WO2012043138A1

WO2012043138A1 - Power source system

Info

Publication number: WO2012043138A1
Application number: PCT/JP2011/070018
Authority: WO
Inventors: 久保　守; 太田垣　和久; 福田　康宏; 正寛牧野; 文生米田; 俊之平田
Original assignee: 三洋電機株式会社
Priority date: 2010-09-29
Filing date: 2011-09-02
Publication date: 2012-04-05
Also published as: JPWO2012043138A1

Abstract

The disclosed power source system is provided with a bidirectional power control circuit (200) containing a buck-boost circuit (200a) and an inverter circuit (200b), connects a battery unit (202) and a system power source (204) by converting DC power and AC power in both directions, and, when charging the battery unit (202) from the system power source (204), allows the inverter circuit (200b) to function as an active filter by means of controlling the switching elements (SW3, SW4, SW5 and SW6) contained in the inverter circuit (200b) in accordance with the difference between the measured value of an alternating current (Ia) flowing to the inverter circuit (200b) from the system power source (204) and a target input current signal of the alternating current (Ia) set depending on the charging current of the battery unit (202).

Description

Power system

The present invention relates to a power supply system, and more particularly to a power supply system having a bidirectional power control circuit.

In recent years, a secondary battery such as a lithium ion battery or a lead battery is used as a storage battery, and a power supply system that supplies electric power to a load using electric charges charged in the storage battery has been used.

As shown in FIG. 4, the conventional power supply system includes a bidirectional power converter 100 including a step-up / down circuit 100a and an inverter circuit 100b. When power is supplied from the battery unit 102 to the load 104, the switching element SW2 of the step-up / step-down circuit 100a is controlled to open and close, and the switching element SW1 is kept closed to boost the output of the battery unit 102 and supply it to the inverter circuit 100b. In the inverter circuit 100b, the DC power from the step-up / step-down circuit 100a is converted into AC power and supplied to the load 104 by opening / closing control of the switching elements SW3, SW4, SW5, and SW6. On the other hand, when charging the battery unit 102 from the system power supply 106, the inverter circuit 100b closes all the switching elements SW3, SW4, SW5 and SW6, and full-wave rectifies the snubber diodes arranged in parallel with these switching elements. After the AC power is rectified and smoothed by the capacitor C2, it is supplied to the step-up / down circuit 100a. The step-up / down circuit 100a controls the opening / closing of the switching element SW1 and keeps the switching element SW2 in the closed state. Is lowered and supplied to the battery unit 102.

JP 2006-67673 A JP 2002-315230 A Japanese Patent No. 3255304

By the way, in the conventional power supply system, when charging the battery unit 102 from the system power supply 106, the switching elements SW3, SW4, SW5 and SW6 of the inverter circuit 100b are all closed and the inverter circuit 100b is used as a diode bridge circuit. Use the rectification. At this time, only when the voltage supplied from the system power supply 106 to the inverter circuit 100b is higher than the voltage Vm for the negative bus of the capacitor C2 provided between the step-up / step-down circuit 100a and the inverter circuit 100b, the system power supply 106 is used. To the inverter circuit 100b. As a result, as shown in FIG. 5, the input current Ia shows an impulse-like waveform on which harmonic components are superimposed.

Such a harmonic component of the input current Ia may cause noise and the like, which may cause the operation of the power supply system to become unstable.

An object of the present invention is to provide a power supply system that can reduce the harmonic component of the input current Ia.

One aspect of the present invention is a step-up / step-down circuit for stepping up and stepping down the voltage of DC power, and an upper arm and a lower arm each composed of a parallel connection of a switching element and a diode, and the upper arm and the lower arm are connected in series. And a bidirectional power control circuit including at least two inverter circuits connected in parallel, and the storage battery and the AC power supply can be connected by bidirectionally converting DC power and AC power connected to the inverter circuit. A target input current signal of an alternating current flowing from the alternating current power source to the inverter circuit, which is set according to a charging current of the storage battery, when charging the storage battery from the alternating current power source, ON / OFF of the switching element included in the inverter circuit is controlled according to a difference between the measured value of the AC current and the actual value. A power supply system according to claim.

Here, it is preferable to perform control so that the alternating current approaches a sine wave synchronized with the system power supply.

In addition, a pulse width modulation circuit that generates a periodic pulse-shaped control signal having an on-duty pulse width according to a difference between the target input current signal of the alternating current and the measured value of the alternating current, It is preferable that the switching element included in the inverter circuit is controlled by a control signal generated in the pulse width modulation circuit.

In addition, a target value of an intermediate voltage between the step-up / step-down circuit and the inverter circuit is set according to a charging current of the storage battery, and the alternating current is based on a difference between the target value and the measured value of the intermediate voltage. It is preferable to set the amplitude of the target input current signal.

According to another aspect of the present invention, there are provided a series of arm circuits in which two circuits are connected in series up and down in a parallel circuit composed of a switching element that responds to a control signal and a diode connected in parallel to the switching element in the opposite direction and a capacitor. Are connected to each other in parallel by connecting each of the upper and lower parallel circuits of the first arm circuit and the second arm circuit of the bridge circuit to a single-phase system power supply via an LP (low pass) filter. A storage battery is connected via a reactor to the connection point between the upper and lower two parallel circuits of the third arm circuit so that the storage battery can be charged from a system power supply, and the electric charge stored in the storage battery is converted into AC power. Then, in a power supply system that enables superposition or single output to the system power supply, when discharging the stored charge of the storage battery, the output of the storage battery is supplied to a third arm circuit. The DC power boosted by turning on and off the switching elements of the lower parallel circuit connected to the negative electrode side of the capacitor is stored in the capacitor, and the electric charge stored in the capacitor is stored between the first arm circuit and the second arm circuit. The switching elements forming the respective parallel circuits are turned on / off based on a PWM (pulse width modulation) method to generate a pseudo sine wave, and when charging the storage battery, the charge stored in the capacitor is replaced with a third charge. The switching element of the upper parallel circuit connected to the positive side of the capacitor of the arm circuit is turned ON / OFF to step down and charge the storage battery according to at least a predetermined constant current or a predetermined constant voltage, and the first arm circuit and the second Each switching element forming a parallel circuit of the arm circuit is synchronized with the system power supply and on the positive side of the capacitor. Driven by an ON / OFF signal obtained by modulating a carrier wave of a predetermined frequency by a difference between a sine wave having an amplitude based on a voltage and a target voltage and a current waveform flowing into the LP filter from the system power supply It is a power supply system.

Here, when discharging the stored charge of the storage battery, the switching element of the parallel circuit above the third arm circuit is controlled to be in the OFF state, and when charging the storage battery, the parallel circuit below the third arm circuit It is preferable to control the switching element in the OFF state.

The storage battery is formed by connecting a plurality of lead storage batteries in series, and it is preferable to set the set voltage higher than the rated voltage of the storage battery.

According to the present invention, in a power supply system including a bidirectional power control circuit, it is possible to reduce harmonic components of the input current when charging the battery unit.

It is a figure which shows the structure of the power supply system in embodiment of this invention. It is a figure which shows the effect | action of the power supply system in embodiment of this invention. It is a figure which shows the specific example of a structure of the power supply system in embodiment of this invention. It is a figure which shows the structure of the conventional power supply system. It is a figure which shows the input current in the charge period of the conventional power supply system.

The power supply system according to the embodiment of the present invention includes a bidirectional power conversion unit 200, a battery unit 202, a system power supply 204, and a control unit 206, as shown in FIG. The bidirectional power converter 200 is connected to a battery unit 202 that is a DC power source and an AC system power source 204. A load 208 is connected to the system power supply 204, and AC power is supplied from the system power supply 204 to the load 208. Further, the battery unit 202 is connected to the load 208 via the bidirectional power conversion unit 200, and DC power from the battery unit 202 is converted into AC power by the bidirectional power conversion unit 200 and supplied to the load 208. The

The battery unit 202 includes a storage battery that is a secondary battery. The battery unit 202 is configured by connecting storage battery cells such as a lithium ion battery and a lead battery in series and parallel, and a lithium battery having a DC open voltage of about 200 V is employed. The battery unit 202 is configured to include a plurality of battery packs configured by connecting 13 lithium ion battery storage battery cells connected in parallel and further connecting 13 sets in series. The battery unit 202 is configured by connecting, for example, four battery pack rows in which five battery packs are connected in series. The battery unit 202 is provided with a voltage detection sensor, a current detection sensor, and a temperature detection sensor, and outputs the output voltage, charge / discharge current, and temperature of the battery unit 202 to the control unit 206.
Moreover, if it is a lead battery, the battery of 6 cells 12V will be comprised in 48V by making 4 series.

The system power source 204 is, for example, an AC commercial power source. In the present embodiment, system power supply 204 is a single-phase 200V AC power supply, but is not limited to this. When the connection to the system power supply 204 is disconnected and the power supply system is operated independently, the AC power supply may be supplied to the load 208 as a single-phase 100V AC power supply.

As described above, the bidirectional power converter 200 converts the DC power output from the battery unit 202 into AC power and supplies it to the load 208, and converts AC power from the system power supply 204 into DC power. Used to charge the battery unit 202.

For example, the battery unit 202 is charged with AC power from the system power supply 204 during a time period when power usage is low, and is discharged from the battery unit 202 and supplied from the system power supply 204 during a time period when power consumption by the load 208 is large. Is supplied to the load 208 in superposition with the electric power generated. Thereby, the amount of power supplied from the system power supply 204 can be averaged, and the peak of power consumption can be reduced. Further, the power supply system can be used as a standby power supply by operating it independently at the time of power failure of the system power supply 204.

Next, the bidirectional power conversion unit 200 will be described. As shown in FIG. 1, the bidirectional power converter 200 includes a step-up / down circuit 200a, an inverter circuit 200b, and a control circuit 200c. The bidirectional power conversion unit 200 is connected to the control unit 206, and the step-up / step-down circuit 200a and the inverter circuit 200b are controlled by the control circuit 200c that receives the control signal from the control unit 206.

The step-up / step-down circuit 200a realizes a function of boosting the voltage output from the battery unit 202 and supplying it to the inverter circuit 200b, and a function of stepping down the voltage output from the inverter circuit 200b and supplying it to the battery unit 202. To do. The step-up / down circuit 200a includes a capacitor C1, an inductor L1, and switching elements SW1 and SW2.

The positive line connected to the positive output terminal of the battery unit 202 and the negative line connected to the negative output terminal are connected to the step-up / down circuit 200a. A capacitor C1 is connected between the positive and negative lines. The positive line is connected to a connection point between the two switching elements SW1 and SW2 via the coil L1. Here, the switching elements SW1 and SW2 are each composed of an N-type transistor and a free-wheeling diode connected in parallel. As the transistors of the switching elements SW1 and SW2, for example, a power transistor that flows a large current, such as an IGBT, is employed. When the transistor is turned on, a current flows from the positive side (collector) to the negative side (emitter). Current is sent from the positive side to the positive side (collector side of the transistor). Note that the switching elements SW1 and SW2 can also be configured using semiconductor elements such as FETs.

Switching element SW1 has its collector connected to the positive bus of inverter circuit 200b and its emitter connected to the collector of switching element SW2. The emitter of the switching element SW2 is connected to the negative line. The gates of the switching elements SW1 and SW2 are connected to the control circuit 200c, and the control circuit 200c controls on / off of the transistors of the switching elements SW1 and SW2. That is, a full-arm DC converter is configured by the coil L1 and the switching elements SW1 and SW2, and the switching circuit SW1 is kept off by the control circuit 200c, and the switching element SW2 is turned on / off to control the inverter circuit 200b. A DC voltage obtained by boosting the output voltage from the battery unit 202 can be obtained on the positive bus side. Further, it is possible to obtain a DC voltage obtained by stepping down the voltage of the positive bus of the inverter circuit 200b at the positive output terminal of the battery unit 202 by keeping the switching element SW2 off and controlling the on / off of the switching element SW1. .

At this time, the power supplied from the battery unit 202 of the step-up / down circuit 200a to the inverter circuit 200b and the battery unit 202 from the inverter circuit 200b are controlled by changing the voltage by controlling the ON / OFF duty ratio of the switching elements SW1 and SW2. It is possible to control the power transfer of the power supplied to.
When charging the battery unit 202, the intermediate voltage Vm is lowered to an arbitrary voltage by maintaining the switching element SW2 in a closed (off) state, periodically turning the switching element SW1 on and off, and changing the on-duty ratio. Can be applied to the terminal of the capacitor C1. Therefore, the on-duty of the switching element SW1 can be feedback controlled based on the terminal voltage of the capacitor C1 and the target voltage. That is, the battery unit 202 can be charged at a constant voltage with the target voltage. Further, the current charged in the battery unit 202 can be obtained from the sensor S1, and the on-duty of the switching element SW1 can be feedback controlled based on the current value and the target current value. That is, the battery unit 202 can be charged with a constant current at a target current, and the battery unit 202 can be charged by switching between the constant current charging and the low voltage charging.
For example, when a lead battery having a rating of 48 V (105 Ah) is used for the battery unit 202, constant current charging with a target current value of 0.1 C (10.5 A) is started, and the terminal voltage of the capacitor C1 (battery unit 202) When the battery voltage reaches 58.8 V (= 48 × 1.225), the target voltage is switched to constant voltage charging of 58.8 V to charge the battery unit 202. The discharge is determined based on the discharge current and the end-of-discharge voltage (not shown), and the end of the discharge of the battery unit 202 is determined. Is used as a voltage for determining the end of discharge.
In addition, although the lead battery of the rating 48V (105Ah) was used for the battery unit 202, it is not restricted to this, You may comprise so that a desired rating value may be obtained by connecting several lead batteries in series / parallel. Each target voltage and target current is appropriately changed.

The control unit 206 receives information on the power supplied from the system power supply 204 obtained by the sensor S4 and obtains power supplied from the battery unit 202 to the load 208, that is, power superimposed from the battery unit 202 to the system power supply 204. (For example, the power to be superimposed on the system power supply 204 is calculated so that the amount of power supplied from the system power supply 204 does not exceed a certain value. Outputs to the control circuit 200c a control signal instructing that the determined power is supplied from the battery unit 202. The control circuit 200c uses the sensor S1 to detect the voltage Vd and charge / discharge current Id of the battery unit 202 and the sensor S2. On the basis of these values and the control signal received from the control unit 206, the on / off duty ratios of the switching elements SW1 and SW2 are controlled so as to achieve a desired power transfer. The negative bus of the inverter circuit 200b to which the emitter of the switching element SW2 is connected, and the switch A capacitor C2 is connected between the positive buses of the inverter circuit 200b to which the collector of the switching element SW1 is connected to smooth the voltage between the positive and negative buses. The voltage at the connection point between the switching elements SW1 and SW2 appears on the positive bus of the capacitor C2 via a freewheeling diode connected in parallel to the switching element SW1.

Generally, the intermediate voltage Vm between the positive and negative buses of the inverter circuit 200b is controlled to be higher than the output voltage Vd of the battery unit 202. However, when the voltage Vd of the battery unit 202 is higher than the intermediate voltage Vm, it is only necessary to provide a step-up / down circuit that can increase the voltage from the intermediate voltage Vm to the battery unit 202 side to supply power and transport the power.

The inverter circuit 200b includes switching elements SW3, SW4, SW5, and SW6. The switching elements SW3, SW4, SW5, and SW6 are each composed of an N-type transistor and a free-wheeling diode connected in parallel. For the transistors of the switching elements SW3, SW4, SW5, and SW6, for example, a power transistor such as an IGBT that allows a large current to flow is adopted. When the transistor is turned on, a current flows from the positive side (collector) to the negative side (emitter). Current flows from the emitter side to the positive side (collector side of the transistor). The switching elements SW3 and SW5 constitute the upper arm of the inverter circuit 200b, and the switching elements SW4 and SW6 constitute the lower arm of the inverter circuit 200b. These switching elements SW4 to SW6 may be configured using FETs similarly to the switching elements SW1 and SW2.

That is, two arms of a series connection of switching elements SW3 and SW4 and a series connection of switching elements SW5 and SW6 are connected between the positive and negative buses of the inverter circuit 200b. The collectors of switching elements SW3 and SW5 are connected to the positive bus, respectively, and the emitters are connected to the collectors of switching elements SW4 and SW6. The emitters of the switching elements SW4 and SW6 are connected to the negative bus. In this way, the single-phase inverter circuit 200b is configured by the switching elements SW3, SW4, SW5, and SW6. In other words, the switching elements SW1 to SW6 are composed of diodes connected in parallel in the opposite direction to semiconductor elements such as IGBT and FET, and the second arm circuit is connected by connecting the switching elements SW3 and SW4 up and down. The switching elements SW5 and SW6 are connected up and down to form a first arm circuit, and the switching elements SW1 and SW2 are connected up and down to form a third arm circuit.

The connection point of the switching elements SW3 and SW4 is an AC output terminal connected to one end of the system power supply 204 via the coil L2 (reactor), and the connection point of the switching elements SW5 and SW6 is the coil L3 (reactor). The AC output terminal is connected to the other end of the system power supply 204 via the reactor). A capacitor C3 is connected between the AC output end sides of the coil L2 and the coil L3 to form an LPF (low pass filter). The coils L2 and L3 and the capacitor C3 are required for the function of removing high frequency components generated in the alternating current of the inverter circuit 200b and the function of bringing the phase of the alternating current close to the phase of the alternating voltage.

The switching elements SW3, SW4, SW5 and SW6 are on / off controlled by the control circuit 200c. By the on / off control of the switching elements SW3, SW4, SW5, and SW6, the DC power supplied from the step-up / down circuit 200a is converted into an inverter when the battery unit 202 is discharged, that is, during the period when power is supplied from the battery unit 202 to the load 208. After being converted into a pseudo sine wave by the circuit 200b, it is converted into converted AC power through the LPF and supplied to the load 208. Specifically, by turning on the switching elements SW3 and SW6 and turning off the switching elements SW4 and SW5, an output in which the AC output terminal on the coil L2 side is positive is obtained, and the switching elements SW3 and SW6 are turned off and the switching elements By turning on SW4 and SW5, an output in which the AC output terminal on the coil L3 side is positive is obtained. Here, the control circuit 200c receives the input voltage Va and the input / output current Ia to the inverter circuit 200b measured by the sensor S3, detects the zero cross point from these signals, and is supplied from the system power supply 204 to the load 208. On / off of the switching elements SW3, SW4, SW5 and SW6 is controlled based on the PWM method so that AC power synchronized with the voltage phase of the power to be output is output from the inverter circuit 200b.

Thereby, AC power can be supplied to the load 208 from both the system power supply 204 and the battery unit 202.

On the other hand, the bidirectional power conversion unit 200 according to the present embodiment causes the inverter circuit 200b to function as an active filter during charging of the battery unit 202, that is, during a period in which power is supplied from the system power supply 204 to the battery unit 202.

In the conventional bidirectional power converter, when the battery unit 202 is charged, the switching elements SW3, SW4, SW5, and SW6 of the inverter circuit 200b are all turned off, and the bridge circuit of the freewheeling diodes included in the switching elements SW3, SW4, SW5, and SW6 The AC power from the system power supply 204 is rectified and supplied to the step-up / step-down circuit 200a only by the above action. On the other hand, in this embodiment, by making the inverter circuit 200b function as an active filter, the input / output current Ia of the inverter circuit 200b can be formed into a sine wave, and the harmonics superimposed on the input / output current Ia. Reduce ingredients.

As shown in FIG. 2, the battery unit 202 is charged in the constant current mode (CC mode) until the voltage Vd of the battery unit 202 reaches a predetermined value Vth. When the voltage Vd reaches the predetermined value Vth, the constant voltage mode (CV Mode). The inverter circuit 200b functions as an active filter at least during charging in the constant current mode.

The control circuit 200c acquires the measured value of the charging current Id from the sensor S1 to the battery unit 202 so that the DC charging current Id becomes a constant charging current and the AC charging current Ia becomes a predetermined value. Therefore, a target input current signal that is a target of the input current Ia to the inverter circuit 200b is set. Then, the control circuit 200c obtains a difference between the actually measured value of the input current Ia measured by the sensor S3 and the set target input current signal, and the switching elements SW3, SW4, SW5 and so on to reduce the difference. SW6 is turned on / off.

Thus, feedback control can be performed such that the input current Ia flowing into the inverter circuit 200b matches the target input current signal. For example, by making the target input current signal a sine wave (or cosine wave), the actual input current Ia can be controlled to be a sine wave (or cosine wave), and is included in the input current Ia. Harmonics can be reduced.

Specifically, as shown in FIG. 3, a pulse width modulation circuit (PWM circuit) 200d is provided in the control circuit 200c, and the switching elements SW3, SW4, SW5, and SW6 are controlled by a pulse signal output from the pulse width modulation circuit 200d. The on / off control may be performed.

The control circuit 200c fixes the switching element SW2 to OFF and controls the ON / OFF duty ratio of the switching element SW1 to step down the intermediate voltage Vm that is the charging voltage of the capacitor C2, thereby charging the battery unit 202 with a charging current. Control is performed so that Id becomes a set value in charging in the constant current mode. At this time, the control circuit 200c receives the measured value of the charging current Id, and calculates the target value of the intermediate voltage Vm necessary for maintaining the value at the set value in charging in the constant current mode. Then, the amplitude of the target input current signal is set according to the difference between the actually measured value of the intermediate voltage Vm measured by the sensor S2 and the target value of the intermediate voltage Vm. That is, if the measured value of the intermediate voltage Vm is smaller than the target value, the amplitude of the sine wave of the target input current signal is set to be larger than the current value. If the measured value of the intermediate voltage Vm is larger than the target value, the target input current signal is set. The amplitude of the sine wave is set to be smaller than the current value.

The PWM circuit 200d can be configured to include a subtractor 20, a PID calculator 22, a triangular wave (carrier wave) generator 24, and a comparator 26. The difference unit 20 calculates the difference between the target input current signal set as described above and the actual value of the input current Ia measured by the sensor S3 and outputs the difference to the PID calculator 22. The PID calculator 22 outputs a PID value indicating the difference between the actual input current Ia and the target input current value according to the absolute value of the input value, the temporal integral value, and the temporal differential value. The comparator 26 compares the PID value from the PID calculator 22 with the triangular wave generated by the triangular wave generator 24 and outputs a PWM pulse signal whose pulse width is modulated according to the magnitude relationship. For example, a PWM pulse signal that outputs a high level only during a period when the PID value from the PID calculator 22 is greater than the triangular wave generated by the triangular wave generator 24 and outputs a low level during other periods is output.

The on / off of the switching elements SW3, SW4, SW5 and SW6 is controlled by the PWM pulse signal thus generated. Thus, the inverter circuit 200b can be controlled so that the target input current signal and the input current Ia match. That is, the active filter is operated so that the voltage (intermediate voltage Vm) of the capacitor C2 becomes constant at the target voltage corresponding to the charging current Id.

In this way, the inverter circuit 200b functions as an active filter when the battery unit 202 is charged. By making the input current Ia flowing from the system power supply 204 into the inverter circuit 200b into a waveform that does not involve a steep change such as an impulse, the harmonic component contained in the input current Ia can be reduced.

In this embodiment, the PWM circuit 200d is configured as described above, but the present invention is not limited to this. In addition, if the system power supply 204 is a three-phase AC power supply, the bidirectional power conversion unit 200 can be similarly processed by providing it in each of the u-phase, v-phase, and w-phase.

10 Buck-Boost Circuit, 12 Inverter Circuit, 20 Differencer, 22 PID Calculator, 24 Triangular Wave Generator, 26 Comparator, 102 Battery Unit, 106 System Power Supply, 200 Bidirectional Power Converter, 200a Buck-Boost Circuit, 200b Inverter Circuit , 200c control circuit, 200d pulse width modulation circuit, 202 battery unit, 204 system power supply, 206 control unit, 208 load.

Claims

A step-up / step-down circuit for stepping up and stepping down the voltage of the DC power;
An inverter circuit in which an upper arm and a lower arm are each composed of a parallel connection of a switching element and a diode, and at least two series connections of the upper arm and the lower arm are connected in parallel;
Including a bidirectional power control circuit including: a power system that enables connection between a storage battery and an AC power source by bidirectionally converting DC power and AC power connected to the inverter circuit,
When charging the storage battery from the AC power supply, the target input current signal of the alternating current flowing from the AC power supply to the inverter circuit set according to the charging current of the storage battery, the actual value of the alternating current, A power supply system that controls on / off of the switching element included in the inverter circuit in accordance with a difference between them.
The power supply system according to claim 1,
A power supply system that performs control so that the alternating current approaches a sine wave synchronized with a system power supply.
The power supply system according to claim 1 or 2,
A pulse width modulation circuit that generates a periodic pulse-shaped control signal with an on-duty pulse width corresponding to the difference between the target input current signal of the alternating current and the actual value of the alternating current;
A power supply system, wherein the switching element included in the inverter circuit is controlled by a control signal generated in the pulse width modulation circuit.
The power supply system according to any one of claims 1 to 3,
A target value of the intermediate voltage between the step-up / step-down circuit and the inverter circuit is set according to the charging current of the storage battery, and the target of the alternating current is based on the difference between the target value and the measured value of the intermediate voltage A power supply system that sets an amplitude of an input current signal.
A parallel circuit composed of a switching element that responds to a control signal and a diode connected in parallel with the switching element in the opposite direction is composed of an arm circuit in which two circuits are connected in series up and down and three rows and a capacitor are connected in parallel. The connection points of the upper and lower two parallel circuits of the first arm circuit and the second arm circuit of the bridge circuit are connected to a single-phase system power supply via an LP (low pass) filter, and the third arm circuit A storage battery is connected to the connection point of the upper and lower two parallel circuits via a reactor, and the storage battery is made chargeable from a system power supply, and the electric charge stored in the storage battery is converted into AC power and superimposed on the system power supply or In a power supply system that enables single output,
When discharging the stored charge of the storage battery, the DC power boosted by turning on / off the switching element of the lower parallel circuit that connects the output of the storage battery to the negative side of the third arm circuit is stored in the capacitor. At the same time, the charge accumulated in this capacitor is turned on / off based on the PWM (pulse width modulation) method for the switching elements forming the parallel circuits of the first arm circuit and the second arm circuit to generate a pseudo sine wave. When generating and charging the storage battery, the switching element of the upper parallel circuit that connects the charge stored in the capacitor to the positive side of the capacitor of the third arm circuit is turned on / off to lower the voltage, and at least a predetermined amount The storage battery is charged according to a constant current or a predetermined constant voltage, and a parallel circuit of the first arm circuit and the second arm circuit is formed. The switching element is synchronized with the system power supply, and a carrier wave having a predetermined frequency is a difference between a sine wave having an amplitude based on the voltage on the positive side of the capacitor and a target voltage and a current waveform flowing from the system power supply into the LP filter It is driven by an ON / OFF signal obtained by modulating the power.
When discharging the stored charge of the storage battery, the switching element of the parallel circuit above the third arm circuit is controlled to be in the OFF state, and when charging the storage battery, the switching element of the parallel circuit below the third arm circuit The power supply system according to claim 5, wherein the power supply system is controlled to be in an OFF state.
The power storage system according to claim 6, wherein the storage battery is formed by connecting a plurality of lead storage batteries in series, and the set voltage is set higher than a rated voltage of the storage battery.