JP2996199B2 - Switching power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching power supply capable of charging first and second capacitors connected in series with each other based on an AC power supply.

[0002]

2. Description of the Related Art The apparatus shown in FIGS. 1 and 2 is known as an uninterruptible power supply for a computer, medical equipment, information communication equipment and the like. FIG.
In the device shown in FIG. 1, the first and second capacitors C1
, C2 and the series circuit of the first and second inverter switches Q1, Q2 are connected in parallel, and the interconnection point of the first and second capacitors C1, C2 is connected to the first and second inverters. An AC load 1 is connected to the interconnection point of the switches Q1 and Q2 via a filter LPF2 including a reactor (choke coil) Lf2 and a capacitor Cf2. First and second based on commercial AC power
In order to charge the capacitors C1 and C2 and the first and second storage batteries B1 and B2 connected in parallel with the capacitors C1 and C2 and supply power to the load 1, the circuit of FIG. Are provided with an input filter LPF1, a boost reactor L1 comprising a choke coil, first and second boost switches Sa and Sb, and first and second diodes Da and Db. The input filter LPF1 comprises a reactor Lf1 having a relatively small inductance value and a high-frequency capacitor Cf1 having a small capacitance.

In the apparatus shown in FIG. 1, during the positive half cycle of the voltage Vs of the AC power supply 2, the second boosting switch Sb is on / off controlled, and the first boosting switch Sa is kept off. It is. As a result, a current flows through the closed circuit of 2-Lf1-L1-Sb-C2 during the ON period of the second boosting switch Sb, and energy is accumulated in the boosting reactor L1. Thereafter, during the OFF period of the second boosting switch Sb, a current flows through the closed circuit of 2-Lf1-L1-Da-C1 and B1, and the capacitor is formed by the sum of the voltage of the power supply 2 and the voltage of the boosting reactor L1. C1 and storage battery B1 are boosted and charged.
During the negative half cycle of the voltage Vs of the power supply 2, the first boosting switch Sa is controlled to be turned on and off, and the second boosting switch Sb is kept off. During the ON period of the first boosting switch Sa, current flows through the closed circuit of 2-C1-Sa-L1-Lf1, and energy is accumulated in the reactor L1. Thereafter, during the off period of the first boosting switch Sa, a current flows through the closed circuit of L1-Lf1-2-C2 and B2-Db, and the capacitor is formed by the sum of the voltage Vs of the power supply 2 and the voltage of the reactor L1. C2 and storage battery B2 are boosted and charged. The first and second inverter switches Q1 and Q2 are alternately turned on and off, and current flows alternately through a closed circuit of C1-Q1-Lf2-1 and a closed circuit of C2-1-Lf2-Q2.

In the apparatus shown in FIG. 1, a series circuit of first and second boosting switches Sa and Sb is composed of a series circuit of first and second capacitors C1 and C2 and first and second storage batteries B1 and B2. When the semiconductor switches (transistors) as the first and second boosting switches Sa and Sb are simultaneously turned on due to a storage operation or the like, a short circuit is formed, A large current may flow. Since the storage batteries B1 and B2 are charged to the same voltage as the capacitors C1 and C2,
When the capacitors C1 and C2 are charged to a relatively high voltage, the storage batteries B1 and B2 must have a high withstand voltage, which increases the cost.

Another conventional device shown in FIG. 2 is one in which the storage battery B has a reduced withstand voltage. The storage battery B is a bidirectional chopper circuit 3 connected to a series circuit of first and second capacitors C1 and C2.
The configuration is the same as that of FIG. The bidirectional chopper circuit 3 includes two switches S
c, Sd, two diodes Dc, Dd and one reactor L2. The switch Sc is on / off controlled during the period when the voltage Vs is generated from the AC power supply 2, and the switch Sd is on / off controlled during the period when the AC power supply 2 is out of power.

When the switch Sc is turned on while the AC power supply voltage Vs is being generated, C2 -C1 -Sc-
L2-B closed circuit or 2-Lf1-L1-Da-Sc-L
A current flows in a closed circuit of 2-BC2, and the storage battery B is stepped down and charged. During the off period of the switch Sc thereafter, L2-
The energy of the reactor L2 is released in the closed circuit of B-Dd. When the AC power supply 2 fails, the switch Sd
Is controlled on / off. While the switch Sd is on, a current flows through the closed circuit of BL-Sb and the reactor L
2 stores energy. After that, during the OFF period of the switch Sd, a current flows through a closed circuit of B-L2-Dc-C1-C2, and the capacitors C1, C2 are charged with the sum of the voltage of the storage battery B and the voltage of the reactor L2. .

The conventional device of FIG. 2 has the advantage that the storage battery B can be used with a low withstand voltage because the storage battery B is stepped down and charged, but the number of switches is larger than that of the device of FIG. Therefore, there is a disadvantage that the cost increases. Also in the device of FIG. 2, there is a possibility that the switches Sa and Sb are turned on at the same time as in FIG. 1 and a short-circuit current flows.

Accordingly, a first object of the present application is to provide a switching power supply device that can prevent the formation of a short circuit by a switch. A second object of the present invention is to configure a circuit capable of lowering the withstand voltage of a storage battery with a small number of switches. A third object of the present invention is to provide a switching power supply device capable of easily and reliably achieving improvement in waveform and power factor.

[0009]

The present invention for achieving the first object is based on a reactor connected to one end of an AC power supply and a first, second, third and fourth diode. A wave rectifying bridge circuit, wherein an interconnection point of the first and second diodes is connected to an output terminal of the reactor, and an interconnection point of the third and fourth diodes is the A diode bridge circuit connected to the other end of the AC power source; an interconnection point between the first and third diodes of the diode bridge circuit; and a second and fourth diode.
A boost switch connected between the nodes
A series circuit of first and second capacitors; a fifth diode connected between an output terminal of the reactor and one end of the series circuit;
And a sixth diode connected between the first and second capacitors and the other end of the AC power supply. The present invention relates to a switching power supply device comprising: a connection unit; and a switch control circuit that controls on / off of the boosting switch at a cycle sufficiently shorter than a cycle of a voltage of the AC power supply. Further, in order to achieve the first and second objects, a storage battery may be connected as described in claim 2, and first and second power supply switches may be provided. Also,
It is desirable to provide a charging circuit for the storage battery as described in claims 3 and 4. Further, an inverter switch can be connected to the output side of the first and second capacitors. In order to achieve the first, second and third objects, it is desirable to form a switch control circuit as described in claim 6 and to provide an input filter as described in claim 7.

[0010]

According to the first aspect of the present invention, since only one boosting switch is provided, there is a problem that two switches are simultaneously turned on and a short circuit is formed as in the conventional device. Does not occur. Therefore, overcurrent of the boosting switch can be prevented. According to the invention of claim 2, an uninterruptible power supply can be provided along with the storage battery. According to the third aspect of the invention, it is possible to compensate for the voltage drop of the storage battery. According to the invention of claim 4, step-down charging of the storage battery can be achieved with a simple circuit. According to the invention of claim 5, an AC output voltage can be easily obtained.
According to the invention of claim 6, power factor improvement and waveform improvement can be favorably achieved. According to the seventh aspect of the present invention, it is possible to remove the high frequency component of the waveform of the input current.

[0011]

Next, an uninterruptible power supply comprising a switching power supply according to an embodiment of the present invention will be described with reference to FIGS. However, in FIG. 3, substantially the same parts as those in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof will be omitted. In the apparatus shown in FIG. 3, as in FIG. 1, first and second capacitors C1 and C2 are provided for supplying AC power to the load 1.
, C2 and the series circuit of the first and second inverter switches Q1, Q2 are connected in parallel, and the interconnection point 3 of the first and second capacitors C1, C2 is connected to the first and second A load 1 as an AC output circuit is connected between the inverter switch Q1 and the interconnection point of Q2 via an output high frequency filter LPF2. The input stage is provided with an AC power supply 2 and an input high-frequency filter LPF1. The input filter LPF1 is a low-pass filter that can pass the fundamental wave (50 Hz) of the power supply voltage Vs, and the output filter LPF2 is a low-pass filter that can pass the fundamental wave of the output voltage of the inverter.

A boosting reactor L1, a boosting switch S1 comprising transistors, and first to sixth diodes D1 to D6 are provided to constitute a boosting circuit. Further, a storage battery B and first and second power supply switching switches Swa and Swb are provided to constitute an uninterruptible power supply circuit. Also, a chopper switch S2 for forming a storage battery charging circuit, a reactor L2, diodes D7 and D8.
Is provided.

The first power switch Swa is connected in series to the output line of the input filter LPF1.
The second power switch SWb is connected to a line branched from the output line of the first power switch SWa. First and second power supply switches Swa, S
The line between the interconnection point of wb and one end of the first capacitor C1 is connected to the step-up reactor L1 and the fifth diode D5.
And are sequentially connected in series. One end of the storage battery B is the second
Reactor L for boosting through power supply switch Swb
1 and the other end of the storage battery B is connected to the first and second capacitors C1, C2 via a sixth diode D6.
Is connected to the other end of the series circuit. First, second, third
And a fourth diode D1, D2, D3, D4 are bridge-connected to form a full-wave rectifier circuit, and an interconnection point of the first and second diodes D1, D2 is a reactor L.
1 and the interconnection point of the third and fourth diodes D3 and D4 is connected to the other end (lower end) of the AC power supply 2. The boosting switch S1 is connected between the interconnection point of the first and third diodes D1 and D3 and the interconnection point of the second and fourth diodes D2 and D4. The other end (lower end) of the storage battery B is connected to the interconnection point of the first and third diodes D1 and D3, and the sixth diode D6 is connected to the first and second capacitors C1 and C2. The other end (lower end) of the series circuit and first and third diodes D
1 and D3.

In order to form a charging circuit for the storage battery B, a seventh diode D7 and a transistor for preventing backflow are connected between one end of a series circuit of the first and second capacitors C1 and C2 and one end of the storage battery B. The switch C2 for chopper and the reactor L2 for smoothing are sequentially connected. Further, an eighth diode D8 for commutation, that is, for smoothing is connected in parallel to the series circuit of the smoothing reactor L2 and the storage battery B.

In order to execute various controls, a current detector 5 for detecting a current flowing through the boosting reactor L1 is provided at an input stage of the boosting reactor L1. Also, an output filter LP for detecting the output voltage
Lines 6 and 7 are connected to the output terminal of F2. Lines 8 and 9 are connected to the upper end of the first capacitor C1 and the lower end of the second capacitor C2 for detecting the voltage of the series circuit of the first and second capacitors C1 and C2. Lines 10 and 11 are connected to the output terminal of the input filter LPF1 for detecting the AC input voltage. Lines 12 and 13 are connected to both ends of the storage battery B to detect the voltage of the storage battery B. Also,
Lines 14 and 15 are connected to control terminals of first and second power supply switching switches Swa and Swb, which are composed of controllable electronic switches or electromagnetic switches. The connection of the first and second inverter switches Q1, Q2, the boost switch S1, and the chopper switch S2 to the control terminal (base) is omitted.

FIG. 4 shows the switches Q1, Q2, S1,.
A control circuit for controlling S2, Swa, and Swb is shown. The output voltage detection circuit 16 is connected to the output terminal of the output filter LPF2 by lines 6 and 7, and detects the output voltage. The power supply voltage detecting circuit 17 is connected to the output terminal of the input filter LPF1 by lines 10 and 11, and detects an input sine wave voltage. The power failure detection circuit 18 is connected to the power supply voltage detection circuit 17 and detects a power failure of the power supply 2 based on the presence or absence or the level of the power supply voltage.
, A low-level (first level) output and a high-level (second level) voltage output during a power failure. The reference sine wave voltage generator 19 is connected to the power supply voltage detection circuit 17 and the power failure detection circuit 18, generates a reference sine wave voltage in synchronization with the power supply voltage in a normal state, and has a built-in sine wave generation means in a power failure. Generates sinusoidal voltage. The inverter control circuit 20 forms a signal for controlling the inverter switches Q1, Q2 of FIG. The inverter control circuit 20 is connected to the output voltage detection circuit 16 and the reference sine wave voltage generator 19, and forms control signals for the inverter switches Q1, Q2 by a known method. The output terminal of the inverter control circuit 20 is connected to the control terminal of the first inverter switch Q1 and the NOT circuit 21
To the control terminal of the second inverter switch Q2. First and second inverter switches Q1
Are shown in FIGS. 6F and 6G.

In FIG. 4, a DC voltage detection circuit 22 is connected to the voltage detection lines 8 and 9 of the capacitors C1 and C2, and performs DC voltage control on a signal indicating the sum of the voltages of the first and second capacitors C1 and C2. To the vessel 23. The DC voltage controller 23 forms an error signal between the DC voltage detection value and the reference value and sends it to the current controller 25. The current controller 25 forms a switch control pulse (PWM pulse) that causes the current detection waveform obtained from the current detection line 5a to follow the reference sine wave supplied from the line 26 in a normal state, and supplies the switch control pulse (PWM pulse) to the boost switch S1. send. In the event of a power failure, a switch control pulse (PWM pulse) is formed based on the gain K, that is, the DC voltage and the current detection signal provided from the coefficient generation circuit 27, and sent to the boosting switch S1.

The contact a of the control switch CS is connected to the power supply voltage detecting circuit 17 and the contact b is connected to the coefficient circuit 27.
, And the common output terminal is connected to the current controller 25. The control terminal of the control switching control switch CS is connected to the power failure detection circuit 18. Therefore, the contact a of the switch CS is turned on in a normal state, and the contact b is turned on in a power failure.

The output terminal of the power failure detection circuit 18 is connected to a first power supply changeover switch S via a NOT circuit 28 and a line 14.
The control terminal of the second power supply switch Swb is connected to the control terminal of the second power supply switch Swb via the line 15 without passing through the NOT circuit 28.

The charge controller 29 is connected to the power failure detection circuit 18 and is connected to the storage battery B of FIG.
Of the chopper switch S2 of FIG.
Connected to the base. The charge controller 29 controls the on / off operation of the step-down chopper switch S2 so as to charge the storage battery B to a constant voltage when the power supply is normal, and turns off the chopper switch S2 during a power failure. The storage battery B is a DC link capacitor C1 when the power supply is normal.
, C2.

FIG. 5 shows the DC voltage controller 23 and the current controller 25 of FIG. 4 in detail. The DC voltage controller 23 includes a reference voltage source 30 and an error amplifier 31.
One input terminal of the error amplifier 31 is a DC voltage detection circuit 2
2 and the other input terminal is connected to the reference voltage source 30, so that an error signal corresponding to the difference between the DC voltage Vdc and the reference voltage is obtained from the error amplifier 31.

The current controller 25 includes a multiplier 32, a current absolute value detection circuit 33, an error amplifier 34, a triangular wave generator 35, and a voltage comparator 36, and approximates a current flowing through the AC power supply 2 to a sine wave, and Capacitor C
1, a circuit for forming a control pulse for keeping the voltage Vdc of C2 constant. Therefore, the current controller 25 can be called a PWM pulse forming circuit. When the power supply is normal, one input terminal of the multiplier 32 is connected to the power supply voltage detection circuit 17 of FIG.
, And the other input terminal is connected to the voltage controller 23. Since the absolute value of the reference sine wave synchronized with the power supply voltage is obtained on the line 26 and a DC voltage is generated from the voltage controller 23, the multiplier 32 controls the voltage Vdc of the capacitors C1 and C2 at a constant voltage. Outputs the absolute value of the corrected sine wave. The output of the multiplier 32 is used as a current command value for controlling the current. The current absolute value detection circuit 33 is connected to the current detector 5 of FIG. 3 via the line 5a, and outputs an absolute value of the AC input current. One input terminal of the error amplifier 34 is connected to the current absolute value detection circuit 33 and the other input terminal is connected to the multiplier 32 for giving a current command value. An output corresponding to the difference from the absolute value (current command value) of the reference sine wave obtained is obtained. That is, an error signal for causing the input current to follow a sine wave and keeping the DC voltage Vdc constant is obtained from the error amplifier 34. The triangular wave generation circuit 35 operates at the frequency of the voltage of the power supply 2 (for example, 50H
A triangular wave voltage is generated at a frequency (for example, 20 kHz) sufficiently higher than z). One input terminal of the voltage comparator 36 is connected to the error amplifier 34 and the other input terminal is connected to the triangular wave generation circuit 35.
6 generates a comparison output between the triangular wave and the error signal. This comparison output is a PWM (pulse width modulation) pulse, and FIG.
Is used to turn on and off the switch S1. At the time of a power failure, a DC detection signal is input to the lines 5a and 26, and a PWM pulse is formed based on the DC detection signal.

Next, referring to FIGS. 6 to 15, FIGS.
The operation of the uninterruptible power supply shown in FIG. FIG. 6 is a waveform diagram showing the operation of each unit when the power supply is normal and during a power failure. FIG.
15 show current paths in each mode in the circuit of FIG. In FIGS. 7 to 15, substantially operating circuits are indicated by solid lines, and substantially inactive circuits are indicated by broken lines. Note that, in the following description, the current paths are indicated only by reference numerals.

In FIG. 6, a section from t0 to t2 indicates a normal time of the power supply 2, and a section from t2 to t3 indicates a power outage. In a normal state, the output of the power failure detection circuit 18 is at a low level, the contact a of the switch CS is turned on, and the first power switch Swa
Turns on. Further, at the time of a power failure, the output of the power failure detection circuit 18 becomes high level, the contact b of the switch CS is turned on, and the second power switch Swb is turned on.

[0025]

[Normal Operation Mode] The normal operation mode has a first mode shown in FIG. 7, a second mode shown in FIG. 8, a third mode shown in FIG. 9, and a fourth mode shown in FIG. In the normal first mode, as shown in FIG.
1 is turned on, and 2-Lf1-Swa-L1-D2-S1-
A current flows through the closed circuit of D3, and energy is accumulated in the boosting reactor L1. In the normal second mode,
Since the switch S1 is turned off, 2-Lf1-
A closed circuit of Swa-L1 -D5 -C1 is formed, and the first power supply 2 and the discharge of the energy stored in the reactor L1 cause the first circuit.
Of the capacitor C1 is boosted and charged. The normal third and fourth modes occur during the negative half cycle of the power supply voltage Vs shown at t1 to t2 in FIG. When the switch S1 is turned on in the normal mode in the third mode, the 2-D switch is turned on as shown in FIG.
A closed circuit of 4-S1-D1-L1-Swa-Lf1 is formed, and energy is stored in the boosting reactor L1 in a direction opposite to the first mode. In the normal mode, the switch S1 is turned off in the fourth mode, and as shown in FIG.
A closed circuit of D6 -D1 -L1 -Swa-Lf1 is formed, and the discharging current of the power supply 2 and the boosting reactor L1 causes the charging current of the second capacitor C2 to flow, whereby the second capacitor C2 is boosted and charged. . Since the boosting switch S1 is controlled by the PWM pulse generated by the current controller 25, the current of the power supply 2 becomes a sine wave substantially in phase with the power supply voltage Vs, and the power factor becomes almost 1. In addition, the first and second
The voltage Vdc of the capacitors C1 and C2 is controlled to be substantially constant.

[0026]

[Power failure mode] When a power failure is detected by the power failure detection circuit 18, the first power switch Swa is turned off and the second power switch Swb is turned on, as shown in FIGS. 6B and 6C. . Further, the contact b of the switch CS in FIG. 4 is turned on. Therefore, the storage battery B is connected to the first and second batteries via the booster circuit.
Connected to the capacitors C1 and C2 of the
5, a constant coefficient (constant voltage value) K of the coefficient circuit 27 is input through the contact b of the switch CS. Therefore, the output of the multiplier 32 and the output of the current absolute value detection circuit 33 in FIG. 5 become flat voltage signals.

At the time of a power failure, there are a first mode in which the switch S1 is turned on and a second mode in which the switch S1 is turned off, as is apparent from the section from t2 to t3 in FIG. Since the switch S1 is turned on in the first mode at the time of the power failure, a closed circuit of B-Swb-L1-D2-S1 is formed as shown in FIG. 11, and energy is accumulated in the boosting reactor L1. In the second mode at the time of the power failure following the first mode at the time of the power failure, the switch S1 is turned off, so that a closed circuit of B-Swb-L1-D5-C1-C2-D6 is formed as shown in FIG. The first and second capacitors C1 and C2 are charged based on the release of energy from B and the boosting reactor L1, and this voltage rises. Since the on / off operation of the step-up switch S1 at the time of the power failure is not related to the improvement of the power factor, a PWM pulse in which pulses of substantially equal width are arranged as shown in the section from t2 to t3 in FIG.

As described above, even during a power failure, the storage battery B
Is boosted using the reactor L1 and a constant DC voltage Vdc is obtained, so that the first and second inverter switches Q1, Q2 are switched on the basis of the first and second capacitors C1, C2 in the same manner as in the normal state. And the power supply to the load 1 can be continued.
The voltage of the backup storage battery B is boosted by also using the booster circuit in the normal state, and the first and second capacitors C1 and C2 are boosted.
Supplied to Therefore, a relatively high DC voltage Vdc can be easily obtained by using a relatively low-cost storage battery B having a low withstand voltage. The on / off of the first and second inverter switches Q1, Q2 constituting the half-bridge inverter circuit is determined by a well-known PWM as shown in FIGS.
Performed by pulse.

[0029]

[Charging Mode] The charging circuit for keeping the voltage of the backup storage battery B constant when the power supply is normal is performed by turning on / off the step-down chopper switch S2. In response to the power failure detection circuit 18 not detecting a power failure, the charge controller 29 of FIG. 4 generates a control signal for controlling the storage battery voltage Vb detected on the lines 12 and 13 to a constant value. Thus, the on / off control of the chopper switch S2 is performed as shown in FIG. The charge controller 29 can be configured by a known technique, for example, an error amplifier to which a storage battery voltage and a reference voltage are input, a triangular wave generating circuit, and a triangular wave of the triangular wave generating circuit and an output of the error amplifier. And the PWM pulse obtained from the comparator is sent to the control terminal of the chopper switch S2.

The storage battery B is charged in the first, second and third modes. In the first mode during charging, the chopper switch S2 is turned on as shown in FIG.
A closed circuit of 7-S2-L2-BD3 is formed, and the storage battery B is stepped down and charged via the reactor L2. The second mode during charging occurs during the period of the negative half-wave of the AC voltage Vs as shown in FIG. In the second mode, C1 -D7
A closed circuit of -S2-L2-B-D1-L1-Swa-Lf1-2 is formed, and the storage battery B is charged down. In the third mode at the time of charging, as shown in FIG.
2 occurs during the off period. At this time, the energy stored in reactor L2 in the first or second mode during charging is L
2-B-D8 is discharged in a closed circuit, and the storage battery B
Charging current flows.

As described above, this embodiment has the following effects. (B) The boost switch S1 is set to the first
And used for boosting charging of the first and second capacitors C1 and C2 by the storage battery B in the event of a power outage, and used for boosting the power of the first and second capacitors C1 and C2 during a power outage. This enables normal operation, power failure operation, and power factor improvement. (B) Since the storage battery B is step-down charged, the storage battery B can be a low-cost low-voltage storage battery. (C) Since there is no equivalent to the first and second switches Sa and Sb connected in series in the conventional circuit shown in FIGS. 1 and 2, both are turned on at the same time to form a short circuit. Problem does not occur. Therefore, the reliability is improved.

[0032]

[Modifications] The present invention is not limited to the above-described embodiment, and for example, the following modifications are possible. (1) The switches S1, S2, Q1, and Q2 can be semiconductor switches such as field effect transistors (FETs). (2) The switches Swa, Swb, and CS can be replaced with electronic switches such as semiconductor switches. (3) Part or all of the circuits shown in FIGS. 4 and 5 can be replaced with digital circuits. When the circuits shown in FIGS. 4 and 5 are constituted by digital circuits, a DSP (Digital Signal Processor) or a microcomputer or a microprocessor is used.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a conventional uninterruptible power supply.

FIG. 2 is a circuit diagram showing another conventional uninterruptible power supply.

FIG. 3 is a circuit diagram illustrating an uninterruptible power supply according to an embodiment of the present invention, omitting a control circuit unit.

FIG. 4 is a block diagram illustrating a control circuit unit of the uninterruptible power supply of FIG. 3;

FIG. 5 is a circuit diagram showing a part of FIG. 4 in detail.

FIG. 6 is a waveform diagram showing a power supply voltage of FIG. 3 and states of respective switches.

FIG. 7 is a circuit diagram illustrating a normal mode first mode of the circuit of FIG. 3;

8 is a circuit diagram showing a normal mode of the circuit of FIG. 3 in a second mode.

FIG. 9 is a circuit diagram showing a third mode in a normal state of the circuit of FIG. 3;

FIG. 10 is a circuit diagram showing a fourth mode in a normal state of the circuit of FIG. 3;

11 is a circuit diagram showing a first mode at the time of a power failure of the circuit of FIG. 3;

FIG. 12 is a circuit diagram showing a second mode at the time of a power failure of the circuit of FIG. 3;

FIG. 13 is a circuit diagram showing a first mode during charging of the circuit of FIG. 3;

FIG. 14 is a circuit diagram showing a second mode at the time of charging of the circuit of FIG. 3;

FIG. 15 is a circuit diagram showing a third mode at the time of charging of the circuit of FIG. 3;

[Explanation of symbols]

 S1 Boosting switch C1, C2 First and second capacitors L1 Boosting reactor B Storage battery

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H02M 3/155 H02J 9/06 504 H02M 7/217 H02M 7/5387

Claims (7)

(57) [Claims] 1. A full-wave rectification type bridge circuit comprising a reactor connected to one end of an AC power supply and first, second, third and fourth diodes, wherein the first and second diodes are connected to each other. An interconnect point of the negative electrode is connected to an output terminal of the reactor;
A diode bridge circuit having an interconnection point of the third and fourth diodes connected to the other end of the AC power supply; and interconnection of the first and third diodes of the diode bridge circuit. A step-up switch connected between a point and an interconnection point of the second and fourth diodes; a series circuit of first and second capacitors; an output terminal of the reactor and the series circuit And a sixth diode connected between the other end of the series circuit and the interconnection point of the first and third diodes. Means for electrically connecting an interconnection point between the first and second capacitors and the other end of the AC power supply; and the step-up switch at a cycle sufficiently shorter than the cycle of the voltage of the AC power supply. And a switch control circuit for controlling on / off of the Switching power supply. 2. A first power supply switch connected between one end of the AC power supply and an input terminal of the reactor, and a first power supply switch between the first power supply switch and the reactor. A second power supply switch connected at one end thereof; a storage battery connected between the other end of the second power supply switch and an interconnection point of the first and third diodes; When a voltage is normally generated from the power supply, the first power supply switch is controlled to be turned on and the second power supply switch is controlled to be turned off. When the AC power supply fails, the first power supply switch is turned off. 2. The switching power supply device according to claim 1, further comprising a power supply switching control circuit that controls a switching switch to be off and controls the second power supply switching switch to be on. 3. The switching power supply device according to claim 2, further comprising a charging circuit that charges the storage battery with a voltage of one or both of the first and second capacitors. 4. The charging circuit includes: a chopper switch connected to one end of a series circuit of the first and second capacitors; and a chopper switch and a second power supply switching switch side of the storage battery. 4. A step-down charging circuit comprising a smoothing reactor connected between terminals and a smoothing diode connected in parallel to a series circuit of the smoothing reactor and the storage battery. A switching power supply as described. 5. A series circuit of first and second inverter switches connected in parallel to the series circuit of the first and second capacitors, and a series circuit of the first and second capacitors. Connection point and the first
5. The switching power supply device according to claim 1, further comprising: an AC output circuit connected between the power supply device and an interconnection point of the second inverter switch. 6. 6. A series connection of the first and second capacitors, wherein the switch control circuit detects a current flowing through the reactor, a power supply voltage detection circuit for detecting a voltage of the AC power supply, Output voltage detecting means for detecting a voltage of the circuit or a voltage on the output side of the series connection circuit having a value corresponding to this voltage; a reference waveform voltage obtained from the power supply voltage detecting circuit; Multiplying means for multiplying the obtained voltage, an error signal forming means for obtaining an output corresponding to a difference between a current detection signal obtained from the current detecting means and a signal obtained from the multiplying means, A triangular wave generating means for generating a triangular wave voltage with a cycle sufficiently shorter than a cycle of the voltage of the power supply; and comparing the output of the error signal forming means with the triangular wave voltage to form a PWM pulse. Claim 1 is characterized in that it comprises a comparison means for supplying to said boost switch
Or the switching power supply device according to 2 or 3 or 4 or 5. 7. An apparatus according to claim 1, further comprising an input filter connected to said AC power supply.
Or the switching power supply according to 4 or 5 or 6.