Power conversion device and method for controlling same

Abstract

This power conversion device is provided with: a first conversion circuit that has a first switching element that performs switching at a high speed, and that converts power input from an input terminal into a first alternating current; and a second conversion circuit that has a second switching element that selects the polarity of the output, converts the first alternating current input from the first conversion circuit, and outputs the converted first alternating current to the output terminal. And a control unit that determines whether the power input to the input terminal is alternating current or direct current, and if it is determined that the input power is alternating current, controls the operation of the first switching element and the second switching element so that the second conversion circuit outputs direct current. When it is determined that the input power is direct current, the operation of the first switching element and the second switching element is controlled so that the second conversion circuit outputs direct current or second alternating current.

Description

Technical Field

[0001] The invention relates to a power conversion device and a control method thereof. Background Art

[0002] A bidirectional power conversion device is needed, which can connect the AC power supplied from the power system to the input terminal, connect the load represented by a battery to the output terminal, convert the AC power and supply it to the output terminal, and supply power from the battery connected to the output terminal to the input terminal.

[0003] Such a power conversion device has a function as a charger for charging a battery of an electric vehicle from AC power, for example, and can supply power from the battery of the electric vehicle to an input terminal.

[0004] The power conversion device shown in Patent Document 1 includes: a first conversion circuit having a switching element provided on the input terminal side; and a second conversion circuit having a switching element provided on the output terminal side. The power conversion device can perform bidirectional power conversion by switching the operating states of the first conversion circuit and the second conversion circuit.

[0005] In this bidirectional power conversion device, when power is supplied from an input terminal to an output terminal, an inverter circuit arranged on the input terminal side generates a high-frequency current, and a rectifier arranged on the output terminal side rectifies the high-frequency current and outputs it to the output terminal.

[0006] When electric power is supplied from the output terminal to the input terminal, the inverter circuit on the output terminal side generates a high-frequency current, and the rectifier disposed on the input terminal side rectifies the high-frequency current and outputs it to the input terminal side.

[0007] Usually, an inverter and a rectifier are not provided on the input side and the output side respectively, but each inverter circuit also functions as a rectifier.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application No. 2019-525707

[0011] Problems to be solved by the invention

[0012] However, in such a bidirectional power conversion device, one of the input and output inverters needs to perform high-frequency switching depending on the direction of power conversion. Therefore, both the first conversion circuit and the second conversion circuit need to be compatible with high-frequency switching, which increases the cost. Summary of the invention

[0013] An object of the present invention is to provide a power conversion device and a control method thereof that can reduce costs.

[0014] The control method of the power conversion device of the present invention controls the operation of the first switching element and the second switching element of the power conversion device having a first conversion circuit and a second conversion circuit, wherein the first conversion circuit has a first switching element that switches at high speed, and the second conversion circuit has a second switching element. The first conversion circuit converts the power input from the input terminal into a first alternating current (first alternating current power). The second switching element selects the polarity of the output. The second conversion circuit converts the first alternating current input from the first conversion circuit and outputs it to the output terminal.

[0015] A control method for a power conversion device determines whether the power input to an input terminal is AC or DC, and when it is determined that the input power is AC, controls the operation of a first switching element and a second switching element so that a second conversion circuit outputs DC power. When it is determined that the input power is DC power, controls the operation of the first switching element and the second switching element so that a second conversion circuit outputs DC power or a second AC power (a second AC power).

[0016] Effects of the Invention

[0017] According to the present invention, it is possible to provide a power conversion device and a control method thereof that can reduce costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a block diagram of the structure of the power conversion device according to the first embodiment of the present invention.

[0019] Figure 2 This is a flowchart showing a control method of the power conversion device according to the first embodiment of the present invention.

[0020] Figure 3 It is a block diagram of the structure of a power conversion device according to the second embodiment of the present invention.

[0021] Figure 4 This is a flowchart showing a control method of a power conversion device according to a second embodiment of the present invention.

[0022] Figure 5 It is a block diagram of the structure of a power conversion device according to a third embodiment of the present invention.

[0023] Figure 6 This is a flowchart showing a control method of a power conversion device according to a fourth embodiment of the present invention.

[0024] Figure 7 This is a flowchart showing a control method of a power conversion device according to a fifth embodiment of the present invention.

[0025] Figure 8 It is a block diagram of the structure of a power conversion device according to the sixth embodiment of the present invention.

[0026] Fig. 9 It is a block diagram of the structure of a power conversion device according to the seventh embodiment of the present invention. DETAILED DESCRIPTION

[0027] Hereinafter, a power conversion device and a control method thereof according to several embodiments of the present invention will be described in detail with reference to the accompanying drawings. The same or corresponding parts in the drawings of the power conversion device and the control method thereof in each embodiment are denoted by the same reference numerals and their description is omitted.

[0028] (First Embodiment)

[0029] Figure 1 1 is a block diagram of a power conversion device according to a first embodiment of the present invention. A power conversion device 1 according to the first embodiment includes an input terminal 2 and an output terminal 3 , a first conversion circuit 4 , a second conversion circuit 5 , and a control circuit 6 .

[0030] When the power conversion device 1 charges the electric vehicle from AC power, AC power is input to the input terminal 2, and the battery of the electric vehicle is connected to the output terminal 3. When the electric vehicle is externally powered, the battery of the electric vehicle is connected to the input terminal 2, and DC power or AC power is output from the output terminal 3.

[0031] Since both AC and DC power may be connected to the input terminal 2 , the control circuit 6 detects and determines whether the power connected to the input is AC or DC using a voltage sensor or the like.

[0032] The first conversion circuit 4 includes a switching element Q1 that switches at high speed, and is a voltage resonance type inverter circuit that converts power input from the input terminal 2 into a first alternating current and outputs the first alternating current to the second conversion circuit 5. The first conversion circuit 4 generates a high-frequency alternating current by repeatedly turning on and off the switching element Q1 at a high frequency.

[0033] The first conversion circuit 4 includes capacitors C1, C2, and C3, an inductor L1 disposed between the switching element Q1 and the AC voltage input unit, and an LC resonant circuit disposed between the switching element Q1 and the output of the first conversion circuit 4. The LC resonant circuit is composed of the inductor L2 and the capacitor C3. The capacitor C2 is connected in parallel with the switching element Q1 and may also be a parasitic capacitance of the switching element Q1.

[0034] The first conversion circuit 4 performs voltage resonance through an LC resonance circuit composed of the inductor L2 and the capacitor C3 to achieve zero voltage switching when the switching element Q1 is turned on, thereby reducing the switching loss of the switching element Q1.

[0035] The switching element Q1 is composed of a unipolar transistor such as a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). The switching element Q1 switches between an on operation and an off operation according to an on / off control signal from the control circuit 6. The switching frequency of the switching element Q1 is, for example, several hundred kHz or 1 MHz to 10 MHz.

[0036] The second conversion circuit 5 includes switching elements Q2 and Q3 that can select the polarity of output, and converts the first AC power input from the first conversion circuit 4 and outputs the converted power to the output terminal 3 .

[0037] The second conversion circuit 5 has a function of selecting the polarity of the voltage output to the output terminal 3. When a positive voltage is output to the output terminal 3, the switch element Q2 on the P side is turned on and the switch element Q3 on the N side is turned off. When a negative voltage is output to the output terminal 3, the second conversion circuit 5 turns on the switch element Q3 on the N side and turns off the switch element Q2 on the P side. Thus, the second conversion circuit 5 outputs direct current or a second alternating current having a frequency lower than the frequency of the first alternating current from the first conversion circuit 4. The frequency of the second alternating current is, for example, the frequency of the alternating current power source, 50 Hz.

[0038] In the second conversion circuit 5, one end of the switching element Q2, the cathode of the diode D1, and one end of the capacitor C4 are connected to one input terminal of the second conversion circuit 5. The anode of the diode D2 and one end of the switching element Q3 are connected to the other end of the switching element Q2. The cathode of the diode D2 and the other end of the capacitor C4 are connected to the other end of the switching element Q3. A series circuit of an inductor L3 and a capacitor C5 is connected to both ends of the capacitor C4, and both ends of the capacitor C5 are connected to the output terminal 3.

[0039] The diodes D1 and D2 and the switching elements Q2 and Q3 function as a rectifier that rectifies the high-frequency AC power from the first conversion circuit 4 .

[0040] The control circuit 6 controls the operations of the switching element Q1 and the switching element Q2. Figure 2 1 is a flowchart showing a control method of a power conversion device according to a first embodiment of the present invention. The control method of the power conversion device is implemented by the operation of the control circuit 6. Figure 2 A control method of the power conversion device will be described.

[0041] The control circuit 6 determines whether the power input to the input terminal 2 is AC or DC (step S1). If the control circuit 6 determines that the input power is AC in step S1, the operation of the switching element Q1 and the switching element Q2 is controlled so that the second conversion circuit 5 outputs DC power (step S2).

[0042] At this time, the control circuit 6 generates high-frequency AC power (first AC power) by causing the switching element Q1 of the first conversion circuit 4 to switch at high speed and outputs it to the second conversion circuit 5. The control circuit 6 controls the rectification direction of the switching elements Q2 and Q3 so that the power output from the second conversion circuit 5 having a rectifier for rectifying the high-frequency AC power from the first conversion circuit 4 becomes DC.

[0043] If the control circuit 6 determines that the input power is DC in step S1, it controls the operation of the switching element Q1 and the switching element Q2 so that the second conversion circuit 5 outputs DC power or the second AC power (step S3). The frequency of the second AC power is lower than that of the first AC power.

[0044] At this time, the control circuit 6 generates high-frequency AC power (first AC power) by causing the switching element Q1 of the first conversion circuit 4 to switch at high speed and outputs it to the second conversion circuit 5. The control circuit 6 controls the rectification direction of the switching elements Q2 and Q3 so that the power output from the second conversion circuit 5 having a rectifier for rectifying the high-frequency AC power from the first conversion circuit 4 becomes DC power or the second AC power.

[0045] According to the power conversion device of the first embodiment, regardless of whether the input power is AC or DC, the switch element Q1 performs high-frequency switching, and the switch elements Q2 and Q3 do not need to perform high-frequency switching. That is, a power conversion device having the function of taking AC as input and outputting DC, and the function of taking DC as input and outputting DC or AC can be realized at low cost.

[0046] In addition, the first conversion circuit 4 controls the voltage / current according to the requirements / limitations from the power supply connected to the input terminal 2 and the limitations of the load connected to the output terminal 3. Therefore, whether it is charging or external power supply, only the first conversion circuit 4 composed of the inverter circuit configured at the input terminal 2 needs to perform switching operations at high frequency. The second conversion circuit 5 with a rectifier always performs only rectification operations. Therefore, it is not necessary to use a high-cost switching element that can operate at high frequency in the rectifier, and charging and external power supply can be achieved by a single power conversion device.

[0047] Furthermore, regardless of whether the input power is AC or DC, the voltage resonance inverter circuit of the first conversion circuit 4 disposed on the input terminal side performs a switching operation, so low-loss switching can be achieved.

[0048] (Second Embodiment)

[0049] Figure 3 FIG. 1 is a block diagram of a power conversion device according to a second embodiment of the present invention. Figure 1 The power conversion device of the first embodiment shown further includes a first communication interface 7 and a second communication interface 8 .

[0050] The first communication interface 7 is provided inside the input terminal 2 and communicates with the outside. The second communication interface 8 is provided inside the output terminal 3 and communicates with the outside. The power storage system 10 includes a storage battery 11 .

[0051] The output terminal 3 is connected to the power storage system 10 via two electric wires 9a. The two electric wires 9a supply the electric power from the second conversion circuit 5 to the storage battery 11 via the output terminal 3 and the two electric wires 9a.

[0052] The signal line 9b is connected to the second communication interface 8 and the power storage system 10. The control circuit 6a communicates with the power storage system 10 via the second communication interface 8 and the signal line 9b.

[0053] The power storage system 10 may be connected to the input terminal 2 via two electric wires 9a, and the signal line 9b may be connected to the first communication interface 7 and the power storage system 10. In this case, the control circuit 6a communicates with the power storage system 10 via the first communication interface 7 and the signal line 9b.

[0054] Next, refer to Figure 4 The flowchart shown in the figure explains in detail the control method of the power conversion device of the second embodiment configured as above. The control method of the power conversion device is realized by the control of the control circuit 6a.

[0055] First, the control circuit 6a determines whether the power input to the input terminal 2 is AC or DC (step S11). If the control circuit 6a determines that the input power is AC in step S11, it determines whether the power storage system 10 is connected to the output terminal 3 (step S12). A voltage sensor or the like is used to detect and determine whether the power storage system 10 is connected to the output terminal 3.

[0056] When the power storage system 10 is connected in step S12 , the control circuit 6 a communicates with the power storage system 10 via the signal line 9 b and the second communication interface 8 , and receives a command related to charging from the power storage system 10 (step S13 ).

[0057] The control circuit 6a controls the operation of the switching element Q1 and the switching element Q2 based on the charge-related command from the power storage system 10 so that the second conversion circuit 5 outputs direct current power and controls the charging of the storage battery 11 (step S14).

[0058] When the control circuit 6a determines that the input power is DC in step S11, it determines whether the power storage system 10 is connected to the input terminal 2 (step S15). In step S15, it is determined whether the power storage system 10 is connected to the input terminal 2 by detecting using a voltage sensor or the like.

[0059] When the power storage system 10 is connected in step S15 , the control circuit 6 a communicates with the power storage system 10 via the signal line 9 b and the first communication interface 7 , and receives a command related to discharge from the power storage system 10 (step S16 ).

[0060] The control circuit 6a determines whether the instruction related to discharge, that is, the output instruction, from the power storage system 10 is DC or AC (step S17). When the control circuit 6a determines that the output instruction is AC in step S17, the operation of the switching element Q1 and the switching elements Q2 and Q3 is controlled so that the second conversion circuit 5 outputs AC to the output terminal 3 (step S18).

[0061] In this case, the switching element Q1 is switched at high speed to convert direct current into high-frequency alternating current, and the switching elements Q2 and Q3 are operated at low speed to convert the converted high-frequency alternating current into low-frequency alternating current.

[0062] When the control circuit 6a determines in step S17 that the output command is a direct current, it controls the operation of the switching element Q1 and the switching elements Q2 and Q3 so that the second conversion circuit 5 outputs a direct current to the output terminal 3 (step S19).

[0063] In this case, the switching element Q1 is switched at high speed to convert direct current into high-frequency alternating current, and the switching elements Q2 and Q3 are rectified to convert the converted high-frequency alternating current into direct current.

[0064] That is, when the power storage system 10 including the battery 11 is connected to the input terminal 2 , the operations of the switching element Q1 and the switching elements Q2 and Q3 are controlled to control the output from the battery 11 to the output terminal 3 .

[0065] According to the drive circuit of the second embodiment, when an external power source such as a storage battery 11 or an external load is connected to the input terminal 2 or the output terminal 3, the control circuit 6a communicates with the power storage system 10 via the first communication interface 7 or the second communication interface 8. The control circuit 6a can control the operation of the switching element Q1 and the switching elements Q2 and Q3 based on the communication result so that the operation is within the range that the external power source can output and can receive the external load.

[0066] When AC power is connected to input terminal 2 and power storage system 10 is connected to output terminal 3, control circuit 6a communicates with power storage system 10. The operation of switching element Q1 and switching elements Q2 and Q3 can be controlled in consideration of charging conditions and procedures required by power storage system 10.

[0067] When the power storage system 10 is connected to the input terminal 2, communication is performed with the power storage system 10 connected to the input terminal 2. The operation of the switching element Q1 and the switching elements Q2 and Q3 can be controlled in consideration of the discharge conditions and process provided by the power storage system 10.

[0068] In addition, when the power storage system 10 is connected to the input terminal 2 and supplies power to the output side, either direct current or alternating current can be selected according to the instruction of the power storage system side and output to the output terminal 3. The user can select the power obtained from the output of the power conversion device by instructing whether to output direct current or alternating current to the power storage system 10.

[0069] (Third Embodiment)

[0070] Figure 5 FIG. 1 is a block diagram of a power conversion device according to a third embodiment of the present invention. Figure 1 The power conversion device of the first embodiment shown above further includes a first communication interface 7 , a second communication interface 8 , and a switching button 13 .

[0071] The input terminal 2 is connected to a power storage system 10 having a storage battery 11 via two electric wires 9a. The signal line 9b is connected to the first communication interface 7 and the power storage system 10. The control circuit 6b communicates with the power storage system 10 via the signal line 9b and the first communication interface 7.

[0072] The switch button 13 is a user-operable button that switches whether to output direct current or alternating current to the output terminal 3 and outputs a switch selection signal to the control circuit 6b. The switch button 13 may be replaced by another user-operable interface such as a dial or a touch panel.

[0073] When direct current is selected based on the switching selection signal from the switching button 13, the control circuit 6b controls the operation of the switching element Q1 and the switching elements Q2 and Q3 to output direct current to the output terminal 3. When alternating current is selected, the control circuit 6b controls the operation of the switching element Q1 and the switching elements Q2 and Q3 to output alternating current to the output terminal 3.

[0074] According to the power conversion device of the third embodiment, when the power storage system 10 is connected to the input terminal 2 and supplies power to the output side, the switching button 13 provided in the power conversion device 1b can select either direct current or alternating current and output it to the output terminal 3. The user can select the power obtained from the output of the power conversion device by directly operating the switching button 13.

[0075] (Fourth Embodiment)

[0076] Figure 6 4 is a flowchart showing a control method of a power conversion device according to a fourth embodiment of the present invention. Figure 6 The flowchart shown in FIG. 6 is a flowchart for explaining in detail the control method of the power conversion device according to the fourth embodiment. The control method of the power conversion device is implemented by the operation of the control circuit 6 c.

[0077] First, the control circuit 6c determines whether the power input to the input terminal 2 is AC or DC (step S21). If the control circuit 6c determines that the input power is AC in step S21, it determines whether the power storage system 10 is connected to the output terminal 3 (step S22). Whether the power storage system 10 is connected to the output terminal 3 is detected and determined using a voltage sensor or the like.

[0078] When the power storage system 10 is connected in step S22 , the control circuit 6 c communicates with the power storage system 10 via the signal line 9 b and the second communication interface 8 , and receives a command related to charging from the power storage system 10 (step S23 ).

[0079] The control circuit 6c controls the operation of the switching element Q1 and the switching element Q2 based on the charge-related command from the power storage system 10 so that the second conversion circuit 5 outputs direct current power and controls the charging of the storage battery 11 (step S24).

[0080] When the control circuit 6c determines in step S21 that the input power is DC, it determines whether the power storage system 10 is connected to the input terminal 2 (step S25). In step S25, it is determined whether the power storage system 10 is connected to the input terminal 2 by detecting using a voltage sensor or the like.

[0081] When the power storage system 10 is connected in step S25 , the control circuit 6 c communicates with the power storage system 10 via the signal line 9 b and the first communication interface 7 , and receives a command related to discharge and an allowable current value from the power storage system 10 (step S26 ).

[0082] The control circuit 6c determines whether the instruction related to discharge, that is, the output instruction, from the power storage system 10 is a direct current or an alternating current (step S27). When the control circuit 6c determines that the output instruction is an alternating current, the first conversion circuit 4 is controlled so as not to exceed the allowable current, and the operation of the switching element Q1 and the switching elements Q2 and Q3 are controlled so that the second conversion circuit 5 outputs an alternating current to the output terminal 3 (step S28).

[0083] In this case, the first conversion circuit 4 changes the operating power by changing the switching frequency of the switching element Q1. The switching frequency is lowered when the power (current) is increased, and the switching frequency is increased when the power (current) is decreased.

[0084] The first conversion circuit 4 controls the switching frequency to an appropriate value so that the current supplied from the power storage system does not exceed the allowable current value transmitted from the power storage system.

[0085] When the control circuit 6c determines that the output command is a DC in step S27, the first conversion circuit 4 controls the operation of the switching element Q1 so as not to exceed the allowable current, and controls the operation of the switching elements Q2 and Q3 so that the second conversion circuit 5 outputs a DC to the output terminal 3 (step S29).

[0086] According to the power conversion device of the fourth embodiment, when the power storage system 10 is connected to the input terminal 2 and supplies power to the output side, information on the current value that the power storage system 10 can allow is received. The current that the storage battery 11 can output varies due to various factors such as the charge state, temperature, and degree of deterioration of the storage battery 11. The control circuit 6c can control the operation of the switching element Q1 and the switching elements Q2 and Q3 so that the input current of the power conversion device does not exceed the allowable current of the power storage system 10 at that moment.

[0087] In addition, when the power storage system 10 is connected to the input terminal 2 and the power storage system 10 is also connected to the output terminal 3, communication is performed with both the power storage system 10 on the input side and the power storage system 10 on the output side. Considering the conditions and processes of charging and discharging of the power storage system 10 on the input side and the power storage system 10 on the output side, the control circuit 6c can control the operation of the switching element Q1 and the switching elements Q2 and Q3.

[0088] (Fifth Embodiment)

[0089] Figure 7 1 is a flowchart showing a control method of a power conversion device according to a fifth embodiment of the present invention. Figure 7 The flowchart shown in FIG. 6 is a flowchart for explaining in detail the control method of the power conversion device according to the fifth embodiment. The control method of the power conversion device is implemented by the operation of the control circuit 6 d.

[0090] First, the control circuit 6d determines whether the power input to the input terminal 2 is AC or DC (step S31). If the control circuit 6d determines that the input power is AC in step S31, it determines whether the power storage system 10 is connected to the output terminal 3 (step S32). Whether the power storage system 10 is connected to the output terminal 3 is detected and determined using a voltage sensor or the like.

[0091] When the power storage system 10 is connected in step S32, the control circuit 6d communicates with the power storage system 10 via the signal line 9b and the second communication interface 8. A command related to charging, an allowable current value, and an allowable voltage value are received from the power storage system 10 (step S33).

[0092] The control circuit 6d controls the first conversion circuit 4 so as not to exceed the allowable voltage and the allowable current, and controls the operation of the switching element Q1 and the switching element Q2 so that the second conversion circuit 5 outputs direct current (step S34).

[0093] When the control circuit 6d determines that the input power is DC in step S31, it determines whether the power storage system 10 is connected to the input terminal 2 (step S35). In step S35, it is determined whether the power storage system 10 is connected to the input terminal 2 by detecting using a voltage sensor or the like.

[0094] When the power storage system 10 is connected in step S35 , the control circuit 6 d communicates with the power storage system 10 via the signal line 9 b and the first communication interface 7 , and receives a command related to discharge and an allowable current value from the power storage system 10 (step S36 ).

[0095] The control circuit 6d determines whether the instruction related to discharge, that is, the output instruction from the power storage system 10 is a direct current or an alternating current (step S37). When the control circuit 6d determines that the output instruction is an alternating current, the first conversion circuit 4 controls the operation of the switching element Q1 so that the allowable current does not exceed. The operation of the switching elements Q2 and Q3 is controlled so that the second conversion circuit 5 outputs an alternating current to the output terminal 3 (step S38).

[0096] In this case, the first conversion circuit 4 changes the operating power by changing the switching frequency of the switching element Q1. The switching frequency is lowered when the power (current) is increased, and the switching frequency is increased when the power (current) is decreased.

[0097] The first conversion circuit 4 controls the switching frequency to an appropriate value so that the electric power supplied from the power storage system does not exceed the allowable current value transmitted from the power storage system.

[0098] When the control circuit 6d determines that the output command is a DC in step S37, the first conversion circuit 4 controls the operation of the switching element Q1 so as not to exceed the allowable current, and controls the operation of the switching elements Q2 and Q3 so that the second conversion circuit 5 outputs a DC to the output terminal 3 (step S39).

[0099] According to the power conversion device of the fifth embodiment, the current that can be output by the power storage system 10 on the input side and the voltage / current that can be received by the power storage system 10 on the output side change due to various factors such as the charge state, temperature, and degree of degradation of the storage battery 11. The control circuit 6d can control the operation of the switching elements Q1, Q2, and Q3 so that the input current does not exceed the allowable current of the power storage system 10 on the input side and the output voltage / output current does not exceed the allowable input voltage and allowable input current of the power storage system 10 on the output side.

[0100] Alternatively, the input terminal 2 and the output terminal 3 may be formed to have the same size. In this case, when the output terminal 3 is connected to an external DC load in order to output DC power, and when the input terminal 2 is connected to an external DC power source in order to input DC power, cables of the same shape can be used.

[0101] (Sixth Embodiment)

[0102] Figure 8 This is a block diagram of a power conversion device according to a sixth embodiment of the present invention. Some power conversion devices are used in a charger mounted on a vehicle and the like with terminals fixed in advance. In this case, the user cannot easily switch between input and output.

[0103] The power conversion device 1e of the sixth embodiment switches input and output in the power conversion device through the first input / output switching unit 17 and the second input / output switching unit 18. In the structure of the power conversion device of the first embodiment, the power conversion device 1e is further provided with terminals 15, 16, the first input / output switching unit 17 and the second input / output switching unit 18.

[0104] The first input / output switching unit 17 is arranged between the terminal 15 and the input terminal 2, and the second input / output switching unit 18 is arranged between the output terminal 3 and the terminal 16. The first input / output switching unit 17 and the second input / output switching unit 18 are composed of electromagnetic relays.

[0105] The first input / output switching unit 17 switches the connection destination from the input terminal 2 to the outside, has terminals a1, b1, c1, and d1, and selects any one of the terminals a1, b1 and the terminals c1 and d1. The second input / output switching unit 18 switches the connection destination from the output terminal 3 to the outside, has terminals a2, b2, c2, and d2, and selects any one of the terminals a2, b2 and the terminals c2 and d2.

[0106] The electric wire 19a is connected to the terminal a1 and the terminal c2. The electric wire 19b is connected to the terminal b1 and the terminal d2. The electric wire 19c is connected to the terminal c1 and the terminal a2. The electric wire 19d is connected to the terminal d1 and the terminal b2.

[0107] Next, the operation of the first input / output switching unit 17 and the second input / output switching unit 18 will be described. First, when the AC power supply is connected to the terminal 15, the first input / output switching unit 17 selects the terminals a1 and b1, and the second input / output switching unit 18 selects the terminals a2 and b2. Thus, the AC from the AC power supply is input to the first conversion circuit 4 via the input terminal.

[0108] When the first input / output switching unit 17 selects the terminals c1 and d1 , a DC power source is connected to the terminal 16 , and a DC power source is input to the first conversion circuit 4 via the wires 19 c and 19 d , the terminals c1 and d1 , and the input terminal 2 .

[0109] According to the power conversion device of the sixth embodiment, even if the power conversion device 1e is used with the terminals fixed in advance, it is possible to select whether to connect the AC power supply or the DC power supply to the input terminal 2 inside the power conversion device 1e.

[0110] (Seventh Embodiment)

[0111] Fig. 9 1 is a block diagram of a power conversion device according to a seventh embodiment of the present invention. The power conversion device according to the seventh embodiment has an outlet 20 added to the structure of the power conversion device according to the first embodiment.

[0112] The lead end 20 is connected to the capacitor C5 and the output terminal 3. In this case, direct current is input to the first conversion circuit 4 at the input terminal 2, and the second conversion circuit 5 supplies alternating current to the output terminal 3. Since the lead end 20 is connected to the output terminal 3, alternating current can be supplied and output to an external load or the like.

[0113] According to the power conversion device of the seventh embodiment, a load using AC power can be used without connecting the lead-out terminal 20 of an inlet for connecting a device using AC power as an independent device.

[0114] Industrial Applicability

[0115] The power conversion device of the present invention can be used to charge a storage battery from AC power and to supply power to the outside from an electric vehicle.

[0116] Explanation of symbols

[0117] 1: Power conversion device

[0118] 2: Input terminal

[0119] 3: Output terminal

[0120] 4: First conversion circuit

[0121] 5: Second conversion circuit

[0122] 6. 6a~6e: Control circuit

[0123] 7: First communication interface

[0124] 8: Second communication interface

[0125] 9a, 19a~19d: Wires

[0126] 9b: Signal line

[0127] 10: Power storage system

[0128] 11: Battery

[0129] 13: Toggle button

[0130] 15, 16: Terminal

[0131] 17: First input / output switching unit

[0132] 18: Second input / output switching unit

[0133] 20: Lead-out terminal

[0134] Q1, Q2, Q3: Switching elements

[0135] L1, L2, L3: Inductors

[0136] C1~C5:Capacitors

Claims

1. A control method for a power conversion device, controlling the operation of a first switching element and a second switching element of the power conversion device, wherein the power conversion device comprises: Input terminals and output terminals; A first conversion circuit including the first switching element that switches at high speed and converts the power input from the input terminal into a first alternating current; a second conversion circuit including the second switching element for selecting a polarity of an output, converting the first alternating current input from the first conversion circuit and outputting the converted alternating current to the output terminal; in, determining whether the power input to the input terminal is AC or DC, When it is determined that the input power is AC, the operations of the first switching element and the second switching element are controlled so that the second conversion circuit outputs DC power. When it is determined that the input power is direct current, operations of the first switching element and the second switching element are controlled so that the second conversion circuit outputs the direct current or the second alternating current.

2. The control method of the power conversion device according to claim 1, wherein: The power conversion device also has a second communication interface for communicating with the outside. Furthermore, it is determined whether a power storage system including a storage battery is connected to the output terminal. When it is determined that the power input to the input terminal is AC, and further when it is determined that the power storage system having the storage battery is connected to the output terminal, communicating with the power storage system via the second communication interface; A charging command is received from the power storage system, and the operations of the first switching element and the second switching element are controlled according to the charging command to control charging of the storage battery.

3. The control method of the power conversion device according to claim 1 or 2, wherein: The power conversion device also has a first communication interface for communicating with the outside. Furthermore, it is determined whether a power storage system including a storage battery is connected to the input terminal. When it is determined that the power input to the input terminal is direct current, and further when it is determined that a power storage system having a storage battery is connected to the input terminal, communicating with the power storage system via the first communication interface; Operations of the first switching element and the second switching element are controlled to control output from the storage battery connected to the input terminal to the output terminal.

4. The control method of the power conversion device according to claim 3, wherein: communicating with the power storage system via the first communication interface and receiving a DC output instruction from the power storage system, controlling the actions of the first switching element and the second switching element so as to output the direct current to the output terminal when receiving the direct current output instruction, An AC output command is received from the power storage system, and operations of the first switching element and the second switching element are controlled so that the second AC power is output to the output terminal when the AC output command is received.

5. The control method of the power conversion device according to claim 3, wherein: Selecting to output any one of the direct current and the second alternating current to the output terminal, When the direct current is selected, the operations of the first switching element and the second switching element are controlled so as to output the direct current to the output terminal. When the second alternating current is selected, operations of the first switching element and the second switching element are controlled so that the second alternating current is output to the output terminal.

6. The control method of the power conversion device according to claim 3, wherein: communicating with the power storage system connected to the input terminal via the first communication interface, receiving information on an allowable output current of the power storage system from the power storage system connected to the input terminal, Based on the received allowable output current, the operations of the first switching element and the second switching element are controlled so that the current input from the input terminal does not exceed the allowable output current.

7. The control method of the power conversion device according to claim 3, wherein: Furthermore, it is determined whether the power storage system including a storage battery is connected to the input terminal. determining whether the power storage system including the storage battery is connected to the output terminal, When it is determined that the power input to the input terminal is direct current, when it is further determined that the power storage system including the storage battery is connected to the input terminal, and when it is further determined that the power storage system including the storage battery is connected to the output terminal, communicating with the power storage system connected to the input terminal via the first communication interface, Operations of the first switching element and the second switching element are controlled to control charging from the power storage system connected to the input terminal to the power storage system connected to the output terminal.

8. The control method of the power conversion device according to claim 7, wherein: receiving, from the power storage system connected to the input terminal, information on an allowable output current of the power storage system connected to the input terminal, receiving, from the power storage system connected to the output terminal, information on an allowable input current and information on an allowable input voltage of the power storage system connected to the output terminal, The operations of the first switching element and the second switching element are controlled so that the current input from the input terminal does not exceed the allowable output current of the power storage system connected to the input terminal, and the current and voltage output from the output terminal do not exceed the allowable input current and the allowable input voltage of the power storage system connected to the output terminal.

9. A power conversion device, comprising: Input terminals and output terminals; A first conversion circuit having a first switching element that performs switching at a high speed and converts the power input from the input terminal into a first alternating current; a second conversion circuit having a second switch element for selecting a polarity of an output, converting the first alternating current input from the first conversion circuit and outputting the converted alternating current to the output terminal; a control circuit for controlling the actions of the first switching element and the second switching element, in, The control circuit determines whether the power input to the input terminal is AC or DC, When it is determined that the input power is AC, the operations of the first switching element and the second switching element are controlled so that the second conversion circuit outputs DC power. When it is determined that the input power is direct current, the operations of the first switching element and the second switching element are controlled so that the second conversion circuit outputs the direct current or a second alternating current having a frequency lower than that of the first alternating current.

10. The power conversion device according to claim 9, wherein: The first conversion circuit comprises: an input inductor disposed between the input terminal and the first switching element; an LC resonant circuit, arranged between the first switching element and the output of the first conversion circuit; a capacitor connected in parallel with the first switching element, The first conversion circuit is a voltage resonance inverter circuit that outputs the first AC power to the second conversion circuit.

11. The power conversion device according to claim 9, wherein: A communication unit is provided, the communication unit is used for communicating with the outside, and has a first communication interface configured at the input terminal and a second communication interface configured at the output terminal, The control circuit controls the operations of the first switching element and the second switching element based on a command obtained from the outside via the communication unit.

12. The power conversion device according to claim 9, wherein: The input terminal is identical to the output terminal.

13. The power conversion device according to claim 9, wherein: have: a first switching unit that switches a connection destination from the input terminal to the outside; A second switching unit switches a connection destination from the output terminal to the outside.

14. The power conversion device according to claim 9, wherein: A lead terminal is provided, and when direct current is input to the input terminal and alternating current is supplied to the output terminal, the lead terminal can supply the alternating current.

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