JP2016043768A - Direct current supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a direct current supply system which has a small-sized configuration and can suppress generation of circulation current.SOLUTION: A direct current supply system includes: a rectifier 10 which converts AC power received from an AC power source into direct current power and supplies the direct current power to an electric motor vehicle via a supply line; a transformer 22 for the rectifier which is provided between the AC power source and the rectifier 10, and steps down and supplies AC power to the rectifier 10; a regenerative inverter 14 which converts regenerative electric power generated during regenerative operation of the electric motor vehicle into AC power; a transformer 20 for the regenerative inverter which regenerates AC power received from the regenerative inverter 14 to the AC power source; and a control apparatus 16 for controlling the regenerative inverter 14. The control apparatus 16 includes: a voltage command generation circuit 50 which generates a voltage command based on a secondary side voltage of the transformer 22 for the rectifier; a voltage detection part 42 which detects a voltage of feed lane 3; and control parts 40, 44 which so control the regenerative inverter 14 that a value detected by the voltage detection part 42 is coincident with a voltage command.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a DC feeding system, and more particularly to control of a regenerative inverter that converts regenerative power of an electric vehicle into AC power and regenerates the AC power.

  For example, as disclosed in Japanese Patent Application Laid-Open No. 2004-351952 (Patent Document 1), a DC power feeding system includes a power running power source that rectifies an AC input with a rectifier and supplies a power running current to an electric vehicle, and constant voltage control Some inverter devices include a regenerative power source that converts a regenerative current from an electric vehicle into alternating current power and regenerates the alternating current input side.

  In the above-mentioned Patent Document 1, as a constant voltage control method for the inverter device, there is a configuration in which the inverter device is controlled such that the voltage is set higher than the DC voltage fluctuation range of the rectifier and the feeder voltage keeps the set voltage. It is disclosed.

Japanese Patent Laid-Open No. 2004-319552

  In the DC feeding system as described above, if the potential difference between the output voltage of the rectifier and the set voltage of the inverter device is large, an excessive circulating current may flow between the rectifier and the inverter device. Since the circulating current causes a circuit loss, the running cost of the DC feeding system is increased. Therefore, in order to suppress an increase in circulating current when switching between power running and regeneration, it is necessary to prevent the output voltage of the rectifier from becoming higher than the set voltage of the inverter device.

  On the other hand, since the output voltage of the rectifier fluctuates in conjunction with the voltage fluctuation on the AC input side, the potential difference between the output voltage of the rectifier and the set voltage also fluctuates in response to the voltage fluctuation of the AC input. For this reason, the output voltage of the rectifier becomes higher than the set voltage, and an excessive circulating current may occur.

  As a countermeasure for suppressing the generation of circulating current during such voltage fluctuation, it has been conventionally studied to control an inverter device in consideration of voltage fluctuation on the AC input side. However, in order to detect an AC input voltage, it is necessary to install an instrument transformer for detecting an extra high voltage. Since such an instrument transformer is large, there is a problem in that the system becomes large. In particular, when the installation space of the system is limited, such as in an underground substation, the above problem becomes significant.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a DC feeding system capable of suppressing the generation of circulating current with a small configuration.

  According to an aspect of the present invention, a DC feeding system is provided between a rectifier that converts AC power received from an AC power source into DC power and supplies the electric vehicle via an electric wire, and the AC power source and the rectifier. A rectifier transformer that steps down AC power and supplies it to the rectifier, a regenerative inverter that converts regenerative power generated during regenerative operation of an electric vehicle into AC power, and regenerates AC power received from the regenerative inverter to an AC power source A transformer for regenerative inverter and a control device for controlling the regenerative inverter are provided. The control device includes a voltage command generation circuit that generates a voltage command based on the secondary side voltage of the rectifier transformer, a voltage detection unit that detects the voltage of the feeder, and a detection value of the voltage detection unit matches the voltage command. And a control unit for controlling the regenerative inverter.

  Preferably, the control device further includes a current detection unit that detects a primary side current of the rectifier transformer, and a correction unit that corrects the voltage command based on a detection value of the current detection unit.

  Preferably, the control device selects a maximum value among a limiter circuit for generating a lower limit value of the voltage command and a voltage command generated by the voltage command generation circuit and an output voltage of the limiter circuit, and outputs the selected voltage to the control unit And a maximum value selection circuit.

  Preferably, a plurality of rectifiers are provided for the feeder. A plurality of rectifier transformers are provided so as to correspond to the plurality of rectifiers, respectively. A plurality of voltage command generation circuits are provided so as to be respectively connected to the secondary sides of the plurality of rectifier transformers. The control device further includes a maximum value selection circuit that selects the maximum one of the plurality of voltage commands generated by the plurality of voltage command generation circuits and outputs the selected voltage command to the control unit.

  Preferably, the control device further includes a limiter circuit for generating a lower limit value of the voltage command. The maximum value selection circuit selects the maximum one of the plurality of voltage commands and the output voltage of the limiter circuit and outputs the selected voltage to the control unit.

  According to the present invention, a DC feeding system capable of suppressing the generation of circulating current can be constructed with a small configuration.

1 is an overall configuration diagram of a DC feeding system according to Embodiment 1 of the present invention. It is a figure for demonstrating the control pattern of a regenerative inverter. It is a functional block diagram of the control apparatus of the regenerative inverter in a prior art. 3 is a functional block diagram illustrating a configuration of a control device for a regenerative inverter according to Embodiment 1. FIG. FIG. 6 is a functional block diagram illustrating a configuration of a control device for a regenerative inverter according to a second embodiment. FIG. 6 is a functional block diagram illustrating a configuration of a control device for a regenerative inverter according to a third embodiment. FIG. 9 is a functional block diagram illustrating a configuration of a control device for a regenerative inverter according to a fourth embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

[Embodiment 1]
(Overall configuration of DC feeding system)
1 is an overall configuration diagram of a DC feeding system according to Embodiment 1 of the present invention.

  Referring to FIG. 1, the DC feeding system according to the first embodiment converts three-phase AC power supplied from AC power supply 1 into DC power and supplies it to electric vehicle 5 via electric wire 3.

  The DC feeding system includes rectifiers 10 and 12, rectifier transformers 22 and 24, a regenerative inverter 14, and a regenerative inverter transformer 20. The direct current feeding system further includes a high voltage general load (high load distribution) 18 and a high distribution transformer 26.

  The primary side of the rectifier transformers 22 and 24 is connected to the power transmission line 2 via the circuit breaker CB, and the secondary side is connected to the rectifier 10. The rectifier transformers 22 and 24 step down the three-phase AC extra high voltage (for example, three-phase AC 77 kV) received from the transmission line 2 to a voltage suitable for feeding (three-phase AC 1200 V in the case of DC 1500 V). To do.

  The rectifiers 10 and 12 are constituted by silicon rectifiers, for example. The rectifier 10 rectifies the three-phase AC power received from the rectifier transformer 22 into DC power. The rectifier 12 rectifies the three-phase AC power received from the rectifier transformer 24 into DC power. The DC power is supplied to the electric vehicle 5 through the feeder 3 as indicated by the dotted arrow in FIG. The rail 4 is used as a current return path for the rectifier 10. A plurality of rectifiers are connected to the feeder 3 and the rail 4. FIG. 1 illustrates two rectifiers 10 and 12.

  The high distribution transformer 26 has a primary side connected to the power transmission line 2 via the circuit breaker CB and a secondary side connected to the high distribution load 18. The high distribution transformer 26 steps down the special high voltage to a voltage suitable for the high distribution load 18 (for example, three-phase alternating current 6.6 kV) and supplies it to the high distribution load 18.

  The regenerative inverter 14 is a device for converting regenerative power generated during regenerative braking of the electric vehicle 5 into AC power. The AC side of the regenerative inverter 14 is connected to the power transmission line 2 via the regenerative inverter transformer 20.

  The regenerative inverter 14 includes a power semiconductor switching element such as a plurality of thyristors. The regenerative inverter 14 is operated by a gate pulse signal input from the control device 16. Since a known configuration can be applied to the configuration of the regenerative inverter 14, detailed description thereof will not be repeated here.

  The regenerative inverter transformer 20 converts the single-phase alternating current output from the regenerative inverter 14 into a three-phase alternating current and regenerates the transmission line 2 side. Thereby, as indicated by the solid line arrow in FIG. 1, the regenerative electric power generated in the electric vehicle 5 at the time of regenerative braking can be regenerated to the power transmission line 2, thereby realizing stable braking operation and effective use of electric power.

  The control device 16 typically includes a CPU (Central Processing Unit), a memory area such as a RAM (Random Access Memory) and a ROM (Read Only Memory), and an input / output interface. And the control apparatus 16 performs control of the regenerative inverter 14, when CPU reads the program previously stored in ROM etc. to RAM and runs it.

(Control structure of regenerative inverter)
Next, the control structure of the regenerative inverter 14 will be described in detail.

  As shown in FIG. 1, the regenerative inverter 14 and the rectifiers 10 and 12 are connected in parallel between the feeder 3 and the rail 4. Therefore, switching between power feeding by the rectifiers 10 and 12 during power running of the electric vehicle 5 and regeneration by the regenerative inverter 14 during regenerative braking of the electric vehicle 5 is automatically and continuously smooth without using a switch or the like. Can be done.

  A control pattern of the regenerative inverter 14 will be described with reference to FIG. FIG. 2 is a diagram showing the output characteristics of the feeder 3 with respect to the load current (the running current of the electric vehicle 5) in the DC feeder system. In FIG. 2, the horizontal axis indicates the load current Id, and the vertical axis indicates the feeder voltage that is the voltage between the feeder 3 and the rail 4. The polarity of the load current Id is positive on the power running side and negative on the regeneration side.

  Referring to FIG. 2, region I indicates a forward conversion region (powering region) in which rectifiers 10 and 12 operate. The feeder voltage Ed corresponds to the output voltage of the rectifiers 10 and 12. In the region I, as the load current (powering current) increases, the wire voltage Ed decreases due to the influence of the internal impedance of the rectifiers 10 and 12.

  Region III indicates an inverse conversion region (regeneration region) in which the regenerative inverter 14 operates. The feeder voltage Ed corresponds to the DC side voltage of the regenerative inverter 14. In region III, the DC side voltage increases due to the influence of the internal impedance of the regenerative inverter 14 and the like as the load current (regenerative current) increases. The control device 16 controls the ignition phase of the thyristor in the regenerative inverter 14 using a control structure described later.

  Region IV indicates a region where the regenerative inverter 14 operates at a constant voltage. When the electric wire voltage Ed rises and exceeds the predetermined voltage Edi as the regenerative current increases, the regenerative operation of the regenerative inverter 14 is controlled so that the electric wire voltage Ed does not exceed the predetermined voltage Edi. The predetermined voltage Edi is set to the rated voltage of the regenerative inverter 14, for example.

  Region II is a transition region where the operation of the regenerative inverter 14 and the operation of the rectifiers 10 and 12 are switched. In the following description, the output voltage Edr0 of the rectifiers 10 and 12 when the load current Id is near zero is referred to as “rectifier no-load voltage”, and the DC side voltage of the regenerative inverter 14 when the load current Id is not loaded. Edi0 is also referred to as “inverter no-load voltage”.

  When the rectifier no-load voltage Edr0 is higher than the inverter no-load voltage Edi0, a circulating current flows from the rectifiers 10 and 12 toward the regenerative inverter. Circuit loss occurs due to the flow of this unnecessary circulating current. As a result, the running cost of the DC feeding system is increased. Therefore, in order to suppress the increase in circulating current, it is necessary to prevent the rectifier no-load voltage Edr0 from becoming higher than the inverter no-load voltage Edi0. In the present embodiment, the potential difference between the inverter no-load voltage Edi0 and the rectifier no-load voltage Edr0 is adjusted by the control of the regenerative inverter 14.

  First, the control structure of the regenerative inverter in the prior art will be described with reference to FIG. FIG. 3 shows a functional block diagram of a control device for a regenerative inverter in the prior art.

  Referring to FIG. 3, the control structure of regenerative inverter 14 in the prior art includes voltage command generation circuit 30, voltage control unit 40, voltage detection unit 42, and gate pulse generation unit 44.

  The voltage command generation circuit 30 generates a voltage command for instructing a DC voltage to be output by the regenerative inverter 14 based on the three-phase AC extra high voltage received from the AC power source 1. Specifically, the voltage command generation circuit 30 includes an instrument transformer (PT: Potential Transformer) 32 and a rectifier 34. The instrument transformer 32 detects a three-phase AC special high voltage received from the AC power supply 1. The instrument transformer 32 converts the detected extra high voltage into a voltage suitable for processing in the voltage control unit 40. The rectifier 32 generates a voltage command by rectifying the AC voltage received from the instrument transformer 32 into a DC voltage. The voltage command generation circuit 30 outputs the generated voltage command to the voltage control unit 40.

  The voltage detector 42 detects the voltage (feeder voltage) between the feeder 3 and the rail 4 and outputs the detected value to the voltage controller 40.

  The voltage control unit 40 controls the regenerative inverter output voltage according to the voltage command instructed from the voltage command generation circuit 30. Specifically, the voltage control unit 40 performs feedback control for increasing or decreasing the feeder voltage based on a comparison between the feeder voltage detected by the voltage detector 42 and the voltage command. The voltage control unit 40 amplifies the feeder voltage deviation with respect to the voltage command, thereby generating a thyristor firing phase command in the regenerative inverter 14 according to the deviation.

  The gate pulse generator 44 generates a gate pulse to be given to the thyristor based on the firing phase command instructed from the voltage controller 40. Each thyristor of the regenerative inverter 14 receives a gate pulse signal from the gate pulse generator 44 at its gate. By turning on the plurality of thyristors at a predetermined timing, DC power can be converted into three-phase AC power.

  When the feeder voltage exceeds the predetermined voltage Edi due to the increase of the regenerative current, the regenerative inverter 14 enters the constant voltage operation region (region IV in FIG. 2). Thereby, the raise of feeder voltage is suppressed and the regeneration invalidity of the electric vehicle 5 is prevented.

  When the control structure of the regenerative inverter 14 is configured as shown in FIG. 3, when the extra high voltage changes on the AC power supply 1 side, the voltage command also changes accordingly. Then, the voltage control unit 40 controls the feeder voltage so as to follow the change of the voltage command. Therefore, in the transition region (region II in FIG. 2) where the power running and the regeneration are switched, the regenerative inverter no-load voltage Edi0 changes in conjunction with the change of the extra high voltage. On the other hand, since the output voltages of the rectifiers 10 and 12 change in conjunction with the change of the extra high voltage, the rectifier no-load voltage Edr0 also changes. That is, when the special high voltage changes, both the regenerative inverter no-load voltage Edi0 and the rectifier no-load voltage Edr0 change in conjunction with the change of the special high voltage. As a result, the potential difference between the regenerative inverter no-load voltage Edi0 and the rectifier no-load voltage Edr0 is suppressed from increasing due to the fluctuation of the extra high voltage. Thereby, it is possible to avoid an increase in circulating current even when the extra high voltage is fluctuating.

  However, in the control structure of the conventional regenerative inverter shown in FIG. 3, a voltage command is generated on the basis of the special high voltage, and therefore a dedicated instrument transformer for detecting the special high voltage (for the instrument of FIG. 3). It is necessary to install a transformer 32). Since the special high voltage is as high as three-phase AC 77 kV, the physique of the instrument transformer 32 (particularly, the physique of the insulator covering the input / output terminals of the transformer) becomes large. Therefore, there is a problem that it is difficult to realize a control structure when the installation space of the system is limited, such as in an underground substation. Further, since an expensive instrument transformer is required to detect the extra high voltage, there has been a problem that the cost of the system increases.

  In order to avoid such a problem, it is possible to adopt a method in which the voltage command is set to a predetermined value (fixed value) without mounting the voltage command generation circuit 30. However, as described above, since the rectifier no-load voltage Edr0 changes in conjunction with the extra high voltage, there are cases where the rectifier no-load voltage Edr0 exceeds the inverter no-load voltage Edi (fixed value). In this case, an excessive circulating current may occur depending on the potential difference. In order to avoid an excessive circulating current, it is necessary to set the voltage command to a high voltage value in advance.

  Therefore, in the control structure of regenerative inverter 14 according to the first embodiment, a voltage command generation circuit is provided on the secondary side of the rectifier transformer. Thereby, a small voltage command generation circuit can be realized. As a result, it is possible to prevent an excessive circulating current from flowing without increasing the size of the system. Further, since the cost of the voltage command generation circuit can be reduced compared to the conventional control structure, it is possible to suppress an increase in system cost.

  FIG. 4 is a functional block diagram showing the configuration of the control device 16 of the regenerative inverter 14 according to the first embodiment. Note that each functional block described in FIG. 4 can be realized by executing software processing by the control device 16 in accordance with a preset program. Alternatively, it is also possible to configure a circuit (hardware) having a function corresponding to the functional block in the control device 16.

  Referring to FIG. 4, control device 16 includes a voltage control unit 40, a voltage detection unit 42, and a gate pulse generation unit 44. Control device 16 further includes a voltage command generation circuit 50.

  The control device 16 according to the first embodiment has a voltage command generation circuit 50 instead of the voltage command generation circuit 30 as compared with the conventional control device shown in FIG. The voltage command generation circuit 50 is connected to the secondary side of the rectifier transformer 22. The voltage command generation circuit 50 generates a voltage command based on the voltage on the secondary side of the rectifier transformer 22. Specifically, the voltage command generation circuit 50 includes an instrument transformer 52 and a rectifier 54. The instrument transformer 52 detects the voltage on the secondary side of the rectifier transformer 22. The instrument transformer 52 converts the detected secondary voltage into a voltage suitable for processing in the voltage control unit 40. The rectifier 54 generates a voltage command by rectifying the AC voltage received from the instrument transformer 52 into a DC voltage. The voltage command generation circuit 50 outputs the generated voltage command to the voltage control unit 40. The voltage control unit 40 controls the feeder voltage in accordance with the voltage command instructed from the voltage command generation circuit 50 in the same manner as described in FIG.

  In the above configuration, the rectifier transformer 22 steps down the extra high voltage (three-phase AC 77 kV) to a voltage suitable for feeding (three-phase AC 1200 V). For this reason, the voltage on the secondary side of the rectifier transformer 22 is significantly lower than the extra high voltage. As a result, a transformer having a smaller physique than the instrument transformer 32 shown in FIG. 3 can be used as the instrument transformer 52 that detects the voltage on the secondary side. Therefore, it is possible to prevent an excessive circulating current from flowing without increasing the size of the system.

  Moreover, since the instrument transformer 52 is less expensive than the instrument transformer 32, the cost of the voltage command generation circuit 50 can be reduced. As a result, an increase in system cost can be suppressed.

  Here, from the viewpoint of miniaturization and cost reduction, it is also conceivable to use the voltage on the secondary side of the high distribution transformer 26 connected to the high distribution load 18 for generating the voltage command. However, since the high distribution load 18 and the electric vehicle 5 are loads that can operate independently of each other, it is difficult to reflect the change in the rectifier no-load voltage Edr0 in the secondary voltage of the high distribution transformer 26. There is. Further, since the high distribution load 18 includes an alternating current load, the generation of the voltage command requires a calculation process in consideration of reactive power, and there is a problem that the control structure becomes complicated. On the other hand, according to the first embodiment, the voltage command is generated using the secondary side voltage of the rectifier transformer 22 that directly reflects the rectifier no-load voltage Edr0. Therefore, the control structure of the regenerative inverter 14 can be simplified.

[Embodiment 2]
In the first embodiment, as the control structure of the regenerative inverter 14, the configuration has been described in which the voltage command is generated using the voltage on the secondary side of the rectifier transformer 22. In the second embodiment, a control structure that improves the accuracy of the voltage command and can more reliably suppress the increase in circulating current will be described. Note that the DC feeding system according to the second embodiment has the same configuration as the DC feeding system of FIG. 1 except for the control device 16A, and therefore its illustration and description are omitted.

  FIG. 5 is a functional block diagram showing the configuration of the control device 16A of the regenerative inverter 14 according to the second embodiment. Referring to FIG. 5, control device 16 </ b> A according to the second embodiment further includes a voltage correction unit 60 as compared with control device 16 shown in FIG. 4.

  The rectifier transformer 22 has an internal impedance. Therefore, the secondary side voltage of the rectifier transformer 22 is lower than the extra high voltage received from the AC power supply 1. As the load increases, the difference between the extra high voltage and the secondary voltage of the rectifier transformer 22 increases. Therefore, when the regenerative inverter 14 is controlled according to the voltage command generated using the secondary side voltage, the potential difference between the inverter no-load voltage Edi0 and the rectifier no-load voltage Edr0 increases, which may lead to an increase in circulating current.

  Therefore, in the control device 16A according to the second embodiment, the voltage command generated by the voltage command generation circuit 50 is corrected to compensate for the voltage drop in the rectifier transformer 22, and the voltage command is determined. To do.

  Referring to FIG. 5, voltage correction unit 60 is a device for correcting a voltage command in accordance with a load current. Specifically, the voltage correction unit 60 includes a current transformer (CT) 62, a rectifier 64, a voltage compensation unit 66, and an addition unit 68.

  The instrument current transformer 62 is connected between the power transmission line 2 and the primary side of the rectifier transformer 22. The instrument current transformer 62 detects the current on the primary side of the rectifier transformer 22. The rectifier 62 rectifies the primary current detected by the instrument current transformer 62 into a direct current and outputs the direct current to the voltage compensator 66.

  When the voltage compensator 66 receives the primary current of the rectifier transformer 22 from the rectifier 62, the voltage compensator 66 calculates a correction amount for compensating for the voltage drop based on the primary current. The adder 68 adds the voltage command generated by the voltage command generator 50 and the correction amount calculated by the voltage compensator 66 to calculate a voltage command that takes into account the voltage drop in the rectifier transformer 22.

  The voltage command corrected by the voltage correction unit 60 is input to the voltage control unit 40. The voltage control unit 40 executes feedback control for increasing or decreasing the feeder voltage based on a comparison between the feeder voltage detected by the voltage detector 42 and the corrected voltage command.

  As described above, according to the second embodiment of the present invention, the voltage command is generated using the voltage on the secondary side of the rectifier transformer, and the generated voltage command is used as the current on the primary side of the rectifier transformer. Correct based on Thereby, since the interlocking of the voltage command with respect to the extra high voltage is enhanced, the accuracy of the voltage command is improved, and an increase in circulating current can be suppressed more reliably.

[Embodiment 3]
In the voltage command generation circuit 50 according to the first and second embodiments, the instrument transformer 52 that detects the secondary side voltage of the rectifier transformer 22 is provided with a fuse for protecting the circuit from overcurrent. It has been. When the fuse blows due to thermal fatigue or failure, the instrument transformer 52 becomes inoperable, and the voltage command may become zero. When the regenerative inverter 14 is controlled according to this voltage command, the potential difference between the inverter no-load voltage Edi0 and the rectifier no-load voltage Edr0 increases, which may lead to an increase in circulating current.

  In the third embodiment, a control structure capable of ensuring stable operation of the regenerative inverter 14 will be described. Note that the DC feeding system according to the third embodiment has the same configuration as the DC feeding system of FIG. 1 except for the control device 16B, and therefore its illustration and description are omitted.

  FIG. 6 is a functional block diagram showing the configuration of the control device 16B of the regenerative inverter 14 according to the third embodiment. Referring to FIG. 6, control device 16 </ b> B according to the third embodiment further includes a limiter circuit 70 and diodes 74 and 76 as compared with control device 16 </ b> A shown in FIG. 5.

  The limiter circuit 70 includes a variable resistor 72. The variable resistor 72 is configured such that the electric resistance value changes according to the amount of operation from the outside. The variable resistor 72 divides the input voltage by the variable resistor 72 and outputs it. The output voltage of the variable resistor 72 is input to the anode of the diode 74. The cathode of the diode 74 is connected to the voltage control unit 40.

  The voltage command corrected by the voltage correction unit 60 is input to the anode of the diode 76. The cathode of the diode 76 is connected to the voltage control unit 40. The diodes 74 and 76 constitute a diode OR circuit. The diode OR circuit receives the output voltage of the limiter circuit 70 and the voltage command, and outputs a voltage having a higher voltage value.

  That is, the diode OR circuit constitutes a maximum value selection circuit. As a result, even when the voltage command is drastically decreased due to the fuse being blown or the like, the voltage command can be limited to be equal to or higher than the output voltage of the limiter circuit 70. As described above, according to the third embodiment, the lower limit value can be set in the voltage command by the limiter circuit 70 and the maximum value selection circuit (diodes 74 and 66). Thereby, since stable operation of the regenerative inverter 14 can be ensured, an increase in circulating current can be suppressed.

[Embodiment 4]
As shown in FIG. 1, when a plurality of rectifiers 10 and 12 are connected to the feeder 3 and the rail 4, a plurality of voltage command generation circuits corresponding to the plurality of rectifier transformers 22 and 24, respectively. Can be provided. When a plurality of voltage commands generated by a plurality of voltage command generation circuits are switched by a mechanical relay, an instantaneous interruption occurs in which the supply of the voltage command is interrupted in a transition period in which the relay contacts are switched. There is a possibility that an excessive circulating current may be generated in the transition period due to the instantaneous interruption of the voltage command. In the fourth embodiment, a control structure capable of switching a plurality of voltage commands without instantaneous interruption will be described.

  FIG. 7 is a functional block diagram showing the configuration of the control device 16C of the regenerative inverter 14 according to the fourth embodiment. Referring to FIG. 7, control device 16C according to the fourth embodiment includes two voltage command generation circuits 50 and 90, and two voltage correction units respectively corresponding to voltage command generation circuits 50 and 90. Control device 16 </ b> C further includes a limiter circuit 70 and diodes 74, 76 and 78.

  The voltage command generation circuit 50 is connected to the secondary side of the rectifier transformer 22. The voltage command generation circuit 50 generates a voltage command based on the voltage on the secondary side of the rectifier transformer 22. The instrument current transformer 62, the rectifier 64, the voltage compensation unit 66, and the addition unit 68 constitute a voltage correction unit for correcting the voltage command generated by the voltage command generation circuit 50.

  The voltage command generation circuit 90 is connected to the secondary side of the rectifier transformer 24. The voltage command generation circuit 90 generates a voltage command based on the voltage on the secondary side of the rectifier transformer 24. The instrument current transformer 82, the rectifier 84, the voltage compensation unit 86, and the addition unit 88 constitute a voltage correction unit for correcting the voltage command generated by the voltage command generation circuit 90. Since the configuration and operation of each voltage correction unit are the same as the configuration and operation of voltage correction unit 60 shown in the second embodiment, detailed description thereof is omitted.

  The voltage command generated by the voltage command generation circuit 50 is input to the anode of the diode 76. The voltage command generated by the voltage command generation circuit 90 is input to the anode of the diode 78. The output voltage of the limiter circuit 70 is input to the anode of the diode 78. As described in the third embodiment, the output voltage of the limiter circuit 70 becomes the lower limit value of the voltage command. The cathodes of the diodes 74, 76, and 78 are commonly connected to the voltage control unit 40. The diodes 74, 76, and 78 constitute a diode OR circuit (maximum value selection circuit). The diode OR circuit receives the voltage command generated by the voltage command generation circuit 50, the voltage command generated by the voltage command generation circuit 90, and the output voltage of the limiter circuit 70, and outputs the one having the highest voltage value.

  By adopting such a configuration, since either one of the two voltage commands and the lower limit value of the voltage command is selected and input to the voltage control unit 40, it is possible to avoid instantaneous interruption of the voltage command. . Accordingly, it is possible to prevent an excessive circulating current from being generated during a transition period in which a plurality of voltage commands are switched.

  Note that the control structure according to the fourth embodiment can also be applied to a configuration in which a plurality of voltage commands are switched by a mechanical relay. For example, in a configuration in which a plurality of voltage commands generated by the plurality of voltage command generation circuits 50 and 90 are switched by a mechanical relay and input to the voltage control unit 40, a maximum value is provided between the mechanical relay and the voltage control unit 40. A selection circuit is provided. The maximum value selection circuit is configured to receive a voltage command input via a mechanical relay and an output voltage of the limiter circuit 70 and output a voltage having a higher voltage value. According to this, in the transition period in which the voltage command is switched by the mechanical relay, the voltage command is set to the lower limit value. Therefore, instantaneous interruption of the voltage command is avoided, and generation of an excessive circulating current can be prevented.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1 AC power supply, 2 transmission line, 3 feeder, 4 rail, 5 electric vehicle, 10, 12, 34, 54, 64, 94 rectifier, 14 regenerative inverter, 16, 16A-16C control device, 18 high load distribution, 20 regenerative Transformer for inverter, 22, 24 Transformer for rectifier, 26 Transformer for high distribution, 30, 50, 90 Voltage command generation circuit, 32, 52, 92 Transformer for instrument, 40 Voltage controller, 42 Voltage detector, 44 Gate pulse generator, 60 voltage corrector, 62 current transformer for instrument, 66,86 voltage compensator, 68,88 adder, 70 limiter circuit, 72 variable resistor, 74,76,78 diode, CB breaker.

Claims (5)

A DC feeder system,
A rectifier that converts AC power received from an AC power source into DC power and supplies the electric vehicle via an electric wire;
A rectifier transformer that is provided between the AC power source and the rectifier, and steps down the AC power and supplies the AC power to the rectifier;
A regenerative inverter that converts regenerative power generated during regenerative operation of the electric vehicle into AC power;
A transformer for regenerative inverter that regenerates AC power received from the regenerative inverter to the AC power source;
A control device for controlling the regenerative inverter;
The controller is
A voltage command generation circuit that generates a voltage command based on a secondary side voltage of the transformer for the rectifier;
A voltage detector for detecting the voltage of the feeder line;
And a control unit that controls the regenerative inverter so that a detection value of the voltage detection unit matches the voltage command. The controller is
A current detector for detecting a primary side current of the rectifier transformer;
The DC feeding system according to claim 1, further comprising a correction unit that corrects the voltage command based on a detection value of the current detection unit. The controller is
A limiter circuit for generating a lower limit value of the voltage command;
The maximum value selection circuit which selects the largest one among the voltage command generated by the voltage command generation circuit and the output voltage of the limiter circuit, and outputs it to the control unit. DC feeding system. A plurality of the rectifiers are provided for the feeder lines,
A plurality of the rectifier transformers are provided so as to correspond to the plurality of rectifiers,
A plurality of the voltage command generation circuits are provided so as to be respectively connected to secondary sides of the plurality of rectifier transformers,
The controller is
3. The direct current control circuit according to claim 1, further comprising a maximum value selection circuit that selects a maximum one of the plurality of voltage commands generated by the plurality of voltage command generation circuits and outputs the selected voltage command to the control unit. Electric system. The controller is
A limiter circuit for generating a lower limit value of the voltage command;
5. The DC feeding system according to claim 4, wherein the maximum value selection circuit selects the maximum one of the plurality of voltage commands and the output voltage of the limiter circuit and outputs the selected voltage to the control unit.

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