Energy storage system

Abstract

To provide a power storage system capable of reducing a switching noise and improving a power conversion efficiency.SOLUTION: A power storage system 1 comprises: an inverter circuit 2; a bi-directional DC / DC converter circuit 3; and a control circuit 6, and further comprises: an ARCP circuit 5; a first switching switch S1 that is interposed between a first connection point X1 of switching elements Q5 and Q6 of the inverter circuit 2 and a terminal To; and a second switching switch S2 that is interposed between a second connection part X2 of switching elements Q7 and Q8 of the bi-directional DC / DC converter circuit 3 and the first connection point X1. The control circuit 6 sets the second switching switch S2 to an ON state as well as setting the first switching switch S1 to an OFF state in the case of making the ARCP circuit 5 perform a resonance operation, and operates the switching elements Q5 and Q6 as a resonance switch of the ARCP circuit 5 at the time of switching the switching elements Q7 and Q8.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a power storage system.

Background Art

[0002] Conventionally, a bidirectional DC / DC converter including an ARCP (Auxiliary Resonant Commutated Pole) circuit has been known (see, for example, Patent Document 1 and Patent Document 2). The ARCP circuit includes a first resonance switch and a second resonance switch connected in series, a resonance reactor, a first resonance capacitor and a second resonance capacitor, a regeneration transformer, and a regeneration diode.

[0003] The ARCP circuit enables soft switching of the main switch by performing an LC resonance operation when the main switch of the bidirectional DC / DC converter is switched. As a result, in the bidirectional DC / DC converter, switching noise can be reduced and power conversion efficiency can be improved.

[0004] Fig. 3 shows a conventional hybrid power storage system 10. The power storage system 10 includes an inverter circuit 20 connected to a single-phase three-wire (U-phase, W-phase, O-phase wiring) of the power grid, a capacitor C4, a bidirectional DC / DC converter circuit 30 connected to a storage battery BT, a DC / DC converter circuit 40 connected to a solar cell PV, and a control circuit (not shown) for controlling the inverter circuit 20, the bidirectional DC / DC converter circuit 30, and the DC / DC converter circuit 40.

[0005] The inverter circuit 20 consists of switching elements Q1 to Q6, capacitors C1 to C3, and choke coils L1 to L3. Diodes D1 to D6 are connected in parallel to the current paths of the switching elements Q1 to Q6. The inverter circuit 20 operates in single-phase two-wire mode when the grid is powered (operation by switching elements Q1 to Q4, capacitor C1, and choke coils L1 and L2), while operating in single-phase three-wire mode when the grid is down (operation by switching elements Q1 to Q6, capacitors C1 to C3, and choke coils L1 to L3).

[0006] The bidirectional DC / DC converter circuit 30 consists of switching elements Q7 and Q8, a capacitor C5, and a choke coil L4. Diodes D7 and D8 are connected in parallel to the current paths of the switching elements Q7 and Q8. The bidirectional DC / DC converter circuit 30 charges and discharges the battery BT by switching the switching elements Q7 and Q8 on and off.

[0007] The DC / DC converter circuit 40 consists of a switching element Q9, a capacitor C6, a choke coil L5, and a diode D10. The diode D9 is connected in parallel to the current path of the switching element Q9. When the solar cell PV is generating power, the DC / DC converter circuit 40 boosts the power generated by the solar cell PV and supplies it to the inverter circuit 20 and / or the bidirectional DC / DC converter circuit 30.

[0008] In conventional energy storage systems 10, the bidirectional DC / DC converter circuit 30 requires a reduction in switching noise of switching elements Q7 and Q8 and an improvement in power conversion efficiency. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2021-19396 [Patent Document 2] Japanese Patent Publication No. 2019-146469 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] The present invention has been made in view of the above circumstances, and its objective is to provide an energy storage system that can reduce switching noise and improve power conversion efficiency. [Means for solving the problem]

[0011] To solve the above problems, the energy storage system according to the present invention is An inverter circuit comprising a first leg connected to a first voltage line of a single-phase three-wire system, a second leg connected to a second voltage line, and a third leg connected to a neutral line, wherein the third leg comprises a first switching element forming an upper arm and a second switching element forming a lower arm, A bidirectional DC / DC converter circuit comprising a fourth leg connected to a power storage means, the ends of which are connected to the ends of the third leg, and the fourth leg comprising a third switching element that constitutes an upper arm and a fourth switching element that constitutes a lower arm, A control circuit that controls the bidirectional DC / DC converter circuit and the inverter circuit, A power storage system equipped with, An ARCP circuit including a resonant reactor, a resonant capacitor, a regenerative transformer, and a regenerative diode, A first changeover switch is interposed in a first power line connecting a first connection point, which is the connection point between the first switching element and the second switching element, and the neutral wire. A second changeover switch is interposed in the second power line connecting the second connection point, which is the connection point between the third switching element and the fourth switching element, and the first connection point, Furthermore, The aforementioned control circuit is When the ARCP circuit is to perform resonant operation, the first changeover switch is set to the OFF state and the second changeover switch is set to the ON state, and when the third switching element or the fourth switching element is switched, the first switching element or the second switching element is operated as a resonant switch for the ARCP circuit.

[0012] With this configuration, the resonant operation of the ARCP circuit can reduce the switching noise of the third and fourth switching elements of the bidirectional DC / DC converter circuit, thereby improving the power conversion efficiency of the bidirectional DC / DC converter circuit. Furthermore, with this configuration, the first and second switching elements of the inverter circuit are reused as resonant switches for the ARCP circuit, thus avoiding an increase in the number of components and costs that would otherwise be incurred by adding resonant switches.

[0013] In the aforementioned energy storage system, The aforementioned control circuit is When the power grid is supplied to the single-phase three-wire system, the first changeover switch is turned off and the second changeover switch is turned on, causing the inverter circuit to operate in single-phase two-wire mode. In the event of a power outage when the grid power is not supplied to the single-phase three-wire system, the first changeover switch can be turned ON and the second changeover switch OFF to cause the inverter circuit to operate in single-phase three-wire mode.

[0014] The aforementioned energy storage system is Between the inverter circuit and the bidirectional DC / DC converter circuit, further comprising capacitors connected in parallel to the third leg and the fourth leg, The resonant reactor is connected in series with the second changeover switch. The resonance capacitor includes a first resonance capacitor connected in parallel to the current path of the third switching element and a second resonance capacitor connected in parallel to the current path of the fourth switching element. The regeneration transformer includes a primary coil and a secondary coil. The primary coil is connected in series to the resonance reactor. The secondary coil can be configured such that both ends are connected to the positive terminal of the capacitor via the regeneration diode.

[0015] In the power storage system, In the ARCP circuit, the first resonance capacitor and the second resonance capacitor are connected in series, and a third connection point, which is the connection point between the first resonance capacitor and the second resonance capacitor, is connected to the second power line. The second switching switch can be configured to be interposed between the third connection point and the second connection point of the second power line.

[0016] The power storage system further includes a DC / DC converter circuit. The DC / DC converter circuit can be configured such that a DC power supply is connected to one end side, and the bidirectional DC / DC converter circuit and the ARCP circuit are connected to the other end side.

Advantages of the Invention

[0017] According to the present invention, it is possible to provide a power storage system capable of reducing switching noise and improving power conversion efficiency.

Brief Description of the Drawings

[0018] [Figure 1] It is a diagram showing a power storage system according to the present invention. [Figure 2]The following are waveform diagrams of various waveforms during operation of the ARCP circuit according to the present invention, where (A) is the gate voltage of the main switch and the resonant switch, (B) is the reactor current and the resonant current, and (C) is the drain current of the main switch and the drain-source voltage. [Figure 3] This diagram shows a conventional energy storage system. [Modes for carrying out the invention]

[0019] Hereinafter, embodiments of the energy storage system according to the present invention will be described with reference to the attached drawings.

[0020] Figure 1 shows an energy storage system 1 according to one embodiment of the present invention. The energy storage system 1 is a hybrid type of energy storage system equipped with a battery charging and discharging function and a solar power generation function, and comprises terminals Tu, Tw, To, terminals Ta, Tb, and terminals Tc, Td.

[0021] Terminals Tu, Tw, and To are connected to the commercial power grid via single-phase three-wire (U-phase, W-phase, and O-phase wiring). Specifically, terminal Tu is connected to the U-phase wiring corresponding to the "first voltage line" of the present invention, terminal Tw is connected to the W-phase wiring corresponding to the "second voltage line" of the present invention, and terminal To is connected to the O-phase wiring corresponding to the "neutral line" of the present invention. Household loads (e.g., home appliances) are connected between each of these wires.

[0022] Terminal Ta is connected to the positive terminal of the battery BT, which corresponds to the "energy storage means" of the present invention, and terminal Tb is connected to the negative terminal of the battery BT. For example, a lithium-ion battery can be used as the battery BT. In addition, terminal Tc is connected to the positive terminal of the solar cell PV, which corresponds to the "DC power supply" of the present invention, and terminal Td is connected to the negative terminal of the solar cell PV.

[0023] The energy storage system 1 comprises an inverter circuit 2, a bidirectional DC / DC converter circuit 3, a DC / DC converter circuit 4, an ARCP circuit 5, and a control circuit 6. For the purposes of this explanation, the main circuit section of the energy storage system 1 is described as being divided into four parts: the inverter circuit 2, the bidirectional DC / DC converter circuit 3, the DC / DC converter circuit 4, and the ARCP circuit 5. However, these four parts are a functional classification, and the four parts may be integrated into a single configuration.

[0024] The inverter circuit 2 comprises a filter circuit composed of capacitors C1 to C3 and choke coils L1 to L3, a U-phase switching circuit (corresponding to the "first leg" of the present invention) in which switching element Q1 constitutes the upper arm and switching element Q2 constitutes the lower arm, a W-phase switching circuit (corresponding to the "second leg" of the present invention) in which switching element Q3 constitutes the upper arm and switching element Q4 constitutes the lower arm, an O-phase switching circuit (corresponding to the "third leg" of the present invention) in which switching element Q5 (corresponding to the "first switching element" of the present invention) constitutes the upper arm and switching element Q6 (corresponding to the "second switching element" of the present invention) constitutes the lower arm, and a first changeover switch S1. Diodes D1 to D6 are connected in parallel to the current paths of switching elements Q1 to Q6.

[0025] The U-phase switching circuit, W-phase switching circuit, and O-phase switching circuit are connected in parallel to each other, and also in parallel to capacitor C4, which will be described later. The connection point between switching element Q1 and switching element Q2 is connected to terminal Tu via choke coil L1. The connection point between switching element Q3 and switching element Q4 is connected to terminal Tw via choke coil L2. The connection point X1 between switching element Q5 and switching element Q6 (corresponding to the "first connection point" of the present invention) is connected to terminal To via first changeover switch S1 and choke coil L3. Capacitor C1 is connected between U-phase and W-phase, capacitor C2 is connected between U-phase and O-phase, and capacitor C3 is connected between O-phase and W-phase.

[0026] In this embodiment, MOSFETs (metal-oxide-semiconductor field-effect transistors) are used as switching elements Q1 to Q6, but other semiconductor switches (e.g., IGBTs) may also be used. Diodes D1 to D6 may be parasitic diodes of switching elements Q1 to Q6, external diodes independent of switching elements Q1 to Q6, or both. The same applies to switching elements Q7 to Q9 and diodes D7 to D9, which will be described later.

[0027] The first changeover switch S1 is interposed in the power line (corresponding to the "first power line" of this invention) that connects the connection point X1 of the O-phase switching circuit and the choke coil L3 of the filter circuit. The first changeover switch S1 switches between an ON state and an OFF state under the control of the control circuit 6. When it is ON, it conducts the O-phase switching circuit and terminal To, and when it is OFF, it electrically disconnects the O-phase switching circuit from terminal To. The first changeover switch S1 may be a semiconductor switch or another type of switch (for example, a relay).

[0028] The bidirectional DC / DC converter circuit 3 comprises a switching circuit (corresponding to the "fourth leg" of the present invention) in which switching element Q7 (corresponding to the "third switching element" of the present invention) constitutes the upper arm and switching element Q8 (corresponding to the "fourth switching element" of the present invention) constitutes the lower arm, as well as a choke coil L4 and a capacitor C5. Diodes D7 and D8 are connected in parallel to the current paths of switching elements Q7 and Q8.

[0029] The switching circuit consisting of switching elements Q7 and Q8 has one end connected to the positive terminal of capacitor C4, and the other end connected to the negative terminal and terminal Tb of capacitor C4. The connection point X2 between switching element Q7 and switching element Q8 (corresponding to the "second connection point" of the present invention) is connected to terminal Ta via choke coil L4. Capacitor C5 is connected between terminals Ta and Tb.

[0030] The DC / DC converter circuit 4 comprises a diode D10, a switching element Q9, a choke coil L5, and a capacitor C6. Diode D9 is connected in parallel to the current path of the switching element Q9.

[0031] Diode D10 has its cathode connected to the positive terminal of capacitor C4, and its anode connected to one end of the current path of switching element Q9. The other end of the current path of switching element Q9 is connected to the negative terminal and terminal Td of capacitor C4. Choke coil L5 has one end connected to the anode of diode D10 and the other end connected to terminal Tc. Capacitor C6 is connected between terminals Tc and Td.

[0032] The ARCP circuit 5 comprises a capacitor C4, a resonant reactor L6, resonant capacitors C7 and C8, a regenerative transformer TR1, regenerative diodes D11 and D12, and a second changeover switch S2. The regenerative transformer TR1 comprises a primary coil N1 and a secondary coil N2.

[0033] Capacitor C4 is connected in parallel to the O-phase switching circuit consisting of switching elements Q5 and Q6 and the switching circuit consisting of switching elements Q7 and Q8. Resonant capacitors C7 and C8 form a series circuit. Resonant capacitor C7 is connected in parallel to the current path of switching element Q7 via the second changeover switch S2, and resonant capacitor C8 is connected in parallel to the current path of switching element Q8 via the second changeover switch S2.

[0034] One end of the resonant reactor L6 is connected to the connection point X1 of the O-phase switching circuit, and the other end is connected to the connection point X3 (corresponding to the "third connection point" of the present invention) between the resonant capacitor C7 and the resonant capacitor C8 via the primary coil N1 of the regenerative transformer TR1. The resonant reactor L6 may also be provided between the primary coil N1 and the connection point X3.

[0035] The secondary coil N2 of the regenerative transformer TR1 has one end connected to the positive terminal of capacitor C4 via regenerative diode D11, the other end connected to the positive terminal of capacitor C4 via regenerative diode D12, and its center tap connected to the negative terminal of capacitor C4. The turns ratio of the primary coil N1 and the secondary coil N2 is, for example, N1:N2=1:2.

[0036] The second changeover switch S2 is interposed between connection point X3 and second connection point X2 in the power line connecting the first connection point X1 and the second connection point X2 (corresponding to the "second power line" of the present invention). The second changeover switch S2 switches between an ON state and an OFF state under the control of the control circuit 6. When it is ON, it enables the operation of the ARCP circuit 5, and when it is OFF, it electrically disconnects the ARCP circuit 5 from the bidirectional DC / DC converter circuit 3. The second changeover switch S2 may be a semiconductor switch or another type of switch (for example, a relay).

[0037] The control circuit 6 is configured to control switching elements Q1 to Q9, the first changeover switch S1, and the second changeover switch S2. The control circuit 6 consists of a control processor, memory, and peripheral circuits, and can be, for example, a microcontroller or a DSP. The control circuit 6 also includes a detection circuit consisting of sensors that detect the voltage and current necessary for control, but the description and illustration of the detection circuit are omitted.

[0038] When the power grid is energized and single-phase three-wire power is supplied from the power grid, the control circuit 6 turns off the first changeover switch S1 while turning on the second changeover switch S2. As a result, the O-phase switching circuit is disconnected from the inverter circuit 2, and the ARCP circuit 5 becomes operational.

[0039] When the grid is powered on, the control circuit 6 causes the inverter circuit 2 to perform single-phase two-wire operation (operation by switching elements Q1~Q4, capacitor C1, and choke coils L1 and L2). When the grid is powered on, the inverter circuit 2 performs DC / AC conversion operation, converting the DC power input from the ARCP circuit 5 side into AC power and outputting it from terminals Tu and Tw, and AC / DC conversion operation, converting the AC power input from terminals Tu and Tw into DC power and outputting it to the ARCP circuit 5 side.

[0040] When the grid is powered on, the control circuit 6 operates the switching elements Q7 and Q8 of the bidirectional DC / DC converter circuit 3 as main switches when charging and discharging the battery BT, and also operates the switching elements Q5 and Q6 of the O-phase switching circuit as resonant switches for the ARCP circuit 5, causing the ARCP circuit 5 to perform resonant operation. The control circuit 6 performs, for example, PWM control on the switching elements Q7 and Q8. The bidirectional DC / DC converter circuit 3 performs a boost operation when discharging the battery BT and a step-down operation when charging the battery BT.

[0041] When the solar PV (photovoltaic) solar cells are generating power, the control circuit 6, when the grid is powered, causes the DC / DC converter circuit 4 to perform a boost operation. The DC / DC converter circuit 4 boosts the DC power generated by the solar PV cells and outputs it to the ARCP circuit 5 and / or the bidirectional DC / DC converter circuit 3.

[0042] During a power outage when the power grid is not supplying power to the single-phase three-wire system, the control circuit 6 turns on the first changeover switch S1 while turning off the second changeover switch S2. This disconnects the ARCP circuit 5 from the bidirectional DC / DC converter circuit 3.

[0043] During a grid outage, the control circuit 6 causes the inverter circuit 2 to operate in single-phase three-wire mode (operation using switching elements Q1-Q6, capacitors C1-C3, and choke coils L1-L3). During a grid outage, the inverter circuit 2 performs DC / AC conversion, converting the DC power input from the ARCP circuit 5 into AC power and outputting it from terminals Tu, Tw, and To. This enables the inverter circuit 2 to provide independent output in single-phase three-wire mode.

[0044] During a grid outage, the control circuit 6 does not activate the ARCP circuit 5, but instead causes the bidirectional DC / DC converter circuit 3 to perform charging and discharging operations on the battery BT, and if the solar panel PV is generating power, it causes the DC / DC converter circuit 4 to perform a boost operation.

[0045] Figures 2(A) to 2(C) show various waveform diagrams when the grid is energized and the battery BT is discharging. Figure 2(A) shows the gate voltage Vgs of switching elements Q6 and Q8, and Figure 2(B) shows the reactor current I flowing through the choke coil L4. L4 and the resonant current I flowing through the resonant reactor L6 L6 Figure 2(C) shows the waveforms of the drain current Id and drain-source voltage Vds of switching element Q8. Switching elements Q6 and Q8 are ON when the gate voltage Vgs is high (H) and OFF when it is low (L).

[0046] At time t1, when the control circuit 6 turns on the switching element Q6, the current that was flowing from the choke coil L4 to the diode D7 is commutated to the primary coil N1 of the regenerative transformer TR1 and the resonant reactor L6. Furthermore, because the resonant reactor L6 acts to draw charge from the resonant capacitors C7 and C8, the resonant reactor L6, the leakage inductance of the regenerative transformer TR1, and the resonant capacitors C7 and C8 resonate. As a result, a resonant current I flows through the resonant reactor L6. L6 As the current flows, the drain-source voltage Vds of the switching element Q8 decreases.

[0047] At time t2, the resonant current IL6 Current waveform and reactor current I during falling edge L4 When the current waveform of the switching element Q6 intersects with that of the switching element Q8, the control circuit 6 turns on the switching element Q8. Since the switching element Q6 is in the ON state, the drain-source voltage Vds of the switching element Q8 becomes approximately 0[V], and the drain current Id of the switching element Q8 rises from 0[A]. As a result, zero-voltage switching and zero-current switching are achieved, and the switching loss when the switching element Q8 is turned on is reduced.

[0048] Resonant current I L6 When current flows through the primary coil N1 of the regenerative transformer TR1, a voltage is induced in the secondary coil N2 of the regenerative transformer TR1. The voltage induced in the secondary coil N2 is regenerated to the capacitor C4 via the regenerative diodes D11 and D12.

[0049] Resonant current I at time t3 L6 After the current becomes 0[A], the control circuit 6 turns off switching element Q6 at time t4, and then turns off switching element Q8 according to the on-duty cycle of the PWM control (time t5).

[0050] At time t5, when the control circuit 6 turns off the switching element Q8, the current flowing through the switching element Q8 is commutated to the resonant capacitors C7 and C8, and the resonant capacitor C8 is charged (and the resonant capacitor C7 is discharged). As the drain current Id of the switching element Q8 decreases relatively quickly, while the drain-source voltage Vds of the switching element Q8 increases slowly, the overlap region between the falling edge of the drain current Id and the rising edge of the drain-source voltage Vds decreases. As a result, zero-voltage switching is achieved, and the switching loss when the switching element Q8 is turned off is reduced.

[0051] In the bidirectional DC / DC converter circuit 3, the operating principle is the same, except that the direction of power transmission differs between the discharge and charging phases of the battery BT. That is, the control circuit 6 during the charging phase of the battery BT controls the main switch, switching element Q7, and the resonant switch, switching element Q5, in the same manner as described above.

[0052] In the ARCP circuit 5, if the period during which resonant current flows is defined as the PWM control unavailable period (for example, time t1 to t3 in Figure 2), and the period during which no resonant current flows is defined as the PWM controllable period (for example, time t3 to t6 in Figure 2), then the control circuit 6 performs PWM control by varying the on-duty cycles of switching elements Q7 and Q8 within the PWM controllable period.

[0053] However, if the on-time of switching elements Q7 and Q8 becomes too short to ensure a period of PWM control unavailable (when the input / output voltage difference is small and the load is light), or if the off-time of switching elements Q7 and Q8 becomes too short (when the input / output voltage difference is large and the load is heavy), then even if the ARCP circuit 5 is operated, soft switching of switching elements Q7 and Q8 cannot be achieved, and switching losses due to switching elements Q5 and Q6 will increase. Therefore, in the case of light or heavy load, it is preferable for the control circuit 6 to stop the operation of the ARCP circuit 5 and switch the operation of the bidirectional DC / DC converter circuit 3 to bidirectional chopper operation with PWM control.

[0054] As described above, according to the energy storage system 1 of this embodiment, when power is supplied to the grid, the resonant operation of the ARCP circuit 5 can reduce the switching noise of the switching elements Q7 and Q8 of the bidirectional DC / DC converter circuit 3, thereby improving the power conversion efficiency of the bidirectional DC / DC converter circuit 3.

[0055] Furthermore, according to the energy storage system 1 of this embodiment, the switching elements Q5 and Q6 of the O-phase switching circuit of the inverter circuit 2 are reused as resonant switches for the ARCP circuit 5, thus avoiding an increase in the number of components and costs (including costs for heat dissipation measures) due to the addition of resonant switches.

[0056] [Differentiation] Although embodiments of the energy storage system according to the present invention have been described above, the present invention is not limited to the above embodiments.

[0057] The present invention provides an energy storage system comprising: an inverter circuit comprising a first leg connected to a first voltage line of a single-phase three-wire system, a second leg connected to a second voltage line, and a third leg connected to a neutral line, wherein the third leg comprises a first switching element forming an upper arm and a second switching element forming a lower arm; a bidirectional DC / DC converter circuit comprising a fourth leg connected to an energy storage means, the ends of which are connected to the ends of the third leg, wherein the fourth leg comprises a third switching element forming an upper arm and a fourth switching element forming a lower arm; and a control circuit for controlling the bidirectional DC / DC converter circuit and the inverter circuit. The energy storage system also comprises a resonant reactor, a resonant capacitor, a regenerative transformer, and a regenerative diode. The control circuit further comprises an ARCP circuit including a switch, a first changeover switch interposed in a first power line connecting a first connection point (the connection point between a first switching element and a second switching element) and the neutral wire, and a second changeover switch interposed in a second power line connecting a second connection point (the connection point between a third switching element and a fourth switching element) and the first connection point. The control circuit can be configured as appropriate to allow the ARCP circuit to perform resonant operation by turning off the first changeover switch and turning on the second changeover switch, and to allow the first switching element or the second switching element to act as a resonant switch for the ARCP circuit when the third or fourth switching element is switched.

[0058] In the above embodiment, the power generated by the solar cell PV is input to terminals Tc and Td of the DC / DC converter circuit 4, but DC power supplied from a DC power source may also be input to terminals Tc and Td of the DC / DC converter circuit 4. [Explanation of symbols]

[0059] 1. Energy storage system 2. Inverter Circuit 3. Bidirectional DC / DC Converter Circuit 4 DC / DC Converter Circuit 5 ARCP circuit 6 Control circuits

Claims

1. An inverter circuit comprising a first leg connected to a first voltage line of a single-phase three-wire system, a second leg connected to a second voltage line, and a third leg connected to a neutral line, wherein the third leg comprises a first switching element forming an upper arm and a second switching element forming a lower arm, A bidirectional DC / DC converter circuit comprising a fourth leg connected to a power storage means, the ends of which are connected to the ends of the third leg, and the fourth leg comprising a third switching element that constitutes an upper arm and a fourth switching element that constitutes a lower arm, A control circuit that controls the bidirectional DC / DC converter circuit and the inverter circuit, A power storage system equipped with, An ARCP circuit including a resonant reactor, a resonant capacitor, a regenerative transformer, and a regenerative diode, A first changeover switch is interposed in a first power line connecting a first connection point, which is the connection point between the first switching element and the second switching element, and the neutral wire. A second changeover switch is interposed in the second power line connecting the second connection point, which is the connection point between the third switching element and the fourth switching element, and the first connection point, Between the inverter circuit and the bidirectional DC / DC converter circuit, a capacitor connected in parallel to the third leg and the fourth leg, Furthermore, The resonant reactor is connected in series with the second changeover switch. The resonant capacitor comprises a first resonant capacitor connected in parallel to the current path of the third switching element and a second resonant capacitor connected in parallel to the current path of the fourth switching element. The regenerative transformer comprises a primary coil and a secondary coil, The primary coil is connected in series with the resonant reactor. The secondary coil is connected at both ends to the positive terminal of the capacitor via the regenerative diode. The ARCP circuit has the first resonant capacitor and the second resonant capacitor connected in series, and the third connection point, which is the connection point between the first resonant capacitor and the second resonant capacitor, is connected to the second power line. The second changeover switch is interposed between the third connection point and the second connection point of the second power line. The aforementioned control circuit is When the ARCP circuit is to perform resonant operation, the first changeover switch is turned off and the second changeover switch is turned on, and when the third switching element or the fourth switching element is switched, the first switching element or the second switching element is operated as a resonant switch for the ARCP circuit. A power storage system characterized by the following features.

2. The aforementioned control circuit is When the power grid is supplied to the single-phase three-wire system, the first changeover switch is turned off and the second changeover switch is turned on, causing the inverter circuit to operate in single-phase two-wire mode. In the event of a power outage when the aforementioned single-phase three-wire system is not supplied with grid power, the first changeover switch is turned ON and the second changeover switch is turned OFF, causing the inverter circuit to operate in single-phase three-wire mode. The energy storage system according to claim 1.

3. It also features a DC / DC converter circuit, The DC / DC converter circuit has a DC power supply connected to one end, and the bidirectional DC / DC converter circuit and the ARCP circuit connected to the other end. The energy storage system according to claim 1 or 2, characterized in that it is the same as described in claim 1 or 2.

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