JP2017112744A - Current voltage conversion circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in the conventional current voltage conversion circuit that surplus power at a load is discharged as waste heat, causing a large device size.SOLUTION: A current voltage conversion circuit includes: a current voltage converter unit 11 which is connected between an input terminal Ti and an output terminal To, to convert a power supply current Ips, which is input through the input terminal Ti, into a load voltage VL to supply operation power to the load 2; and a power regeneration unit 12 which, during a period of the load voltage VL of the current voltage converter unit 11 being larger than a preset load voltage set value, produces a state of a reduced voltage difference between the output terminal To and the input terminal Ti, to regenerate surplus power to a power supply device 3 through the output terminal To, as regenerative power.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a current-voltage conversion circuit, and more particularly to a current-voltage conversion circuit that converts a current transmitted over a long distance into a voltage and supplies power to a load.

  In the long-distance DC power supply technology that supplies DC power to devices located far away, power is supplied with a constant current in order to suppress voltage attenuation in the transmission line. In this long-distance DC power feeding technique, a current-voltage conversion circuit that generates a voltage to be applied to a load from a current supplied on the device side is used. An example of this current-voltage conversion circuit is disclosed in Patent Document 1.

  A circuit diagram of the current-voltage conversion circuit 101 shown in FIG. 4 of Patent Document 1 is shown in FIG. As shown in FIG. 6, in Patent Document 1, a current supplied from a power feeding device 103 that performs constant current output is converted into a voltage by a Zener diode provided in a current-voltage conversion circuit 101. The voltage generated by the current-voltage conversion circuit 101 is applied to the load 102.

JP-A-7-115390

  However, in the technique described in Patent Document 1, when power is not consumed by the load 102 because the load 102 is in a stopped state, the power applied to the Zener diode becomes excessive and the Zener diode generates heat. Therefore, in the technique described in Patent Document 1, it is necessary to use a high power type element for the Zener diode, or to use a power Zener diode as the Zener diode. In addition, when the power consumption fluctuation of the load 102 is large, the above-mentioned measures are not sufficient, and a heat radiation resistor or the like that converts the fluctuation of the power consumption into heat energy and releases it is necessary. That is, the technique described in Patent Document 1 has a problem in that the device size of the current-voltage conversion circuit is increased in a device that receives power when the variation in power consumption of the load 102 is large.

  An aspect of the current-voltage conversion circuit according to the present invention is a current-voltage conversion circuit that converts a supply current transmitted from a power feeding device into a load voltage and supplies operating power to the load, and includes an input terminal, an output terminal, A current-voltage conversion unit that is connected between the input terminal and the output terminal, converts the feeding current input through the input terminal into the load voltage, and applies the operating power to the load; In the current-voltage converter, the surplus power is obtained after reducing the voltage difference between the output terminal and the input terminal during a period when the load voltage is larger than a preset load voltage setting value. A power regeneration unit that regenerates power to the power supply device as regenerative power through the output terminal, and is provided between the current-voltage conversion unit and the output terminal, and current from the output terminal side to the current-voltage conversion unit Reverse And a second current backflow prevention unit provided between the power regeneration unit and the output terminal to prevent current backflow from the output terminal side to the power regeneration unit. Part.

  ADVANTAGE OF THE INVENTION According to this invention, the apparatus size of the current-voltage conversion circuit which gives operating electric power to load based on the electric current transmitted by long-distance DC electric power feeding can be reduced in size.

1 is a block diagram of a long-distance DC power feeding system to which a current-voltage conversion circuit according to a first embodiment is applied. 1 is a circuit diagram of a current-voltage conversion circuit according to a first embodiment; 3 is a timing chart illustrating a first example of the operation of the current-voltage conversion circuit according to the first embodiment; 6 is a timing chart illustrating a second example of the operation of the current-voltage conversion circuit according to the first embodiment; 6 is a timing chart illustrating a third example of the operation of the current-voltage conversion circuit according to the first embodiment; 2 is a circuit diagram of a current-voltage conversion circuit described in Patent Document 1. FIG.

Embodiment 1
Embodiments of the present invention will be described below with reference to the drawings. For clarity of explanation, the following description and drawings are omitted and simplified as appropriate. Moreover, in each drawing, the same code | symbol is attached | subjected to the same element and duplication description is abbreviate | omitted as needed.

  FIG. 1 shows a block diagram of a long-distance DC power feeding system to which the current-voltage conversion circuit according to the first embodiment is applied. In the example illustrated in FIG. 1, the long-distance DC power supply system includes a plurality of current-voltage conversion circuits 1, a plurality of loads 2, a power supply device 3, a power supply wiring 4, and a return wiring 5. The power feeding device 3 is a constant current source that applies a constant current to the plurality of current-voltage conversion circuits 1, for example. In the long-distance DC power supply system of FIG. 1, the current output from the power supply device 3 is transmitted to the plurality of current-voltage conversion circuits 1 through the power supply wiring 4. The plurality of current-voltage conversion circuits 1 are arranged so as to be cascaded on the power supply wiring 4. In addition, the plurality of current-voltage conversion circuits 1 provide operating power to the corresponding power feeding devices 3. Among the plurality of current-voltage conversion circuits 1, the current-voltage conversion circuit 1 provided in the final stage and the power feeding device 3 are connected by a return wiring 5. The return wiring 5 is a wiring for regenerating the surplus power surplus in the plurality of current-voltage conversion circuits 1 to the power feeding device 3.

  The current-voltage conversion circuit 1 includes a current-voltage conversion unit 11, a power regeneration unit 12, a first current backflow prevention unit (for example, a diode D1), a second current backflow prevention unit (for example, a diode D2), and an input terminal. Ti, an output terminal To, a first load connection terminal TLp, and a second load connection terminal TLn.

  The current-voltage conversion unit 11 is connected between the input terminal Ti and the output terminal To, converts a feeding current input via the input terminal Ti into a load voltage, and gives operating power to the load 2. The power regeneration unit 12 reduces the voltage difference between the output terminal To and the input terminal Ti during the period when the load voltage VL is larger than the preset load voltage set value in the current-voltage conversion unit 11. The surplus power is regenerated to the power feeding device 3 as regenerative power via the output terminal. Further, the power regeneration unit 12 brings the voltage difference between the output terminal To and the input terminal Ti close to the load voltage setting value in a state where the regenerative power is not regenerated in the power feeding device 3. The diode D1 is provided between the current-voltage conversion unit 11 and the output terminal To, and prevents a backflow of current from the output terminal To side to the current-voltage conversion unit 11. The diode D2 is provided between the power regeneration unit 12 and the output terminal To, and prevents a backflow of current from the output terminal To side to the power regeneration unit 12. Hereinafter, the current-voltage conversion circuit 1 will be described in more detail.

  FIG. 2 shows a circuit diagram of the current-voltage conversion circuit according to the first embodiment. In the example shown in FIG. 2, only one current-voltage conversion circuit 1 is provided on the current path by the power supply wiring 4 and the return wiring 5 without cascading the current-voltage conversion circuits 1. In FIG. 2, the supply current Ips output by the power supply device 3, the voltage difference between the return wiring 5 and the power supply wiring 4 is the power supply voltage Vps, the voltage applied to the load 2 is the load voltage VL, and the current that flows through the load 2 Is shown as the load current IL, and the voltage output by the power regeneration unit 12 is shown as the regenerative voltage Vrc.

  As illustrated in FIG. 2, the current-voltage conversion unit 11 includes a first capacitor (for example, a capacitor C1). The capacitor C1 is provided between the input terminal Ti and the diode D1, and applies a voltage generated between both ends to the load 2 as a load voltage VL.

  The power regeneration unit 12 includes a switching control unit 20, a switching transistor Q1, a diode D3, an inductor L, and a second capacitor (for example, a capacitor C2). The power regeneration unit 12 uses these elements to set the regenerative voltage Vrc to a voltage obtained by stepping down the load voltage VL during a period in which the load voltage VL is equal to or less than the load voltage set value, and a period in which the load voltage VL is greater than the load voltage set value In this case, the switching transistor Q1 is maintained in the ON state, and the surplus power is regenerated in the power feeding device 3.

  The switching transistor Q1 has a drain connected to the first terminal on the input terminal Ti side of the capacitor C1, and a PWM signal applied to the gate. The diode D3 has a cathode connected to the source of the switching transistor Q1, and an anode connected to the second terminal on the output terminal To side of the capacitor C1. The inductor L has one end connected to the source of the switching transistor Q1 and the other end connected to the diode D2. Capacitor C2 is connected between the other end of inductor L and the second terminal of capacitor C1.

  The switching control unit 20 maintains the switching transistor Q1 in an on state in response to the voltage across the capacitor C1 reaching the load voltage set value, and the voltage across the capacitor C1 becomes equal to or less than the load voltage set value. In this case, a PWM signal to be supplied to the switching transistor Q1 is generated.

  The switching control unit 20 includes a constant voltage source 21, a comparator 22, and a PWM signal generation unit 23. The constant voltage source 21 outputs a voltage corresponding to the load voltage set value as a constant voltage. The comparator 22 compares the load voltage set value output from the constant voltage source 21 with the load voltage VL generated at both ends of the capacitor C1. The comparator 22 sets the output value to a low level if the load voltage VL is greater than the load voltage set value, and sets the output value to a high level if the load voltage VL is equal to or less than the load voltage set value. The PWM signal generator 23 maintains the switching transistor Q1 in the on state if the output value of the comparator 22 is low level, and provides the PWM signal to the gate of the switching transistor Q1 if the output value of the comparator 22 is high level.

  Here, the operation of the current-voltage conversion circuit 1 according to the first embodiment will be described. First, the power regeneration unit 12 charges the capacitor C1 until the load voltage VL generated at both ends of the capacitor C1 becomes larger than the load voltage set value. Thereafter, the power regenerator 12 charges the switching transistor Q1 until the regenerative voltage Vrc generated at both ends of the capacitor C2 reaches the load voltage set value with the switching transistor Q1 in a conductive state. Thereafter, when the load current IL decreases, the difference (Ips−IL) charges the capacitor C1, and the switching transistor Q1 becomes conductive as the load voltage VL increases. As a result, power is supplied to the capacitor C 2, and further passes through the diode D 2 and is regenerated to the power feeding device 3 via the return wiring 5. That is, the current that is not consumed by the load 2 is regenerated to the power feeding device 3 via the return wiring 5.

  On the other hand, when the load 2 starts operation, the power consumed by the load 2 increases. At this time, since the current supplied from the power supply device 3 is consumed by the load 2, the load voltage VL becomes smaller than the load voltage set value. As a result, the power regeneration unit 12 switches the switching transistor Q1 to lower the regenerative voltage Vrc.

  The current-voltage conversion circuit 1 according to the first embodiment performs the above-described operation. The above-described operation will be described in more detail with reference to FIGS. FIG. 3 is a timing chart illustrating a first example of the operation of the current-voltage conversion circuit according to the first embodiment. In the first example, one current-voltage conversion circuit 1 is provided for the power feeding device 3. In addition, the example illustrated in FIG. 3 is an example in which the load 2 starts to operate after a predetermined period after the power supply device 3 starts to supply power to the current-voltage conversion circuit 1.

  As shown in FIG. 3, when the power feeding device 3 starts feeding power while the load 2 is not consuming power, power feeding is performed until the power feeding current Ips output from the power feeding device 3 reaches a preset constant current value. Increase the current Ips. Further, as the power supply current Ips increases, charging of the capacitor C1 proceeds, so that the load voltage VL increases. The feeding current Ips maintains the current value after reaching a preset constant current value.

  When the load voltage VL reaches the load voltage set value output from the constant voltage source 21, the switching transistor Q1 is maintained in the on state and charging of the capacitor C2 is started. Thereby, the regenerative voltage Vrc output from the power regeneration unit 12 increases. When the regenerative voltage Vrc rises, the voltage of the return wiring 5 rises, so the power supply voltage Vps, which is the voltage difference between the return wiring 5 and the power supply wiring 4, decreases. Thereafter, when the regenerative voltage Vrc becomes substantially equal to the load voltage VL, the increase of the regenerative voltage Vrc stops, and the power supply current Ips output from the power supply device 3 via the power regeneration unit 12 and the return wiring 5 is regenerated to the power supply device 3. Is done.

  During this regenerative operation, the load voltage VL generated at the capacitor C1 and the regenerative voltage Vrc generated at the capacitor C2 are substantially the same voltage, so that the voltage difference between both ends of the switching transistor Q1 becomes substantially zero. Therefore, in the power regeneration unit 12, heat generated in the switching transistor Q1 during the regeneration operation is suppressed.

  Thereafter, when the load 2 starts operation, the load current IL varies. The fluctuation of the load current IL is caused by the operation at the time of starting up the load 2, and the load current IL of the load 2 is stabilized after a certain period. At this time, when the load current IL fluctuates so as to increase, the load voltage VL slightly decreases and falls below the load voltage set value. Therefore, the power regeneration unit 12 switches the switching transistor Q1 during the period when the load current IL is increasing. Is switched to lower the regenerative voltage Vrc. By reducing the regenerative voltage Vrc in this way, the voltage difference between the power supply wiring 4 and the return wiring 5 is opened, so that the power supply voltage Vps increases. On the other hand, when the load current IL fluctuates so as to decrease, the load voltage VL slightly increases and exceeds the load voltage set value. Therefore, the power regeneration unit 12 switches the switching transistor Q1 during the period when the load current IL is decreasing. Maintaining the conductive state, the capacitor C2 is charged to increase the regenerative voltage Vrc.

  Each time the load current IL is consumed by the load 2, the power regeneration unit 12 performs a step-down operation, whereby the charge amount of the capacitor C2 is reduced and the regenerative voltage Vrc becomes sufficiently small, and the power supply voltage Vps is loaded. The voltage is close to the voltage VL.

  FIG. 4 is a timing chart illustrating a second example of the operation of the current-voltage conversion circuit according to the first embodiment. In the second example, two current-voltage conversion circuits 1 are provided for the power feeding device 3. Further, in the example shown in FIG. 4, the load 2 connected to the first-stage current-voltage conversion circuit 1 after a predetermined period after the power-supply device 3 starts to supply power to the two current-voltage conversion circuits 1 and This is an example in which the load 2 connected to the second-stage current-voltage conversion circuit 1 starts to operate simultaneously. Two loads 2 show the same load fluctuation.

  In the example shown in FIG. 4, since the two loads 2 cause the same load fluctuation, the two current-voltage conversion circuits 1 perform the same operation. The operations of the two current-voltage conversion circuits 1 in the example of FIG. 4 are the same as those in the example shown in FIG. When the two current-voltage conversion circuits 1 are connected to the power feeding device 3, the regenerative voltage Vrc1 of the first-stage current-voltage conversion circuit 1 and the regenerative voltage Vrc2 of the second-stage current-voltage conversion circuit 1 are sufficiently small. The supply voltage Vps in the state is twice as large as the load voltage VL.

  FIG. 5 is a timing chart illustrating a third example of the operation of the current-voltage conversion circuit according to the first embodiment. In the third example, two current-voltage conversion circuits 1 are provided for the power feeding device 3. Further, in the example shown in FIG. 5, the load 2 connected to the first-stage current-voltage conversion circuit 1 after a predetermined period after the power-supply device 3 starts to supply power to the two current-voltage conversion circuits 1 and This is an example in which the load 2 connected to the second-stage current-voltage conversion circuit 1 sequentially starts operation.

  In the example shown in FIG. 5, the same regenerative operation as the current-voltage conversion circuit 1 of the example shown in FIG. 3 is performed at different timings according to fluctuations in the load current IL of the load 2 corresponding to the two current-voltage conversion circuits 1. Performs step-down operation. The power supply voltage Vps when the regenerative voltage Vrc1 of the first-stage current-voltage conversion circuit 1 and the regenerative voltage Vrc2 of the second-stage current-voltage conversion circuit 1 are sufficiently small is twice as large as the load voltage VL. .

  From the above description, in the current-voltage conversion circuit 1 according to the first embodiment, at the time of power regeneration, the voltage difference between both ends of the switching transistor Q1 in the power regeneration unit 12 is almost zero and is not consumed by the load 2. The generated power is regenerated to the power feeding device 3 through the return wiring 5. Thereby, in the current-voltage conversion circuit 1 according to the first embodiment, power regeneration to the power feeding device 3 is performed while suppressing heat generation of the switching transistor Q1 due to power that is not consumed by the load 2. That is, in the current-voltage conversion circuit 1 according to the first embodiment, since the heat generation of the element including the switching transistor Q1 can be suppressed during power regeneration, the current-voltage conversion can be performed without using a cooling component for heat dissipation of the element. The device size of the circuit 1 can be reduced.

  In addition, in the current-voltage conversion circuit 1 according to the first embodiment, the power consumption of the power supply device 3 is suppressed by causing the power supply device 3 to regenerate surplus power that has been conventionally released as waste heat of the Zener diode and the heat radiation resistor. can do.

  In the current-voltage conversion circuit 1 according to the first embodiment, the magnitude of the load voltage VL is set by the load voltage setting value output from the constant voltage source 21. Here, the magnitude of the load voltage setting value output from the constant voltage source 21 can be arbitrarily set. That is, in the current-voltage conversion circuit 1 according to the first embodiment, the degree of freedom in setting the load voltage VL can be increased.

  In the current-voltage conversion circuit 1 according to the first embodiment, in the state where power is consumed by the load 2, the regenerative voltage Vrc output from the power regeneration unit 12 is stepped down to increase the power supply voltage Vps. Thereby, in a state where the load 2 is consuming power, the power feeding device 3 can appropriately supply the load voltage VL to the load 2 or the current-voltage converter 11.

  The path from the power supply wiring 4 to the return wiring 5 can be considered as one wiring. That is, the current-voltage conversion circuit 1 according to the first embodiment is suitable for a one-wire DC power supply system.

  Note that the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Current voltage conversion circuit 2 Load 3 Power supply apparatus 4 Power supply wiring 5 Return wiring 11 Current voltage conversion part 12 Power regeneration part 20 Switching control part 21 Constant voltage source 22 Comparator 23 PWM signal generation part Q1 Switching transistor C1 Capacitor C2 Capacitor D1 Diode D2 Diode D3 Diode L Inductor Ti Input terminal To Output terminal TLp First load connection terminal TLn Second load connection terminal Vps Feed voltage Ips Feed current VL Load voltage IL Load current Vrc Regenerative voltage

Claims (5)

A current-voltage conversion circuit that converts a feeding current transmitted from a feeding device into a load voltage and supplies operating power to the load,
An input terminal;
An output terminal;
A current-voltage conversion unit that is connected between the input terminal and the output terminal, converts the feeding current input via the input terminal into the load voltage, and applies the operating power to the load;
In the current-voltage converter, the surplus power after the voltage difference between the output terminal and the input terminal is reduced during the period when the load voltage is larger than a preset load voltage setting value A power regeneration unit for regenerating to the power feeding device as regenerative power via the output terminal,
A first current backflow prevention unit which is provided between the current voltage conversion unit and the output terminal and prevents a backflow of current from the output terminal side to the current voltage conversion unit;
A second current backflow prevention unit that is provided between the power regeneration unit and the output terminal and prevents a backflow of current from the output terminal side to the power regeneration unit;
A current-voltage conversion circuit.   2. The current-voltage conversion circuit according to claim 1, wherein the power regeneration unit brings a voltage difference between the output terminal and the input terminal closer to the load voltage setting value in a state where the regenerative power is not regenerated in the power feeding device. . The current-voltage converter is
A first capacitor that is provided between the input terminal and the first current backflow prevention unit and applies a voltage generated between both ends to the load as the load voltage;
The power regeneration unit is
A switching transistor having a drain connected to the first terminal on the input terminal side of the first capacitor and a PWM signal applied to the gate;
The switching transistor is maintained in an on state in response to the voltage across the first capacitor reaching the load voltage set value, and the voltage across the first capacitor is less than or equal to the load voltage set value. A switching control unit for generating the PWM signal to be given to the switching transistor when
A diode having a cathode connected to the source of the switching transistor and an anode connected to a second terminal on the output terminal side of the first capacitor;
An inductor having one end connected to the source of the switching transistor and the other end connected to the second current backflow prevention unit;
The current-voltage conversion circuit according to claim 1, further comprising a second capacitor connected between the other end of the inductor and the second terminal of the first capacitor. The input terminal is connected to a power supply wiring for transmitting the power supply current,
4. The current-voltage conversion circuit according to claim 1, wherein a return wiring that transmits the regenerative power to the power feeding device is connected to the output terminal. 5. The current-voltage conversion circuit includes a plurality of cascade-connected input terminals connected to the output terminal of the current-voltage conversion circuit in the previous stage, and output terminals connected to the input terminal of the current-voltage conversion circuit in the subsequent stage. One of the current-voltage conversion circuits,
The current-voltage conversion circuit arranged in the first stage is connected to a power supply wiring that transmits the power supply current to the input terminal,
4. The current-voltage conversion circuit according to claim 1, wherein a return wiring for transmitting the regenerative power to the power feeding device is connected to the current-voltage conversion circuit arranged in the final stage. 5.

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