KR100268136B1 - Power saving type 3phase motor driving apparatus - Google Patents

Abstract

PURPOSE: A power saving apparatus for driving a three-phase motor is provided to ensure easy operation, correct control and reduced number of parts by ensuring the same input to three power modules for three phases. CONSTITUTION: The first signal conditioning device(SC) conditions the power(R) of one phase to convert into a signal level suitable for one opto-isolator(ISO). The opto-isolator(ISO) generates an output proportional to the first signal conditioning device(SC), and electrically separates front and rear ends. Each of the second conditioning devices(SCD1,SCD2,SCD3) is arranged in one phase, diverges the output of the opto-isolator(ISO) to be converted into a signal for gating each of power modules(PM1,PM2,PM3), and delays the signal suitable for each phase. Each of the power modules(PM1,PM2,PM3) is arranged for each phase, and is gated in response to the gating signals from the second conditioning devices(SCD1,SCD2,SCD3) to control power supplied to a motor(M).

Description

Power saving type 3 phase motor driving apparatus

Until now, many kinds of driving devices have been developed to reduce power consumption of three-phase motors, but most of them automatically control the power supplied to the motor according to the load of the motor. It is a driving device that reduces the power wasted when the load is low by increasing the power supply when the load is low and the load is low.

However, such a power-saving motor drive device is generally complicated in structure or has a separate control device for each phase. In particular, when each device has a separate control device for each phase, individual characteristics of each device and device may vary and Even if a device or device with the same model name has a tolerance, the value at design time does not fit well when manufacturing the driving device, but each device has a device for fine adjustment. It is often not easy to adjust.

Accordingly, in the prior application patent application No. 87-7184 of the present invention, as shown in the schematic block diagram in FIG. First conditioning device SC for level conversion into a signal having an appropriate size according to ISO2, ISO3), and branching the converted signal to produce an output proportional to the output of the first conditioning device SC, Three opto-isolators (ISO1, ISO2, ISO3) and one opto-isolator (ISO1, ISO2, ISO3), one for each phase, are delayed by 60 degrees or 120 degrees with respect to either phase for electrical separation. A second conditioning device (SCD1) for converting three power modules PM1, PM2, and PM3 into a signal level suitable for gating, so as to have substantially the same phase as each phase of the three-phase power source to be controlled. SCD2, SCD3), The gating time is adjusted according to the output of the second conditioning apparatus SCD1, SCD2, SCD3 and consists of three power modules PM1, PM2, PM3 that control the power supply of each phase to the motor M. have.

With this configuration, when the load of the motor increases and the voltage of the three-phase power source increases, the first conditioning apparatus SC, the opto-isolator ISO1, ISO2, ISO3, and the second conditioning apparatus SCD1, SCD2, SCD3 accordingly. The voltages of the outputs of the power amplifier) also increase, so that the gating voltage input to the gating terminals G1, G2, and G3 of the power modules PM1, PM2, and PM3 reaches a threshold voltage that can be gated faster. As the gating of the war modules PM1, PM2, PM3 occurs early, more power is supplied to the motor M by the power modules PM1, PM2, PM3.

On the contrary, when the load of the motor decreases, the voltage of the three-phase power supply is lowered, and the threshold voltage that the gating voltages input to the gating terminals G1, G2, and G3 of the power modules PM1, PM2, and PM3 can gate. Since the power module PM1, PM2, PM3 is late, the power module PM1, PM2, PM3 is supplied to the motor M by the power module PM1, PM2, PM3.

Therefore, since power supply proportional to the load of the motor can be provided, power saving can be achieved by reducing reactive power that may occur when the load of the motor is low.

However, this prior application preferably uses one optoisolator of the same model name for each phase in order to facilitate adjustment. However, even in this case, the optoisolator is used in the actual apparatus as compared to elements such as resistors, capacitors, and power devices. In general, even if the opto-isolator having a large tolerance and the same model name responds very sensitively according to the operating conditions, the driving device according to the prior application is not the same characteristics of each opto-isolator, each drive device There is a difficulty to make a complicated adjustment every time, and if the correct adjustment is not made, the accurate control is impossible, thereby greatly reducing the power saving effect.

SUMMARY OF THE INVENTION An object of the present invention is to provide a three-phase motor driving apparatus for controlling a motor using a three-phase power source, wherein one of the three-phase power sources passes through only one opto-isolator, and branches the output of the opto-isolator, By equally input to the three power modules for the phase, to provide a power saving drive device for a three-phase motor, the adjustment is simple, the control is more accurate, the number of parts is reduced.

More precisely, the object of the present invention is to use only one opto-isolator, so that the power saving drive device for a three-phase motor can solve the problem that it is difficult to precisely adjust the opto-isolator for each phase as in the prior art. To provide.

1 is a block diagram of the prior art;

2 is a block diagram of the present invention

3 is a specific embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

SC: first conditioning device

ISO: Opto Isolator

SCD1, SCD2, SCD3: Second Conditioning Device

PM1, PM2, PM3: Power Module

R, S, T: 3-phase power

TC1, TC2, TC3: Triac

TF: Transformer

VR, VR1, VR2, VR3: variable resistor

TR: Transistor

Referring to FIG. 2 schematically showing the configuration of the present invention, the configuration of the present invention is a first conditioner for conditioning one phase power source R among three phase power sources and converting them into a signal level suitable for one opto-isolator ISO. Branches the tuning device SC, only one opto-isolator ISO for generating an output that is output to the output of the first signal conditioning means and electrically separating the front and rear ends, and the output of the opto-isolator ISO. Converts each power module (PM1, PM2, PM3) to a signal level for gating and delays the signal (delays 60 and 120 degrees for each phase) as appropriate for each phase of the three-phase power supply. Power supplied to the motor M by being gated according to the gating signals from the second conditioning devices SCD1, SCD2 and SCD3 and the second conditioning devices SCD1, SCD2 and SCD3, one for each phase. For each phase that controls It includes one by one power modules (PM1, PM2, PM3).

The operating principle of the present invention will be described with reference to FIG. 2, whereby the load M of the motor is increased to increase the current of the three-phase power sources R, S, and T, and thus is input to the first conditioning device SC. The amplitude of the current in the phase becomes large, and the voltage amplitude of the output waveform of the first conditioning apparatus SC also increases, and the output of the first conditioning apparatus SC is input to a single opto-isolator ISO. In this case, the amplitude of the output waveform of the opto-isolator ISO is also increased. When the output of the single opto-isolator ISO is branched and input to three second conditioning devices SCD1, SCD2 and SCD3, one for each phase, the second conditioning devices SCD1, SCD2 and SCD3 are input. ), The outputs of the other two second conditioning apparatuses are delayed by about 60 degrees and 120 degrees, respectively, with respect to the output of any one of the second conditioning apparatuses, so that they are substantially in phase with the phases of the three-phase power source. The amplitudes of the outputs of the two conditioning apparatus SCD1, SCD2, SCD3 also become large, so that the voltages of these amplitudes are applied to the gating terminals of the three power modules PM1, PM2, PM3. Since the amplitude of the gating voltage is also increased, the threshold voltage capable of gating the power modules PM1, PM2, and PM3 is reached earlier, so that the gating of the power modules PM1, PM2, and PM3 occurs early, thus causing The war modules PM1, PM2, and PM3 supply more power to the motor M.

On the contrary, when the load of the motor M decreases, the output amplitude of the second conditioning apparatus SCD1, SCD2, SCD3 also decreases on the same principle as the above increase, and the power modules PM1, PM2, PM3 When the threshold voltage capable of gating is reached later, the gating of the power module occurs later, so that less power is supplied to the motor M by the power modules PM1, PM2, and PM3.

In this way, a single opto-isolator (ISO) is used, and its output is split and inputted equally to the three second conditioning devices (SCD1, SCD2, and SCD3), one opto for each phase, as in the prior application of the applicant. In the case of using an isolator, the actual operating characteristics of each optoisolator are inconsistent, so that precise adjustments are not required to correct such discrepancies in the second conditioning device, and the adjustment is simpler, and the number of opto isolators required Also, the production cost is reduced.

Now, the configuration and operation of FIG. 3 showing a specific embodiment of the present invention will be described with reference to the operation principle in FIG. 2.

When input to three-phase AC power (R, S, T), one of these three-phase power (R, S, T) (R in FIG. 3) is converted from the transformer (TF) to a signal level suitable for the subsequent opto-isolator. The converted signal is half-wave rectified, the unnecessary high frequency components are removed by the capacitor C, and adjusted to the amplitude by the variable resistor VR as necessary, and then by the opto-isolator ISO. The front and rear ends are electrically separated and produce an output proportional to the input from the front end. This opto-isolator (ISO) serves to prevent the destruction of devices (second conditioning devices, power modules, motors, etc.) in the latter stage due to abnormal excessive output voltage at the front of the opto-isolator (ISO). Do it.

The output of the optoisolator (ISO) thus formed is amplified by the amplifier (TR) to convert the signal to a signal level suitable for the gating terminals of the rear triacs (TC1, TC2, TC3) and then branched into three, The branched output is delayed by 60 degrees or 120 degrees from one phase to the other by the capacitors C1, C2 and C3 and the variable resistors VR1, VR2 and VR3, respectively. The phases are converted to have substantially the same phase and applied to the gating terminals of the triacs TC1, TC2, TC3 that control the power supplied to the motor M.

The half-wave rectified sine wave with an amplitude varying according to the load of the motor M is appropriately delayed at each gating terminal of the triacs TC1, TC2, and TC3 controlling the power supplied to the motor M. Since the triacs TC1, TC2, and TC3, which supply power to the motor M, have a large load, a half-wave rectified sine wave having a large amplitude is input to the gating terminals, so that gating starts early. And supply a lot of power to the three-phase terminals (MR, MS, MT) of the motor (M), and when the load is small, a half-wave rectified sine wave with a small amplitude is input to the gating terminal, and gating is started late, so that less power is supplied to the motor. By supplying to (M), the invalid power consumption in the motor M is reduced and power saving is possible.

In FIG. 3, which is a specific embodiment of the present invention, a parallel configuration of the transistor TR, the capacitors C1, C2, and C3 and the variable resistors VR1, VR2, and VR3 is used to implement the second conditioning device of FIG. 2. Instead of this configuration, the op amp and a plurality of delay devices each delaying a phase of about 60 degrees form a series to form a gating voltage of triacs TC1, TC2, and TC3 at 3 degrees of output of each delay device. You can do that. It is also possible to modify the specific part to use thyristors instead of triacs TC1, TC2, TC3 at 3 degrees, or to use full-wave rectification circuits instead of half-wave rectification circuits by diode D.

Although the present invention has been described in some specific and preferred forms or embodiments for the convenience of description, these descriptions are presented by way of example only, and those skilled in the art may have an effect similar to the present invention without departing from the spirit and scope of the present invention. It should be noted that the branch can vary.

The present invention uses only one opto-isolator to generate a control signal to the power module for each phase controlling the power supply of the motor, branching the output of the opto-isolator to convert the signal level and phase, By supplying a common power module for each phase, the control is accurate and the number of parts can be reduced.

Claims (6)

In the driving device for a power-saving three-phase motor for controlling the power supplied to the three-phase motor to enable power saving, the driving device is First conditioning means for adjusting the amplitude of one phase of the three-phase power source, One separating means for generating an output proportional to the output of the first conditioning means and electrically separating the front and rear ends; A second conditioner for generating one output for each phase which causes the output of the separating means to have a phase difference substantially equal to the phase difference of each phase of the three-phase power source and to a signal level suitable for gating the power control module. With shuning means, And power control means, one for each phase for gating the respective three-phase power supplies by the respective outputs of the second conditioning means to output each of the gated three-phase power supplies to the three-phase motor. Driving device for a three-phase motor, characterized in that. A drive device for a three-phase motor as claimed in claim 1 wherein said first conditioning means comprises a transformer. 2. A drive device for a three-phase motor according to claim 1, wherein said separating means comprises an opto-isolator. The drive device for a three-phase motor according to claim 1, wherein the power control means includes a thyristor. 4. A drive device for a three-phase motor according to claim 1, wherein the power control means comprises a triac. In the driving method for a power-saving three-phase motor to control the power supplied to the three-phase motor to enable power saving, the driving method is Adjusting the amplitude of one phase of the three-phase power source, Generating an output proportional to the output of the adjusting step and electrically separating the front and rear ends; Generating one output for each phase which causes the output of said separating step to have a phase difference substantially equal to the phase difference of each phase of said three-phase power supply and to a signal level suitable for gating a power control module; Gating said three-phase power by each output of said generating step, and outputting each gated three-phase power to said three-phase motor.

Images