电设备以MPS方式从供电设备抽电所形成的维持电流只存在于两个线对之中，从而避免因线对中的实际电流达不到维持供电设备与受电设备之间持续处于供电状态的要求而导致受电设备掉电的问题。
附图说明
为了更清楚地说明本申请中的技术方案，下面将对实施例描述中所需要使用的附图作简单地介绍，显而易见地，对于本领域普通技术人员而言，在不付出创造性劳动性的前提下，还可以根据这些附图获得其他的附图。
图1为本申请以太网供电方法一个实施例的流程图；
图2为本申请PSE一个实施例的结构示意图；
图3为本申请PD一个实施例的结构示意图。
具体实施方式
在本申请中，PSE可以通过符合电子工业联盟/通信工业联盟(Electronic Industries Alliance/Telecommunications Industry Association，EIA/TIA)T568A标准或EIA/TIA T568B标准的以太网线向PD供电。当所述以太网线为符合EIA/TIA 568B标准的双绞线时，所述以太网线所包括的四个线对可以被分为两个双绞线组。通常情况下可以将太网线中的橙白-橙线对及绿白-蓝线对作为一个双绞线组；并将太网线中的蓝白-绿线对及棕白-棕线对作为另一个双绞线组。
为便于描述，以下将橙白-橙线对及绿白-蓝线对两个线对称作第一双绞线组；并将蓝白-绿线对及棕白-棕线对两个线对称作第二双绞线组。PSE可以仅通过第一双绞线组包括的两个线对或第二双绞线组包括的两个线对为PD供电，也可以同时通过第一双绞线组与第二双绞线组包括的四个线对为PD供电。
参见图1，为本申请以太网方法一个实施例的流程图，该方法包括如下步骤：
步骤101，供电设备用一个以太网端口的四个线对为连接到该以太网端口的单个受电设备供电，受电设备用四个线对从供电设备抽电。
当PD通过以太网线连接到PSE的某个以太网端口时，PSE在启动之后，可以用连接到该以太网端口的以太网线中的两个双绞线组为PD供电，即，PSE在启动之后同时使用四个线对为PD供电，PD用四个线对从PSE抽电。
步骤102，所述供电设备检测所述以太网端口的输出功率以得到第一输出功率。
在使用两个双绞线组为PD供电的过程中，PSE可以检测所述以太网端口的输出功率以得到第一输出功率。其中，第一输出功率可以等于所述PD用两个双绞线组从所述PSE抽电的功率加上在电力在通过以太网线传输过程中损耗的功率。
步骤103，如果由于受电设备降低从所述供电设备抽电的功率，使得所述第一输出功率低于第一预定功率，则所述供电设备用所述四个线对中的两个线对为所述受电设备供电。
其中，所述第一预定功率可以按照需要进行设置，可以大于或等于PD经由四个线对抽电并满足MPS要求的最小电流时PSE的输出功率。第一预定功率一般小于PSE通过一个 双绞线组为PD供电时所能提供的最大供电功率。例如，PD经由四个线对抽电时的总电流为20mA时，两个双绞线组的总电流为20mA，其中至少一个绞线组的电流大于等于10mA，满足MPS要求的最小电流。当PSE的供电电压为48伏特(V)，PD抽电的电流为20mA时，PSE的输出功率为0.96瓦特(w)，第一预定功率可以在0.96w至30w之间。如果供电电压为54V，第一预定功率可以在1.08w至30w之间。因此，所述第一预定功率可以为约1w。
如果PD需要进入空闲状态，并维持所述PSE与所述PD之间处于供电状态，那么所述PD可以首先将从所述PSE抽电的功率降低至第一预定功率以下，从而使第一输出功率低于第一预定功率，当第一输出功率低于第一预定功率时，PSE可以判定所述PD可能需要维持PSE与PD之间处于供电状态。
其中，所述PD降低从所述供电设备抽电的功率的方式可以有多种。
可选的，PD可以将抽电功率降低至第一预设功率以下，并持续从所述PSE抽电。例如，所述PD可以将从所述供电设备抽电的功率降至第三预设功率，并以第三预设功率持续从PSE抽电。其中，第三功率小于所述第一预定功率。
可选的，PD也可以直接以MPS方式从所述PSE抽电，从而使PSE检测到的第一输出功率低于第一预定功率。
在采用两个双绞线组为PD供电的过程中，如果所述PD从PSE降低至第一预定功率以下甚至暂停从PSE抽电时，PSE可以并不立即停止为PD供电，而是保留所述两个双绞线组中的一个为所述受电设备供电，以便于PD可以以MPS方式进行抽电。当PD未以MPS方式进行抽电时，再停止为PD供电。
从采用两个双绞线组为PD供电切换为采用一个双绞线组为PD供电时，PSE可以保留任意一个双绞线组为PD供电。例如，PSE可以停止使用第一双绞线组为PD供电，而仅保留第二双绞线组为PD供电；也可以停止使用第二双绞线组为PD供电，而仅保留第一双绞线组为PD供电。并在确定所述供电设备用所述四个线对中的两个线对为所述受电设备供电。PSE停止使用某双绞线组为PD供电时，撤除该双绞线组所包括的两个线对上PSE与PD之间的电势差即可。
PSE可以按照预设规则保留两个双绞线组中的一个为PD供电。PSE也可以自主选择保留哪一个双绞线组为PD供电。
可选地，PSE在确定保留一组双绞线组为PD供电之后，可以向受电设备发送第一供电方式通知，以指示PSE将使用哪一个双绞线组为PD供电。
PSE可以在与PD用链路层发现协议(英文：Link Layer Discovery Protocol，LLDP)通信的过程中，用LLDP数据单元(英文：LLDP data unit，LLDPDU)中的类型-长度-值(英文：type-length-value，TLV)向PD发送第一供电方式通知，从而告知PD所述PSE将使用哪一个双绞线组为PD供电。
可选的，所述PSE可以用经由介质相关接口供电(Power via MDI)TLV中的指定比特向PD发送第一供电方式通知。例如，PSE可以在Power via MDI TLV增加用于指示供电所用双绞线组的指定字节，通过指定字节的不同取值指示用于为PD供电的双绞线组。当所述指定字节的取值为1时，表示PSE将用第一双绞线组为PD供电。当所述指定字节的值为2时，表示PSE将用第二双绞线组为PD供电。当所述指定字节的值为3时，表示PSE将用两个双绞线组为PD供电。而取值为0表示供电方式不变或供电方式未知。取值4至取值255的含义保留，以便后续用于其他用途。或者，PSE也可以利用Power via MDI TLV中的保留比特指示用于为PD供电的双绞线组，通过保留比特的不同取值指示不同的双绞线组。
可选的，PSE也可以在与PD进行LLDP协商的过程中向PD发送供电方式(power model)TLV。power model TLV可以专门用于指示PSE为PD供电所采用的双绞线,通过power model TLV的不同取值来指示用于为PD供电的不同双绞线组。所述power model TLV的长度可以为一个字节。当power model TLV的首比特取值为1时，表示PSE将同时使用两个双绞线组为PD供电。当power model TLV的首比特取值为0时，表示PSE将使用预定双绞线组为PD供电，其中，所述预定双绞线组既可以是第一双绞线组；也可以是第二双绞线组。
为避免由于输出功率不稳定造成PSE在采用两个双绞线组供电与采用一个双绞线组供电之间来回切换，PSE可以在输出功率小于第一预定功率的状态持续预定时长后，再使用一个双绞线组为所述PD供电。
步骤104，受电设备以MPS方式用所述两个线对从所述供电设备抽电维持所述受电设备与所述供电设备之间的供电状态。
在PSE保留一个双绞线组为PD供电后，PD可以持续用该双绞线组从PSE抽电，也可以以MPS方式从该双绞线抽电。
由于PD仅可以用该双绞线组中的两个线对从PSE抽电，因此该双绞线组两个线对中的电流就是PD从PSE抽电的总电流。如果PD以MPS方式从PSE抽电，那么仅会在该双绞线组所包含的两个线对中存在抽电电流，当PD从PSE抽电的总电流大于10mA时，该双绞线组所包含的两个线对中的电流也会大于10mA，使得该双绞线组所包含的两个线对中的电流可以满足MPS的要求，从而可以维持PSE与PD之间处于供电状态。
由于在用所述两个线对为所述受电设备供电的过程中，PSE仅保留一个双绞线组为PD供电，因此PD仅能通过两个线对从PSE抽电，因此在PD以MPS方式从PSE抽电时，用于为PD供电的两个线对中，实际电流可以到达维持PSE与PD之间持续处于供电状态的要求，从而可以避免PD在处于空闲状态时发生掉电。
如果受电设备不以MPS方式从PSE抽电，例如受电设备停止抽电，则PSE停止为PD供电。
采用本实施所提供的方式，供电设备可以在受电设备的功率需求较小时，仅保留两个线对为受电设备供电，使受电设备以MPS方式从供电设备抽电所形成的维持电流只存在于两个线对之中，从而避免因线对中的实际电流达不到维持供电设备与受电设备之间持续处于供电状态的要求而导致受电设备掉电的问题。
当所述PD从空闲状态进入工作状态时，PD可以根据自身的功率需求从所述PSE抽电。由于PD在处于空闲状态时，PSE仅保留一个双绞线组的两个线对为PD供电。为避免因PD的功率需求超出PSE使用一个双绞线组供电时的供电能力，导致供电过程出现问题，PSE可以在PD从空闲状态进入工作状态时恢复使用两个双绞线组，即四个线对，为PD供电。可选地，在步骤104之后，还可以包括：
步骤105，在所述供电设备使用两个线对为所述受电设备供电的过程中，所述供电设备检测到所述以太网端口的输出功率以得到第二输出功率。
在使用一个双绞线组为PD供电的过程中，PSE可以检测所述以太网端口的输出功率以得到第二输出功率。其中，第二输出功率可以等于所述PD用一个双绞线组从所述PSE抽电的功率加上在电力在通过以太网线传输过程中损耗的功率。
其中，所述供电设备使用两个线对为所述受电设备供电的过程，既可以包括PD以MPS方式用两个线对从PD抽电的过程，也可以包括PD用两个线对持续从PD抽电的过程。
步骤106，如果由于受电设备提升从所述供电设备抽电的功率，使得所述第二输出功率高于第二预定功率，所述供电设备用所述四个线对为所述受电设备供电。
所述PD可以首先提升从所述PSE抽电的功率提高至第二预定功率以上，从而使PSE可以获知PD将要从空闲状态进入工作状态。
其中，第二预定功率大于等于第一预定功率，并小于等于PSE通过一个双绞线组为PD供电时所能提供的最大供电功率。通常情况下，所述第二预定功率小于所述PD在工作状态时实际的功率需求。可选地，为避免由于输出功率不稳定造成PSE在采用一个双绞 线组供电与采用两个双绞线组供电之间频繁切换，所述第二预定功率可以大于第一预定功率。例如，当所述第一预定功率为1w时，所述第二预定功率可以是2w。
所述PD将从所述PSE抽电的功率提高至第二预定功率以上会导致所述以太网端口的输出功率,即第二输出功率，高于第二预定功率。如果所述第二输出功率高于第二预定功率，则说明所述PD将要从空闲状态转换为工作状态，为保证供电效率和供电能力，PSE可以恢复使用所述四个线对为所述受电设备供电。
为避免PSE在采用一个双绞线组为PD供电与采用两个双绞线组为PD供电之间频繁切换，还可以预先设定一个或多个预定条件。所述第二输出功率高于第二预定功率，并且满足所述预定条件时，PSE再恢复使用四个线对为PD供电。
例如，所述预定条件可以为所述第二输出功率在预定时长内未发生变。所述PSE可以在所述第二输出功率高于第二预定功率并且在预定时长内未发生变时，再恢复使用四个线对为PD供电。第二输出功率在预定时长内的变化幅度小于预定幅度时，可以认为所述第二输出功率在预定时长内未发生变化。
在恢复使用四个线对为PD供电之前，PSE还可以向受电设备发送第二供电方式通知，所述第二供电方式通知用于指示所述供电设备将用所述四个线对为所述受电设备供电。其中，所述第二供电方式通知可以由PSE通过Power-via-MDI TLV的指定比特或power model TLV向所述受电设备发送。具体方式可以参见前述第一供电方式通知的相关内容，在此就不再赘述。
在恢复使用两个双绞线组为所述PD用电之后，PSE还可以继续监测自所述以太网端口的输出功率以得到第一输出功率，并在所述第一输出功率低于第一预定功率时，则所述供电设备用所述四个线对中的两个线对为所述受电设备供电。具体过程可以参见步骤102至步骤104，在此就不再赘述。
在PSE恢复使用四个线对为PD供电之后，PD可以按照自身的功率需求用四个线对从PSE抽电。其中，PD的功率需求可以大于所述第二预定功率，也可以小于或等于所述第二预定功率。
例如，如果所述PSE在处于工作状态是的功率需求为40W，当PD在需要从空闲状态切换到工作状态时，如果PSE用一个双绞线组为PD供电，那么PD可以首先将用一个双绞线组从PSE抽电的功率提升到15W；等所述PSE切换为使用两个双绞线组为PSE供电时，PD可以再将从PSE抽电的功率提升到40W。其中，15W及40W均为举例说明，在实际使用中也可以为其他功率值。
采用本实施例，PSE可以在PD的功率需求较高时，恢复使用两个双绞线组为PD供电，从而提高供电效率，满足PD的功率需求。
参见图2，为本申请PSE一个实施例的结构示意图。其中，用于虚线表示的部分为可选部分。所述PSE也可以不包括虚线部分所包含的电路及电路之间的连接关系。
如图2所示，所述PSE可以包括：供电电路201及以太网端口202；所述以太网端口202包括四个线对，其中，所述四个线对与单个受电设备连接；所述供电电路201和所述以太网端口202连接；所述供电电路201，用于用所述四个线对为所述受电设备供电，检测所述以太网端口202的输出功率以得到第一输出功率，以及在所述第一输出功率低于第一预定功率时，用所述四个线对中的两个线对为所述受电设备供电。
可选的，所述供电电路201，还用于检测所述以太网端口202的输出功率以得到第二输出功率；以及在所述第二输出功率高于第二预定功率时，用所述四个线对为所述受电设备供电。采用此实现方式，供电设备可以从使用两个线对为受电设备的供电，改变为使用四个线对为受电设备供电，从而可以满足受电设备的功耗需求。
所述供电电路201，包括PSE芯片与电源。图2中的实线所示，所述电源和所述PSE芯片连接，并向所述PSE芯片供电。图2种以虚线表示供电电路201的一种可选结构。该结构中，PSE芯片控制电源为以太网端口供电。PSE芯片也可以直接为以太网端口供电，这种情况中的供电电路201的结构较为简单，不另外提供示意图。
如果PSE芯片直接为以太网端口供电，所述PSE芯片和所述以太网端口202连接(图中未示出)。所述PSE芯片，用于用所述四个线对为所述受电设备供电，检测所述以太网端口202的输出功率以得到第一输出功率，以及在所述第一输出功率低于第一预定功率时，用所述四个线对中的两个线对为所述受电设备供电。所述PSE芯片，还可以用于检测所述以太网端口202的输出功率以得到第一输出功率，以及在所述第二输出功率高于第二预定功率时，用所述四个线对向所述四个线对供电。
如果PSE芯片可以控制电源为以太网端口供电，所述供电电路201，还包括开关电路。如图2中的虚线部分所示，所述电源经由所述开关电路和所述以太网端口202连接，并向所述以太网端口202的所述四个线对供电；所述PSE芯片，用于检测所述以太网端口202的输出功率以得到第一输出功率，以及在所述第一输出功率低于第一预定功率时，控制所述开关电路以使所述电源向所述四个线对中的两个线对供电。所述PSE芯片，还可以用于检测所述以太网端口202的输出功率以得到第二输出功率，以及在所述第二输出功率高于第二预定功率时，控制所述开关电路以使所述电源向所述四个线对供电。其中， 所述开关电路可以包括两个开关，每一个开关都可以被所述PSE芯片控制。可选的，其中一个开关用于控制第一个双绞线组与电源之间的电路通断，另一个开关用于控制第二双绞线组与电源之间的电路通断。可选的，其中一个开关为总开关，用于控制两个双绞线组与电源之间的电路通断，另一个开关仅用于单独控制所述两个双绞线组其中之一与电源之间的电路通断。所述开关可以是金属氧化物半导体场效应管(英文：metal–oxide–semiconductor field-effect transistor，缩写：MOSFET)，也可以是其他有开关功能的器件，例如结型场效应管(英文：junction gate field-effect transistor，缩写：JFET)或者双极性结型晶体管(英文：bipolar junction transistor，缩写：BJT)等。
可选的，所述PSE还可以包括：处理器，用于通过所述以太网端口202向所述受电设备发送第一供电方式通知，所述第一供电方式通知用于指示所述供电设备将使用所述两个线对为所述受电设备供电。所述处理器，还可以用于通过所述以太网端口202向所述受电设备发送第二供电方式通知，所述第二供电方式通知用于指示所述供电设备将使用所述四个线对为所述受电设备供电。
参见图3，为本申请PD一个实施例的结构示意图。
如图3所示，所述PD包括：受电电路301及以太网端口302。
所述以太网端口302包括四个线对，其中，所述四个线对与供电设备连接；所述受电电路301和所述以太网端口302连接；所述受电电路301，用于用四个线对从所述供电设备抽电；在用四个线对从所述供电设备抽电的过程中，将从所述供电设备抽电的功率降低至第一预定功率以下，以使所述供电设备使用所述四个线对中的两个线对为所述受电设备供电；以MPS方式用所述两个线对从所述供电设备抽电以维持所述受电设备与所述供电设备之间的供电状态。
可选的，所述受电电路301，还用于将从所述供电设备抽电的功率提高至第二预定功率以上，以使所述供电设备使用所述四个线对为所述受电设备供电，其中，所述第二预定功率大于或等于所述第一预定功率；用四个线对从供电设备抽电。其中，所述受电电路可以包括PD芯片，直流变换电路等，从而可以根据所述PD中各电路元件的需求为各电路元件供电。
本申请中的技术方案可以以软件产品的形式体现出来，该软件产品可以存储在存储介质中，如只读存储器(ROM)、随机存取存储器(RAM)、磁碟、光盘等，包括若干指 令用以使得一台计算机设备(可以是个人计算机，服务器，或者网络设备等)执行本申请各个实施例或者实施例的某些部分所述的方法。
本说明书中的各个实施例之间相同相似的部分互相参见即可。以上所述的本申请实施方式，并不构成对本申请保护范围的限定。

Claims (10)

  1. 一种以太网供电方法，其特征在于，包括：
    供电设备用一个以太网端口的四个线对为连接到所述以太网端口的单个受电设备供电；
    所述供电设备检测所述以太网端口的输出功率以得到第一输出功率；
    在所述第一输出功率低于第一预定功率时，所述供电设备用所述四个线对中的两个线对为所述受电设备供电。
  2. 如权利要求1所述的方法，其特征在于，在所述供电设备用所述四个线对中的两个线对为所述受电设备供电之前，还包括：
    所述供电设备向所述受电设备发送第一供电方式通知，所述第一供电方式通知用于指示所述供电设备将使用所述两个线对为所述受电设备供电。
  3. 如权利要求2所述的方法，其特征在于，
    所述第一供电方式通知为经由介质相关接口供电类型-长度-值(TLV)中的指定比特；或
    所述第一供电方式通知为供电方式TLV。
  4. 一种以太网供电方法，其特征在于，包括：
    受电设备用四个线对从供电设备抽电；
    所述受电设备将用四个线对从所述供电设备抽电的功率降低至第一预定功率以下，以使所述供电设备使用所述四个线对中的两个线对为所述受电设备供电；
    所述受电设备以维持功率特征(MPS)方式用所述两个线对从所述供电设备抽电，以维持所述受电设备与所述供电设备之间的供电状态。
  5. 如权利要求4所述的方法，其特征在于，还包括：
    所述受电设备将用所述两个线对从所述供电设备抽电的功率提高至第二预定功率以上，以使所述供电设备使用所述四个线对为所述受电设备供电，其中，所述第二预定功率大于或等于所述第一预定功率；
    在符合预定条件时，所述受电设备用四个线对按照功率需求从供电设备抽电。
  6. 一种以太网供电设备(PSE)，其特征在于，包括：供电电路及以太网端口；
    所述以太网端口包括四个线对，其中，所述四个线对与单个受电设备连接；
    所述供电电路和所述以太网端口连接；
    所述供电电路，用于用所述四个线对为所述受电设备供电，检测所述以太网端口的输出功率以得到第一输出功率，以及在所述第一输出功率低于第一预定功率时，用所述四个线对中的两个线对为所述受电设备供电。
  7. 如权利要求6所述的PSE，其特征在于，还包括：
    处理器，用于通过所述以太网端口向所述受电设备发送第一供电方式通知，所述第一供电方式通知用于指示所述供电设备将使用所述两个线对为所述受电设备供电。
  8. 如权利要求6或7所述的PSE，其特征在于，
    所述供电电路，包括PSE芯片、开关电路与电源；
    所述电源经由所述开关电路和所述以太网端口连接，并向所述以太网端口的所述四个线对供电；
    所述PSE芯片，用于检测所述以太网端口的输出功率以得到第一输出功率，以及在所述第一输出功率低于第一预定功率时，控制所述开关电路以使所述电源向所述四个线对中的两个线对供电。
  9. 如权利要求6或7所述的PSE，其特征在于，
    所述供电电路，包括PSE芯片与电源；
    所述电源和所述PSE芯片连接，并向所述PSE芯片供电；
    所述PSE芯片和所述以太网端口连接；
    所述PSE芯片，用于用所述四个线对为所述受电设备供电，检测所述以太网端口的输出功率以得到第一输出功率，以及在所述第一输出功率低于第一预定功率时，用所述四个线对中的两个线对为所述受电设备供电。
  10. 一种以太网受电设备(PD)，其特征在于，包括：受电电路及以太网端口；
    所述以太网端口包括四个线对，其中，所述四个线对与供电设备连接；
    所述受电电路和所述以太网端口连接；
    所述受电电路，用于用四个线对从所述供电设备抽电；在用四个线对从所述供电设备抽电的过程中，将从所述供电设备抽电的功率降低至第一预定功率以下，以使所述供电设备使用所述四个线对中的两个线对为所述受电设备供电；以维持功率特征(MPS)方式用所述两个线对从所述供电设备抽电以维持所述受电设备与所述供电设备之间的供电状态。
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