TWI583098B - Power supply and the use of its non-power supply system - Google Patents

Description

Power supply unit and uninterruptible power supply system using same

The present invention relates to a power supply device that performs power conversion between direct current and alternating current.

Recently, a system with a DC power supply such as a battery, a solar battery, or a fuel cell has been developed because of the awareness of environmental protection on the earth. In such systems, it is necessary to convert DC power into AC power and supply it to a power supply device of a load or a commercial power source. Further, when the commercial power source uses a battery to continuously supply power to the load even if the power is turned off, an uninterruptible power supply system including a battery is required.

Patent Document 1 discloses an uninterruptible power supply device including an inverter (a bidirectional converter circuit), a bidirectional DC-DC converter, and a battery (a step-up/down chopper circuit). The uninterruptible power supply device charges the battery when the chain voltage (the voltage at the connection point between the bidirectional converter circuit and the buck-boost chopper circuit and the link voltage) is equal to or greater than a predetermined value, and when the chain voltage is lower than a predetermined value, The battery is discharged. Thereby, it is intended to limit the input from the AC power source while supplying the power for the load from the inverter.

[Previous Technical Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2003-52134

When the inverter converts the power input from the AC power source to the DC side, that is, the AC-DC operation of the chain voltage connected to the bidirectional DC-DC converter, it is necessary to control the input current from the AC power source to a sine wave. Shape to improve the power factor. However, when the chain voltage is lower than the voltage appearing when the AC power source voltage is passively rectified by the inverter, it is difficult to control the input current from the AC power source to a sinusoidal shape, and the power factor is likely to be low. Therefore, the chain voltage is preferably higher than the voltage that occurs when the AC power supply voltage is passively rectified by the inverter.

On the other hand, in general, the converter has a large switching loss when the chain voltage is high. Similarly, in the bidirectional DC-DC converter, the switching loss is likely to increase when the chain voltage is high. Further, when the bidirectional DC-DC converter is an insulated type including a transformer, the output voltage from the battery input power to the discharge voltage of the chain voltage, that is, the higher the chain voltage, is applied to the switch having the input power to the battery. The voltage of the switching element of the circuit becomes high, and it is necessary to use a switching element having a high withstand voltage. When the withstand voltage becomes high in the switching element, the ON resistance becomes large, and the conduction loss is likely to become large. Further, when the battery voltage is low, the boosting ratio of the bidirectional DC-DC converter at the time of discharge becomes high, and the loss tends to become large.

As described above, in order to maintain the input power factor from the AC power supply high and the chain voltage to be high, the loss of the inverter and the bidirectional DC-DC converter is increased, and the efficiency is likely to be lowered.

It is an object of the present invention to provide an efficient power supply unit.

In order to achieve the above object, the present invention is characterized in that: an inverter is provided, wherein an alternating current terminal is connected to an alternating current power source, and a direct current terminal is connected to a chain voltage; and a bidirectional DC-DC converter is connected to the chain voltage and the battery. And charging and discharging the battery; and the voltage of the chain when discharging the battery is greater than a voltage appearing between the DC terminals when the maximum voltage of the AC power source is passively rectified by the inverter low.

According to the present invention, an efficient power supply device can be provided.

1,1a, 1b‧‧‧Power supply unit

2, 2a, 2b‧‧‧ Inverter

3,3a,3b‧‧‧bidirectional DC-DC converter

4,4a,4b‧‧‧Battery

5,5a,5b‧‧‧ relay

6,6a,6b‧‧‧AC power supply

7,7a,7b‧‧‧load

8a, 8b, 9a, 9b‧‧‧ switch circuit

10‧‧‧Control means

11~13, 21, 22‧‧‧ AC terminal of the inverter

14,15,24,25‧‧‧DC converter DC terminals

100,100a,100b‧‧‧No power outage system

Vlink‧‧‧ chain voltage

C1~C8‧‧‧ capacitor

L1~L6‧‧‧Inductors

Cr1, Cr2‧‧‧ resonant capacitor

Lr1, Lr2‧‧‧ Resonant Inductors

T1, T2‧‧‧ transformer

N1~N4‧‧‧Reel

Q1~Q6, H1~H4, S1~S4‧‧‧ Switching components

D1~D6, DH1~DH4, DS1~DS4‧‧‧ diode

Nd1~Nd5‧‧‧ nodes

Fig. 1 is a schematic configuration diagram of a power supply system 1 of the first embodiment and a power supply system using the uninterruptible power supply system 100.

Fig. 2 is a circuit configuration diagram of a power supply device 1a of the second embodiment and an uninterruptible power supply system 100a using the same.

[Fig. 3] illustrates the chain voltage of the commercial power supply mode and the battery power supply mode. A diagram of the Vlink setting method.

Fig. 4 is a circuit configuration diagram of a power supply device 1b of the third embodiment and an uninterruptible power supply system 100b using the same.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Example 1]

1 is a schematic configuration diagram of a power supply system 1 of the present invention and a power supply system using the uninterruptible power supply system 100. The power supply device 1 includes a relay 5, an inverter 2, and a bidirectional DC-DC converter 3. The uninterruptible power supply system 100 includes a power supply device 1 and a battery 4.

The AC side of the inverter 2 is connected to the AC power source 6 through the relay 5 and is connected to the load 7. The DC side of the inverter 2 is connected to a DC link voltage Vlink. The bidirectional DC-DC converter 3 is connected between the chain voltage Vlink and the battery 4 to charge and discharge the battery 4.

In the power supply device 1, the relay 5 is turned on, the power is supplied from the AC power supply 6 to the load 7, and the inverter 2 is supplied with the power of the AC power supply 6, and the output chain voltage Vlink is output. The bidirectional DC-DC converter 3 is provided. The battery 4 is charged by inputting a link voltage Vlink.

When the AC power supply 6 is powered off, the relay 5 is turned off, the bidirectional DC-DC converter 3 discharges the battery 4, the output chain voltage Vlink, and the inverter 2 is supplied with the link voltage Vlink, and the load 7 is supplied. Give AC power. Thereby, the power supply to the load 7 is continued even when the AC power source 6 is powered off.

Here, when the inverter 2 performs the electric power input to the AC power source 6 and the AC-DC operation of the output chain voltage Vlink, it is necessary to control the input current from the AC power source 6 to be sinusoidal to increase the power factor. However, when the chain voltage Vlink at this time is lower than the voltage which occurs when the voltage of the AC power source 6 is passively rectified by the inverter 2, it is difficult to control the input current from the AC power source 6 to be sinusoidal, and the power factor is easy. Go low. Therefore, the chain voltage Vlink is preferably increased to a higher voltage than when the voltage of the AC power source 6 is passively rectified by the inverter 2.

On the other hand, in general, the inverter 2 tends to have a large switching loss when the chain voltage Vlink is high. Similarly, in the bidirectional DC-DC converter 3, the switching loss is likely to increase when the chain voltage Vlink is high. When the bidirectional DC-DC converter 3 is an insulated type including a transformer, the electric power input from the battery 4 is output to the discharge voltage output voltage of the chain voltage Vlink, that is, when the chain voltage Vlink is high, the battery is applied to the battery. The voltage of the switching element of the switching circuit of the input power is increased, and it is necessary to use a switching element having a high withstand voltage. When the withstand voltage becomes high in the switching element, the ON resistance becomes large, and the conduction loss is likely to become large. Further, when the voltage of the battery 4 is low, the boosting ratio of the bidirectional DC-DC converter 3 at the time of discharge becomes high, and the loss is likely to increase.

Thus, in order to maintain the input power factor from the AC power source 6 high and the chain voltage Vlink to be high, the losses of the inverter 2 and the bidirectional DC-DC converter 3 become large, and the efficiency is liable to drop. low.

Therefore, in the power supply device 1 of the present invention, the chain voltage Vlink at the time of discharging the battery 4 is lowered to be lower than the voltage which occurs when the inverter 2 is passively rectified at the maximum voltage of the AC power supply 6. Thereby, the inverter 2 and the bidirectional DC-DC converter 3 all reduce the loss and improve the efficiency.

At this time, the chain voltage Vlink is raised to be higher than the voltage which occurs when the nominal voltage (rated voltage) of the AC power source 6 is passively rectified by the inverter 2. Therefore, for the load 7, a voltage corresponding to the nominal voltage (rated voltage) of the AC power source 6 can be supplied from the inverter 2 with less strain. Of course, when the voltage at which the chain voltage Vlink is generated when the nominal voltage (rated voltage) of the AC power source 6 is passively rectified by the inverter 2 is low, the voltage waveform supplied from the inverter 2 to the load 7 is easy. deformation.

Further, the chain voltage Vlink when the battery 4 is charged is lowered to a voltage higher than that which occurs when the inverter 4 is passively rectified at the maximum voltage of the AC power source 6. Therefore, the input power factor can be maintained high even in the case where the voltage of the AC power source 6 is maximum.

[Example 2]

Fig. 2 is a circuit configuration diagram of a power supply device 1a of the present invention and an uninterruptible power supply system 100a using the same. The power supply device 1a includes a relay 5a, an inverter 2a that is connected to the AC power supply 6a via the relay 5a, and an inverter 2a that is connected to the link voltage Vlink on the DC side, and is connected to the chain voltage. A bidirectional DC-DC converter 3a between the Vlink and the battery 4a, and a control means 10 for controlling the same.

The AC power supply 6a is a single-phase three-wire type, and can supply two systems of 100V system and one system of 200V system. In addition, a voltage of about 85V to 132V is widely used as the voltage of the 100V system, and a voltage of about 170V to 265V is used as the voltage of the 200V system.

The inverter 2a receives power between the DC link voltage Vlink connected between the DC terminals 14-15 and the AC line connected between the AC terminals 11 to 13. A battery 4a is connected between the DC terminals 14-15 via a bidirectional DC-DC converter 3a. Between the AC terminals 11 to 13, the AC power source 6a is connected via the relay 5a, and the load 7a is connected.

The inverter 2a includes a first switch leg portion in which the switching elements Q1 and Q2 are connected in series by the node Nd1, a second switch leg portion in which the switching elements Q3 and Q4 are connected in series by the node Nd2, and a capacitor connected in series at the node Nd3. The first capacitor leg of C1 and C2, the second capacitor leg of the capacitors C3 and C4 connected in series by the node Nd4, and the third switch leg of the switching elements Q5 and Q6 are connected in series by the node Nd5. The first to third switch leg portions are connected in parallel to the first capacitor leg portion. The inductor L1 is connected between one end of the second capacitor leg (capacitor C3) and the node Nd1, and the inductor L2 is connected between the other end of the second capacitor leg (capacitor C4) and the node Nd2, and between the node Nd3 and the node Nd5. Connect inductor L3. The node Nd3 is connected to the node Nd4.

The diodes D1 to D6 are connected in anti-parallel to the switching elements Q1 to Q6, respectively. Here, MOSFETs are used as switching elements Q1 to Q6. In the case of the diodes D1 to D6, a parasitic diode of the MOSFET can be used.

The two ends of the first capacitor leg are defined as the DC terminals 14-15 and connected to the chain voltage Vlink. Further, in the present embodiment, the chain voltage Vlink is connected between both ends of the capacitor leg, but the chain voltage Vlink may be connected between both ends of the capacitor C1 or between both ends of the capacitor C2.

The connection point between the inductor L1 and the capacitor C3 is the AC terminal 11, the connection point of the inductor L2 and the capacitor C4 is the AC terminal 12, and the connection point of the capacitors C3 and C4 is the AC terminal 13. Between the AC terminals 11-13, that is, between the two ends of the capacitor C3, a phase is formed, and between the AC terminals 13-12, that is, between the two ends of the capacitor C4, the b phase is formed, and the alternating current terminal 11-12 is also An ab phase is formed between both ends of the second capacitor leg. Further, the voltage of the AC terminal 11 of the AC terminal 13 is defined as the a-phase voltage Va, the voltage of the AC terminal 13 of the AC terminal 12 is defined as the b-phase voltage Vb, and the voltage of the AC terminal 11 of the AC terminal 12 is defined. Is the ab phase voltage Vab.

The capacitors C1 and C2 divide the voltage between the DC terminals 14-15, and the Nd3 generates an intermediate voltage of the voltage between the DC terminals 14-15. The switching elements Q5, Q6, and the inductor L3 share the voltages of the capacitors C1 and C2 by controlling the switching elements Q5 and Q6.

When the electric power input to the AC power supply 6a between the AC terminals 11 to 13 is converted into DC, and the chain voltage Vlink is output, the switching elements Q1 and Q2 are controlled to flow a current through the inductor L1, and the switching elements Q3 and Q4 are controlled to the inductor. L2 circulating current, the electricity input from the AC power source 6a The flow is controlled to be sinusoidal, making the power factor high.

When the chain voltage Vlink input between the DC terminals 14-15 is converted into an alternating current and the DC-AC supplied to the load 7a is operated, the switching elements Q1 and Q2 are controlled to generate the a-phase voltage Va, and the switching elements Q3 and Q4 are controlled to generate b phase voltage Vb.

The bidirectional DC-DC converter 3a includes capacitors C7 and C8, switch circuits 8a and 9a, a transformer T1 that magnetically couples the winding wires N1 and N2, and an inductor L4 (smooth inductor). The chain is connected between the two ends of the capacitor C7. The voltage Vlink is supplied with electric power between the battery 4a connected between both ends of the capacitor C8.

The switch circuit 8a is a full bridge type connection switching element H1 to H4. The eleventh switch leg portion in which the switching elements H1 and H2 are connected in series is connected in parallel, and the twelfth switch leg portion of the switch element H3 and H4 is connected in series, and the capacitor C7 is connected between both ends of the eleventh switch leg portion (between the DC terminals). The winding wire N1 is connected between the connection point of the switching elements H1 and H2 and the connection point of the switching elements H3 and H4 (between the alternating current terminals).

The switch circuit 9a is a full bridge type connection switching element S1 to S4. The 13th switch leg portion in which the switching elements S1 and S2 are connected in series is connected in parallel, and the 14th switch leg portion of the switching elements S3 and S4 are connected in series, and the inductor is connected in series between the both ends of the 13th switch leg portion (between the DC terminals) L4 and capacitor C8 connect the winding wire N2 between the connection point of the switching elements S1 and S2 and the connection point of the switching elements S3 and S4 (between the alternating current terminals).

The diodes DH1 to DH4 and DS1 to DS4 are connected in anti-parallel to the switching elements H1 to H4 and S1 to S4, respectively. Here, as a switching element When MOSFETs are used for H1 to H4 and S1 to S4, parasitic diodes of MOSFETs can be used as the diodes DH1 to DH4, DS1, and DS4.

When the charging operation of supplying power to the battery 4a from the chain voltage Vlink is performed, the switching elements H1 to H4 are switched, and a voltage is applied to the winding N1. The voltage generated by the winding line N2 is rectified by the switching circuit 9a, and the current smoothed by the inductor L4 and the capacitor C8 is supplied to the battery 4a.

When the battery 4a performs the discharge operation of supplying power to the chain voltage Vlink, the switching elements S1 to S4 are switched, and the current accumulated in the inductor L4 is distributed to the winding N2. The current induced by the winding line N1 is rectified by the switching circuit 8a, and the voltage smoothed by the capacitor C7 is supplied to the chain voltage Vlink.

The power supply device 1a of the present embodiment is configured to cooperate with the battery 4a, and is configured to provide an uninterruptible power supply system 100a that is capable of redundantly supplying power to the load 7a even if the AC power supply 6a that is a commercial power system is powered off. In the normal state in which the power failure level occurs, the relay 5a is turned on, the power of the AC power source 6a is supplied to the load 7a, and the commercial power supply mode for charging the battery 4a is operated. When the system such as a power failure is abnormal, the relay 5a is turned off, and the battery 7a is supplied with power from the battery 4a to perform backup operation in the battery power supply mode.

Hereinafter, a method of setting the chain voltage Vlink in the commercial power supply mode and the battery power supply mode will be described using FIG. In Fig. 3, Vnom is the nominal voltage (rated voltage) (effective value) of the ab phase voltage of the AC power source 6a, for example, 200V, Vmax is the ab phase voltage of the AC power source 6a. The maximum voltage (effective value), for example, 220V, Vab_nom is the waveform of the ab phase voltage at the nominal voltage, Vab_max is the waveform of the ab phase voltage at the maximum voltage, and Vm_nom is the amplitude of the ab phase voltage at the nominal voltage ( The wave top value), for example, 283V (= √ 2 × Vnom), Vm_max is the amplitude (wave top value) of the ab phase voltage at the time of the maximum voltage, for example, 311V (= √ 2 × Vmax), and Vlink_charge is performed on the battery 4a. The chain voltage at the time of charging (in the commercial power supply mode) and Vlink_discharge are the chain voltages when discharging the battery 4a (in the battery power supply mode). In this case, the maximum voltage Vmax of the ab phase voltage of the AC power source 6a is set to 1.1 times the nominal voltage Vnom, but may be other values such as 1.15 times, for example, as the power supply device 1a or the uninterruptible power supply system 100a. Specifications can also be set.

In the commercial power supply mode, the inverter 2a performs an AC-DC operation, an output chain voltage Vlink, and a bidirectional DC-DC converter 3a that inputs a chain voltage Vlink to perform a charging operation. Here, when the maximum voltage Vmax of the AC power source 6a is passively rectified by the diodes D1 to D4 of the inverter 2a, the voltage appearing between the DC terminals 14-15 is input to the AC terminal 11-12 at this time. The amplitude Vm_max of the ab phase voltage between them is slightly equal. When the amplitudes of the a-phase voltage Va and the b-phase voltage Vb are different, the voltage appearing between the DC terminals 14-15 when the diodes D1 to D4 of the inverter 2a are passively rectified is The amplitudes of the a-phase voltage Va and the b-phase voltage Vb are twice as large as the amplitude.

Here, in the AC-DC operation of the inverter 2a, it is necessary to control the input current from the AC power source 6a to be sinusoidal, and to enhance the work. Rate factor. However, when the chain voltage Vlink at this time is lower than the voltage which is generated when the voltage of the AC power source 6a is passively rectified by the diodes D1 to D4 of the inverter 2a, the instantaneous value of the voltage at the AC power source 6a exceeds the chain voltage. In the timing of Vlink, it is difficult to control the input current value from 6a, so it becomes difficult to control the input current to a sinusoidal shape, and the power factor is liable to become low.

Therefore, the chain voltage Vlink_charge at the time of the commercial power supply mode is set to be higher than the amplitude Vm_max of the maximum voltage of the AC power supply 6a. Thereby, even when the voltage of the AC power source 6a is maximum, it is easy to control the input current to a sinusoidal waveform to increase the power factor.

Next, in the battery power supply mode, the bidirectional DC-DC converter 3a performs a discharge operation, outputs a chain voltage Vlink, the inverter 2a performs a DC-AC operation, inputs a link voltage Vlink, and supplies AC power to the load 7a. When the bidirectional DC-DC converter 3a of the present embodiment is subjected to the discharge operation, as described above, the switching elements S1 to S4 are switched, and the current accumulated in the inductor L4 is distributed to the winding N2. At this time, when an inductance component such as a leakage inductance or a wiring inductance of the transformer T1 is connected in series to the winding wires N1 and N2, a surge voltage is likely to occur when the switching elements S1 to S4 are turned off. Therefore, the voltage applied to the switching elements S1 to S4 during discharge operation is more likely to be higher than during the charging operation. When the voltage applied to the switching elements S1 to S4 is excessively high, of course, the switching loss is increased, and it is necessary to use a switching element having a high withstand voltage. When the withstand voltage becomes high in the switching element, the ON resistance increases, and the conduction loss increases, which tends to cause a decrease in efficiency. Moreover, when the voltage of the battery 4a is low, the bidirectional DC-DC converter 3a The boost ratio becomes higher and the loss is still prone to become larger.

In addition, when the number of turns of the transformer T1 is reduced (N2/N1), the voltage applied to the switching elements S1 to S4 can be reduced, but a sufficient output voltage cannot be obtained during the charging operation.

Therefore, the chain voltage Vlink_discharge in the battery power supply mode is set to be lower than the amplitude Vm_max when the maximum voltage of the AC power source 6a is exceeded. Thereby, the voltages of the winding wires N1 and N2 are lowered as compared with the case where the chain voltage is set to be higher than the amplitude Vm_max when the maximum voltage of the AC power source 6a is set, and the voltage applied to the switching elements S1 to S4 can be suppressed to Lower. Further, the switching loss of the switching elements Q1 to Q6 of the inverter 2a can be suppressed to be small.

The amplitude Vm_nom when the chain voltage Vlink_discharge is set to the nominal (rated) voltage in the battery power supply mode is also high. Therefore, from the viewpoint that the inverter 2a outputs a voltage corresponding to the nominal voltage (rated voltage) of the AC power source 6a to the load 7a, the deformation of the output voltage waveform can be suppressed to be small. Further, if the chain voltage is lower than the voltage amplitude Vm_nom output from the inverter 2a to the load 7a, the output voltage waveform is easily deformed. In the above description, the nominal voltage (rated voltage) is output from the inverter 2a to the load 7a. However, when the output voltage of the current changer 2a is changed, the chain voltage is not lower than the desired output. The voltage amplitude can be changed by changing the chain voltage.

As described above, in the present embodiment, the battery power supply mode, that is, the chain voltage Vlink_discharge when discharging the battery 4a is set to be the maximum voltage Vmax of the AC power supply 6a as D1 of the inverter 2a. When the D4 is passively rectified, the voltages appearing between the DC terminals 14-15 are substantially equal, and are lower than the amplitude Vm_max of the maximum voltage of the AC power source 6a, thereby suppressing the withstand voltages of the switching elements S1 to S4 to be low. Moreover, the switching loss of the switching elements Q1 to Q6 and S1 to S4 can be suppressed, and the power can be supplied from the battery 4a to the load 7a with high efficiency.

Further, in the present embodiment, the amplitude Vm_nom at the nominal voltage (rated voltage) of the ab phase voltage

<Chain voltage Vlink_discharge when discharging battery 4a

<Amplitude Vm_max at the maximum voltage of the ab phase voltage

<The voltage of the chain voltage Vlink_charge at the time of charging the battery 4a raises the voltage. Thereby, even when the voltage of the AC power source 6a is maximum, it is easy to control the input current when charging the battery 4a to a sinusoidal waveform to increase the power factor. Moreover, the deformation of the voltage waveform of the load 7a at the time of discharging the battery 4a can be suppressed to be small.

[Example 3]

Fig. 4 is a circuit configuration diagram of a power supply device 1b of the present invention and an uninterruptible power supply system 100b using the same. The power supply device 1b includes a relay 5b, an inverter 2b that is connected to the AC power supply 6b via the relay 5b, and an inverter 2b that is connected to the link voltage Vlink on the DC side and a bidirectional DC that is connected between the link voltage Vlink and the battery 4b. -DC converter 3b. The AC power source 6b is a single-phase two-wire type.

The inverter 2b is a DC link chain voltage Vlink connected between the DC terminals 24-25 and an AC line connected between the AC terminals 21-22. Receiving electricity between. A battery 4b is connected between the DC terminals 24-25 through the bidirectional DC-DC converter 3b. Between the AC terminals 21-22, the AC power source 6b is connected through the relay 5b, and the load 7b is connected.

The inverter 2b includes a first switch leg portion in which the switching elements Q1 and Q2 are connected in series by the node Nd1, and a second switch leg portion in which the switching elements Q3 and Q4 are connected in series by the node Nd2, and is connected in parallel to the first and second terminals. The capacitor C5 of the switch leg is connected to the inductors L5 and L6 and the capacitor C6 connected in series between the nodes Nd1-Nd2. The two ends of the capacitor C5 are set between the DC terminals 24-25 and connected to the chain voltage Vlink. Further, the capacitor C6 is set to be between the AC terminals 21-22.

As a result, the inverter 2b of the present embodiment is a single-phase two-wire full-bridge inverter, and the number of parts can be reduced as compared with the inverter 2a of the second embodiment.

The bidirectional DC-DC converter 3b includes capacitors C7 and C8, switching circuits 8b and 9b, a transformer T2 that magnetically couples the winding wires N3 and N4, resonant inductors Lr1 and Lr2, and resonant inductors Cr1 and Cr2, which are connected to the capacitor C7. The chain voltage Vlink between the ends is connected to the battery 4b connected between the both ends of the capacitor C8.

The switching circuits 8b and 9b are constructed such that the inductor L4 is omitted from the switching circuits 8a and 9a of the second embodiment, and the resonant inductor Lr1 and the resonant capacitor Cr1 are inserted in series with the winding N3, and inserted in series with the winding N4. The resonant inductor Lr2 is different from the resonant capacitor Cr2.

Thus, the bidirectional DC-DC converter 3b of the present embodiment becomes a resonant converter, compared to the bidirectional DC-DC converter of the second embodiment. 3a, charging and discharging can be performed efficiently even when the voltage of the battery 4b is high.

Even in the present embodiment, the effects of the present invention can be obtained in the same manner as in the embodiment.

1‧‧‧Power supply unit

2‧‧‧Inverter

3‧‧‧Bidirectional DC-DC converter

4‧‧‧Battery

5‧‧‧ Relay

6‧‧‧AC power supply

7‧‧‧load

100‧‧‧No power outage system

Claims (12)

A power supply device comprising: an inverter, wherein an AC terminal is connected to an AC power source, and a DC voltage is connected between the DC terminals; and a bidirectional DC-DC converter is connected between the chain voltage and the battery And charging and discharging the battery; and the chain voltage when discharging the battery is lower than a voltage appearing between the DC terminals when the maximum voltage of the AC power source is passively rectified by the inverter. The power supply device according to claim 1, further comprising: a relay inserted between the alternating current power source and the inverter; and a commercial power supply mode connected to the alternating current terminal of the inverter Connecting the load to turn on the relay, supplying power to the load from the AC power source, and charging the battery; and in the battery power supply mode, turning off the relay to discharge the battery from the battery pair The aforementioned load performs power supply. The power supply device according to claim 1 or 2, wherein the bidirectional DC-DC converter has an insulation type that electrically insulates the chain voltage from the function of the battery. The power supply device according to claim 1 or 2, wherein the chain voltage when the battery is charged is larger than when the maximum voltage of the alternating current power source is passively rectified by the inverter. The voltage is still high. The power supply device according to the first or second aspect of the invention, wherein the chain voltage when discharging the battery is passively rectified by the inverter when a nominal voltage of the alternating current power source is reversed. The voltage that appears is also high. The power supply device according to the first or second aspect of the invention, wherein the inverter includes: a first switch leg portion, the first switch device and the second switch device are connected in series; and the second switch leg portion a third switching element and a fourth switching element are connected in series and connected in parallel to the first switching leg; the first capacitor leg is connected in series with the first capacitor and the second capacitor, and is connected in parallel to the first switch a second capacitor leg portion, wherein the third capacitor and the fourth capacitor are connected in series, and a connection point between the third capacitor and the fourth capacitor is connected to a connection point between the first capacitor and the second capacitor; The first inductor is connected between a connection point between the first switching element and the second switching element and an end of the second capacitor leg; and The second inductor is connected between a connection point between the third switching element and the fourth switching element and another end of the second capacitor leg; and the first capacitor or the second capacitor or the first capacitor The leg portion is connected in parallel with the link voltage, and between the both ends of the third capacitor and/or between the two ends of the fourth capacitor is defined as an alternating current terminal of the inverter. The power supply device according to claim 6, wherein the inverter includes a third switch leg portion that is connected in series to the fifth switching element and the sixth switching element, and is connected in parallel to the first switch pin. And a third inductor connected between a connection point between the fifth switching element and the sixth switching element and a connection point between the first capacitor and the second capacitor. The power supply device according to claim 1 or 2, wherein the bidirectional DC-DC converter includes a first switching circuit that connects the link voltage between DC terminals and is connected between AC terminals. The primary switching circuit is a second switching circuit that connects the battery between the DC terminals and connects the secondary winding between the AC terminals; and the transformer magnetically couples the primary coil and the secondary coil. A power supply device as recited in claim 8 wherein The bidirectional DC-DC converter includes a resonant capacitor and a resonant inductor, and is connected in series to the primary coil and/or the secondary coil. The power supply device according to claim 8, wherein the bidirectional DC-DC converter includes a smoothing inductor between a DC terminal of the second switching circuit and the battery. The power supply device according to the first or second aspect of the invention, wherein the maximum voltage of the alternating current power source is 1.1 times the nominal voltage of the alternating current power source. An uninterruptible power supply system characterized by comprising the power supply device according to any one of the items 1 to 11 and the battery.