JPH08152928A - Voltage regulator - Google Patents

Abstract

PURPOSE: To improve the dimension, weight, conversion efficiency, waveform distortion and responsiveness or the like of a voltage regulator by suppressing a transient phenomenon such as an overvoltage or an overcurrent to be generated inside a circuit at the time of switching operation of the regulator to the minimum. CONSTITUTION: One terminal of a switch 4-2 is connected to one terminal on the input side of the regulator 4. The other terminal of the switch 4-2 is connected to one terminal of a switch 4-3. The outer terminal of the switch 4-2 is connected to the other terminal on the input side of the regulator 4. Both the terminals serially connecting a switch 4-1 and an impedance element 4-5 are connected to both the terminals of the switch 4-2. Both the terminals serially connecting a switch 4-1 and an impedance element 4-6 are connected to both the terminals of the switch 4-3. Pulse width modulated signals d1, d2, d3 and d4 of an output circuit 8-1 at a control part 8 are respectively connected to the switches 4-1, 4-2, 4-4 and 4-4 of the adjuster 4. The setting signal of an output setter 9 is connected to the input side of a PWM circuit part 8-2. A load 7 is connected between output terminals 6-1 and 6-2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is capable of adjusting the voltage supplied from a commercial power source or other AC power source to a load such as AC electrical equipment to an arbitrarily set voltage value.
The present invention relates to a compact, lightweight, highly accurate, low cost voltage regulator.

[0002]

2. Description of the Related Art A conventional CVT type, sliding type, magnetic amplifier type, thyristor phase control type or inverter type voltage regulator is large in size and weight, resulting in high manufacturing cost, waveform distortion and response. The sex is not good either.
Further, self-heating due to poor conversion efficiency is also a problem.

[0003]

It is generally said that it is very difficult to switch an electric circuit during a load (while a load current is flowing). This is because the switching causes high voltage, short circuit current, inrush current, electromagnetic noise, and momentary interruption of electricity, resulting in electrical breakdown of the circuit element or shortening of the service life of each circuit element. This is because the amount of heat generated increases and electromagnetic interference is given to the surroundings. Therefore, in the present invention, the circuit configuration of the regulator and the switching method are improved in order to suppress transient phenomena such as overvoltage and overcurrent that occur in the circuit during the switching operation of the regulator, and the conventional voltage regulator The purpose of the present invention is to significantly improve the problems of size, weight, conversion efficiency, manufacturing cost increase, waveform distortion, response, etc., which are disadvantages, and bring economic effects in various fields.

[0004]

To achieve the above object, in the voltage regulator of the present invention, the input side of the pre-stage filter is connected between the AC power supply input terminals. In order to cut off the AC power supply by a control signal or connect with an impedance element, or to short the output of the regulator through the impedance element or the impedance element, a plurality of bidirectional AC switching elements of the regulator consisting of a circuit connected in series and parallel Connect the output side of the pre-filter to the input side. The output side of the regulator is connected to the input side of the post filter. Connect the output side of the post-stage filter between the output terminals. To arbitrarily adjust the output of the regulator,
The pulse width modulation signal output by the control unit is connected to each bidirectional AC switch element that constitutes the adjuster.
The setting signal of the output voltage setting device is connected to the input side of the PWM circuit unit. A load is connected to the output terminal.

[0005]

The operation of the voltage regulator of the present invention having the above construction will be described below. Load voltage applied to the load (hereinafter EL
Will be given by the output of the regulator connected through the output terminal and the post-filter. The PWM control signal of the control unit is equivalent to an input voltage (hereinafter abbreviated as Es) applied to the AC power input terminal by switching each bidirectional AC switch element of the regulator at a constant ratio. The sine wave output voltage can be output to the output terminal through the post-stage filter. When the load voltage EL applied to the load is set to a high value, the switching operation of the regulator by the PWM control signal is set so that the ON time of the switch is lengthened and the OFF time is shortened, the output of the regulator becomes large. As a result, EL also becomes larger. When the load voltage EL applied to the load is set to a low value, if the switching operation of the regulator by the PWM control signal is made to lengthen the switch on time and shorten the off time, the output of the regulator becomes large. As a result, EL becomes smaller.

[0006]

Embodiments of the present invention will now be described in detail with reference to the drawings.

(Embodiment) The voltage regulator of this embodiment is an embodiment of the present invention, and as shown in FIG. 1, the input side of the pre-filter 3 is connected to the AC power supply input terminal 2. The output side of the pre-stage filter 3 is connected to the input side of the regulator 4. Adjuster 4
Is connected to the input side of the post-stage filter 5. The output side of the post-stage filter 5 is connected to the output terminal 6. One end of a bidirectional AC switch element (hereinafter abbreviated as a switch) 4-2 is connected to one end on the input side of the adjuster 4. Switch 4
-2 is connected to the other end of the switch 4-3. The other end of the switch 4-3 is connected to the other input end of the regulator 4.
Both ends of the switch 4-1 and the impedance element 4-5 connected in series are connected to both ends of the switch 4-2. Both ends of the switch 4-4 and the impedance element 4-6 connected in series are connected to both ends of the switch 4-3. In order to arbitrarily adjust the output of the adjuster 4, the pulse width modulation signals d1, d2, d3, d4 output by the output circuit 8-1 of the control unit 8 are switched to the switches 4-1, 4-2, 4 of the adjuster 4. -3 and 4-4, respectively. The setting signal of the output setter 9 is connected to the input side of the PWM circuit section 8-2. A load 7 is connected between the output terminals 6-1 and 6-2 to supply power source power to the load.

Next, the operation of the above embodiment will be described.
The input voltage Es as shown in FIG. 2A is input from the input terminal 2 to the front filter 3, the regulator 4, the rear filter 5, and the output terminal 6.
Is applied to the load 7 as a load voltage EL. The output of the adjuster 4 has a distorted waveform as shown in FIG. 2B due to the switching operation, is smoothed to the original sine wave by the post-stage filter 5, and is output to the output terminal 6. As a measure for suppressing abrupt changes (transient phenomenon) in the voltage and current generated inside the switch circuit and the load due to the switching operation during energization, the PWM control signals d1 and d of the control unit 8 are used.
2, d3, d4 are switches 4-1 of the regulator 4,
4-2, 4-3, and 4-4 are driven at the timing of FIG. As shown in FIG. 2C, during the period of Ton, the switches 4-1 and 4-2 are turned on and the switches 4-3 and 4-4 are turned off, during which Es passes through the switches 4-1 and 4-2 and is sent to the latter stage. It is output to the output terminal 6 via the filter 5. Further, in the period of Toff, the ON operation and the OFF operation of the switches 4-1 and 4-2 and the switches 4-3 and 4-4 are inverted to each other, the switches 4-1 and 4-2 are turned off, and the switch 4 is turned off.
-3 and 4-4 are turned on, and Es is switched to 4-
The input side of the post-stage filter 5 is short-circuited by the switch 4-3 or short-circuited by the switch 4-4 through the impedance element 4-6. In the next Ton period, the switches 4-1 and 4-2 and the switches 4-3 and 4 again.
-4 are inverted from each other and the switching operation is repeated in the same manner. In this way, the input side of the post-stage filter 5 is shown in FIG.
A voltage Eout having a waveform obtained by PWM-switching Es as shown in (b) is applied, and the voltage smoothed by the post-stage filter 5 is applied to the load. In each period of Ton and Toff, the switching operation is performed in a two-step system in order to suppress a transient phenomenon at the time of switching. Period Ton
Then, after the switch 4-1 is turned on, the switch 4-2 is turned on with a certain time delay, and when the switch 4-2 is turned off, the switch 4-1 is turned off with a certain time delay after the switch 4-2 is turned off. Switch 4-
2 is an impedance element 4 for suppressing overvoltage or overcurrent
-5 are connected in series, and the switching operation of the switch 4-2 is performed while the switch 4-1 is in the ON state, thereby suppressing a sharp change in voltage and current during switching. Similarly, in the period Toff, the switch 4-4 is turned on with a certain time delay after the switch 4-3 is turned on, and when the switch 4-4 is turned on, the switch 4-4 is turned off with a certain time delay after the switch 4-4 is turned off.
3 turns off. An impedance element 4-6 that suppresses an overvoltage or an overcurrent is connected in series to the switch 4-3 as well, and the switching operation of the switch 4-4 is performed while the switch 4-3 is in the ON state to perform switching. Suppresses sharp changes in voltage and current. The two-step method of the switching operation described above requires three steps, four steps,
It can also be increased in 5 steps, -----. As the number of stages increases, the effect of suppressing transient phenomena such as overvoltage and overcurrent that occur during switching increases. As a result, harmonic current and switching noise are reduced. A one-stage system can also be used. At this time, the switch 4-1, the impedance element 4-5 and the switch 4-3, and the impedance element 4-6 are removed from the adjuster 4, and only the switch 4-2 and the switch 4-4 are used. Switching operation will be performed.
In this case, when the switches 4-2 and 4-4 are reversed from each other, it is possible to delay the turn-on of the switches for a while so that the switches are simultaneously turned on and the power source is not short-circuited. The pre-stage filter 3 suppresses the influence of switching noise and harmonic current generated during the switching operation of the regulator 4 on the power supply line.

The load voltage EL applied to the load 7 after the waveform of the output of the regulator 4 is shaped by the post-filter 5 is Es as shown in FIG. 2, the switch-on time of the regulator 4 is Ton, and When the cycle is T, it can be expressed by the following equation. EL≈ (TON / T) × Es As can be seen from this expression, EL can be adjusted from zero to around Es by changing the ON time TON or T of the switch of the adjuster 4 by the PWM control signal. When the load voltage EL is set to a high value by the output voltage adjuster 9, if the ON time TON of the switch of the adjuster 4 is increased by the PWM control signal of the controller 8, E
L also becomes larger. When the load voltage EL is set to a low value by the output voltage regulator 9, the PWM of the control unit 3
ON time TON of the switch of the adjuster 4 according to the control signal
The smaller EL becomes, the smaller EL becomes. Power transistors, field effect transistors (MOSFETs), IGBTs, GTOs, SITs are used as bidirectional AC switching elements.
It is possible to use a circuit incorporated by a power device such as. Impedance elements 4-5 and 4-6 can be choke coils, resistors or capacitors, or combinations thereof. It is also possible to connect a snubber circuit or a surge absorbing element to the switch element or the circuit in order to suppress the surge voltage generated during the switching operation of the regulator 4. The output side of the post-stage filter 5 and the output terminal 6
Insert an isolation transformer or autotransformer between the load voltage E
It is also possible to adjust L to be equal to or higher than the input voltage Es.

[0010]

It is understood that the present invention having the above-mentioned operation has the following effects and, therefore, is extremely superior to other systems. (1) Since the switching operation is performed in a two-stage system, transient phenomena such as overvoltage and overcurrent that occur at the time of switching can be suppressed, the capacitance of the switching element and filter becomes relatively small, and the snubber circuit loss is also compared. Can be made smaller. As a result, harmonic currents and switching noise are reduced, and a compact, lightweight, and highly efficient voltage regulator that has never been obtained can be obtained. (2) A sinusoidal voltage with relatively little distortion can be applied to the load. (3) Two-stage switching operation and continuously variable PW
The output voltage can be freely adjusted from zero to an arbitrary voltage by M control.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a voltage regulator according to the present invention.

FIG. 2 is a waveform diagram of a voltage regulator according to the present invention.

[Explanation of symbols]

1 is AC power supply 2 is AC power supply input terminal 3, 5 is filter 3-1, 5-1 is choke coil 3-2, 5-2 is capacitor 4 is regulator 4-1, 4-2, 4-3 4-4 are bidirectional AC switching elements 4-5, 4-6 are impedance elements 6 are output terminals 7 are loads 8 are control sections 8-1 are output circuit sections 8-2 are PWM circuit sections 9 are outputs Voltage setting device

Claims (1)

[Claims] 1. An input side of a pre-stage filter is connected between AC power source input terminals, the AC power source is cut off by a control signal or connected by an impedance element, or the output of a regulator is short-circuited or shorted through an impedance element, The output side of the pre-stage filter is connected to the input side of the regulator consisting of a circuit in which a plurality of bidirectional AC switching elements are connected in series and parallel, and the output side of the regulator is connected to the input side of the post-stage filter. The output side of the filter is connected between the output terminals, and in order to arbitrarily adjust the output of the adjuster, the pulse width modulation signal output by the control unit is connected to each bidirectional AC switch element that constitutes the adjuster. The voltage regulator is characterized in that the setting signal of the output voltage setting device is connected to the input side of the PWM circuit section and the load is connected to the output terminal in order to supply power to the load. .