Power Conversion Device

Abstract

To provide a power conversion device that can handle multiple types of power-supply sources while suppressing an increase in the number of components and an enlargement of the device in outer dimensions.SOLUTION: A power conversion device according to an embodiment of the present invention comprises: a transformer including a primary coil connected to an external power supply and a secondary coil for outputting a first single-phase AC power; a first converter for converting an alternating-current power to a direct-current power; a first circuit breaker connected between the secondary coil and the first converter; a generator for generating a three-phase alternating-current power; a first contactor connected between the generator and the first converter; and a control unit for controlling the operation of the first converter. The first converter includes a first to sixth switching elements. The control unit converts, in a first operational mode, the three-phase alternating-current power into the direct-current power using first to sixth switching elements, and converts, in a second operational mode, the first single-phase AC power into the direct-current power using first to fourth switching elements.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a power conversion device that converts AC power into DC power. [Background technology]

[0002] When power is supplied from a generator, a three-phase two-level converter converts three-phase AC to DC. When power is supplied from an overhead line, a single-phase two-level converter converts single-phase AC to DC. To accommodate two types of power supply sources, a generator and an overhead line, two types of power conversion devices are required: a three-phase two-level converter and a single-phase two-level converter. Also, when power is supplied from an overhead line, an overvoltage suppression function is required when the DC voltage rises due to transient fluctuations caused by the disconnection and reconnection of the current collector. In this way, when two power supply sources are used, the number of items increases and the external dimensions of the device become larger. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2013 / 114546 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a power conversion device that can accommodate a plurality of types of power supply sources while suppressing an increase in the number of products and an increase in the external dimensions of the device. [Means for solving the problem]

[0005] The power conversion device according to the embodiment includes a transformer having a primary winding connected to an external power supply and a secondary winding for outputting a first single-phase AC power, and a transformer for converting the AC power into DC power. The first to sixth switching elements are included.a first converter, a first circuit breaker connected between the secondary winding and the first converter, a generator that generates three-phase AC power, and a first contactor connected between the generator and the first converter; a first potential line and a second potential line connected to the first converter and through which the DC power is output, and a protection circuit configured to suppress an overvoltage between the first potential line and the second potential line, the protection circuit including a resistor; and a control unit that controls an operation of the first converter, the control unit converting the three-phase AC power into DC power using the first to sixth switching elements in a first operation mode, and converting the first single-phase AC power into DC power using the first to fourth switching elements in a second operation mode. In the second operation mode, one of the first to sixth switching elements and the resistor configure the protection circuit. [Brief description of the drawings]

[0006] [Figure 1] FIG. 1 is a circuit diagram of a power conversion device according to a first embodiment. [Diagram 2] FIG. 2 is a circuit diagram of a power conversion device according to the second embodiment. [Diagram 3] FIG. 3 is a circuit diagram of a power conversion device according to the third embodiment. [Figure 4] FIG. 4 is a circuit diagram of a power conversion device according to the fourth embodiment. [Diagram 5] FIG. 5 is a circuit diagram of a power conversion device according to the fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, the embodiments will be described with reference to the drawings. Some of the embodiments shown below are examples of devices and methods for embodying the technical idea of ​​the present invention, and the technical idea of ​​the present invention is not specified by the shape, structure, arrangement, etc. of the components. In the following description, elements having the same functions and configurations are given the same reference numerals, and duplicated descriptions are omitted.

[0008] [1] First embodiment [1-1] Configuration of power conversion device 1 1 is a circuit diagram of a power conversion device 1 according to the first embodiment. The power conversion device 1 includes a transformer 10, a charging circuit 11, a generator 15, a three-phase contactor 16, a converter 17, a voltage detection circuit (VD) 20, a filter capacitor 21, an overvoltage protection circuit 22, and a control unit 27.

[0009] The transformer 10 is an isolation transformer including a primary winding W1 and a secondary winding W2. The transformer 10 converts a primary voltage (the voltage of the primary winding W1) into a secondary voltage (the voltage of the secondary winding W2) proportional to the turn ratio between the primary winding W1 and the secondary winding W2. The primary winding W1 of the transformer 10 is connected in series between the current collector 2 and the ground terminal 3.

[0010] A primary winding W1 of the transformer 10 is connected to a power source that supplies single-phase AC power. In this embodiment, as an example, a case will be described in which the power conversion device 1 is used in a drive device for an electric locomotive. One end of the primary winding W1 of the transformer 10 is connected to a current collector 2, and the other end of the primary winding W1 of the transformer 10 is connected to a ground terminal 3.

[0011] The current collector 2 may be a current collector such as a pantograph that receives single-phase AC power from an overhead line, or a current collector shoe that receives single-phase AC power from a third rail. The ground terminal 3 is a wheel that is grounded via the rail. It is assumed that the power source connected to the primary winding W1 of the transformer 10 is an unstable power source.

[0012] One end of the secondary winding W2 of the transformer 10 is connected to a node N1 of the converter 17 via the charging circuit 11. The other end of the secondary winding W2 of the transformer 10 is connected to a node N2 of the converter 17.

[0013] The charging circuit 11 includes a charging contactor 12 and a charging resistor 13. The charging contactor 12 is a normally open contactor. One end of the charging contactor 12 is connected to a secondary winding W2 of the transformer 10, and the other end of the charging contactor 12 is connected to one end of the charging resistor 13. The other end of the charging resistor 13 is connected to a node N1 of the converter 17. The charging circuit 11 has a function of charging the filter capacitor 21 before the converter 17 starts up.

[0014] One end of the circuit breaker 14 is connected to the secondary winding W2 of the transformer 10, and the other end of the circuit breaker 14 is connected to a node N1 of the converter 17. The circuit breaker 14 is an a-contact circuit breaker. The circuit breaker 14 connects or disconnects the path between the transformer 10 and the converter 17.

[0015] The generator 15 generates three-phase AC power consisting of U-phase, V-phase, and W-phase. The three-phase terminals of the generator 15 are connected to one end of a three-phase contactor 16. The other end of the three-phase contactor 16 is connected to nodes N1, N2, and N3 of the converter 17. The three-phase contactor 16 is an a-contact contactor and has contacts for three phases. The three-phase contactor 16 connects or disconnects a three-phase path between the generator 15 and the converter 17.

[0016] The converter 17 includes six switching elements Q1 to Q6. The switching elements Q1 to Q6 are, for example, IGBTs (Insulated Gate Bipolar Transistors). The switching elements Q1 to Q6 are not limited to a specific element as long as they are elements that can be switched on / off. The switching elements Q1 to Q6 may be bipolar transistors, MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), GTOs (Gate Turn Off thyristors), or the like.

[0017] The switching elements Q1 and Q2 are connected in series via a node N1 between a high potential line 18 and a low potential line 19. The collector of the switching element Q1 is connected to the high potential line 18, and the emitter of the switching element Q1 is connected to the collector of the switching element Q2 via the node N1. The emitter of the switching element Q2 is connected to the low potential line 19.

[0018] The switching elements Q3 and Q4 are connected in series via a node N2 between a high potential line 18 and a low potential line 19. The collector of the switching element Q3 is connected to the high potential line 18, and the emitter of the switching element Q3 is connected to the collector of the switching element Q4 via the node N2. The emitter of the switching element Q4 is connected to the low potential line 19.

[0019] The switching elements Q5 and Q6 are connected in series via a node N3 between a high potential line 18 and a low potential line 19. The collector of the switching element Q5 is connected to the high potential line 18, and the emitter of the switching element Q5 is connected to the collector of the switching element Q6 via the node N3. The emitter of the switching element Q6 is connected to the low potential line 19.

[0020] The switching elements Q1 to Q6 each have a gate to which an operation signal for controlling the switching operation is input.

[0021] Converter 17 includes six diodes D1 to D6. Diodes D1 to D6 are connected in anti-parallel to switching elements Q1 to Q6. Diodes D1 to D6 are freewheeling diodes and have a function of protecting switching elements Q1 to Q6 when a reverse current is supplied to switching elements Q1 to Q6.

[0022] Converter 17 can function as a three-phase two-level converter or as a single-phase two-level converter. That is, converter 17 converts three-phase AC power generated by generator 15 into DC power. Converter 17 also converts single-phase AC power generated by transformer 10 into DC power. The DC power converted by converter 17 is output to high potential line 18 and low potential line 19.

[0023] The voltage detection circuit 20 is connected between the high potential line 18 and the low potential line 19. The voltage detection circuit 20 detects the voltage (DC voltage) between the high potential line 18 and the low potential line 19. The voltage value detected by the voltage detection circuit 20 is sent to the control unit 27.

[0024] The filter capacitor (also simply referred to as a capacitor) 21 is connected between the high potential line 18 and the low potential line 19. The filter capacitor 21 smoothes the output voltage of the converter 17. In addition, the capacitor 21 has a function of removing AC components (voltage ripples) generated in the DC power transmitted to the high potential line 18 and the low potential line 19.

[0025] The overvoltage protection circuit 22 includes a switching element 23, diodes 24 and 25, and a resistor 26. The switching element 23 is configured, for example, with the same element as the switching element included in the converter 17. The switching element 23 has a gate to which an operation signal for controlling a switching operation is input. The collector of the switching element 23 is connected to the high potential line 18, and the emitter of the switching element 23 is connected to the cathode of the diode 25 and one end of the resistor 26. The anode of the diode 25 and the other end of the resistor 26 are connected to the low potential line 19. The diode 24 is connected inversely parallel to the switching element 23. When an overvoltage occurs between the high potential line 18 and the low potential line 19, the overvoltage protection circuit 22 has a function of suppressing the overvoltage by discharging the charge stored in the filter capacitor 21 to the low potential line 19 via the resistor 26.

[0026] A load 4 is connected between the high potential line 18 and the low potential line 19. In the case of an electric locomotive embodiment, the load 4 includes an inverter and an electric motor.

[0027] The control unit 27 comprehensively controls the operation of the power conversion device 1. The control unit 27 receives a power supply switching command from the outside. The control unit 27 generates various control signals based on the power supply switching command.

[0028] Specifically, the control unit 27 supplies a closing signal to each of the charging contactor 12, the circuit breaker 14, and the three-phase contactor 16, and controls the open / closed states thereof. The control unit 27 supplies an operation signal to the switching element 23, and controls the on / off of the switching element 23. The control unit 27 supplies an operation signal to the switching elements Q1 to Q6 included in the converter 17, and controls the conversion operation from AC power to DC power by the converter 17. The operation signal supplied to the converter 17 is a gate signal that controls the on / off of the switching elements Q1 to Q6.

[0029] [1-2] Operation Next, the operation of the power conversion device 1 configured as above will be described.

[0030] In this embodiment, the power conversion device 1 can execute two operating modes: a first operating mode in which the generator 15 is used as the power supply source, and a second operating mode in which the current collector 2 and the transformer 10 are used as the power supply source.

[0031] The control unit 27 receives a power supply switching command from the outside as shown in Fig. 1. The power supply switching command is given to the control unit 27, for example, from a control circuit on the vehicle side or from the ground side via an on-board monitor device. The control unit 27 selects and executes either the first operation mode or the second operation mode based on the power supply switching command.

[0032] First, the first operation mode in which the generator 15 serves as the power supply source will be described. In the first operation mode, the control unit 27 sends a closing command to the three-phase contactor 16 to instruct the three-phase contactor 16 to be in a closed state (conductive state). This causes the three-phase contactor 16 to be in a closed state. The charging contactor 12 and the circuit breaker 14 are in an open state. That is, the converter 17 is electrically disconnected from the current collector 2 and the transformer 10.

[0033] The generator 15 generates three-phase AC power. The three-phase AC power generated by the generator 15 is supplied to the converter 17.

[0034] The control unit 27 sends operation signals capable of causing the six switching elements Q1 to Q6 to perform switching operations to the converter 17 (specifically, to the gates of the switching elements Q1 to Q6). The converter 17 operates as a three-phase full-wave rectifier circuit, and converts three-phase AC power into DC power.

[0035] The DC power output from the converter 17 is supplied to the load 4 via a high potential line 18 and a low potential line 19 .

[0036] Next, a second operation mode in which the current collector 2 and the transformer 10 are used as the power supply source will be described. In the second operation mode, the three-phase contactor 16 is in an open state. That is, the converter 17 is electrically disconnected from the generator 15.

[0037] The control unit 27 sends a closing command to the charging contactor 12 to instruct the charging contactor 12 to close. As a result, the charging contactor 12 is in the closed state. The circuit breaker 14 is in the open state. The single-phase AC power generated by the transformer 10 is supplied to the filter capacitor 21 via the charging resistor 13 and the diodes D1 to D4 of the converter 17. As a result, the filter capacitor 21 is charged.

[0038] Next, the control unit 27 sends a closing command to the circuit breaker 14 to instruct the circuit breaker 14 to close. As a result, the circuit breaker 14 is in the closed state. The control unit 27 sends a command to the charging contactor 12 to instruct the charging contactor 12 to open. As a result, the charging contactor 12 is in the open state. The control unit 27 sends an operation signal to the converter 17 that can cause the four switching elements Q1 to Q4 to perform switching operations. At this time, the switching elements Q5 and Q6 are not operated. The converter 17 operates as a single-phase full-wave rectifier circuit, and converts the single-phase AC power into DC power.

[0039] The DC power output from the converter 17 is supplied to the load 4 via a high potential line 18 and a low potential line 19 .

[0040] The voltage detection circuit 20 detects the voltage (DC voltage) between the high potential line 18 and the low potential line 19. The voltage value detected by the voltage detection circuit 20 is sent to the control unit 27. The control unit 27 sends an operation signal capable of controlling ON / OFF to the gate of the switching element 23 included in the overvoltage protection circuit 22 according to the voltage value detected by the voltage detection circuit 20. Specifically, the control unit 27 turns on the switching element 23 when the voltage value detected by the voltage detection circuit 20 exceeds a threshold voltage. This allows the charge stored in the filter capacitor 21 to be discharged to the low potential line 19 via the resistor 26 when an overvoltage occurs between the high potential line 18 and the low potential line 19. Therefore, the overvoltage occurring between the high potential line 18 and the low potential line 19 is suppressed.

[0041] [1-3] Effects of the first embodiment According to the first embodiment, the converter 17 can operate as a three-phase two-level converter and a single-phase two-level converter. That is, the converter 17 can convert three-phase AC power into DC power and convert single-phase AC power into DC power. This makes it possible to realize a power conversion device that can handle multiple types of power supply sources while suppressing an increase in the number of products and an increase in the external dimensions of the device.

[0042] Moreover, even if unstable power is supplied to the current collector 2, the overvoltage protection circuit 22 can be used to suppress overvoltage between the high potential line 18 and the low potential line 19. This makes it possible to protect the power conversion device 1 from overvoltage.

[0043] [2] Second embodiment In the second embodiment, a switching element included in the converter 17 is used to configure an overvoltage protection circuit.

[0044] [2-1] Configuration of power conversion device 1 2 is a circuit diagram of the power converter 1 according to the second embodiment. The power converter 1 includes a DC contactor 30 and a resistor .

[0045] The DC contactor 30 is a contactor of a contact. One end of the DC contactor 30 is connected to the node N3 of the converter 17, and the other end of the DC contactor 30 is connected to one end of the resistor 26. The other end of the resistor 26 is connected to the low potential line 19.

[0046] The switching element Q5, diodes D5 and D6, the DC contactor 30, and the resistor 26 included in the converter 17 constitute an overvoltage protection circuit. In other words, by providing the DC contactor 30 and the resistor 26, the configuration corresponds to the overvoltage protection circuit 22 of the first embodiment, in which the switching element Q5 corresponds to the switching element 23, the diode D5 corresponds to the diode 24, and the diode D6 corresponds to the diode 25. When the overvoltage protection circuit is thus constituted, the switching element Q6 connected in parallel to the diode D6 is not used as an electric circuit and is therefore always in an off state. The other configurations are the same as those of the first embodiment.

[0047] [2-2] Operation Next, the operation of the power converter 1 configured as above will be described. The first operation mode in the second embodiment is the same as that in the first embodiment. In the first operation mode, the DC contactor 30 is in an open state.

[0048] In the second operation mode, the control unit 27 uses the charging circuit 11 to charge the filter capacitor 21, and then closes the circuit breaker 14.

[0049] Next, the control unit 27 sends an operation signal capable of causing the four switching elements Q1 to Q4 to perform a switching operation to the converter 17. The converter 17 operates as a single-phase full-wave rectifier circuit, and converts the single-phase AC power into DC power. In this power conversion operation, the switching elements Q5 and Q6 are not used.

[0050] The control unit 27 sends a closing command to the DC contactor 30 to instruct the DC contactor 30 to close. This causes the DC contactor 30 to close. The control unit 27 sends an operation signal capable of controlling ON / OFF to the switching element Q5 included in the converter 17 according to the voltage value detected by the voltage detection circuit 20. Specifically, the control unit 27 turns on the switching element Q5 when the voltage value detected by the voltage detection circuit 20 exceeds a threshold voltage. The switching element Q6 remains OFF. The diode D6 connected in inverse parallel to the switching element Q6 is used as a freewheeling diode.

[0051] As a result, when an overvoltage occurs between the high potential line 18 and the low potential line 19, the charge stored in the filter capacitor 21 can be discharged to the low potential line 19 via the switching element Q5, the DC contactor 30, and the resistor 26. Thus, the overvoltage occurring between the high potential line 18 and the low potential line 19 is suppressed.

[0052] [2-3] Effects of the second embodiment According to the second embodiment, the power conversion device 1 having the power conversion function and the overvoltage suppression function of a single-phase two-level converter can be realized by simply adding the DC contactor 30 and the resistor 26. This makes it possible to suppress an increase in the number of items and an increase in the external dimensions of the device. The other effects are the same as those of the first embodiment.

[0053] [3] Third embodiment In the third embodiment, in a second operation mode in which the current collector 2 and the transformer 10 serve as power supply sources, power conversion is performed using a single-phase two-level converter having a two-group configuration.

[0054] [3-1] Configuration of power conversion device 1 3 is a circuit diagram of the power conversion device 1 according to the third embodiment. The power conversion device 1 includes a circuit breaker 31, a first converter 17, and a second converter 32. The first converter 17 corresponds to the converter 17 described in the first embodiment.

[0055] The transformer 10 is an isolation transformer including a primary winding W1, a secondary winding W2, and a tertiary winding W3. The transformer 10 converts a primary voltage (the voltage of the primary winding W1) into a secondary voltage (the voltage of the secondary winding W2) and a tertiary voltage (the voltage of the tertiary winding W3). The tertiary voltage is set to be the same as the secondary voltage.

[0056] One end of the tertiary winding W3 of the transformer 10 is connected to one end of the circuit breaker 31, and the other end of the tertiary winding W3 is connected to a node N5 of the second converter 32. The other end of the circuit breaker 31 is connected to a node N4 of the second converter 32. The circuit breaker 31 is an a-contact circuit breaker. The circuit breaker 31 connects or disconnects the path between the transformer 10 and the second converter 32.

[0057] The second converter 32 includes four switching elements Q7 to Q10. The switching elements Q7 to Q10 are, for example, IGBTs. The switching elements Q7 to Q10 are not limited to a specific element as long as they are elements that can be switched on and off. The switching elements Q7 to Q10 may be bipolar transistors, MOSFETs, GTOs, or the like.

[0058] Switching elements Q7 and Q8 are connected in series via node N4 between high potential line 18 and low potential line 19. The collector of switching element Q7 is connected to high potential line 18, and the emitter of switching element Q7 is connected to the collector of switching element Q8 via node N4. The emitter of switching element Q8 is connected to low potential line 19.

[0059] Switching elements Q9 and Q10 are connected in series via node N5 between high potential line 18 and low potential line 19. The collector of switching element Q9 is connected to high potential line 18, and the emitter of switching element Q9 is connected to the collector of switching element Q10 via node N5. The emitter of switching element Q10 is connected to low potential line 19.

[0060] Switching elements Q7 to Q10 have gates to which operation signals for controlling the switching operation are input.

[0061] The second converter 32 includes four diodes D7 to D10. The diodes D7 to D10 are connected in anti-parallel to the switching elements Q7 to Q10, respectively. The other configurations are the same as those in the first embodiment.

[0062] [3-2] Operation Next, an operation of the power conversion device 1 configured as above will be described. The first operation mode in the third embodiment is the same as that in the first embodiment. In the first operation mode, the circuit breaker 31 is in an open state.

[0063] In the second operation mode, the control unit 27 charges the filter capacitor 21 using the charging circuit 11, and then closes the circuit breaker 14. The control unit 27 sends a closing command to the circuit breaker 31 to instruct the circuit breaker 31 to close. As a result, the circuit breaker 31 is closed.

[0064] The control unit 27 sends an operation signal capable of causing the four switching elements Q1 to Q4 to perform switching operations to the first converter 17. At this time, the switching elements Q5 and Q6 are not operated. The first converter 17 operates as a single-phase full-wave rectifier circuit, and converts single-phase AC power into DC power.

[0065] The control unit 27 sends an operation signal capable of causing the four switching elements Q7 to Q10 to perform switching operations to the second converter 32. The second converter 32 operates as a single-phase full-wave rectifier circuit, and converts the single-phase AC power into DC power.

[0066] Furthermore, the control unit 27 controls the overvoltage protection circuit 22 in accordance with the voltage value sent from the voltage detection circuit 20. The operation of the overvoltage protection circuit 22 is the same as in the first embodiment.

[0067] [3-3] Effects of the third embodiment According to the third embodiment, in the power conversion operation (second operation mode) of single-phase AC power, a single-phase two-level converter having a two-group configuration including the first converter 17 and the second converter 32 can be used. This makes it possible to realize a power conversion device 1 capable of supplying larger power. Also, it makes it possible to realize a power conversion device 1 having higher reliability.

[0068] Furthermore, by supplying power using two groups of converters, the load on each converter can be reduced, thereby achieving a more reliable power conversion device 1. Other effects are the same as those of the first embodiment.

[0069] [4] Fourth embodiment In the fourth embodiment, a two-group converter is used, and a switching element included in the first converter 17 is utilized to configure an overvoltage protection circuit.

[0070] [4-1] Configuration of power conversion device 1 4 is a circuit diagram of the power conversion device 1 according to the fourth embodiment. As in the third embodiment, the power conversion device 1 includes a first converter 17 and a second converter 32. As in the second embodiment, the power conversion device 1 includes a DC contactor 30 and a resistor 26.

[0071] The DC contactor 30 is a contactor of a contact. One end of the DC contactor 30 is connected to the node N3 of the first converter 17, and the other end of the DC contactor 30 is connected to one end of the resistor 26. The other end of the resistor 26 is connected to the low potential line 19.

[0072] The switching element Q5, diodes D5 and D6, the DC contactor 30, and the resistor 26 included in the first converter 17 constitute an overvoltage protection circuit. In other words, by providing the DC contactor 30 and the resistor 26, the configuration corresponds to the overvoltage protection circuit 22 of the third embodiment, in which the switching element Q5 corresponds to the switching element 23, the diode D5 corresponds to the diode 24, and the diode D6 corresponds to the diode 25. When the overvoltage protection circuit is thus constituted, the switching element Q6 connected in parallel to the diode D6 is not used as an electric circuit and is therefore always in an off state. The other configurations are the same as those of the third embodiment.

[0073] [4-2] Operation Next, a description will be given of the operation of the power conversion device 1 configured as above. The power conversion operation of three-phase AC power and the power conversion operation of single-phase AC power are the same as those in the third embodiment.

[0074] In the second operation mode, the control unit 27 sends a closing command to the DC contactor 30 to instruct the DC contactor 30 to be in a closed state. This causes the DC contactor 30 to be in a closed state. The control unit 27 sends an operation signal capable of controlling ON / OFF to the switching element Q5 included in the first converter 17 according to the voltage value detected by the voltage detection circuit 20. Specifically, the control unit 27 turns on the switching element Q5 when the voltage value detected by the voltage detection circuit 20 exceeds a threshold voltage. The switching element Q6 remains OFF. The diode D6 connected in inverse parallel to the switching element Q6 is used as a freewheeling diode.

[0075] As a result, when an overvoltage occurs between the high potential line 18 and the low potential line 19, the charge stored in the filter capacitor 21 can be discharged to the low potential line 19 via the switching element Q5, the DC contactor 30, and the resistor 26. Thus, the overvoltage occurring between the high potential line 18 and the low potential line 19 is suppressed.

[0076] [4-3] Effects of the fourth embodiment According to the fourth embodiment, the power conversion device 1 having the power conversion function and the overvoltage suppression function of a single-phase two-level converter can be realized by simply adding the DC contactor 30 and the resistor 26. This makes it possible to suppress an increase in the number of items and an increase in the external dimensions of the device. The other effects are the same as those of the third embodiment.

[0077] [5] Fifth embodiment In the fifth embodiment, the number of elements is further reduced, and the power conversion device 1 is configured to include a three-phase two-level converter and a single-phase two-level converter configured in two groups.

[0078] [5-1] Configuration of power conversion device 1 5 is a circuit diagram of the power conversion device 1 according to the fifth embodiment. The power conversion device 1 includes a first converter 17 and a second converter 32. The configuration of the second converter 32 is the same as that of the third embodiment.

[0079] The first converter 17 is configured as a single-phase two-level converter. The first converter 17 includes switching elements Q1 to Q4 and diodes D1 to D4. The switching elements Q1 and Q2 are connected in series between the high potential line 18 and the low potential line 19 via a node N1. The switching elements Q3 and Q4 are connected in series between the high potential line 18 and the low potential line 19 via a node N2. The diodes D1 to D4 are connected in anti-parallel to the switching elements Q1 to Q4, respectively.

[0080] The three-phase terminals of the generator 15 are connected to one end of the three-phase contactor 16. The other end of the three-phase contactor 16 is connected to nodes N1 and N2 of the first converter 17 and a node N4 of the second converter 32. In other words, the U-phase and V-phase of the generator 15 are connected to the first converter 17 via the three-phase contactor 16, and the W-phase of the generator 15 is connected to the second converter 32 via the three-phase contactor 16.

[0081] The other configurations are the same as those in the third embodiment.

[0082] [5-2] Operation Next, the operation of the power conversion device 1 configured as above will be described.

[0083] First, a description will be given of the first operation mode in which the generator 15 is used as the power supply source. In the first operation mode, four switching elements Q1 to Q4 included in the first converter 17 and two switching elements Q7 and Q8 included in the second converter 32 are used to convert three-phase AC power into DC power.

[0084] In the first operation mode, the control unit 27 sends a closing command to the three-phase contactor 16 to instruct the three-phase contactor 16 to be in the closed state. As a result, the three-phase contactor 16 is in the closed state. The charging contactor 12, the circuit breaker 14, and the circuit breaker 31 are in the open state. That is, the first converter 17 and the second converter are electrically disconnected from the current collector 2 and the transformer 10.

[0085] The generator 15 generates three-phase AC power. Two phases (e.g., U-phase and V-phase) of the three-phase AC power generated by the generator 15 are supplied to the first converter 17, and the remaining phase (e.g., W-phase) is supplied to the second converter 32.

[0086] The control unit 27 sends an operation signal capable of switching the four switching elements Q1 to Q4 to the first converter 17, and sends an operation signal capable of switching the two switching elements Q7 and Q8 to the second converter 32. At this time, the switching elements Q9 and Q10 included in the second converter 32 are not operated. The first converter 17 and a part of the second converter 32 operate as a three-phase full-wave rectifier circuit, and convert the three-phase AC power into DC power.

[0087] The DC power output from the first converter 17 and the second converter 32 is supplied to the load 4 via a high potential line 18 and a low potential line 19 .

[0088] Next, a second operation mode in which the current collector 2 and the transformer 10 are used as the power supply source will be described. In the second operation mode, the three-phase contactor 16 is in an open state. That is, the first converter 17 and the second converter 32 are electrically disconnected from the generator 15.

[0089] The control unit 27 sends a closing command to the charging contactor 12 to instruct the charging contactor 12 to close. As a result, the charging contactor 12 is in the closed state. The circuit breaker 14 and the circuit breaker 31 are in the open state. The single-phase AC power generated by the transformer 10 is supplied to the filter capacitor 21 via the charging resistor 13 and the diodes D1 to D4 of the first converter 17. As a result, the filter capacitor 21 is charged.

[0090] Next, the control unit 27 sends a closing command to the circuit breaker 14 and the circuit breaker 31 to instruct them to be in the closed state. As a result, the circuit breaker 14 and the circuit breaker 31 are in the closed state. The control unit 27 sends a command to the charging contactor 12 to instruct it to be in the open state. As a result, the charging contactor 12 is in the open state.

[0091] The control unit 27 sends an operation signal capable of causing the four switching elements Q1 to Q4 to perform a switching operation to the first converter 17. The control unit 27 also sends an operation signal capable of causing the four switching elements Q7 to Q10 to perform a switching operation to the second converter 32. The first converter 17 and the second converter 32 each operate as a single-phase full-wave rectifier circuit, and convert the single-phase AC power into DC power.

[0092] The DC power output from the first converter 17 and the second converter 32 is supplied to the load 4 via a high potential line 18 and a low potential line 19 .

[0093] The operation of the overvoltage protection circuit 22 is the same as in the first embodiment.

[0094] [5-3] Effects of the fifth embodiment According to the fifth embodiment, in a power conversion operation (first operation mode) of three-phase AC power, a three-phase two-level converter can be configured using four switching elements Q1 to Q4 included in the first converter 17 and two switching elements Q7, Q8 included in the second converter 32 out of the two groups of single-phase two-level converters (first converter 17 and second converter 32).

[0095] Furthermore, in the power conversion operation (second operation mode) of single-phase AC power, a single-phase two-level converter having a two-group configuration consisting of the first converter 17 and the second converter 32 can be used. This makes it possible to realize a power conversion device 1 capable of supplying larger power. Also, it makes it possible to realize a power conversion device 1 having higher reliability.

[0096] Moreover, by simply adding two more switching elements to the six switching elements required for the power conversion operation of three-phase AC power, a power conversion device 1 having a power conversion function between a three-phase two-level converter and a single-phase two-level converter configured in two groups can be realized. This makes it possible to suppress an increase in the number of products and an increase in the external dimensions of the device. Other effects are the same as those of the first embodiment.

[0097] In the above embodiments, an electric locomotive is taken as an example of a system to which the power conversion device 1 is applied, but the present invention is not limited thereto. The present embodiments are applicable to various systems including a function of converting AC power to DC power. The present embodiments are particularly effective when the AC power source to which single-phase AC power is supplied is unstable. The present embodiments are also applicable to, for example, a trolley bus.

[0098] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0099] 1...power conversion device, 2...current collector, 3...ground terminal, 3...generator, 4...load, 10...transformer, 11...charging circuit, 12...charging contactor, 13...charging resistor, 14...circuit breaker, 15...generator, 16...three-phase contactor, 17...converter, 18...high potential line, 19...low potential line, 20...voltage detection circuit, 21...filter capacitor, 22...overvoltage protection circuit, 23...switching element, 24, 25...diode, 26...resistor, 27...control unit, 30...DC contactor, 31...circuit breaker, 32...converter, D1 to D10...diodes, Q1 to Q10...switching elements.

Claims

1. a transformer having a primary winding connected to an external power supply and a secondary winding outputting a first single-phase AC power; a first converter that converts AC power into DC power and includes first to sixth switching elements; a first circuit breaker connected between the secondary winding and the first converter; A generator that generates three-phase AC power; a first contactor connected between the generator and the first converter; a first potential line and a second potential line connected to the first converter and through which the DC power is output; a protection circuit configured to suppress an overvoltage between the first potential line and the second potential line, the protection circuit including a resistor; A control unit that controls an operation of the first converter; Equipped with The control unit is in a first operation mode, converting the three-phase AC power into DC power using the first to sixth switching elements; in a second operation mode, converting the first single-phase AC power into DC power using the first to fourth switching elements; In the second operation mode, one of the first to sixth switching elements and the resistor constitute the protection circuit. Power conversion equipment.

2. The power supply further includes a filter capacitor connected between the first potential line and the second potential line. The power conversion device according to claim 1 .

3. The protection circuit includes a second contactor connected between one of the first to sixth switching elements and the resistor. The power conversion device according to claim 1 or 2.

4. Further comprising a detection circuit for detecting a voltage between the first potential line and the second potential line; The control unit controls the second contactor based on a detection result of the detection circuit. The power conversion device according to claim 3 .

5. The power supply further includes first to sixth diodes connected in anti-parallel to the first to sixth switching elements, respectively. the fifth switching element and the sixth switching element are connected in series between the first potential line and the second potential line, one end of the second contactor is connected to a node between the fifth switching element and the sixth switching element; The other end of the second contactor is connected to one end of the resistor, the other end of the resistor is connected to the second potential line; In the second operating mode, the fifth switching element, the sixth diode, the second contactor, and the resistor constitute the protection circuit. The power conversion device according to claim 3 or 4.

6. A second circuit breaker; a second converter including eighth to eleventh switching elements; Further comprising: the transformer includes a tertiary winding that outputs a second single-phase AC power; the second circuit breaker is connected between the tertiary winding and the second converter; The control unit converts the second single-phase AC power into DC power using the eighth to eleventh switching elements in the second operation mode. The power conversion device according to any one of claims 1 to 5.

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