JP2001037229A - Ac voltage stabilizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make possible a continuous operation of a machine when an actuator of a motor, etc., is within an operable range even if there is an instantaneous large fluctuation in voltage supplied to the machine by controlling the supply voltage to a control circuit. SOLUTION: The supply voltage of a power supply equipment 1 is preliminarily stepped up by a transformer 2 by such a value which is estimated to drop from the nominal voltage or a value considered from an operable range of a motor, etc., generally 30% of the nominal voltage. The voltage between voltage checking terminals C and D is detected by a voltage detector 3, the output of the detector 3 is inputted into a comparator 4 to compare the voltage with the nominal voltage value set by a voltage setting unit 6, and then a deviation is inputted into a gate circuit 5. The gate circuit 5 controls the gate timing of a thyristor unit 7 so that the voltage between the terminals C and D may be the set voltage. As for the thyristor unit 7, such one which can make a two-way control is used. By this method of controlling, the voltage between the terminals C and D can be kept nearly at the nominal voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to stabilization of an AC voltage of an AC control circuit or the like.

[0002]

2. Description of the Related Art There are products in which a driving voltage adjustment period is combined with a servomotor and products using a magnetic amplifier. However, the size is large, and the accuracy is too high for a control circuit and the price is high. In addition, the range of the supply power supply voltage with respect to the voltage fluctuation range is narrow, and there is no device suitable for a machine control circuit.

[0003]

In a machine using an actuator such as a motor, the supply voltage is generally reduced by 10%.
In this case, the operation of the motor and the like can be continued, but the control circuit such as the sequencer does not function and the operation stops.

According to the present invention, the supply voltage to the control circuit is controlled to be constant, so long as the actuator such as a motor can operate even if the supply voltage to the machine temporarily fluctuates greatly. This is a device that enables the machine to operate continuously.

[0005]

Means for Solving the Problems and Functions Generally, the fluctuation of the supply voltage to the machine often becomes negative, but it is necessary to cope with the fluctuation. For the minus voltage, the expected voltage is added using a transformer, and for the added voltage and the plus voltage of the supply voltage, the AC output voltage is controlled using a semiconductor such as a thyristor or a switching transistor. Keep at nominal voltage.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, an embodiment of the present invention will be described based on an embodiment. As shown in FIG. 1, a voltage considered to be lower than the nominal voltage by the transformer 2 from the power supply device 1, or a voltage considered from an operable range of a motor or the like that requires a large amount of power, generally a nominal voltage. Outputs plus 30% corresponding to minus 30%.

When the voltage fluctuation of the power supply device 1 is plus 30% minus 30% from the nominal value, the voltage check terminals A and B
The voltage between them will be plus 60% minus 0% fluctuation range,
The output of the voltage detector 3 for detecting the voltage between the voltage check terminals C and D is input to the comparator 4 with respect to this voltage fluctuation width, and is compared with the voltage set to the nominal voltage value by the voltage setting device 6 to obtain the deviation. -
Input to the gate circuit 5, the gate circuit 5 is a thyristor unit
By controlling the gate timing of 7, the thyristor unit 7 is controlled so that the voltage between C and D becomes the set voltage. The thyristor unit 7 uses a device capable of bidirectional control.

By controlling in this way, the voltage between C and D is kept substantially at the nominal voltage. At this time, the control accuracy can be reduced by increasing the sensitivity, but it may be a level necessary for the operation of the machine, and generally may be about ± 5%.

FIG. 2 is a block diagram using a switching transistor. In the apparatus shown in FIG. 1, the waveform distortion rate is poor and is improved. The functions up to the comparator 4 are the same as those described above, and a description thereof will be omitted. The ON / OFF ratio controller 8 has an oscillator of several kilocycles. At this frequency, the ON / OFF signal is output to the switching transistor unit 9 by the signal from the comparator 4 to check the voltage.
Controls the voltage between C and D. The switching transistor unit 9 needs to be controlled in both plus and minus directions in order to control the AC voltage, and is configured by connecting two transistors called an IGBT in reverse.

The ON / OFF ratio control is 100/100 when the voltage between the voltage check terminals A and B is close to the nominal value, and 1/160 when the voltage is 60% higher than the nominal value.
Voltage control is performed so that the ON ratio becomes 00, that is, the nominal voltage corresponding to the voltage between A and B becomes the ON ratio. The control speed at this time is determined by the oscillation frequency of the oscillator, but the control speed of the entire control system depends on the time constant of the voltage detector 3 and the like. As a result, when the voltage between A and B is close to the nominal value, continuous O
As the voltage N becomes higher, the ON ratio is shortened to control the voltage between the voltage check terminals C and D, that is, the output voltage to a nominal value. Since the AC voltage is directly controlled at high speed in this manner, the waveform distortion rate is improved.

FIG. 3 shows a voltage waveform of one cycle when controlled in FIG. 1, and FIG. 4 shows an image diagram of a voltage waveform in one cycle when controlled in FIG. FIG. 5 shows the effective value of the voltage of each part in FIGS.

In FIGS. 1 and 2, the transformer 2 is described as having multiple windings, but may be a single winding transformer. In order to increase the response speed, feedback is taken from between the voltage check terminals A and B and between A and B. May be used for the minor loop of the control system. Although this device has been described as a single-phase circuit, in the case of three phases, three devices can be used for three phases.

[0013]

According to the present invention, the capacity of the transformer only needs to be equal to the sum of the voltages, and the device can be miniaturized as compared with a conventional driving voltage adjusting period or a magnetic amplifier type. Since it is simple in price, it is inexpensive and does not easily break down, and it responds quickly to large temporary voltage fluctuations using semiconductors. In the method of FIG. 2, since the AC voltage is directly controlled at a high frequency, the waveform distortion rate is good. Therefore, the present apparatus is cheap to be incorporated in the control device of the machine, and the machine can be operated stably even with a large voltage fluctuation. This is particularly effective for a brake circuit in which the stop position is a problem.

[Brief description of the drawings]

FIG. 1 is a block diagram when a thyristor is used.

FIG. 2 is a block diagram when a transistor is used.

FIG. 3 is an image diagram of one cycle of a voltage between C and D in FIG. 1

FIG. 4 is an image diagram of one cycle of a voltage between C and D in FIG. 2;

FIG. 5 is a diagram showing a range of an effective value voltage of each part in FIGS. 1 and 2;

[Explanation of symbols]

 1 Power supply 2 Transformer 3 Voltage detector 4 Comparator 5 Gate circuit 6 Voltage setting unit 7 Thyristor unit 8 ON / OFF ratio controller 9 Switching transistor unit A, B, C, D Voltage check terminals

Claims (3)

[Claims] 1. An AC voltage stabilizing device comprising a transformer which outputs a voltage drop expected from a nominal voltage of a power supply voltage, which is about 30% higher than a nominal voltage, in advance and controls this voltage to a nominal voltage by a thyristor or a switching transistor. Equipment to do. 2. The method according to claim 1, wherein an output of the transformer is added to a power supply voltage. 3. An apparatus using a switching transistor according to claim 1, wherein the ON / OFF switching ratio is set to a nominal voltage corresponding to the voltage between the voltage check terminals A and B in FIG.
Controls the N ratio at a speed of several kilocycles.