Power conversion device and control method thereof

Abstract

The present invention comprises: a first conversion circuit that has a first switching element which performs high-speed switching and that converts power input from an input terminal into a first AC power; and a second conversion circuit that has a second switching element which selects polarity of output and that converts an !th AC power input from an !th conversion circuit and outputs to an output terminal. It is determined whether the power input into the input terminal is AC or DC. When it is determined that the input power is AC, operations of the first switching element and the second switching element are controlled such that the second conversion circuit outputs DC power. When it is determined that the input power is DC, operations of the first switching element and the second switching element are controlled such that the second conversion circuit outputs DC power or a second AC power.

Description

[Technical Field]

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

[0002] There is a demand for a bidirectional power conversion device that can connect AC power supplied from a power grid to its input terminal, connect a load such as a storage battery to its output terminal, convert the AC power and supply it to the output terminal, and then supply power from the storage battery connected to the output terminal to the input terminal.

[0003] Such a power conversion device can supply power from the storage battery of the electric vehicle to the input terminal while also functioning as a charger that charges the storage battery of the electric vehicle from AC power, for example.

[0004] The power conversion device disclosed 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 enables 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 the input terminal to the output terminal, the inverter circuit located on the input terminal side generates a high-frequency current, and the rectifier located on the output terminal side rectifies the high-frequency current and outputs it to the output terminal.

[0006] When 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 arranged 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, and each inverter circuit also functions as a rectifier. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Special table number 2019-525707 Summary of the Invention [Problem to be solved by the invention]

[0009] However, in such a bidirectional power conversion device, either the input or output inverter must perform high-frequency switching depending on the direction of power conversion, which requires both the first and second conversion circuits to support high-frequency switching, resulting in increased costs.

[0010] An object of the present invention is to provide a power conversion device and a control method thereof that can reduce costs. [Means for solving the problem]

[0011] A control method for a power conversion device according to the present invention controls the operation of a first switching element and a second switching element of a power conversion device having a first conversion circuit having a first switching element that switches at high speed and a second conversion circuit having a second switching element. The first conversion circuit converts power input from an input terminal into first AC power. The second switching element selects the polarity of the output. The second conversion circuit converts the first AC power input from the first conversion circuit and outputs it to an output terminal.

[0012] The control method for a power conversion device determines whether power input to an input terminal is AC or DC, and when the input power is determined to be AC, controls the operation of a first switching element and a second switching element so that a second conversion circuit outputs DC power.When the input power is determined to be DC, controls the operation of the first switching element and the second switching element so that the second conversion circuit outputs DC power or second AC power. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a power conversion device and a control method thereof that can reduce costs. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a configuration block diagram of a power conversion device according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a flowchart showing a control method for a power conversion device according to the first embodiment of the present invention. [Figure 3] FIG. 3 is a configuration block diagram of a power conversion device according to a second embodiment of the present invention. [Figure 4] FIG. 4 is a flowchart showing a control method for a power conversion device according to the second embodiment of the present invention. [Figure 5] FIG. 5 is a configuration block diagram of a power conversion device according to a third embodiment of the present invention. [Figure 6] FIG. 6 is a flowchart showing a control method for a power conversion device according to the fourth embodiment of the present invention. [Figure 7] FIG. 7 is a flowchart showing a control method for a power conversion device according to the fifth embodiment of the present invention. [Figure 8] FIG. 8 is a configuration block diagram of a power conversion device according to a sixth embodiment of the present invention. [Figure 9] FIG. 9 is a configuration block diagram of a power conversion device according to a seventh embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] 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 drawings. The same or corresponding parts in the drawings of the power conversion device and the control method according to each embodiment will be assigned the same reference numerals and their description will be omitted.

[0016] (First embodiment) 1 is a block diagram of a power conversion device according to a first embodiment of the present invention. The power conversion device 1 according to the first embodiment has an input terminal 2, an output terminal 3, a first conversion circuit 4, a second conversion circuit 5, and a control circuit 6.

[0017] When charging an electric vehicle from AC power, the power conversion device 1 inputs AC power to the input terminal 2 and connects the electric vehicle's storage battery to the output terminal 3. When external power is supplied from the electric vehicle, the electric vehicle's storage battery is connected to the input terminal 2 and DC power or AC power is output from the output terminal 3.

[0018] Since either AC or DC power may be connected to input terminal 2, control circuit 6 detects and determines whether the power connected to the input is AC or DC using a voltage sensor or the like.

[0019] The first conversion circuit 4 is a voltage resonant inverter circuit that has a switching element Q1 that switches at high speed, converts power input from the input terminal 2 into first AC power, and outputs the first AC power to the second conversion circuit 5. The first conversion circuit 4 generates a high-frequency AC current by repeatedly turning the switching element Q1 on and off at a high frequency.

[0020] The first conversion circuit 4 has capacitors C1, C2, and C3, an inductor L1 arranged between the switching element Q1 and the AC voltage input section, and an LC resonant circuit arranged between the switching element Q1 and the output of the first conversion circuit 4. The LC resonant circuit consists of an inductor L2 and a capacitor C3. The capacitor C2 is connected in parallel with the switching element Q1 and may be a parasitic capacitance of the switching element Q1.

[0021] The first conversion circuit 4 uses an LC resonant circuit consisting of an inductor L2 and a capacitor C3 to achieve voltage resonance and zero voltage switching when the switching element Q1 is turned on, thereby reducing the switching loss of the switching element Q1.

[0022] The switching element Q1 is configured by a unipolar transistor such as a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor). The switching element Q1 switches between on and off operation in response to an on / off control signal from a control circuit 6. The switching frequency of the switching element Q1 is, for example, several hundred kHz or 1 MHz to 10 MHz.

[0023] The second conversion circuit 5 has switching elements Q2 and Q3 that can select the polarity of the output, and converts the first AC power input from the first conversion circuit 4 and outputs it to the output terminal 3.

[0024] The second conversion circuit 5 has the role of selecting the polarity of the voltage output to the output terminal 3. When outputting a positive voltage to the output terminal 3, the second conversion circuit 5 turns on the P-side switching element Q2 and turns off the N-side switching element Q3. When outputting a negative voltage to the output terminal 3, the second conversion circuit 5 turns on the N-side switching element Q3 and turns off the P-side switching element Q2. This causes the second conversion circuit 5 to output second AC power having a frequency lower than the frequency of the DC power or the first AC power from the first conversion circuit 4. The frequency of the second AC power is, for example, 50 Hz, the frequency of the AC power supply.

[0025] In the second conversion circuit 5, one input terminal of the second conversion circuit 5 is connected to one end of a switching element Q2, the cathode of a diode D1, and one end of a capacitor C4. The other end of the switching element Q2 is connected to the anode of a diode D2 and one end of a switching element Q3. The other end of the switching element Q3 is connected to the cathode of the diode D2 and the other end of a capacitor C4. A series circuit of an inductor L3 and a capacitor C5 is connected to both ends of the capacitor C5, and both ends of the capacitor C5 are connected to the output terminal 3.

[0026] 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.

[0027] The control circuit 6 controls the operations of the switching elements Q1 and Q2. Fig. 2 is a flowchart showing a control method for the power conversion device according to the first embodiment of the present invention. The control method for the power conversion device is realized by the operation of the control circuit 6. The control method for the power conversion device will be described with reference to Fig. 2.

[0028] 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 in step S1 that the input power is AC, it controls the operations of the switching elements Q1 and Q2 so that the second conversion circuit 5 outputs DC power (step S2).

[0029] At this time, the control circuit 6 performs high-speed switching operation on the switching element Q1 of the first conversion circuit 4 to generate high-frequency AC power (first AC power) and output it to the second conversion circuit 5. The control circuit 6 controls the rectification directions of the switching elements Q2 and Q3 so that the power output from the second conversion circuit 5, which has a rectifier that rectifies the high-frequency AC power from the first conversion circuit 4, becomes DC.

[0030] In step S1, when the control circuit 6 determines that the input power is DC, it controls the operations of the switching elements Q1 and Q2 so that the second conversion circuit 5 outputs DC or second AC power (step S3). The frequency of the second AC power is lower than the frequency of the first AC power.

[0031] At this time, the control circuit 6 performs high-speed switching operation on the switching element Q1 of the first conversion circuit 4 to generate high-frequency AC power (first AC power) and output it to the second conversion circuit 5. The control circuit 6 controls the rectification directions of the switching elements Q2 and Q3 so that the power output from the second conversion circuit 5, which has a rectifier that rectifies the high-frequency AC power from the first conversion circuit 4, becomes DC or second AC power.

[0032] According to the power conversion device of the first embodiment, regardless of whether the input power is AC or DC, switching element Q1 performs high-frequency switching, and switching elements Q2 and Q3 do not need to perform high-frequency switching. That is, it is possible to realize, at low cost, a power conversion device that has the function of receiving AC power as input and outputting DC power, and the function of receiving DC power as input and outputting DC power or AC power.

[0033] Furthermore, the first conversion circuit 4 controls the voltage and current according to the requirements and constraints from the power source connected to the input terminal 2 and the constraints of the load connected to the output terminal 3. As a result, the only circuit that needs to perform high-frequency switching operations during both charging and external power supply is the first conversion circuit 4, which consists of an inverter circuit located at the input terminal 2. The second conversion circuit 5, which has a rectifier, always performs only rectification operations. This eliminates the need to use high-cost switching elements capable of high-frequency operation in the rectifier, making it possible to achieve both charging and external power supply with a single power conversion device.

[0034] Furthermore, whether the input power is AC or DC, the voltage resonant inverter circuit of the one conversion circuit 4 arranged on the input terminal side performs switching operations, thereby achieving low-loss switching.

[0035] (Second embodiment) Fig. 3 is a configuration block diagram of a power conversion device according to a second embodiment of the present invention. The power conversion device according to the second embodiment further includes a first communication interface 7 and a second communication interface 8 in addition to the components of the power conversion device according to the first embodiment shown in Fig. 1.

[0036] 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 has a storage battery 11.

[0037] The output terminal 3 is connected to the power storage system 10 via two power lines 9a. The two power lines 9a supply power from the second conversion circuit 5 to the storage battery 11 via the output terminal 3 and the two power lines 9a.

[0038] 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.

[0039] In addition, there may be a case where the power storage system 10 is connected to the input terminal 2 via two power lines 9a, and the signal line 9b is 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.

[0040] Next, a control method for the power conversion device according to the second embodiment configured as above will be described in detail with reference to the flowchart shown in Fig. 4. The control method for the power conversion device is realized by the control of the control circuit 6a.

[0041] 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 in step S11 that the input power is AC, it determines whether the power storage system 10 is connected to the output terminal 3 (step S12). Whether the power storage system 10 is connected to the output terminal 3 is detected and determined using a voltage sensor or the like.

[0042] In step S12, if the power storage system 10 is connected, the control circuit 6a communicates with the power storage system 10 via the signal line 9b and the second communication interface 8, and receives a command related to charging from the power storage system 10 (step S13).

[0043] In response to a command related to charging from the power storage system 10, the control circuit 6a controls the operations of the switching elements Q1 and Q2 so that the second conversion circuit 5 outputs DC power to control charging of the storage battery 11 (step S14).

[0044] In step S11, when the control circuit 6a determines that the input power is DC, it determines whether or not the power storage system 10 is connected to the input terminal 2 (step S15). In step S15, it detects and determines whether or not the power storage system 10 is connected to the input terminal 2 using a voltage sensor or the like.

[0045] In step S15, if the power storage system 10 is connected, the control circuit 6a communicates with the power storage system 10 via the signal line 9b and the first communication interface 7, and receives a command related to discharge from the power storage system 10 (step S16).

[0046] The control circuit 6a determines whether the command related to discharge, i.e., the output command, from the power storage system 10 is DC or AC (step S17). If the control circuit 6a determines in step S17 that the output command is AC, it controls the operations of the switching element Q1 and the switching elements Q2 and Q3 so that the second conversion circuit 5 outputs AC to the output terminal 3 (step S18).

[0047] In this case, the switching element Q1 is switched at high speed to convert DC into high-frequency AC, and the converted high-frequency AC is converted into low-frequency AC by operating the switching elements Q2 and Q3 at low speed.

[0048] In step S17, if the control circuit 6a determines that the output command is DC, it controls the operation of the switching element Q1 and the switching elements Q2 and Q3 so that the second conversion circuit 5 outputs DC to the output terminal 3 (step S19).

[0049] In this case, the switching element Q1 is switched at high speed to convert DC into high-frequency AC, and the converted high-frequency AC is converted back into DC by rectifying the switching elements Q2 and Q3.

[0050] That is, when a power storage system 10 having a storage battery 11 is connected to the input terminal 2, the operation of the switching element Q1 and the switching elements Q2 and Q3 is controlled so as to control the output from the storage battery 11 to the output terminal 3.

[0051] According to the drive circuit of the second embodiment, when an external power supply or an external load such as a storage battery 11 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. Based on the communication result, the control circuit 6a can control the operation of the switching element Q1 and the switching elements Q2 and Q3 so that the operation is within a range that the external power supply can output and that the external load can accept.

[0052] Furthermore, when AC power is connected to the input terminal 2 and the power storage system 10 is connected to the output terminal 3, the control circuit 6a communicates with the power storage system 10. Taking into consideration the conditions and procedures for charging required by the power storage system 10, the operation of the switching element Q1 and the switching elements Q2 and Q3 can be controlled.

[0053] Furthermore, 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 operations of the switching element Q1 and the switching elements Q2 and Q3 can be controlled taking into consideration the conditions and procedures for discharging provided by the power storage system 10.

[0054] Furthermore, when the power storage system 10 is connected to the input terminal 2 and power is supplied to the output side, either DC or AC can be selected and output to the output terminal 3 according to an instruction from the power storage system. By instructing the power storage system 10 to output either DC or AC, the user can select the power obtained from the output of the power conversion device.

[0055] (Third embodiment) Fig. 5 is a configuration block diagram of a power conversion device according to a third embodiment of the present invention. The power conversion device according to the third embodiment further includes a first communication interface 7, a second communication interface 8, and a switching button 13 in addition to the components of the power conversion device according to the first embodiment shown in Fig. 1.

[0056] The input terminal 2 is connected via two power lines 9a to a power storage system 10 having a storage battery 11. A 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.

[0057] The switching button 13 is a button that can be operated by the user, and switches between outputting DC power and AC power to the output terminal 3, and outputs a switching selection signal to the control circuit 6b. Instead of the switching button 13, other interfaces that can be operated by the user, such as a dial or a touch panel, may be used.

[0058] When DC power is selected, the control circuit 6b controls the operation of the switching element Q1 and the switching elements Q2, Q3 so as to output DC power to the output terminal 3, based on a switching selection signal from the switching button 13. When AC power is selected, the control circuit 6b controls the operation of the switching element Q1 and the switching elements Q2, Q3 so as to output AC power to the output terminal 3.

[0059] According to the power conversion device of the third embodiment, when the power storage system 10 is connected to the input terminal 2 and power is supplied to the output side, the switching button 13 provided in the power conversion device 1b can be used to select either DC or AC to be output to the output terminal 3. By directly operating the switching button 13, the user can select the power obtained from the output of the power conversion device.

[0060] (Fourth embodiment) Fig. 6 is a flowchart showing a control method for a power conversion device according to a fourth embodiment of the present invention. The control method for a power conversion device according to the fourth embodiment will be described in detail with reference to the flowchart shown in Fig. 6. The control method for a power conversion device is realized by the operation of a control circuit 6c.

[0061] 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 in step S21 that the input power is AC, 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.

[0062] In step S22, if the power storage system 10 is connected, the control circuit 6c communicates with the power storage system 10 via the signal line 9b and the second communication interface 8, and receives a command related to charging from the power storage system 10 (step S23).

[0063] In response to a command related to charging from the power storage system 10, the control circuit 6c controls the operations of the switching elements Q1 and Q2 so that the second conversion circuit 5 outputs DC power to control charging of the storage battery 11 (step S24).

[0064] In step S21, when the control circuit 6c determines that the input power is DC, it determines whether or not the power storage system 10 is connected to the input terminal 2 (step S25). In step S25, it detects and determines whether or not the power storage system 10 is connected to the input terminal 2 using a voltage sensor or the like.

[0065] In step S25, if the power storage system 10 is connected, the control circuit 6c communicates with the power storage system 10 via the signal line 9b and the first communication interface 7, and receives a command regarding discharge and an allowable current value from the power storage system 10 (step S26).

[0066] The control circuit 6c determines whether the command related to discharge from the power storage system 10, i.e., the output command, is DC or AC (step S27). When the control circuit 6c determines that the output command is AC, the control circuit 6c controls the first conversion circuit 4 so that the allowable current is not exceeded, and controls the operation of the switching element Q1 and the switching elements Q2 and Q3 so that the second conversion circuit 5 outputs AC to the output terminal 3 (step S28).

[0067] In this case, the first conversion circuit 4 changes the operating power by varying the switching frequency of the switching element Q1. When increasing the power (current), the switching frequency is lowered, and when decreasing the power (current), the switching frequency is raised.

[0068] 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.

[0069] In step S27, when the control circuit 6c determines that the output command is DC, the first conversion circuit 4 controls the operation of the switching element Q1 so that the allowable current is not exceeded, and the second conversion circuit 5 controls the operation of the switching elements Q2 and Q3 so that DC is output to the output terminal 3 (step S29).

[0070] According to the power conversion device of the fourth embodiment, a power storage system 10 is connected to the input terminal 2, and when power is supplied to the output side, information on the current value that the power storage system 10 can tolerate is received. The current that the storage battery 11 can output varies depending on various factors such as the state of charge, 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 time.

[0071] Furthermore, when a power storage system 10 is connected to the input terminal 2 and also to the output terminal 3, communication is performed with both the input-side power storage system 10 and the output-side power storage system 10. Taking into consideration the conditions and procedures for charging and discharging the input-side power storage system 10 and the output-side power storage system 10, the control circuit 6c can control the operations of the switching element Q1 and the switching elements Q2 and Q3.

[0072] (Fifth embodiment) Fig. 7 is a flowchart showing a control method for a power conversion device according to a fifth embodiment of the present invention. The control method for a power conversion device according to the fifth embodiment will be described in detail with reference to the flowchart shown in Fig. 7. The control method for a power conversion device is realized by the operation of a control circuit 6d.

[0073] 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 in step S31 that the input power is AC, 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.

[0074] In step S32, if the power storage system 10 is connected, the control circuit 6d communicates with the power storage system 10 via the signal line 9b and the second communication interface 8. The control circuit 6d receives a command related to charging, an allowable current value, and an allowable voltage value from the power storage system 10 (step S33).

[0075] The control circuit 6d controls the first conversion circuit 4 so that the allowable voltage and allowable current are not exceeded, and controls the operations of the switching elements Q1 and Q2 so that the second conversion circuit 5 outputs DC power (step S34).

[0076] In step S31, when the control circuit 6d determines that the input power is DC, it determines whether or not the power storage system 10 is connected to the input terminal 2 (step S35). In step S35, it detects and determines whether or not the power storage system 10 is connected to the input terminal 2 using a voltage sensor or the like.

[0077] In step S35, if the power storage system 10 is connected, the control circuit 6d communicates with the power storage system 10 via the signal line 9b and the first communication interface 7, and receives a command regarding discharge and an allowable current value from the power storage system 10 (step S36).

[0078] The control circuit 6d determines whether the command related to discharge from the power storage system 10, i.e., the output command, is DC or AC (step S37). If the control circuit 6d determines that the output command is AC, the first conversion circuit 4 controls the operation of the switching element Q1 so that the allowable current is not exceeded. The second conversion circuit 5 controls the operation of the switching elements Q2 and Q3 so that AC is output to the output terminal 3 (step S38).

[0079] In this case, the first conversion circuit 4 changes the operating power by varying the switching frequency of the switching element Q1. When increasing the power (current), the switching frequency is lowered, and when decreasing the power (current), the switching frequency is raised.

[0080] The first conversion circuit 4 controls the switching frequency to an appropriate value so that the power supplied from the power storage system does not exceed the allowable current value transmitted from the power storage system.

[0081] In step S37, when the control circuit 6d determines that the output command is DC, the first conversion circuit 4 controls the operation of the switching element Q1 so that the allowable current is not exceeded, and the second conversion circuit 5 controls the operation of the switching elements Q2 and Q3 so that DC is output to the output terminal 3 (step S39).

[0082] According to the power conversion device of the fifth embodiment, the current that can be output by the input-side power storage system 10 and the voltage and current that can be accepted by the output-side power storage system 10 vary depending on various factors such as the state of charge, temperature, and degree of deterioration 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 input-side power storage system 10 and so that the output voltage and output current do not exceed the allowable input voltage and allowable input current of the output-side power storage system 10.

[0083] The input terminal 2 and the output terminal 3 may be formed to be the same size. In this case, the same cable shape can be used when connecting the output terminal 3 to an external DC load to output DC power, and when connecting the input terminal 2 to an external DC power supply to input DC power.

[0084] (Sixth embodiment) 8 is a block diagram of a power conversion device according to a sixth embodiment of the present invention. Some power conversion devices, such as a charger installed in a vehicle, have terminals that are fixed in advance. In this case, the user cannot easily switch between input and output.

[0085] A power conversion device 1e according to the sixth embodiment switches between input and output within the power conversion device using a first input / output switching unit 17 and a second input / output switching unit 18. The power conversion device 1e further includes terminals 15 and 16, the first input / output switching unit 17, and the second input / output switching unit 18 in addition to the configuration of the power conversion device according to the first embodiment.

[0086] A first input / output switching unit 17 is disposed between terminal 15 and input terminal 2, and a second input / output switching unit 18 is disposed between output terminal 3 and terminal 16. The first input / output switching unit 17 and the second input / output switching unit 18 are configured by electromagnetic relays.

[0087] 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 either the terminals a1 and b1 or 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 either the terminals a2 and b2 or the terminals c2 and d2.

[0088] A power line 19a is connected between terminals a1 and c2. A power line 19b is connected between terminals b1 and d2. A power line 19c is connected between terminals c1 and a2. A power line 19d is connected between terminals d1 and b2.

[0089] Next, the operation of the first input / output switching unit 17 and the second input / output switching unit 18 will be described. First, when an AC power supply is connected to the terminal 15, the first input / output switching unit 17 selects terminals a1 and b1, and the second input / output switching unit 18 selects terminals a2 and b2. As a result, AC from the AC power supply is input to the first conversion circuit 4 via the input terminals.

[0090] When the first input / output switching unit 17 selects terminals c1 and d1, a DC power supply is connected to terminal 16, and DC is input to the first conversion circuit 4 via power lines 19c and 19d, terminals c1 and d1, and input terminal 2.

[0091] According to the power conversion device of the sixth embodiment, even in the case of the power conversion device 1e in which the terminals are fixed in advance before use, it is possible to select whether to connect an AC power supply or a DC power supply to the input terminal 2 inside the power conversion device 1e.

[0092] (Seventh embodiment) 9 is a configuration 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 further includes an outlet 20 in addition to the configuration of the power conversion device according to the first embodiment.

[0093] The outlet 20 is connected to the capacitor C5 and the output terminal 3. In this case, DC power is input to the input terminal 2 of the first conversion circuit 4, and the second conversion circuit 5 supplies AC power to the output terminal 3. Since the outlet 20 is connected to the output terminal 3, it is possible to supply output AC power to an external load or the like.

[0094] According to the power conversion device of the seventh embodiment, a load that uses AC power can be used without connecting an outlet 20 for connecting the inlet of a device that uses AC power as a separate device. [Industrial Applicability]

[0095] The power conversion device of the present invention is applicable to charging a storage battery from AC power and external power supply from an electric vehicle. [Explanation of symbols]

[0096] 1 Power conversion device 2 input terminals 3 Output terminal 4. First conversion circuit 5 Second conversion circuit 6, 6a to 6e Control circuit 7 First communication interface 8 Second communication interface 9a,19a~19d Power line 9b signal line 10 Energy storage system 11 Storage battery 13 Switch button 15,16 terminals 17 First input / output switching unit 18 Second input / output switching unit 20 Outlets Q1, Q2, Q3 switching elements L1, l2, l3 inductors C1~C5 capacitors

Claims

1. an input terminal and an output terminal; a first conversion circuit having a first switching element that switches at high speed and converts power input from the input terminal into first AC power; a second conversion circuit having a second switching element for selecting an output polarity, converting the first AC power input from the first conversion circuit and outputting the converted power to the output terminal; A control method for a power conversion device, which controls operations of the first switching element and the second switching element of a power conversion device having: determining whether the power input to the input terminal is AC or DC; controlling operations of the first switching element and the second switching element so that the second conversion circuit outputs DC power when it is determined that the input power is AC; When the input power is determined to be DC, the second conversion circuit controls operations of the first switching element and the second switching element so that the second conversion circuit outputs the DC power or the second AC power. A method for controlling a power conversion device.

2. The power conversion device further includes a second communication interface for communicating with an external device, Furthermore, it is determined whether or not a power storage system having 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; receiving a charging command from the power storage system, and controlling operations of the first switching element and the second switching element in response to the charging command so as to control charging of the storage battery; The method for controlling a power conversion device according to claim 1 .

3. The power conversion device further includes a first communication interface for communicating with an external device, Furthermore, it is determined whether or not a power storage system having 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; controlling operations of the first switching element and the second switching element so as to control an output from the storage battery connected to the input terminal to the output terminal; A method for controlling a power conversion device according to claim 1 or 2.

4. communicating with the power storage system via the first communication interface and receiving a DC output command from the power storage system; When the DC output command is received, the operation of the first switching element and the second switching element is controlled so as to output the DC power to the output terminal; receiving an AC output command from the power storage system, and controlling operations of the first switching element and the second switching element so as to output the second AC power to the output terminal when the AC output command is received; The method for controlling a power conversion device according to claim 3 .

5. selecting whether to output the DC power or the second AC power to the output terminal; When the DC power is selected, the operation of the first switching element and the second switching element is controlled so that the DC power is output to the output terminal; When the second AC power is selected, 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. The method for controlling a power conversion device according to claim 3 .

6. communicating with the power storage system connected to the input terminal via the first communication interface, and receiving information about an output allowable current of the power storage system from the power storage system connected to the input terminal; controlling operations of the first switching element and the second switching element based on the received output allowable current so that the current input from the input terminal does not exceed the output allowable current; The method for controlling a power conversion device according to claim 3 .

7. Furthermore, it is determined whether the power storage system having a storage battery is connected to the input terminal; determining whether the power storage system having the storage battery is connected to the output terminal; When it is determined that the power input to the input terminal is DC, when it is determined that the power storage system having the storage battery is connected to the input terminal, and 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 connected to the input terminal via the first communication interface; controlling operations of the first switching element and the second switching element so as to control charging from the power storage system connected to the input terminal to the power storage system connected to the output terminal; The method for controlling a power conversion device according to claim 3 .

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

9. an input terminal and an output terminal; a first conversion circuit having a first switching element that switches at high speed and converts power input from the input terminal into first AC power; a second conversion circuit having a second switching element for selecting an output polarity, converting the first AC power input from the first conversion circuit and outputting the converted power to the output terminal; A power conversion device having a control circuit that controls operations of the first switching element and the second switching element, the control circuit determines whether the power input to the input terminal is AC or DC; When the input power is determined to be AC, the operation of the first switching element and the second switching element is controlled so that the second conversion circuit outputs DC power; when it is determined that the input power is DC, the second conversion circuit controls operations of the first switching element and the second switching element so that the second conversion circuit outputs second AC power having a frequency lower than the DC power or the frequency of the first AC power. Power conversion device.

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

11. a communication unit for communicating with an external device, the communication unit having a first communication interface disposed at the input terminal and a second communication interface disposed at the output terminal; The power conversion device according to claim 9 , wherein the control circuit controls operations of the first switching element and the second switching element based on a command received from an external device via the communication unit.

12. The input terminal and the output terminal are the same. The power conversion device according to claim 9.

13. a first switching unit that switches a connection destination from the input terminal to an external device; a second switching unit that switches a connection destination from the output terminal to an external device, The power conversion device according to claim 9.

14. an outlet capable of supplying AC power when DC power is input to the input terminal and AC power is supplied to the output terminal; The power conversion device according to claim 9.

Images