JP2009159729A - Dc power distribution system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the deterioration of the efficiency of a system as a whole, caused by the effects of conversion loss in an DC/DC converter. <P>SOLUTION: When the input voltage V2 of the DC/DC converter 1 is below a threshold voltage Vth, an operation start signal is output from a control circuit 30 to a drive circuit 10 to start the operation of the DC/DC converter 1. When the output voltage V2 is higher than the threshold voltage Vth, an operation stop signal is output from the control circuit 30 to the drive circuit 10, to stop the operation of the DC/DC converter 1. While the DC/DC converter 1 is stopped, power is supplied to a load through a bypass circuit 2. The DC/DC converter 1 is operated, only when it is necessary; while it is stopped , when it is not necessary, thus enabling suppression of deterioration in the efficiency of the system as a whole, caused by effects of the conversion loss in the DC/DC converter 1. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a DC power distribution system.

  2. Description of the Related Art Conventionally, there has been provided a DC power distribution system that distributes indoors DC power obtained by AC / DC conversion of AC power supplied from a power system (commercial power system) (see, for example, Patent Document 1).

In the DC power distribution system described in Patent Document 1, in addition to the AC / DC converter (AC / DC converter) and the secondary battery, the DC voltage output from the AC / DC converter or the secondary battery is set to a desired level. A distribution board that houses a DC / DC converter (DC / DC converter) for converting to a DC voltage in an insulating container in the same form as the branch switch was built in the distribution board.
Japanese Patent Laying-Open No. 2005-224066 (FIG. 6, paragraph 0028)

  By the way, in the above conventional example, since the DC voltage of the DC power system is boosted to a desired level by the DC / DC converter and supplied to the load, a capacity higher than the total power consumed by all the loads is required. there were. For this reason, there is a problem that the influence of the loss in the DC / DC converter is relatively large and the efficiency of the entire system is lowered, and the DC / DC converter is enlarged.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a DC distribution system capable of suppressing a reduction in efficiency of the entire system due to the influence of loss in the DC / DC converter and miniaturizing the DC / DC converter. It is to provide.

  In order to achieve the above object, the invention according to claim 1 converts the DC voltage input to the input terminal into a DC voltage of a desired level by connecting the input terminal in parallel to the power supply path from the DC power system to the load. A step-down DC / DC converter that outputs from an output terminal connected in series to the power supply path, and a DC / DC converter that monitors the input voltage of the DC / DC converter and the input voltage exceeds a predetermined threshold value. A control device for stopping the conversion device and a bypass circuit connected in parallel to the output terminal of the DC / DC conversion device and conducting when the DC / DC conversion device is stopped are provided.

  According to the first aspect of the present invention, since the DC voltage output from the DC / DC converter is superimposed on the DC voltage of the DC power system and supplied to the load, the DC voltage of the DC power system is converted by the DC / DC converter. Compared to boosting the voltage to the desired level and supplying power to the load, the power capacity required for the DC / DC converter is reduced, and the load power is supplied mainly through the bypass circuit, reducing the loss in the DC / DC converter. Can be reduced. As a result, it is possible to suppress a reduction in the efficiency of the entire system due to the influence of loss in the DC / DC converter, and to reduce the size of the DC / DC converter.

  According to a second aspect of the present invention, in the first aspect of the invention, the bypass circuit has an anode connected to the output terminal on the low potential side of the DC / DC converter and the output terminal on the high potential side of the DC / DC converter. It consists of a diode to which a cathode is connected.

  According to the invention of claim 2, since the configuration of the bypass circuit can be simplified and the power supply of the bypass circuit is unnecessary, it is possible to further suppress the reduction in the efficiency of the entire system.

  ADVANTAGE OF THE INVENTION According to this invention, while the efficiency fall of the whole system by the influence of the loss in a DC / DC converter can be suppressed, a DC / DC converter can be reduced in size.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

The DC power distribution system of the present embodiment is connected to a main switch MB connected to a power system (commercial power system) AC as shown in FIG. 2 and a plurality of branch paths branched through the main switch MB. A main distribution board PB1 that houses therein an AC / DC converter AD that converts AC power supplied from the power system AC to the DC power via a plurality of branch switches SB1, the main switch MB, and a distribution path Lp Are provided with a plurality of distributed distribution boards PB2 ₁ , PB2 ₂ ,... Each storing therein a power conversion block DD connected to the output side of the AC / DC converter AD.

  The main distribution board PB1, for example, is configured by housing an AC / DC converter AD in a space (for example, a limiter space) of an internal unit in a general residential distribution board for AC distribution. AC power of 100 volts or 200 volts is distributed to the branch circuit branched through the branch switch SB1.

  The AC / DC converter AD is composed of a step-up, step-down or step-up / down converter circuit, and converts AC power of 100 volts or 200 volts into DC power of a desired level (for example, 24 volts). That is, in this embodiment, the DC power system is realized by converting AC power supplied from the commercial power system AC into DC power by the AC / DC converter AD. However, since such an AC / DC converter AD is well known in the art, detailed illustration and description thereof will be omitted.

All the power conversion blocks DD housed in each of the distributed distribution boards PB2 _n (n = 1, 2,...) Have the same configuration. As shown in FIG. 2, the power conversion block DD has input terminals T1 and T1 connected in parallel to a power supply path from a DC power system to a load, and applies a DC voltage V1 input to the input terminals T1 and T1 to a desired level. A step-down DC / DC converter 1 that converts to DC voltage V2 and outputs it from output terminals T2 and T2 connected in series to the power supply path, and a diode that is connected in parallel to output terminals T2 and T2 of DC / DC converter 1 And a control device 3 that controls on / off of the operation of the DC / DC converter 1.

  The DC / DC converter 1 includes a conventionally known flyback converter circuit having a flyback transformer T, a diode D, a smoothing capacitor C0, and a switching element Q, and is input by switching the switching element Q at a high frequency by a driving circuit 10. An output voltage V2 having a desired level lower than the voltage V1 is generated. Here, a smoothing capacitor C1 is connected to the power supply path in parallel with the output terminals T2 and T2, and the output voltage V2 of the DC / DC converter 1 is superimposed on the voltage V1 across the smoothing capacitor C1, so that V1 + V2. The DC voltage is supplied to the load as the output voltage of the power conversion block DD. When the DC / DC converter 1 is stopped, the bypass circuit 2 is turned on to bypass the output terminals T2 and T2 of the DC / DC converter 1, and the DC voltage V1 is supplied to the load. It will be.

  The control device 3 includes an amplifier AP that outputs a signal corresponding to the difference between the output voltage V1 + V2 and the reference voltage Vr, a comparator CP that compares the DC voltage V1 of the DC power system with a predetermined threshold Vth, and a control signal ( The switching element Q is PWM controlled via the drive circuit 10 so that the output signal of the amplifier AP becomes almost zero by transmitting the PWM signal), and the operation of the drive circuit 10 is turned on / off according to the output of the comparator CP. And a control unit 30. Here, if the voltage required for the load is, for example, 24 volts, the reference voltage Vr is set to the voltage of 24 volts, and the threshold voltage Vth is a value lower than the voltage, for example, 20 volts. Set to Therefore, the comparator CP outputs a high level signal if the input voltage V1 is equal to or higher than the threshold voltage Vth, and outputs a low level signal if the input voltage V1 is less than the threshold voltage Vth.

  In the control unit 30, when a low level signal is output from the comparator CP, a PWM signal is output to the drive circuit 10 to operate the DC / DC converter 1 so that the output of the amplifier AP becomes zero. PWM control is performed, and when the high level signal is output from the comparator CP, the DC signal is not output to the drive circuit 10 to stop the DC / DC converter 1.

  Here, the degree of decrease in the input voltage V1 of the power conversion block DD (DC / DC conversion device 1) changes according to the wiring length of the distribution path Lp from the AC / DC conversion device AD to the power conversion block DD, As the power consumption of the load increases, the amount of current flowing through the distribution path Lp increases and the voltage drop in the distribution path Lp also increases. However, when the voltage drop in the distribution line Lp is large due to a large power consumption in the load (heavy load) or the like, the input voltage V1 of the DC / DC converter 1 is lower than the threshold voltage Vth, so that the output of the comparator CP is When the control unit 30 operates the DC / DC converter 1, the output voltage V2 obtained by stepping down the input voltage V1 is superimposed on the load. On the other hand, when the voltage drop in the distribution line Lp is small due to low power consumption at the load (light load) or the like, the input voltage V1 of the DC / DC converter 1 becomes equal to or higher than the threshold voltage Vth, so the output of the comparator CP Becomes a high level, and the controller 30 stops the DC / DC converter 1 by not outputting the PWM signal to the drive circuit 10.

  Thus, since the DC voltage V2 output from the DC / DC converter 1 is superimposed on the DC voltage V1 of the DC power system and fed to the load, the DC voltage V1 of the DC power system is boosted DC / DC converted. Compared with the case where the device boosts the voltage to a desired level and supplies power to the load, the power capacity required for the step-down DC / DC converter 1 is reduced, and the load power is mainly supplied through the bypass circuit 2 so that direct current is supplied. / Loss in DC converter 1 is reduced. As a result, the efficiency reduction of the entire system due to the influence of the loss in the DC / DC converter 1 can be suppressed, and the DC / DC converter 1 can be downsized. In addition, since the operation of the DC / DC converter 1 is turned on / off by the control device 3, the DC / DC converter 1 is operated only when necessary, and the DC / DC converter 1 is stopped when unnecessary. As a result, it is possible to further suppress a decrease in efficiency of the entire system due to the influence of loss in the DC / DC converter 1. In the present embodiment, the bypass circuit 2 is constituted by a diode, and the configuration of the bypass circuit 2 can be simplified and the power supply of the bypass circuit 2 is unnecessary, so that the reduction in efficiency of the entire system can be further suppressed. There is.

  Here, FIG. 3 shows another system configuration example of the DC power distribution system according to the present invention. The system is applied to various houses H such as detached houses and apartment houses. In this house H, a DC power supply unit 101 that outputs DC power and a DC device 102 as a load driven by DC power are provided, and a DC supply line connected to the output end of the DC power supply unit 101 DC power is supplied to the DC device 102 through Wdc. A current flowing through the DC supply line Wdc is monitored between the DC power supply unit 101 and the DC device 102. When an abnormality is detected, power is supplied from the DC power supply unit 101 to the DC device 102 on the DC power supply line Wdc. A DC breaker 114 is provided for limiting or blocking the current.

  The DC supply line Wdc is used as both a DC power supply path and a communication path, and is connected to the DC supply line Wdc by superimposing a communication signal for transmitting data on a DC voltage using a high-frequency carrier wave. Enables communication between devices. This technique is similar to a power line carrier technique in which a communication signal is superimposed on an AC voltage in a power line that supplies AC power.

  The DC supply line Wdc is connected to the home server 116 via the DC power supply unit 101. The in-home server 116 is a main device for constructing a home communication network (hereinafter referred to as “home network”), and communicates with a subsystem constructed by the DC device 102 in the home network.

  In the example shown in the drawing, as an subsystem, an illumination system comprising an information equipment system K101 comprising an information-system DC device 102 such as a personal computer, a wireless access point, a router, and an IP telephone, and an illumination system DC equipment 102 such as a lighting fixture. K102, K105, an intercom system K103 including a DC device 102 for handling visitors and monitoring intruders, a residential alarm system K104 including a DC device 102 for an alarm system such as a fire detector, and the like. Each subsystem constitutes a self-supporting distributed system, and can operate even with the subsystem alone.

  The DC breaker 114 described above is provided in association with a subsystem. In the illustrated example, four DC breakers are associated with the information equipment system K101, the lighting system K102 and the intercom system K103, the house alarm system K104, and the lighting system K105. 114 is provided. When a plurality of subsystems are associated with one DC breaker 114, a connection box 121 for dividing the system of the DC supply line Wdc is provided for each subsystem. In the illustrated example, a connection box 121 is provided between the illumination system K102 and the intercom system K103.

  As the information equipment system K101, there is provided an information equipment system K101 composed of a DC equipment 102 connected to a DC outlet 131 arranged in advance in the house H (constructed when the house H is constructed) in the form of a wall outlet or a floor outlet.

  The lighting systems K102 and K105 include a lighting system K102 including a lighting fixture (DC device 102) arranged in advance in the house H, and a lighting fixture (DC device 102) connected to a hook ceiling 132 arranged in advance on the ceiling. An illumination system K105 is provided. At the time of interior construction of the house H, the contractor attaches the lighting fixture to the hook ceiling 132, or the resident himself attaches the lighting fixture.

  In addition to using an infrared remote control device, a control instruction for the lighting apparatus that is the DC device 102 constituting the lighting system K102 can be given using a communication signal from the switch 141 connected to the DC supply line Wdc. That is, the switch 141 has a communication function together with the DC device 102. In addition, a control instruction may be given by a communication signal from another DC device 102 in the home network or the home server 116 regardless of the operation of the switch 141. The instructions to the lighting fixture include lighting, extinguishing, dimming, and blinking lighting.

  Since any DC device 102 can be connected to the DC outlet 131 and the hooking ceiling 132 described above and DC power is output to the connected DC device 102, the DC outlet 131 and the hooking ceiling 132 are distinguished below. When it is not necessary, it is called “DC outlet”.

  These DC outlets have a plug-in connection port into which a contact (not shown) provided directly on the DC device 102 or a contact (not shown) provided via a connection line is inserted into the body. The contact receiver that directly contacts the contact inserted into the connection port is held by the container. That is, the direct current outlet supplies power in a contact manner. When the DC device 102 connected to the DC outlet has a communication function, a communication signal can be transmitted through the DC supply line Wdc. A communication function is provided not only in the DC device 102 but also in the DC outlet.

  The home server 116 not only is connected to the home network, but also has a connection port connected to the wide area network NT that constructs the Internet. When the in-home server 116 is connected to the wide area network NT, it is possible to receive services from the center server 200 that is a computer server connected to the wide area network NT.

  The service provided by the center server 200 includes a service that enables monitoring and control of equipment (including mainly the DC equipment 102 but also other equipment having a communication function) connected to the home network through the wide area network NT. is there. This service makes it possible to monitor and control devices connected to the home network using a communication terminal (not shown) having a browser function such as a personal computer, Internet TV, or mobile phone.

  The in-home server 116 has both functions of communication with the center server 200 connected to the wide area network NT and communication with equipment connected to the home network, and identification information on equipment in the home network ( Here, it is assumed that an IP address is used).

  The home server 116 enables monitoring and control of home devices through the center server 200 from a communication terminal connected to the wide area network NT by using a communication function with the center server 200. The center server 200 mediates between home devices and communication terminals on the wide area network NT.

  When monitoring and controlling home devices from a communication terminal, monitoring and control requests are stored in the center server 200, and the home device periodically performs one-way polling communication to monitor from the communication terminal. And receive control requests. With this operation, it is possible to monitor and control devices in the house from the communication terminal.

  Further, when an event that should be notified to the communication terminal, such as a fire detection, occurs in the home device, the home device notifies the center server 200, and the center server 200 notifies the communication terminal by e-mail.

  An important function among the communication functions with the home network in the home server 116 is the detection and management of devices constituting the home network. The home server 116 automatically detects devices connected to the home network by applying UPnP (Universal Plug and Play). The home server 116 includes a display device 117 having a browser function, and displays a list of detected devices on the display device 117. The display device 117 has a configuration with a touch panel type or an operation unit, and can perform an operation of selecting desired contents from options displayed on the screen of the display device 117. Therefore, the user (contractor or householder) of the home server 116 can monitor or control the device on the screen of the display device 117. The display device 117 may be provided separately from the home server 116.

  The in-home server 116 manages information related to device connection, and grasps the type, function, and address of the device connected to the home network. Accordingly, the devices in the home network can be operated in conjunction with each other. Information on the connection of the device is automatically detected as described above. In order to operate the device in an interlocking manner, the device itself is automatically associated with the attribute held by the device itself, and the home server 116 is configured as a personal computer. It is also possible to connect various information terminals and use the browser function of the information terminals to associate devices.

  Each device holds the relationship of the interlocking operation of the devices. Therefore, the device can operate in an interlocked manner without passing through the home server 116. By associating the linked operations for each device, for example, by operating a switch that is a device, it is possible to turn on or off the lighting fixture that is the device. In many cases, the association of the interlocking operations is performed within the subsystem, but the association beyond the subsystem is also possible.

  By the way, the DC power supply unit 101 basically generates DC power by power conversion of an AC power supply AC supplied from outside the house like a commercial power supply. In the configuration shown in the figure, the AC power source AC is input to an AC / DC converter 112 including a switching power source through a main circuit breaker 111 attached to the distribution board 110 as an internal unit. The DC power output from the AC / DC converter 112 is connected to each DC breaker 114 through the cooperative control unit 113.

  The DC power supply unit 101 is provided with a secondary battery 162 in preparation for a period in which power is not supplied from the AC power supply AC (for example, a power failure period of the commercial power supply AC). It is also possible to use a solar cell 161 or a fuel cell 163 that generates DC power. The solar battery 161, the secondary battery 162, and the fuel battery 163 are distributed power supplies with respect to the main power supply including the AC / DC converter 112 that generates DC power from the AC power supply AC. In the illustrated example, the solar cell 161, the secondary battery 162, and the fuel cell 163 include a circuit unit that controls the output voltage, and the secondary battery 162 includes a circuit unit that controls charging as well as discharging.

  Of the distributed power sources, the solar cell 161 and the fuel cell 163 are not necessarily provided, but the secondary battery 162 is preferably provided. The secondary battery 162 is charged in a timely manner by a main power source or other distributed power source, and the secondary battery 162 is discharged not only in a period in which power is not supplied from the AC power source AC but also in a timely manner as necessary. The cooperation control unit 113 performs charge / discharge of the secondary battery 162 and cooperation between the main power source and the distributed power source. That is, the cooperative control unit 113 functions as a DC power control unit that controls the distribution of power from the main power supply and the distributed power supply constituting the DC power supply unit 101 to the DC devices 102. Note that a configuration may be adopted in which the outputs of the solar cell 161, the secondary battery 162, and the fuel cell 163 are converted into AC power and used as input power of the AC / DC converter 112.

  Since the driving voltage of the DC device 102 is selected from a plurality of types of voltages according to the device, the cooperative control unit 113 is provided with the DC / DC converter 1 of the present embodiment, the bypass circuit 2, and the control device 3 described above. The DC voltage obtained from the main power supply and the distributed power supply is converted to the required voltage. Normally, one type of voltage is supplied to one subsystem (or DC device 102 connected to one DC breaker 114), but three or more wires are used for one subsystem. A plurality of types of voltages may be supplied. Alternatively, it is possible to adopt a configuration in which the DC supply line Wdc is of a two-wire type and the voltage applied between the lines is changed with time. The DC / DC converter 1, the bypass circuit 2, and the control device 3 may be provided in a distributed manner in the same manner as the DC breaker 114.

  In the above configuration example, only one AC / DC converter 112 is illustrated, but a plurality of AC / DC converters 112 can be arranged in parallel, and when a plurality of AC / DC converters 112 are provided. It is desirable to increase or decrease the number of AC / DC converters 112 that are operated according to the magnitude of the load.

  The AC / DC converter 112, the cooperative control unit 113, the DC breaker 114, the solar cell 161, the secondary battery 162, and the fuel cell 163 described above are provided with a communication function, and include a main power source, a distributed power source, and a DC device 102. It is possible to perform cooperative operations that deal with the load status. The communication signal used for this communication is transmitted in the form of being superimposed on the DC voltage in the same manner as the communication signal used for the DC device 2.

  In the above example, the AC / DC converter 112 is arranged in the distribution board 110 in order to convert the AC power output from the main breaker 111 into DC power by the AC / DC converter 112. On the output side, a branch breaker (not shown) provided in the distribution board 110 branches the AC supply line into a plurality of systems, and an AC / DC converter is provided on the AC supply line of each system to convert it into DC power for each system. You may employ | adopt the structure to do.

  In this case, since the DC power supply unit 101 can be provided for each floor or room of the house H, the DC power supply unit 101 can be managed for each system, and the DC device 102 that uses DC power Since the distance of the DC supply line Wdc between the two is reduced, the power loss due to the voltage drop in the DC supply line Wdc can be reduced. Also, the main breaker 111 and the branch breaker are housed in the distribution board 110, and the AC / DC converter 112, the cooperative control unit 113, the DC breaker 114, and the home server 116 are housed in a separate board from the distribution board 110. Also good.

It is a block diagram of the principal part which shows embodiment of this invention. It is a system block diagram which shows the other system configuration same as the above. It is a system configuration | structure figure which shows other system configuration | structure same as the above.

Explanation of symbols

1 DC / DC converter 2 Bypass circuit 3 Controller

Claims (2)

  A step-down type that has an input terminal connected in parallel to the power supply path from the DC power system to the load, converts the DC voltage input to the input terminal into a DC voltage of a desired level, and outputs it from the output terminal connected in series to the power supply path A direct current / direct current converter, a control device that monitors the input voltage of the direct current / direct current converter and stops the direct current / direct current converter when the input voltage exceeds a predetermined threshold, and a direct current / direct current converter A DC power distribution system comprising: a bypass circuit connected in parallel to the output terminal and conducting when the DC / DC converter is stopped.   The bypass circuit includes a diode having an anode connected to an output terminal on a low potential side of the DC / DC converter and a cathode connected to an output terminal on a high potential side of the DC / DC converter. Item 5. A DC power distribution system according to item 1.

Images