JPH0564451A - Power source apparatus - Google Patents

Abstract

PURPOSE:To improve the power factor of power by providing the power input part of a load device with it additionally without changing the power source itself of the load device consisting of electronic equipment constituted for commercial power source. CONSTITUTION:Input terminals T1 and T2 are connected with rectifying circuits 1, and these rectifying circuits are connected with an active filter 2, which makes input current waves into sine waves by switching input AC voltage several times per half a cycle so as to take out power. For the active filter 2, the output is supplied to a PWM inverter 3 as power source power, and the PWM inverter 3 is driven by the AC input at input ends T1 and T2. The waveform of the output of the PWM inverter 3 is faired by a filter 4, and the output is output from the output terminals T3 and T4. Since the power factor can be improved as an AC-AC inverter, the power factor can be improved by inserting it between the AC plug socket of a commercial power source and the electronic equipment being a load device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device used as a power supply for an electronic device operated by a commercial power supply,
In particular, it relates to a power supply device capable of improving the power factor.

[0002]

2. Description of the Related Art Many conventional power factor improving techniques in power supply devices improve the power factor as an AC-DC converter. Such an AC-DC converter that improves the power factor includes, for example, a switching power supply with a power factor improving rectifier circuit called an active filter, and Japanese Patent Laid-Open No. 57-156678 (inventor and applicant). Is the same as the present invention) and there is an AC-DC converter which simultaneously performs power factor improvement and isolation.

The active filter is constructed as shown in FIG. That is, the alternating current (AC) power supply input is full-wave rectified by the rectifier circuit RF formed of a diode bridge, and the outputs appearing at both ends of the capacitor C1 connected between the output terminals of the rectifier circuit RF are connected via the coil L. The switching transistor Q switches a plurality of times for each half cycle of the AC input, and the output generated between the collector and the emitter of the switching transistor Q is rectified and smoothed by the diode D and the capacitor C2 and output as direct current (DC). The terminal voltage of the capacitor C2 is given to the PWM control circuit PC via the amplifier A, and the P
The final DC output is stabilized by controlling the switching of the switching transistor Q by the PWM (pulse width modulation) signal output from the WM control circuit PC.

In this case, the capacitor C1 in the latter stage of the rectifier circuit RF has a small capacity, and a step-up type switching circuit using the coil L and the switching transistor Q is used to plot the waveform of the AC input current as shown in FIG. As shown in 10, the power factor is improved by approaching the sine curve.

Since the output of such an active filter is not isolated, it is used when isolation is required. Therefore, an isolated type switching regulator is connected to the DC output of this active filter. It is a rate improvement type switching power supply. Further, Japanese Patent Application Laid-Open No. 57-156678 discloses an AC in which power factor correction, isolation and constant voltage can be performed at once.
A DC converter is shown. Each of the circuits described above obtains a DC output of a constant voltage from an AC input.

[0006]

In the above-mentioned conventional circuit, the power factor can be improved, but since the output is DC, the power supply section is designed to improve the power factor when designing the device. It needs to be a type of power supply. Therefore, if the power supply of the device currently in use, such as a personal computer, is not a power factor improving type, even if the user wants to improve the power factor, the user cannot apply the power factor improving technique described above and the user side Can't handle it. That is, office automation (O
A) For an electronic device such as a device having a poor power factor of the power source, the user cannot do anything even if he / she wants to improve the power factor of the power source of the device currently used.

The present invention has been made in view of the above-mentioned circumstances, and the power supply input section of the load device without changing the power supply itself of the load device composed of electronic equipment configured for commercial power supply. It is an object of the present invention to provide a power supply device that can be additionally provided to improve the power factor of the power supply.

[0008]

A power supply device according to the present invention is a power factor improving type in which an input current waveform has a sine wave shape by switching an input AC voltage a plurality of times in each half cycle to extract electric power. AC-DC converting means, and DC for re-converting the DC power output from the AC-DC converting means into an AC voltage approximate to the input AC voltage.
-AC conversion means is provided, and it is configured to be used by being inserted between a commercial power source and a load device for the commercial power source.

[0009]

In the power supply device of the present invention, the DC output of the power factor improving type AC-DC converting means is reconverted into the AC voltage by the DC-AC converting means, so that the power factor is changed as the AC-AC inverter. Can be improved, commercial power A
The power factor can be improved by inserting it between the C outlet and the electronic device which is the load device.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of a power supply device according to a first embodiment of the present invention. In FIG. 1, a rectifier circuit 1 is connected to the input terminals T1 and T2.
Is connected to the active filter 2. The DC output of the active filter 2 is supplied to the PWM inverter 3 as power source power, and the PWM inverter 3 receives the input terminal T
Driven by AC inputs at 1 and T2. PW
The output of the M inverter 3 is waveform-shaped by the filter 4 and output from the output terminals T3 and T4.

The rectifying circuit 1 is composed of bridge-connected diodes D1 to D4. The active filter 2 is constituted by capacitors C11 and C12, a coil L1, a switching transistor Q1, a diode D11, an amplifier A1 and a PWM control circuit PC1 in substantially the same manner as that shown in FIG. The capacitors C11, C12, the coil L1, the switching transistor Q1, the diode D11, the amplifier A1 and the PWM control circuit PC1 are the same as the capacitors C1 and C2 in FIG.
, Coil L, switching transistor Q, diode D, amplifier A, and PWM control circuit PC.

In the PWM inverter 3, the AC input from the input terminals T1 and T2 is given to the amplifier A2, and the output of this amplifier A2 is given to the PWM control circuit PC2. Bridged switching transistors Q11 to Q14 are connected between the output of the active filter 2, that is, between the terminals of the capacitor C12. The switching transistors Q11 to Q14 are on / off switched by the output of the PWM control circuit PC2, and the connection point between the emitter of the switching transistor Q11 and the collector of the switching transistor Q12 and the switching transistor Q13.
The output is obtained from the connection point between the emitter of the switch and the collector of the switching transistor Q14. The filter 4 is PWM
The coils L2 and L3 are respectively provided at the output terminals of the inverter 3.
A capacitor C13 is connected through the capacitor C13, and outputs from both ends of the capacitor C13 are led to output terminals T3 and T4.

Next, the operation of the power supply device configured as described above will be described. The rectifier circuit 1 and the active filter 2 convert the AC inputs of the input terminals T1 and T2 into DC. The PWM-converted voltage output from the active filter 2 is returned to AC by the PWM inverter 3. PWM inverter 3
The driving signal of A is input to the input terminals T1 and T2.
By using the C signal as it is, a voltage having the same frequency, voltage, and phase as the AC input is output as an AC output from the output terminals T3 and T4. As shown in the input voltage and current waveforms in FIG. 2 and in the input voltage and current waveforms in FIG. 3, if the AC input and output phases are the same, the peak of the output current becomes the peak of the input voltage, and the active filter 2
The power loss at is minimal.

In the power supply device according to this embodiment, an electronic device that operates using a commercial power supply is used as a load device, and is inserted between such a load device and the commercial power supply. Specifically, for example, as shown in FIG. 4, the power plug 6a of the power supply device 6 according to this embodiment is connected to the outlet 7 of the commercial power supply, and the output device 6b provided in the power supply device 6 is connected to the load device such as the personal computer 8. The power plug 8a is connected. That is, the AC input terminals T1 and T2 are connected to a commercial power source, and the AC output terminals T3 and T4 are connected to the power line of the load device.

As described above, since the power factor can be improved as the AC-AC inverter, it is possible to connect a device operating with a normal commercial power source to the load, and the A of the commercial power source can be connected.
Just insert it between the C outlet and the load later,
The power factor can be easily improved. Note that FIG.
In the configuration shown in, the AC power supply input is used as it is as the drive signal of the PWM inverter 3, but an oscillator for separately generating an AC signal having a sine curve equivalent to that of the AC power supply input is provided and the output thereof is used. The PWM inverter 3 may be driven.

FIG. 5 shows the configuration of a power supply unit according to the second embodiment of the present invention. In the second embodiment, instead of the active filter in the first embodiment, an AC-type filter similar to that shown in Japanese Patent Laid-Open No. 57-156678 is used.
A DC converter is used and a high-efficiency amplifier circuit described later is used instead of the PWM inverter to improve the power factor and achieve isolation between the input and output.

In the power supply device shown in FIG. 5, instead of the rectifier circuit 1 and the active filter 2 shown in FIG. 1, an AC-unit capable of performing power factor correction, isolation and constant voltage at a time.
Using the DC converter 11, a DC-AC inverter 12 using a high-efficiency amplifier circuit that amplifies an AC input signal by using the AC-DC converter 11 as a power source instead of the PWM inverter 3 and the filter 4 in FIG. The small transformer 1 is provided in the supply path of the AC input signal to the DC-AC inverter 12 in order to perform isolation between them.
3 is inserted.

The AC-DC converter 11 is specifically constructed, for example, as shown in FIG. In FIG. 6, a primary coil L11 and two secondary coils L12 and L13 are wound around the core of the transformer 21 with the polarities shown in the figure.
The AC input is applied to the primary coil L11 by the line filter 22.
And the switch S11. The switch S11 switches the voltage of the AC input at a cycle shorter than its half cycle, that is, a plurality of times during each positive and negative half cycle of the AC input voltage. The switch S11 can be configured by a bidirectional element such as a triac. Switches S12 and S13 are connected to the secondary coils L12 and L13. The switches S12 and S13 are for rectifying the AC component generated on the secondary side by the switching on the primary side and are alternately turned on / off with the switch S11. Since these switches S12 and S13 are for allowing the current to flow only in one direction, they can be composed of unidirectional elements having sufficient reverse withstand voltage, such as transistors and diodes. Two secondary coils, L12 and L13, are provided in order to rectify the AC input voltage itself by switching the coil to be used according to the polarity of the AC input voltage. The induced voltage of the secondary coils L12 and L13 is smoothed by the capacitor 23 and becomes a load DC-
It is supplied to the AC inverter 12. The line filter 22 inserted in the primary side is for preventing the switching ripple current from flowing into the power source side.

In the configuration of FIG. 6, when the switch S11 is turned on and the primary current of the transformer 21 reaches a predetermined value, the switch S11 is turned off, and at the same time, the switch S12 or S13.
Power is transmitted by turning on the power for a certain period of time. Since the switch S11 is turned off when the primary current reaches a predetermined value, the peak value of the primary current can be limited to an appropriate value. The current detector 24 detects the primary current for this control.

The switching control circuit 25 controls the switching of the switches S11, S12 and S13 based on the current detected by the current detector 24 described above. Comparator 26 is DC
By comparing the output voltage with the voltage of the reference power supply 27 and controlling the on time of the switch S11, the DC output voltage is controlled to be always constant. That is, when the DC output voltage becomes low, the ON time is extended so that a large amount of electric power is transmitted to the secondary side, and when the DC output voltage becomes high, the ON time is narrowed and the electric power is transmitted to the secondary side. Limit the power to be used.

The DC-AC inverter 12 is an AC-DC
This is a high-efficiency amplifier circuit that uses the converter 11 as a power source and amplifies an AC input signal provided through the small isolation transformer 13 and is configured as shown in FIG. 7, for example. In FIG. 7, only the portion corresponding to the positive half-wave is shown in detail, but the negative half-wave is also configured in substantially the same manner as the positive half-wave.

In FIG. 7, a high-efficiency current buffer circuit 32 capable of supplying current with high efficiency but having a slow response to a change in input signal is inserted in the main power supply path 31, and an auxiliary power supply path 33.
A high-speed voltage buffer circuit 34, which has a fast response to a change in the input signal but has a large loss, is inserted in and the currents I31 and I33 of both power supply paths 31 and 33 are added at an addition point 35,
Transistor Qa (Qa ') and resistor Ra (Ra')
Load current IRL to the load to which the AC output is supplied via
(= I31 + I33) is supplied. The current detection circuit 36 detects the magnitude of the auxiliary current I33, and accordingly the control circuit 37 is detected.
The high-efficiency current buffer circuit 32 is controlled via the to adjust the main current I31. The high-speed voltage buffer circuit 34 supplies the shortage (IRL-I31) in the main current I31 as the auxiliary current I33. The collector voltage of the output transistor Qa is AC
Since it is only slightly higher than the output voltage, the loss of the output transistor Qa is minimized. As for the load current IRL, the auxiliary current I33 first responds to the steep rise of the input, and the main current I31 gradually becomes dominant. Since the auxiliary current I33 rises at an extremely high speed, no loss occurs in the output waveform. The auxiliary current I33 is supplied only for a short time, and the energy is mainly supplied by the main current I31 from the main power supply path 31 with small loss, so that the efficiency is high as a whole. As a result, a power amplifier circuit with high efficiency and good slew rate is realized. As described above, this circuit operates using the DC output of the AC-DC converter 11 as a power source.

By doing so, an AC-AC converter with improved power factor and isolated input and output can be obtained.

[0024]

As described above, according to the present invention,
The DC output of the power factor improving AC-DC converting means is set to DC-A.
AC conversion is performed again by the C conversion means, and AC-
By improving the power factor as an AC inverter and inserting it between an AC outlet of a commercial power source and an electronic device that is a load device, the power source itself of the load device including the electronic device configured for the commercial power source is changed. It is possible to provide a power supply device that can be additionally provided in the power supply input part of the load device to improve the power factor of the power supply.

[Brief description of drawings]

FIG. 1 is a circuit configuration diagram showing a configuration of a power supply device according to a first embodiment of the present invention.

FIG. 2 is a waveform diagram of an input voltage / current for explaining the device of FIG.

FIG. 3 is a waveform diagram of an output voltage / current for explaining the device of FIG.

FIG. 4 is a perspective view for explaining an example of a usage state of the power supply device of FIG.

FIG. 5 is a block diagram showing a configuration of a power supply device according to a second embodiment of the present invention.

6 is a circuit configuration diagram showing in detail a part of the configuration of the embodiment of FIG.

FIG. 7 is a block diagram showing in detail another part of the configuration of the embodiment of FIG.

FIG. 8 is a circuit configuration diagram showing an example of a configuration of an active filter.

9 is a waveform diagram of an input voltage / current for explaining the device of FIG.

10 is a waveform diagram of input voltage and current for explaining the device of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rectifier circuit, 2 ... Active filter, 3 ... PWM inverter, 4 ... Filter, 6 ... Power supply device, 7 ... Outlet, 8 ... Personal computer, 11 ... AC-DC converter, 12 ... DC-AC inverter, 13, 21 …
Transformer, 22 ... Line filter, 23, C11 to C13 ...
Capacitor, 24 ... Current detector, 25 ... Switching control circuit, 26 ... Comparator, 27 ... Reference power supply, 31 ...
Main power supply path, 32 ... High-efficiency current buffer, 33 ... Auxiliary power supply path, 34 ... High-speed voltage buffer, 35 ... Addition point, 36 ... Current detection circuit, 37 ... Control circuit, A1, A2 ... Amplifier, D
1 to D4, D11 ... Diodes, L1 to L3, L11 to L13
... Coil, PC1, PC2 ... PWM control circuit, Q1, Q
11 to Q14, Qa, Qa '... Transistor, Ra, Ra'
...... Resistance, S11 to S13… Switch.

Claims (1)

[Claims] 1. A power factor improving AC-D in which an input current waveform has a sine wave shape by switching an input AC voltage a plurality of times in each half cycle to extract electric power.
C-converting means and DC-A for re-converting the DC power output from the AC-DC converting means into an AC voltage that is similar to the input AC voltage.
A power supply device comprising a C conversion means and configured to be inserted and used between a commercial power supply and a load device for the commercial power supply.