JP4912269B2 - Power receiving device, power feeding device, and power transmission system - Google Patents

Description

  The present invention relates to a power transmission system that transmits power using a LAN cable.

  Conventionally, to supply power to devices connected to a LAN (Local Area Network) cable, an AC adapter is required, and an outlet is provided at the installation location of the device. Met. Under these circumstances, PoE (Power over Ethernet (registered trademark)) technology for supplying power using a twisted pair cable for transmitting data has been developed, and the standard IEEE 802.3af has been established. This technology is widely used in office IP (Internet Protocol) telephone systems, network camera systems, and the like.

  The PoE control flow defined by IEEE 802.3af is as follows. First, when a device is connected to a power supply port of a power supply device (Power Sourcing Equipment: PSE), the PSE determines whether the connected device is a power receiving device (Powered Device: PD) compliant with IEEE 802.3af. to decide. Specifically, the PSE applies a weak voltage (2.8 to 10 VDC) to the device. Since the PD conforming to the standard is supposed to mount a characteristic resistance of 25 kΩ for detection, the PSE can detect the characteristic resistance of the PD from the load current value, and further connected based on this result. It can be determined whether or not the device is a standard-compliant PD.

  When the connection of the PD is recognized in the above determination process, the PSE next applies 15.5 to 20.5 VDC to the power supply port, and measures the load current value at that time to determine the power class of the power supply. To do. The power class classifies the maximum power supplied to one port into several levels. The PD is designed such that when this voltage is applied, a load current corresponding to a specific power class flows by a constant current power source or a resistor.

  As described above, IEEE 802.3af defines a control flow in which the PSE executes detection processing at the moment when the PD is connected to the device itself, and then determines the power to be supplied to the power supply port. Therefore, even if the power consumption of the PD varies, the power class cannot be changed dynamically. Further, the power supply capacity that can be mounted on the PSE is limited due to cost and mounting limitations.

  From such a background, the actual PSE has a specification that sets an upper limit value of the power supply capacity commensurate with the cost, and stops supplying more power when a PD having a capacity exceeding that is connected.

  On the other hand, a technique for effectively utilizing the limited power supply capacity has been proposed. As an example, Patent Document 1 below describes a system that dynamically controls the power supply / stop of the PSE according to the operation status of the PD.

  Further, in Patent Document 2 below, when priority is set for a port and power demand exceeding the capability of the power supply device occurs, power supply to a port with a low priority is stopped, or power is supplied between a plurality of power supply devices. It describes a process that covers the shortage of power supply through interchange.

  As described above, in the systems disclosed in Patent Documents 1 and 2 below, when the power supply capacity of the PSE is exceeded, the power supply to some ports is stopped to effectively utilize the limited power to the maximum.

JP 2005-303593 A JP 2007-088809 A

  However, there is a problem that the method of stopping the power supply to some of the ports cannot be adopted for a system that needs to always supply power, such as a network camera system. In addition, the process described in Patent Document 2 is a process that functions only when a plurality of power supply apparatuses exist, and cannot be established by a single power supply apparatus.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a power transmission system capable of effectively utilizing limited power without stopping power supply to some ports. To do.

  In order to solve the above-described problems and achieve the object, the present invention provides a power receiving apparatus that receives power supply from a power supply apparatus in a power transmission system that performs data transmission and power supply using the same LAN cable. Power reception control means for requesting power lower than the maximum power consumption of the apparatus, power monitoring means for constantly measuring power consumption of the apparatus itself, power storage means capable of charging and discharging electric charge, and amount of power supplied based on the request And power control means for controlling power consumption of each part in the apparatus and charge / discharge by the power storage means based on the measurement result of the power consumption.

  According to the present invention, there is an effect that the power supply device can effectively use the limited power without stopping the power supply to some ports.

  Embodiments of a power transmission system according to the present invention will be described below in detail with reference to the drawings. In the following embodiment, as an example, the power feeding device (PSE) is a switching hub, and the power receiving device (PD) is a turning network camera. Note that the present invention is not limited to these embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a configuration example of a first embodiment of a network camera system to which a power transmission system according to the present invention is applied. The network camera system in the present embodiment includes a PoE switch (PSE) 1, a turning camera (PD) 2, and LAN cables 3-1 to 3-n, and the PoE switch 1 and the turning camera 2 are, for example, a LAN. Assume that the cables 3-2 are connected. In FIG. 1, only the turning camera 2 is shown as a PD, but other PDs may be connected.

  The PoE switch 1 includes power supply control units 10-1 to 10-n and power supply ports 11-1 to 11-n. The turning camera 2 includes a power receiving port 20, a power receiving control unit 21, a power storage device 22, a charge / discharge control unit 23, a power control unit 24, a power monitor 25, a camera control unit 26, a lens driving circuit 27, and a lens driving motor 28. And.

  Each power supply control unit of the PoE switch 1 supplies power to the PD via a corresponding power supply port. The LAN cable is a twisted pair cable conforming to IEEE 802.3af, and performs power transmission as well as data transmission.

  Since the turning camera 2 has a pan / tilt / zoom function and a function of driving a lens, the power consumption is higher than that of a fixed camera. The maximum power consumption is about 5 W in the case of a fixed network camera, and can be covered by Class 2 in the power class defined by IEEE 802.3af. On the other hand, in a revolving camera, the maximum power consumption exceeds 10 W due to the presence of the lens drive motor. FIG. 2 is a diagram showing a combination of PSE supply power and PD power consumption corresponding to each power class defined in IEEE 802.3af. According to this figure, the power class of the turning camera 2 needs to be set to Class 0 or 3.

  The power receiving port 20 receives power supply from the PoE switch 1 via a LAN cable. The power reception control unit 21 has a function of causing a load current value to flow so that the turning camera 2 is recognized as a power class corresponding to power lower than the maximum power consumption of the turning camera 2.

  The power storage device 22 is, for example, a secondary battery such as a battery, and can store and release charges. The charge / discharge control unit 23 controls charging and discharging by the power storage device 22. The power control unit 24 appropriately supplies power to each unit of the turning camera 2 based on a report from the power monitor 25 that constantly monitors the power consumption of the entire turning camera 2.

  The camera control unit 26 controls the turning camera 2. The lens driving circuit 27 and the lens driving motor 28 drive the lens under the control of the camera control unit 26.

  Next, the operation of the network camera system configured as described above will be described. For example, the turning camera 2 requires a large amount of power when driving the lens at high speed. That is, the scene (maximum power consumption state) that requires the maximum power in the turning camera 2 is very short, and the power consumption for most of the time is almost the same as the fixed camera (low power consumption state).

  Therefore, when the turning camera 2 is connected to the PoE switch 1, the power reception control unit 21 sets a load current (a power class identification load current value) at which a supply power smaller than the maximum power consumption 10W of the turning camera 2 is set. ) To the PoE switch 1, a power class lower than the power class corresponding to the maximum power consumption 10 W is requested. In the case of the turning camera 2 having a maximum power consumption of 10 W, Class 3 is conventionally set. However, in this embodiment, Class 2 is set by the PoE switch 1 by adjusting the load current value for power class identification, for example. So that

  The power monitor 25 constantly monitors the power consumption of the turning camera 2 while the turning camera 2 is connected to the network camera system. Therefore, while the power monitor 25 detects the low power consumption state, the power supply control unit 24 issues a command to the charge / discharge control unit 23 to charge. Then, the power supply control unit 24 controls the power supplied from the PoE switch 1 via the power receiving port 20 so that it is consumed by the camera control unit 26 and the like (S1 in FIG. 1). In addition, the charge / discharge control unit 23 transmits a signal instructing charging based on the command from the power supply control unit 24 to the power storage device 22, and the charging device 22 that has received this instruction charges the remaining power (FIG. 1). S2).

  On the other hand, when the power monitor 25 detects a temporary increase in power consumption due to the high-speed driving of the lens drive motor 28 and a power demand exceeding the set power class occurs, the power control unit 24 is notified accordingly. And the power supply control part 24 issues the instruction | indication which should discharge to the charging / discharging control part 23, and the charging / discharging control part 23 which received this outputs the signal which instruct | indicates discharge based on this instruction | indication in the electrical storage device 22 Send to. Thereby, even when the power demand exceeding the power class is generated, the insufficient power can be supplemented from the power storage device 22, so that the lens driving motor 28 can be operated smoothly (see FIG. 1 S3).

  Thereafter, the power supply control unit 24 determines whether or not the lens drive motor 28 is driven at high speed based on the notification from the power monitor 25 by determining whether or not the power consumption has become lower than the power corresponding to the set power class. Determine if it is finished. For example, when it is determined that the power consumption is low and the high-speed driving is finished, the power supply control unit 24 issues a command to the charge / discharge control unit 23 to charge again, Control to switch to charging.

  As described above, according to the present embodiment, a battery is provided inside the PD, and excess power is stored in the battery, thereby covering a shortage due to a temporary increase in power consumption of the PD. In other words, when the PD is connected to the PSE, power lower than the maximum power consumption of the PD is required. As a result, the PSE can effectively use the limited power of the PSE without stopping power supply to some ports and without having to exchange power among a plurality of PSEs.

  In the present embodiment, a turning camera has been described as an example of a PD having a large power consumption fluctuation. However, the present invention is not limited to this, and the power transmission control of the present embodiment can be applied to other types of PDs. It is.

Embodiment 2. FIG.
In the first embodiment, for a PD that is connected to a PoE switch and once set with a power class, the power class is maintained until the PD is disconnected from the system. In the present embodiment, a case will be described in which the power class of each PD is dynamically switched in accordance with the connection status of a plurality of PDs including a turning camera once connected to a PoE switch and once set with a power class. In the present embodiment, a configuration and operation different from those of the above-described first embodiment will be described.

  The network camera system according to the present embodiment includes a PoE switch 1B instead of the PoE switch 1 described above. FIG. 3 is a diagram illustrating a configuration example of the PoE switch 1B. The PoE switch 1B is different from the first embodiment in that it further includes a power control unit 12 and a command processing unit 13.

  The configuration of the turning camera of the second embodiment is the same as that of the turning camera 2 of the first embodiment, but in this embodiment, the power class of the PD is dynamically switched using the power reception control unit 21. FIG. 4 is a diagram illustrating a configuration example of the power reception control unit 21 of the turning camera 2. The power reception control unit 21 includes a command processing unit 31 and a load current control unit 32. In the following description, the turning camera 2 is shown and described as an example of a connected PD, but the constituent elements other than the camera control unit 26, the lens driving circuit 27, and the lens driving motor 28 are common to the other PDs. To prepare.

  Next, the operation of the network camera system configured as described above will be described. Here, it is assumed that a plurality of PDs are connected to the PoE switch 1B in the processing of the first embodiment, and a power class is once set for each PD.

  In this situation, for example, when the power control unit 12 of the PoE switch 1B determines that the number of PDs connected to each power supply port is small and there is room to supply the maximum power to all the connection ports, the PD The power class 0 shown in FIG. 2 is set for the power supply control unit of each port to which is connected. That is, each power supply control unit distributes power so that a maximum of 15.4 W can be supplied to the corresponding PD.

  When the power control unit 12 of the PoE switch 1B determines that the number of PDs connected to each power supply port increases and the maximum power is supplied to all the ports, the power processing unit 12 Request reduction of power supply. In the above, since power class 0 is set, for example, switching to power class 1 or 2 is requested.

  Hereinafter, the processing after the command processing unit 13 receives the supply power reduction request will be described with reference to FIG. FIG. 5 is a sequence diagram showing dynamic switching of power classes in the configuration of the second embodiment.

  The command processing unit 13 that has received the supply power reduction request first transmits a reduction request command for requesting reduction of the supply power to all PDs connected through the power supply ports (step ST1).

  The power reception control unit of each PD including the turning camera 2 receives the reduction request command, and the command processing unit 31 can reduce the supply power based on the monitoring result by the power monitor 25 notified from the power supply control unit 24. It is determined whether or not. For example, when the command processing unit 31 of the turning camera 2 determines that the current power consumption is low and the supply power can be reduced, the command processing unit 31 returns an Ack indicating that the supply power can be reduced to the PoE switch 1B (step ST2). . On the other hand, when it is determined that the lowering is impossible, Nack is returned to the PoE switch 1B. Here, the case where the turning camera 2 responds to the reduction of the supplied power will be described as an example. However, the present invention is not limited to this, and the operation is the same when one or more other PDs respond to the reduction.

  In this way, when it is determined that the turning camera 2 can be lowered and Ack is transmitted, the command processing unit 13 of the PoE switch 1B requests the turning camera 2 to switch to battery operation. A switching request command is transmitted (step ST3).

  The command processing unit 31 of the turning camera 2 that has received the battery operation switching request command instructs the power supply control unit 24 to switch the power supply source to the power storage device 22, and thereafter, the power supply control unit 24 performs the embodiment. 1, control for switching the power supply source to the power storage device 22 (switching control from charge to discharge) is performed. When the switching process is completed, the command processing unit 31 returns Ack indicating that the switching process is completed to the PoE switch 1B (step ST4).

  The command processing unit 13 of the PoE switch 1B that has received Ack indicating that the switching process has been completed notifies the power control unit 12 of the fact. And the electric power control part 12 which received this stops the electric power supply from an applicable electric power feeding control part.

  Further, after switching the power supply source in the above processing, the command processing unit 31 of the turning camera 2 changes the setting of the power class identification load current value to the load current control unit 32 simultaneously with the transmission of the switching completion Ack. Notify instructions. In order to identify a new power class (for example, Class 2), the load current control unit 32 changes the setting so that an appropriate power class identification load current can flow, and when the setting change is completed, the command processing unit 31 notifies that fact. Notice. Thereafter, the command processing unit 31 transmits Ack indicating completion of setting change of the power class identification load current value to the PoE switch 1B (step ST5).

  The command processing unit 13 of the PoE switch 1B that has received the setting change completion Ack notifies the power control unit 12 of the fact, and the power control unit 12 performs a new operation according to the PD detection / power class setting sequence based on IEEE 802.3af. The power class (for example, Class 2) is reset (step ST6). Then, when the setting of the new power class is completed, the power control unit 12 instructs the power supply control unit to which the turning camera 2 is connected to restart the power supply to the port. As a result, the power supply control unit resumes power supply (step ST7).

  At this time, in the turning camera 2 that has detected the resumption of power supply via the power receiving port 20, the power supply control unit 24 instructs the charge / discharge control unit 23 to stop discharging and stops battery operation (discharge → Charge switching control).

  Although the case where the supply power is reduced has been described here, for example, the case where the number of PDs connected to the PoE switch 1B is reduced and the supply power is increased can be realized by the same operation.

  As described above, according to the present embodiment, when the PD connection status changes and the supply power becomes insufficient, the PSE dynamically switches the power class of each PD according to the PD connection status. It was decided. At this time, the PD uses the built-in battery to switch the power class without stopping the operation. As a result, the power can be managed with higher accuracy, so that the power limited by the PSE can be utilized more effectively.

Embodiment 3 FIG.
In the first and second embodiments, in order to effectively use the power supplied by the PSE, a battery is provided in the PD, and the power supplied is set statically or dynamically low. In the third embodiment, a case will be described in which, in addition to the configuration of the second embodiment, a function of dynamically setting supply power in consideration of a power storage state is further provided. In the present embodiment, a configuration and operation different from those of the first and second embodiments will be described.

  FIG. 6 is a diagram illustrating a configuration example of the turning camera 2C. The turning camera 2C further includes a charge monitor 29 in addition to the configuration of the turning camera 2 of the second embodiment. Since other configurations are the same as those in the first or second embodiment, the same reference numerals are given and description thereof is omitted.

  The charge monitor 29 is connected to the charge / discharge control unit 23 and constantly monitors the charging state of the power storage device 22. When the charge monitor 29 detects that the remaining power of the power storage device 22 has become a predetermined value or less, the charge monitor 29 notifies the power reception control unit 21 to that effect.

  Next, the operation of the network camera system according to the present embodiment will be described. Here, for example, it is assumed that the power class of the turning camera 2C is set to Class2. In this state, when the charge monitor 29 detects that the remaining amount of charge of the power storage device 22 has become a predetermined value or less, the charge monitor 29 notifies the power reception control unit 21 to that effect (S4 in FIG. 6).

  Receiving the notification that the remaining charge is low, the power reception control unit 21 notifies the PoE switch 1B via the power receiving port 20 of a request for raising the supply power in order to secure power.

  On the PoE switch 1B side that has received the request for raising the supply power, if there is a margin in the power that can be supplied, the sequence after step ST3: “battery operation switching request” in the sequence diagram of FIG. Increase the power supplied to the. On the other hand, if there is no surplus power that can be supplied, step ST1: “power class reduction request” and subsequent operations in the sequence diagram of FIG. 5 are executed. If there is a PD that meets the request, supply to the turning camera 2C is performed. Increase power. When the power class is reset when the sequence is executed, the load current control unit 32 of the turning camera 2C determines an appropriate power class identification load in order to identify a new power class (for example, Class 0) with a large supply power. Change the setting to allow current to flow.

  As described above, according to the present embodiment, the power remaining amount of the power storage device provided in the PD is monitored, and control is performed so that the power storage device is always kept above a certain value. PD malfunction can be prevented.

  As described above, the power transmission system according to the present invention is useful for effectively using the power supplied from the power supply apparatus, and is particularly suitable for a network system in which the power reception apparatus must be constantly operated.

It is a figure which shows the structural example of the network camera system to which the electric power transmission system concerning this invention is applied. It is a table | surface of the power class corresponding to the combination of the power supplied of PSE and the power consumption of PD prescribed | regulated by IEEE802.3af. It is a figure which shows the structural example of a PoE switch. It is a figure which shows the structural example of the electric power reception control part of a turning camera. FIG. 10 is a sequence diagram of dynamic switching of power classes in the configuration of the second embodiment. It is a figure which shows the structural example of a turning camera.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,1B PoE switch 2,2C Turning camera 3-1 to 3-n LAN cable 10-1 to 10-n Feed control part 11-1 to 11-n Feed port 12 Power control part 13 Command processing part 20 Power receiving port 21 Power reception control unit 22 Power storage device 23 Charge / discharge control unit 24 Power supply control unit 25 Power monitor 26 Camera control unit 27 Lens drive circuit 28 Lens drive motor 29 Charge monitor 31 Command processing unit 32 Load current control unit

Claims (10)

In a power transmission system that performs data transmission and power supply using the same LAN cable, a power receiving device that receives power supply from a power feeding device,
Power reception control means for requesting power lower than the maximum power consumption of the device itself;
Power monitoring means for constantly measuring the power consumption of its own device;
An electric storage means capable of charging and discharging electric charge;
Based on the amount of power supplied based on the request and the measurement result of the power consumption, power control means for controlling power consumption of each part in the device and charge / discharge by the power storage means;
A power receiving device comprising:   The power control means performs control to charge the power storage means with surplus power, and performs control to switch the power storage means to discharge when the amount of power supplied based on the request is temporarily insufficient. The power receiving device according to claim 1.   The power reception control means requests a power class lower than the power class corresponding to the maximum power consumption as a power lower than the maximum power consumption of the own device in the power class setting process defined by the standard IEEE 802.3af. The power receiving device according to claim 1.   The power reception control means can appropriately change the load current for power class identification defined in the standard IEEE 802.3af based on the supply power change request from the power supply apparatus side and the measurement result by the power monitoring means. The power receiving device according to claim 1, 2, or 3. When the power reception control means determines that the load current for power class identification can be changed based on the supply power change request from the power supply apparatus side and the measurement result by the power monitor means,
The power control means includes
5. The power receiving device according to claim 4, wherein control is performed to discharge the power charged in the power storage unit over a power supply stop period associated with a power class change process by the power feeding device. Charge monitoring means for monitoring the remaining power of the power storage means;
Further comprising
The power reception control means includes
When it is detected that the remaining power of the power storage means has become a predetermined value or less, a switching request for requesting switching to a higher power class is transmitted to the power supply apparatus, and then the standard IEEE 802 6. The power receiving device according to claim 4, wherein a load current for power class identification specified in .3af is changed to a current value for recognizing the higher power class. A power supply device for supplying power to a single or a plurality of power receiving devices according to claim 4 or 5,
Power control means for controlling the amount of power supplied to each power receiving device;
With
The power control means transmits a supply power change request in response to a change in the connection status of the power receiving apparatus, and then at least one power receiving apparatus responds to the standard IEEE 802.3af in response to the supply power change request. A power supply device that performs control to switch the power class of the power receiving device based on the load current value after the change when the load current for identifying the specified power class is changed.   When a power class switching request is received from a power receiving apparatus and the power receiving apparatus changes the load current for power class identification specified in the standard IEEE 802.3af, the power receiving apparatus is based on the changed load current value. The power supply apparatus according to claim 7, wherein control is performed to switch the power class. A power receiving device according to claim 4 or 5,
A power feeding device according to claim 7,
A power transmission system comprising: The power receiving device according to claim 6;
A power feeding device according to claim 8,
A power transmission system comprising:

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