Power conversion device

Abstract

To suppress a rush current generated in a relay circuit when a phase of an input AC power supply is switched.SOLUTION: A power conversion device includes a power conversion circuit, a phase switching circuit, and a control circuit. The power conversion circuit includes a plurality of power semiconductors. The phase switching circuit includes a relay circuit capable of switching a connection destination of a pair of power semiconductors corresponding to other phase among the plurality of power semiconductors between a specific phase and other phase. The control circuit controls operation of the power conversion circuit and the phase switching circuit. When an external power supply is a single-phase AC power supply, the control circuit turns on a predetermined power semiconductor among the plurality of power semiconductors, detects a zero cross point of a power supply voltage from the single-phase AC power supply based on an inter-contact voltage of the relay circuit in a state in which the predetermined power semiconductor is turned on, and switches a connection destination of a pair of power semiconductors corresponding to other phase to a specific phase by operating the relay circuit within a zero period after the zero cross point.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a power conversion device.

Background Art

[0002] Conventionally, power conversion devices such as in - vehicle chargers operable with input of AC voltages from, for example, each of a three - phase AC power source and a single - phase AC power source are known. In such a power conversion device, for example, between a plurality of power conversion circuits corresponding to each phase of the AC power source, the phase of the AC power source corresponding to each of the plurality of power conversion circuits, and a phase common to the plurality of power conversion circuits, a relay circuit for switching the connection destination of the plurality of power conversion circuits is provided. Also, in such a power conversion device, in order to suppress the inrush current generated in the relay circuit when switching the phase of the input AC power source, a technique of operating the relay circuit at the zero - cross point of the AC power source where the voltage between the contacts of the relay circuit becomes zero is known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, due to variations in circuits and components, fluctuations in the external environment, or the fact that the zero - cross point is an instantaneous timing, in practice, the connection destination of the relay circuit may be switched at a timing deviated from the zero - cross point. Therefore, there has been room for improvement regarding suppression of the inrush current generated in the relay circuit when switching the phase of the input AC power source.

[0005] One of the problems to be solved by the present disclosure is to suppress the inrush current generated in the relay circuit when switching the phase of the input AC power source.

Means for Solving the Problems

[0006] The power conversion device according to the present disclosure includes a power conversion circuit, a phase switching circuit, and a control circuit. The power conversion circuit has a plurality of power semiconductors including a pair of power semiconductors corresponding to a specific phase among a plurality of phases of a multi-phase AC power supply which is an external power supply, and a pair of power semiconductors corresponding to another phase of the specific phase. The phase switching circuit has a relay circuit capable of switching a connection destination of the pair of power semiconductors corresponding to the other phase between the specific phase and the other phase. The control circuit controls operations of the power conversion circuit and the phase switching circuit. When the external power supply is a single-phase AC power supply, the control circuit turns on a predetermined power semiconductor among the plurality of power semiconductors, detects a zero-cross point at which a power supply voltage from the single-phase AC power supply becomes zero-cross while the predetermined power semiconductor is turned on, based on a voltage between contacts of the relay circuit, and switches a connection destination of the pair of power semiconductors corresponding to the other phase to the specific phase by operating the relay circuit within a zero period after the zero-cross point.

Advantages of the Invention

[0007] According to the present disclosure, it is possible to suppress an inrush current generated in the relay circuit when switching the phase of the input AC power supply.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0009] Hereinafter, embodiments of a power conversion device, a vehicle, a control method of the power conversion device, a program, and a recording medium according to the present disclosure will be described with reference to the drawings.

[0010] In the description of the present disclosure, for components having the same or substantially the same functions as those described above with respect to the previously shown drawings, the same reference numerals may be given, and the description may be omitted as appropriate. Also, even when representing the same or substantially the same part, there are cases where the dimensions and ratios are shown differently in the drawings. Further, for example, from the viewpoint of ensuring the visibility of the drawings, only main components are given reference numerals in the description of each drawing, and there are cases where components having the same or substantially the same functions as those described above in the previously shown drawings are not given reference numerals.

[0011] In the description of the present disclosure, components having the same or substantially the same functions may be described by adding alphanumeric characters to the end of the reference numerals for distinction. Alternatively, when not distinguishing a plurality of components having the same or substantially the same functions, they may be integrally described by omitting the alphanumeric characters attached to the end of the reference numerals.

[0012] FIG. 1 is a diagram schematically showing an example of the configuration of a charging system 1 including a power conversion device 3 according to an embodiment. The charging system 1 illustrated in FIG. 1 includes a single-phase AC power supply 9a or a three-phase AC power supply 9b, and a vehicle 2 equipped with the power conversion device 3.

[0013] As an example, the power conversion device 3 according to the embodiment may be mounted on the vehicle 2, for example, as an in-vehicle charger. For example, the power conversion device 3 may be an in-vehicle charger that converts AC power supplied from an external single-phase AC power supply 9a or three-phase AC power supply 9b into DC power and supplies the converted DC power to a battery (not shown) mounted on the vehicle 2. In other words, the power conversion device 3 according to the embodiment may be realized as an in-vehicle charger mounted on the vehicle 2 together with a battery, and supplying power to the battery of the vehicle 2 using AC power from an external single-phase AC power supply 9a or three-phase AC power supply 9b.

[0014] Note that the power conversion device 3 according to the embodiment may be provided not only in the vehicle 2 but also in, for example, an aircraft, amusement equipment, an uninterruptible power conversion circuit, or the like.

[0015] Note that as the vehicle 2, various moving bodies configured to be driven using power from a battery or to be able to drive its equipment (electrical equipment), such as a passenger car, a freight car, a bus, a motorcycle, and an electric kick scooter, can be appropriately used. Examples of this electrical equipment include a navigation device, an audio device, an air conditioner, power windows, a defroster, an ECU (Electronic Control Unit), a GPS (Global Positioning System) module, and an in-vehicle camera. Also, the battery of the vehicle 2 only needs to be able to store power for driving a traveling motor (main electric motor) mounted on the vehicle 2, electrical equipment, etc. For example, any battery such as a lithium-ion battery, a nickel-metal hydride battery, and a all-solid-state battery can be appropriately used.

[0016] The single-phase AC power supply 9a and the three-phase AC power supply 9b are each an arbitrary external power supply such as a power supply mounted on a rapid charging facility or a commercial power supply, for example. Note that the AC power supply 9 is not limited to a single-phase AC power supply and a three-phase AC power supply (multi-phase AC power supply), and a two-phase AC power supply (multi-phase AC power supply) may be used. In this embodiment, a case where the single-phase AC power supply 9a and the three-phase AC power supply 9b can be used as the AC power supply 9 that supplies AC power to the power conversion device 3 is illustrated. That is, in this embodiment, the power conversion device 3 configured to be operable with either the AC power from the single-phase AC power supply 9a or the input of the AC power from the three-phase AC power supply 9b is illustrated.

[0017] FIG. 2 is a diagram showing an example of the configuration of the power conversion device 3 in FIG. 1.

[0018] As shown in FIG. 2, the power conversion device 3 has a plurality of input terminals 301a to 301d to which an external power source is connected. Note that FIG. 2 illustrates a case where a single-phase AC power source 9a is connected to the power conversion device 3 as an external power source. The power conversion device 3 also has a pair of output terminals 302a and 302b to which a load such as an in-vehicle battery (not shown) is connected.

[0019] The input terminal 301a is connected to one end of the single-phase AC power source 9a. In the power conversion device 3, a power line L1 through which a single-phase current from the single-phase AC power source 9a flows is electrically connected to the input terminal 301a. Note that when a three-phase AC power source 9b is connected to the power conversion device 3 as an external power source, the power line L1 is a wire through which, for example, a U-phase (first phase) current from the three-phase AC power source 9b flows.

[0020] The input terminal 301b is not connected to the single-phase AC power source 9a. In the power conversion device 3, a power line L2 through which a single-phase current from the single-phase AC power source 9a flows via a relay circuit 51a is electrically connected to the input terminal 301b. Note that when a three-phase AC power source 9b is connected to the power conversion device 3 as an external power source, the power line L2 is a wire through which, for example, a V-phase (second phase) current from the three-phase AC power source 9b flows.

[0021] The input terminal 301c is not connected to the single-phase AC power source 9a. In the power conversion device 3, a power line L3 through which a single-phase current from the single-phase AC power source 9a flows via a relay circuit 51b is electrically connected to the input terminal 301c. Note that when a three-phase AC power source 9b is connected to the power conversion device 3 as an external power source, the power line L3 is a wire through which, for example, a W-phase (third phase) current from the three-phase AC power source 9b flows.

[0022] The input terminal 301d is electrically connected to each of the other end of the single-phase AC power source 9a and the ground potential. That is, the input terminal 301d is a ground terminal. In the power conversion device 3, a power line N which is neutral is electrically connected to the input terminal 301d.

[0023] As shown in FIG. 2, the power conversion device 3 includes a control circuit 4, a phase switching circuit 5, and a power conversion circuit 6.

[0024] The control circuit 4 is electrically connected to each of the phase switching circuit 5 and the power conversion circuit 6 via, for example, signal lines for control signals. The phase switching circuit 5 is electrically connected to a plurality of input terminals 301a to 301d via a plurality of power lines L1 to L3, N. Further, the phase switching circuit 5 is electrically connected to the subsequent power conversion circuit 6 via a plurality of power lines L1 to L3, N. The power conversion circuit 6 is electrically connected to a pair of output terminals 302a, 302b via a pair of output power lines.

[0025] Here, the output power line electrically connected to the output terminal 302a is electrically connected to the power line L1 via the MOSFET 61a of the power conversion circuit 6, electrically connected to the power line L2 via the MOSFET 61c, electrically connected to the power line L3 via the MOSFET 61e, and also electrically connected to the power line N via the MOSFET 61g. Similarly, the output power line electrically connected to the output terminal 302b is electrically connected to the power line L1 via the MOSFET 61b of the power conversion circuit 6, electrically connected to the power line L2 via the MOSFET 61d, electrically connected to the power line L3 via the MOSFET 61f, and also electrically connected to the power line N via the MOSFET 61h.

[0026] The control circuit 4 is electrically connected to the control terminals of the two relay circuits 51a, 51b of the phase switching circuit 5 via signal lines for control signals. Further, the control circuit 4 is electrically connected to the control terminals of the plurality of MOSFETs 61a to 61h of the power conversion circuit 6 via signal lines for control signals.

[0027] The control circuit 4 has at least one processor and at least one memory, and may have a hardware configuration using a normal computer.

[0028] As the processor of the control circuit 4, for example, a CPU (Central Processing Unit) can be used. The processor of the control circuit 4 comprehensively controls the operation of the control circuit 4 by executing a program, for example, and realizes various functions that the control circuit 4 has. In this embodiment, an example is given in which the processor realizes each function of the control circuit 4 by executing a program stored in a ROM or the like, but the present invention is not limited to this. A form in which some or all of the functions of the control circuit 4 are realized by a dedicated hardware circuit (such as a semiconductor integrated circuit) may also be possible.

[0029] As the memory of the control circuit 4, for example, a ROM (Read Only Memоry) and a RAM (Random Access Memory) can be used. The ROM of the control circuit 4 is a non-volatile memory and stores various information such as programs and parameters executed by the processor of the control circuit 4. The RAM of the control circuit 4 is a volatile memory having a working area for the processor. Note that the memory of the control circuit 4 is not limited to ROM and RAM, and various recording media and recording devices such as an HDD (Hard Disk Drive), an SSD (Solid State Drive), and a Flash memory may be further used.

[0030] Note that the control circuit 4 may be realized by a computer such as an ECU (Electronic Control Unit) provided inside the vehicle 2, a DCU (Domain Control Unit) such as a CDC (Cockpit Domain Controller) that integrates a plurality of ECUs, or an OBU (On Board Unit).

[0031] Note that the control circuit 4 may transmit and receive information to and from other ECUs mounted on the vehicle 2 or an external power source (AC power source 9) connected to the vehicle 2 via an in-vehicle network including CAN (Controller Area Network), Ethernet (registered trademark), USB (Universal Serial Bus (registered trademark)), etc. in the vehicle 2, or may communicate with an information processing device outside the vehicle 2 via a network such as the Internet.

[0032] The control circuit 4 controls the operations of the phase changeover circuit 5 and the power conversion circuit 6. As an example, the control circuit 4 loads a program stored in a ROM (memory) etc. into a RAM (memory) and executes the loaded program by a processor, thereby realizing various functions of the control circuit 4 including a switching control function and a conversion control function.

[0033] The switching control function of the control circuit 4 controls the operations of the phase changeover circuit 5 and the power conversion circuit 6.

[0034] As an example, the switching control function determines the phase of an external power source connected to the power conversion device 3. For example, the switching control function determines whether the external power source connected to the power conversion device 3 is single-phase or other multiple phases of single-phase based on the output (read value) of a voltage sensor (not shown) configured to be able to measure the voltage values applied to the input terminal 301, that is, applied to the power lines L1~L3, N.

[0035] As an example, when a single-phase AC power source 9a is connected to the power conversion device 3, the switching control function turns on a predetermined MOSFET 61 at a predetermined timing.

[0036] For example, this predetermined timing is when the power supply voltage from the single-phase AC power source 9a is at the "negative" peak. In this case, the switching control function turns on the MOSFETs 61c, 61e. Specifically, the switching control function generates a control signal for turning on each switch of the MOSFETs 61c, 61e when the power supply voltage is at the "negative" peak, and supplies the generated control signal to the MOSFETs 61c, 61e.

[0037] For example, this predetermined timing is when the power supply voltage from the single-phase AC power supply 9a reaches the "positive" peak. In this case, the switching control function turns on the MOSFETs 61d and 61f. Specifically, the switching control function generates a control signal to turn on each switch of the MOSFETs 61d and 61f when the power supply voltage reaches the "positive" peak, and supplies the generated control signal to the MOSFETs 61d and 61f.

[0038] As an example, after turning on a predetermined MOSFET 61 at a predetermined timing, the switching control function detects the voltage between the contacts of the relay circuit 51 and detects the zero crossing point (ZCP) of the power supply voltage at which the voltage between the contacts becomes zero or substantially zero. In other words, the switching control function detects the zero crossing point at which the power supply voltage from the single-phase AC power supply 9a crosses zero with the MOSFET 61 being in the on state, based on the voltage between the contacts of the relay circuit 51. Here, the voltage between the contacts of the relay circuit 51a indicates the potential difference between the power lines L1 and L2. Similarly, the voltage between the contacts of the relay circuit 51b indicates the potential difference between the power lines L1 and L3. Note that the voltage between the contacts being substantially zero means that the voltage (potential difference) is within a threshold range, which is, for example, preset and stored in a memory or the like, and can be regarded as zero. Hereinafter, even when simply described as zero, it includes the case of being substantially zero.

[0039] As an example, after a predetermined MOSFET 61 is turned on at a predetermined timing and the zero crossing point is detected, the switching control function switches the short-circuit / open state by the relay circuit 51 during a predetermined period (referred to as the zero period in the present disclosure) after the zero crossing point. This zero period, which is a predetermined period after the zero crossing point, is, for example, about 1 / 4 cycle of the power supply voltage, but its time width can vary depending on, for example, the capacitance of the electrolytic capacitor 69, the amount of charge stored, and the circuit configuration of the power conversion device 3.

[0040] For example, the zero period is a period during which the voltage between the contacts of the relay circuit 51, starting from the zero crossing point, is within a predetermined threshold range. This threshold range is, for example, predetermined and stored in the memory of the control circuit 4 or the like. This threshold range is based on, for example, a substantially zero range in which the voltage between the contacts of the relay circuit 51 can be regarded as zero.

[0041] For example, the zero period is a period during which, after the MOSFETs 61c and 61e are turned on when the power supply voltage from the single-phase AC power supply 9a reaches the "negative" peak, and after the zero crossing point where the voltage between the contacts of the relay circuit 51 becomes zero, the increase amount of the power supply voltage is "positive".

[0042] For example, the zero period is a period during which, after the MOSFETs 61d and 61f are turned on when the power supply voltage from the single-phase AC power supply 9a reaches the "positive" peak, and after the zero crossing point where the voltage between the contacts of the relay circuit 51a (the potential difference between the power supply lines L1 and L2) becomes zero, the increase amount of the power supply voltage is "negative".

[0043] For example, the switching control function operates the relay circuit 51a to short-circuit the power supply lines L1 and L2 during the zero period. Specifically, the switching control function generates a control signal for switching the short-circuiting / opening between the power supply lines L1 and L2 by operating the relay circuit 51a during the zero period, and supplies the generated control signal to the relay circuit 51a. Also, for example, the switching control function operates the relay circuit 51b to short-circuit the power supply lines L1 and L3 during the zero period. Specifically, the switching control function generates a control signal for switching the short-circuiting / opening between the power supply lines L1 and L3 by operating the relay circuit 51b, and supplies the generated control signal to the relay circuit 51b.

[0044] As an example, the switching control function turns off a predetermined MOSFET 61 that was on at a predetermined timing immediately after short-circuiting each of the power supply lines L1 and L2 and the power supply lines L1 and L3.

[0045] For example, this predetermined timing is immediately after short-circuiting each of the power lines L1 and L2 and the power lines L1 and L3 during the zero period after the MOSFETs 61c and 61e are turned on when the power supply voltage from the single-phase AC power supply 9a reaches the "negative" peak, and when the power supply voltage from the single-phase AC power supply 9a reaches the "positive" peak. In this case, the switching control function turns off the MOSFETs 61c and 61e. Specifically, the switching control function generates a control signal for turning off each switch of the MOSFETs 61c and 61e at the predetermined timing, and supplies the generated control signal to the MOSFETs 61c and 61e.

[0046] For example, this predetermined timing is immediately after short-circuiting each of the power lines L1 and L2 and the power lines L1 and L3 during the zero period after the MOSFETs 61d and 61f are turned on when the power supply voltage from the single-phase AC power supply 9a reaches the "positive" peak, and when the power supply voltage from the single-phase AC power supply 9a reaches the "negative" peak. In this case, the switching control function turns off the MOSFETs 61d and 61f. Specifically, the switching control function generates a control signal for turning off each switch of the MOSFETs 61d and 61f at the predetermined timing, and supplies the generated control signal to the MOSFETs 61d and 61f.

[0047] The conversion control function of the control circuit 4 controls the operation of the power conversion circuit 6.

[0048] As an example, the conversion control function starts power conversion that rectifies (converts) AC power from the single-phase AC power supply 9a into DC power at an arbitrary timing after a predetermined MOSFET 61 that has been turned on by the switching control function is turned off.

[0049] As an example, the conversion control function generates a control signal for turning on / off each switch of the MOSFET 61 so that a DC voltage of a desired voltage value is output using the input AC power, and supplies the generated control signal to the MOSFET 61.

[0050] Note that the control circuit 4 that realizes the switching control function and the control circuit 4 that realizes the conversion control function may be realized as independent circuits respectively. Also, the control circuit 4 that controls the operation of the phase changeover circuit 5 and the control circuit 4 that controls the operation of the power conversion circuit 6 may be realized as independent circuits respectively.

[0051] As shown in FIG. 2, the phase changeover circuit 5 has two relay circuits 51a and 51b.

[0052] The relay circuit 51 is, for example, an SPDT (Single-Pole Double-Throw) switch circuit. The relay circuit 51 is an example of a circuit capable of switching the connection destination of a pair of power semiconductors corresponding to another phase of a specific phase among the three phases of a three-phase AC power supply 9b between the specific phase and the other phase.

[0053] One of the pair of input terminals of the relay circuit 51a is electrically connected between the input terminal 301a and the surge resistance 65a on the power line L1. Also, the other input terminal is electrically connected to the input terminal 301b via the power line L2. Further, the output terminal of the relay circuit 51a is electrically connected to the surge resistance 65b via the power line L2.

[0054] One of the pair of input terminals of the relay circuit 51b is electrically connected between the input terminal 301a and the surge resistance 65a on the power line L1. Also, the other input terminal is electrically connected to the input terminal 301c via the power line L3. Further, the output terminal of the relay circuit 51b is electrically connected to the surge resistance 65c via the power line L3.

[0055] For example, relay circuit 51a switches the phase of the AC power supply supplied to power line L2 between, for example, the V phase (second phase) corresponding to power line L2 and a single phase common to a plurality of power lines L1 to L3 according to the control signal input from control circuit 4. Specifically, relay circuit 51a switches the connection destination of power line L2 electrically connected to MOSFETs 61c and 61d of power conversion circuit 6 between power line L2 electrically connected to input terminal 301b and power line L1 electrically connected to input terminal 301a according to the control signal input from control circuit 4. In other words, relay circuit 51a switches the short circuit / open circuit between power lines L1 and L2 according to the control signal input from control circuit 4.

[0056] For example, relay circuit 51b switches the phase of the AC power supply supplied to power line L3 between, for example, the W phase (third phase) corresponding to power line L3 and a single phase common to a plurality of power lines L1 to L3 according to the control signal input from control circuit 4. Specifically, relay circuit 51b switches the connection destination of power line L3 electrically connected to MOSFETs 61e and 61f of power conversion circuit 6 between power line L3 electrically connected to input terminal 301c and power line L1 electrically connected to input terminal 301a according to the control signal input from control circuit 4. In other words, relay circuit 51b switches the short circuit / open circuit between power lines L1 and L3 according to the control signal input from control circuit 4.

[0057] The control signal supplied to relay circuit 51 is, for example, a signal indicating the connection state of relay circuit 51, and is, for example, a rectangular wave signal taking two values of high level or low level. Note that relay circuit 51 is not limited to mechanical switching means and may be configured by semiconductor switching elements.

[0058] As shown in FIG. 2, the power conversion circuit 6 includes high-side MOSFETs 61a, 61c, 61e, 61g, low-side MOSFETs 61b, 61d, 61f, 61h, three capacitors 63a to 63c, three surge resistors 65a to 65c, three coils 67a to 67c, and an electrolytic capacitor 69. Here, MOSFETs 61a to 61h are an example of a plurality of power semiconductors included in the power conversion circuit.

[0059] The MOSFET 61 is configured with, for example, a switch, a capacitor, and a diode to form its simplified equivalent circuit, and operates according to a control signal from the control circuit 4. For example, in the simplified equivalent circuit, the switch, the capacitor, and the diode are electrically connected in parallel. For example, in the high-side MOSFET 61, the anode and cathode of the diode are electrically connected to the input side (input terminal 301 side) and the output side (output terminal 302 side) of each MOSFET 61, respectively. On the other hand, in the low-side MOSFET 61, the anode and cathode of the diode are electrically connected to the output side and the input side of each MOSFET 61, respectively. The switch is turned on / off at a timing according to the control signal from the control circuit 4 to switch its conduction / non-conduction. In each MOSFET 61, charges from the AC power supply are accumulated in the capacitor during the period when the switch is off (non-conducting), generating a potential difference between the input and output terminals thereof. In this embodiment, the turning on / off of this internal switch is expressed as the turning on / off of the MOSFET 61.

[0060] MOSFETs 61a and 61b are an example of a pair of power semiconductors related to power line L1, that is, corresponding to a specific phase among multiple phases of a three-phase AC power supply 9b. When a single-phase AC power supply 9a is connected, it may also be referred to as a first power conversion circuit including MOSFETs 61g and 61h as well. The input sides of MOSFETs 61a and 61b are electrically connected to each other, and power line L1 is connected between MOSFETs 61a and 61b. The side of MOSFET 61a opposite to MOSFET 61b (output side) is electrically connected to output terminal 302a. The side of MOSFET 61b opposite to MOSFET 61a (output side) is electrically connected to output terminal 302b. Specifically, MOSFETs 61a and 61b rectify a single-phase current flowing through power line L1 from a single-phase AC power supply 9a. Alternatively, MOSFETs 61a and 61b rectify, for example, a U-phase (first phase) current flowing through power line L1 from a three-phase AC power supply 9b.

[0061] MOSFETs 61c and 61d are an example of a pair of power semiconductors related to power line L2, that is, corresponding to another specific phase among multiple phases of a three-phase AC power supply 9b. When a single-phase AC power supply 9a is connected, it may also be referred to as a second power conversion circuit including MOSFETs 61g and 61h as well. The input sides of MOSFETs 61c and 61d are electrically connected to each other, and power line L2 is connected between MOSFETs 61c and 61d. The side of MOSFET 61c opposite to MOSFET 61d (output side) is electrically connected to output terminal 302a. The side of MOSFET 61d opposite to MOSFET 61c (output side) is electrically connected to output terminal 302b. Specifically, MOSFETs 61c and 61d rectify a single-phase current flowing through power line L2 from a single-phase AC power supply 9a. Alternatively, MOSFETs 61c and 61d rectify, for example, a V-phase (second phase) current flowing through power line L2 from a three-phase AC power supply 9b.

[0062] MOSFETs 61e and 61f are an example of a pair of power semiconductors related to the power line L3, that is, corresponding to the other phases of a specific phase among the multiple phases of the three-phase AC power supply 9b. When a single-phase AC power supply 9a is connected, it may be further referred to as a third power conversion circuit including MOSFETs 61g and 61h as well. The input sides of MOSFETs 61e and 61f are electrically connected to each other, and the power line L3 is connected between MOSFETs 61e and 61f. The side of MOSFET 61e opposite to MOSFET 61f (output side) is electrically connected to the output terminal 302a. The side of MOSFET 61f opposite to MOSFET 61e (output side) is electrically connected to the output terminal 302b. Specifically, MOSFETs 61e and 61f rectify the single-phase current flowing through the power line L3 from the single-phase AC power supply 9a. Alternatively, MOSFETs 61c and 61d rectify, for example, the W-phase (third phase) current flowing through the power line L3 from the three-phase AC power supply 9b.

[0063] MOSFETs 61g and 61h are an example of a pair of power semiconductors related to the power line N, that is, corresponding to the neutral power line. The input sides of MOSFETs 61g and 61h are electrically connected to each other, and the power line N is connected between MOSFETs 61g and 61h. The side of MOSFET 61g opposite to MOSFET 61h (output side) is electrically connected to the output terminal 302a. The side of MOSFET 61h opposite to MOSFET 61g (output side) is electrically connected to the output terminal 302b. Specifically, MOSFETs 61g and 61h form a circuit for returning the single-phase current flowing through the power lines L1 to L3 from the single-phase AC power supply 9a to the AC power supply 9 side.

[0064] The capacitor 63 is an X capacitor connected between power lines (between lines). For example, the capacitor 63a is an X capacitor electrically connected between the lines of the power lines L1 and N. For example, the capacitor 63b is an X capacitor connected between the lines of the power lines L2 and N. For example, the capacitor 63c is an X capacitor connected between the lines of the power lines L3 and N. One end of each of the capacitors 63a to 63c is electrically connected between each of the MOSFETs 61g and 61h and the input terminal 301d on the power line N. The other end of the capacitor 63a is electrically connected between the connection node with the relay circuit 51a and the inrush resistance 65a on the power line L1. The other end of the capacitor 63b is electrically connected between the output terminal of the relay circuit 51a and the inrush resistance 65b on the power line L2. The other end of the capacitor 63c is electrically connected between the output terminal of the relay circuit 51b and the inrush resistance 65c on the power line L3.

[0065] The inrush resistance 65 is an inrush current prevention element such as a temperature fuse resistance, a cement resistance, or a thermistor. The inrush resistance 65 suppresses the flow of inrush current into the power conversion circuit 6. The inrush resistance 65a is electrically connected between the connection node with the capacitor 63a and the coil 67a on the power line L1. The inrush resistance 65b is electrically connected between the connection node with the capacitor 63b and the coil 67b on the power line L2. The inrush resistance 65c is electrically connected between the connection node with the capacitor 63c and the coil 67c on the power line L3. Note that in the power conversion device 3, the inrush resistance 65 is not an essential component and may not be provided. For example, in the phase changeover circuit 5, when the relay circuit 51a defaultly connects the coil 67b and the input terminal 301b on the power line L2, and the relay circuit 51b defaultly connects the coil 67c and the input terminal 301c on the power line L3, the inrush resistance 65 may not be provided.

[0066] The coil 67 is a common-mode choke coil, or a normal-mode choke coil, etc. The coil 67a is electrically connected between the inrush resistor 65a and each of the MOSFETs 61a and 61b in the power line L1. The coil 67b is electrically connected between the inrush resistor 65b and each of the MOSFETs 61c and 61d in the power line L2. The coil 67c is electrically connected between the inrush resistor 65c and each of the MOSFETs 61e and 61f in the power line L3.

[0067] Note that the capacitor 63 and the coil 67 form a noise filter. This noise filter suppresses (removes noise) the entry of noise from the AC power supply 9 into the power conversion circuit 6 and the outflow of noise from the power conversion circuit 6 to the AC power supply 9. For example, the capacitor 63a and the coil 67a are noise filters provided in the power line L1. For example, the capacitor 63b and the coil 67b are noise filters provided in the power line L2. For example, the capacitor 63c and the coil 67c are noise filters provided in the power line L3.

[0068] The electrolytic capacitor 69 is electrically connected between the output terminals 302a and 302b, that is, between a pair of output power lines.

[0069] Next, an operation example of the power conversion device 3 configured as described above will be described.

[0070] Figure 3 is a flowchart showing an example of the flow of control processing executed by the control circuit 4 in Figure 2. The flow in Figure 3 starts when an external power supply (single-phase AC power supply 9a or three-phase AC power supply 9b) is connected to the power conversion device 3, for example. Figure 4 is a timing chart for explaining the operation timing of each part of the power conversion device 3 by the control circuit 4 in Figure 2.

[0071] The control circuit 4 determines whether it is a single-phase input (S101).

[0072] In the example of FIG. 4, at "t0", the control circuit 4 determines whether the AC power input to the power conversion device 3 is single-phase.

[0073] In the case of single-phase input (S101: Yes), the control circuit 4 turns on a predetermined MOSFET 61 of the power conversion circuit 6 when the power supply voltage reaches the "negative (positive)" peak (S102).

[0074] In the example of FIG. 4, in the case of single-phase input and at "t1" where the power supply voltage is at the "negative" peak, the control circuit 4 turns on MOSFETs 61c and 61e.

[0075] After the predetermined MOSFET 61 is turned on, the control circuit 4 detects the voltage between the contacts of the relay circuit 51 and determines whether a zero-crossing point is detected based on the detected voltage between the contacts (S103). If the zero-crossing point is not detected (S103: No), the process of S103 is repeated at a predetermined period, for example, until the zero-crossing point is detected. On the other hand, if the zero-crossing point is detected (S103: Yes), the control circuit 4 switches the short-circuit destination by the relay circuit 51 within a predetermined period in which the increase amount of the power supply voltage after the zero-crossing point is detected is "positive (negative)", that is, within the zero period (S104).

[0076] In the example of FIG. 4, a zero-crossing point is detected at "t6". In this case, the control circuit 4 switches the short-circuit destination by the relay circuit 51 at "t7" within the zero period "t6 to t8" in which the increase amount of the power supply voltage after the zero-crossing point of "t6" is "positive", and short-circuits each of the power lines L1, L2 and the power lines L1, L3.

[0077] For example, if a zero-crossing point is detected at "t2", the control circuit 4 switches the short-circuit destination by the relay circuit 51 within the zero period "t2 to t3" after the zero-crossing point of "t2". Also, for example, if a zero-crossing point is detected at "t4", the control circuit 4 switches the short-circuit destination by the relay circuit 51 within the zero period "t4 to t5" after the zero-crossing point of "t4".

[0078] After the short - circuit destination is switched by the relay circuit 51 within the zero period when the increase amount of the power supply voltage is "positive (negative)", when the power supply voltage immediately after the switching is at the "positive (negative)" peak, the control circuit 4 turns off the MOSFET 61 that was turned on in the process of S102 (S105).

[0079] In the example of FIG. 4, at "t8" where the power supply voltage is at the "positive" peak immediately after the power supply lines L1, L2 and the power supply lines L1, L3 are short - circuited respectively at "t7", the control circuit 4 turns off the MOSFETs 61c, 61e that were turned on at "t1".

[0080] After the process of S101 or S106, the control circuit 4 executes power conversion (S106).

[0081] In the example of FIG. 4, the control circuit 4 starts power conversion at "t9" at an arbitrary timing after the MOSFETs 61c, 61e that were turned on at "t1" are turned off at "t8".

[0082] For example, when single - phase AC power from a single - phase AC power supply 9a is input, each of the relay circuits 51a, 51b is short - circuited to the power supply line L1. As a result, the single - phase AC current flowing through the power supply line L1 is supplied to the MOSFETs 61a, 61b via the coil 67a, and is distributed to the coils 67b, 67c by the relay circuits 51a, 51b and supplied to each of the MOSFETs 61c, 61d and the MOSFETs 61e, 61f. Thereby, even when the connected external power supply is a single - phase AC power supply 9a, a plurality of sets of MOSFETs 61 with a small rated capacity can be used, so that the rated capacity of the entire power conversion device 3 can be increased.

[0083] For example, when three-phase AC power from a three-phase AC power supply 9b is input, the relay circuits 51a and 51b are connected to the power lines L2 and L3, so that the first-phase AC current flowing through the power line L1 is supplied to the MOSFETs 61a and 61b via the coil 67a, the second-phase AC current flowing through the power line L2 is supplied to the MOSFETs 61c and 61d via the coil 67b, and the third-phase AC current flowing through the power line L3 is supplied to the MOSFETs 61e and 61f via the coil 67c. Thereby, by using the sets of MOSFETs 61 provided for each phase, the rated capacity of the entire power conversion device 3 can be made larger.

[0084] Conventionally, due to variations in circuits and components or fluctuations in the external environment, or because the zero-crossing point is at an instantaneous timing, in actuality, there has been a case where the connection destination of the relay circuit is switched at a timing deviated from the zero-crossing point. When the connection destination of the relay circuit is switched at a timing deviated from the zero-crossing point, it means that the connection destination of the relay circuit is switched at a timing when the voltage between the contacts of the relay circuit is not zero. For this reason, an inrush current flows from the AC power supply to the X capacitor via the relay circuit, and there has been a problem that the relay circuit may become stuck. Therefore, there has been room for improvement regarding the suppression of the inrush current generated in the relay circuit when the phase of the input AC power supply is switched.

[0085] Under such circumstances, the power conversion device 3 according to the embodiment is configured to correspond to the input of single-phase and multi-phase AC power supplies. In the case of single-phase input, the short-circuit destination by the relay circuit 51 is switched in a state where a predetermined MOSFET 61, that is, a part of the power semiconductor, is temporarily turned on at a predetermined timing based on the waveform of the power supply voltage.

[0086] According to this configuration, a zero period during which the voltage between the contacts of the relay circuit 51 becomes zero can be formed starting from the zero crossing point. That is, according to the above configuration, since the relay circuit 51 is switched during the zero period after the zero crossing point of the power supply voltage at which the voltage between the contacts of the relay circuit 51 becomes zero, inrush current can be suppressed. In other words, according to the above configuration, the inrush current generated in the mechanical relay (relay circuit 51) at the time of phase switching of the AC power supply can be suppressed by a combination of the switching operations of the power semiconductors. Also, since the inrush current can be suppressed by a combination of the switching operations of the power semiconductors, that is, without newly adding components, low cost / small space can be maintained.

[0087] Note that in the above-described embodiment, "determining whether it is A" may mean "determining that it is A", or "determining that it is not A", or "determining whether it is A or not".

[0088] The program executed by the control circuit 4 of the power conversion device 3 in the above-described embodiment may be configured to be provided by being pre-embedded in a memory such as a ROM.

[0089] Also, the program executed by the control circuit 4 of the power conversion device 3 in the above-described embodiment may be recorded on a computer-readable recording medium such as a CD-ROM, FD, CD-R, DVD, SD card, etc. in an installable format or an executable format file and provided.

[0090] Also, the program executed by the control circuit 4 of the power conversion device 3 may be configured to be stored on a computer connected to a network such as the Internet and downloaded via the network for providing. Also, the program executed by the control circuit 4 of the power conversion device 3 may be configured to be provided or distributed via a network such as the Internet.

[0091] In addition, the program executed by the control circuit 4 of the power conversion device 3 in the above-described embodiment has a module configuration including each functional unit that realizes each of the above-described functions. As actual hardware, a processor such as a CPU reads a program from a memory such as a ROM and executes it, so that each of the above functional units is loaded onto a RAM, and each of the above functional units may be generated on the RAM.

[0092] According to at least one of the embodiments described above, it is possible to suppress the inrush current generated in the relay circuit when the phase of the input AC power supply is switched.

[0093] 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 embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and its equivalent scope.

[0094] (Supplementary Note) From the description of the above embodiments, the following technology is disclosed. (1) A power conversion circuit having a plurality of power semiconductors including a pair of power semiconductors corresponding to a specific phase among a plurality of phases of a multi-phase AC power supply that is an external power supply, and a pair of power semiconductors corresponding to another phase of the specific phase, A phase switching circuit having a relay circuit capable of switching the connection destination of the pair of power semiconductors corresponding to the other phase between the specific phase and the other phase, A control circuit that controls the operations of the power conversion circuit and the phase switching circuit, When the external power supply is a single-phase AC power supply, the control circuit turns on a predetermined power semiconductor among the plurality of power semiconductors, Detect a zero-crossing point at which the power supply voltage from the single-phase AC power supply crosses zero with the predetermined power semiconductor turned on, based on the voltage across the contacts of the relay circuit. During a zero period after the zero-crossing point, operate the relay circuit to switch the connection destination of the pair of power semiconductors corresponding to the other phase to the specific phase. Power conversion device. (2) When the power supply voltage from the single-phase AC power supply reaches a negative peak, the control circuit turns on the predetermined power semiconductor on the high-side among the plurality of power semiconductors. The power conversion device according to (1) above. (3) The zero period is a period during which the increase amount of the power supply voltage from the single-phase AC power supply after the predetermined power semiconductor on the high-side is turned on is positive. The power conversion device according to (2) above. (4) When the power supply voltage from the single-phase AC power supply reaches a positive peak immediately after operating the relay circuit during the zero period, the control circuit turns off the predetermined power semiconductor on the high-side that is turned on. The power conversion device according to (2) or (3) above. (5) When the power supply voltage from the single-phase AC power supply reaches a positive peak, the control circuit turns on the predetermined power semiconductor on the low-side among the plurality of power semiconductors. The power conversion device according to (1) above. (6) The zero period is a period during which the increase amount of the power supply voltage from the single-phase AC power supply after the predetermined power semiconductor on the low-side is turned on is negative. The power conversion device according to (5) above. (7) When the power supply voltage from the single-phase AC power supply reaches a negative peak immediately after operating the relay circuit during the zero period, the control circuit turns off the predetermined power semiconductor on the low-side that is turned on. The power conversion device according to (5) or (6) above. (8) The zero period is a period during which the voltage between the contacts of the relay circuit is within a predetermined threshold range starting from the zero crossing point. The power conversion device according to any one of (1) to (7) above. (9) The control circuit After operating the relay circuit during the zero period, turn off the predetermined power semiconductor that is on. After turning off the predetermined power semiconductor, start power conversion that converts AC power from the single-phase AC power supply into DC power. The power conversion device according to any one of (1) to (8) above. (10) A power conversion circuit having a plurality of power semiconductors including a pair of power semiconductors corresponding to a specific phase among a plurality of phases of a multi-phase AC power supply that is an external power supply, and a pair of power semiconductors corresponding to another phase of the specific phase, A phase switching circuit having a relay circuit capable of switching the connection destination of the pair of power semiconductors corresponding to the other phase between the specific phase and the other phase, A control method for a power conversion device including a control circuit that controls the operations of the power conversion circuit and the phase switching circuit, When the external power supply is a single-phase AC power supply, by the control circuit, Turn on a predetermined power semiconductor among the plurality of power semiconductors, Detect a zero crossing point at which the power supply voltage from the single-phase AC power supply crosses zero while the predetermined power semiconductor is on, based on the voltage between the contacts of the relay circuit, During the zero period after the zero crossing point, operate the relay circuit to switch the connection destination of the pair of power semiconductors corresponding to the other phase to the specific phase. A control method for a power conversion device. (11) The control circuit includes turning on the predetermined power semiconductor on the high side among the plurality of power semiconductors when the power voltage from the single-phase AC power supply reaches the negative peak. The control method of the power conversion device according to (10) above. (12) The zero period is a period during which the increase amount of the power voltage from the single-phase AC power supply after the predetermined power semiconductor on the high side is turned on is positive. The control method of the power conversion device according to (11) above. (13) The control circuit further includes turning off the predetermined power semiconductor on the high side that is on when the power voltage from the single-phase AC power supply reaches the positive peak immediately after operating the relay circuit during the zero period. The control method of the power conversion device according to (11) or (12) above. (14) The control circuit includes turning on the predetermined power semiconductor on the low side among the plurality of power semiconductors when the power voltage from the single-phase AC power supply reaches the positive peak. The control method of the power conversion device according to (10) above. (15) The zero period is a period during which the increase amount of the power voltage from the single-phase AC power supply after the predetermined power semiconductor on the low side is turned on is negative. The control method of the power conversion device according to (14) above. (16) The control circuit turns off the predetermined power semiconductor on the low side that is on when the power voltage from the single-phase AC power supply reaches the negative peak immediately after operating the relay circuit during the zero period. The control method of the power conversion device according to (14) or (15) above. (17) The zero period is a period starting from the zero crossing point and within a predetermined threshold range of the voltage between the contacts of the relay circuit. The control method of the power conversion device according to any one of (10) to (16) above. (18) By the control circuit, after operating the relay circuit during the zero period, turning off the predetermined power semiconductor that is on, and after turning off the predetermined power semiconductor, starting power conversion to convert AC power from the single-phase AC power supply into DC power, further comprising. The control method of the power conversion device according to any one of (10) to (17) above. (19) At least one processor, and a memory storing at least one program executed by the at least one processor, comprising. The at least one processor is configured to realize the control method of the power conversion device according to any one of (10) to (18) above by executing the at least one program. Power conversion device. (20) A program for causing a computer to execute the control method of the power conversion device according to any one of (10) to (18) above. (21) A program executed by a computer, and a recording medium (Computer Program Product) on which the program according to (20) above is recorded. (22) The power conversion device according to any one of (1) to (9) and (19) above for converting AC power from an external AC power supply into DC power, and a battery charged using the DC power converted by the power conversion device, comprising. Vehicle.

Explanation of Signs

[0095] 1 Charging system 2 Vehicle 3 Power conversion device 301a~301d Input terminals Output terminals 302a, 302b 4 Control circuit 5 Phase changeover circuit Relay circuits 51a, 51b 6 Power conversion circuit MOSFETs 61a to 61h Capacitors 63a to 63c Surge resistors 65a to 65c Coils 67a to 67c Electrolytic capacitor 69 AC power supplies 9a, 9b Power lines L1, L2, L3, N

Claims

1. A power conversion circuit having a plurality of power semiconductors including a pair of power semiconductors corresponding to a specific phase among a plurality of phases of a multi-phase AC power supply which is an external power supply, and a pair of power semiconductors corresponding to another phase of the specific phase; A phase switching circuit having a relay circuit capable of switching the connection destination of the pair of power semiconductors corresponding to the other phase between the specific phase and the other phase; A control circuit for controlling the operations of the power conversion circuit and the phase switching circuit, wherein when the external power supply is a single-phase AC power supply, the control circuit turns on a predetermined power semiconductor among the plurality of power semiconductors, detects a zero-crossing point at which the power supply voltage from the single-phase AC power supply crosses zero with the relay circuit contact voltage in a state where the predetermined power semiconductor is turned on, switches the connection destination of the pair of power semiconductors corresponding to the other phase to the specific phase by operating the relay circuit within a zero period after the zero-crossing point, a power conversion device.

2. The control circuit turns on the predetermined power semiconductor on the high side among the plurality of power semiconductors when the power supply voltage from the single-phase AC power supply is at a negative peak, The power conversion device according to Claim 1.

3. The zero period is a period in which an increase amount of the power supply voltage from the single-phase AC power supply after the predetermined power semiconductor on the high side is turned on is positive, The power conversion device according to Claim 2.

4. The control circuit turns off the predetermined power semiconductor on the high side that is turned on when the power supply voltage from the single-phase AC power supply is at a positive peak immediately after operating the relay circuit in the zero period, The power conversion device according to Claim 2 or 3.

5. The control circuit turns on the predetermined power semiconductor on the low side among the plurality of power semiconductors when the power supply voltage from the single-phase AC power supply is at a positive peak, The power conversion device according to Claim 1.

6. The zero period is a period in which an increase amount of the power supply voltage from the single-phase AC power supply after the predetermined power semiconductor on the low side is turned on is negative, The power conversion device according to Claim 5.

7. The control circuit turns off the predetermined power semiconductor on the low side that is turned on when the power supply voltage from the single-phase AC power supply is at a negative peak immediately after operating the relay circuit in the zero period, The power conversion device according to Claim 5 or 6.

8. The zero period is a period during which the voltage between the contacts of the relay circuit starting from the zero crossing point is within a predetermined threshold range. The power conversion device according to claim 1.

9. The control circuit After operating the relay circuit during the zero period, turns off the predetermined power semiconductor that is on. After turning off the predetermined power semiconductor, starts power conversion that converts AC power from the single-phase AC power supply into DC power. The power conversion device according to claim 1.

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