JPS62160092A - Electric power controlling method for motor - Google Patents

Abstract

PURPOSE:To prevent a wasteful power consumption from occurring by controlling the power consumption in proportion to the work amount of a load operation to effectively use the power. CONSTITUTION:A variation in the voltage of a load circuit is detected by the reverse AC control element side power terminal position X of an induction motor M and a triac TRIC position Y. An adder ADD adds the detection waveform to the waveform compared at 0-cross point to obtain an added waveform of a duty ratio inversely proportional to the load current. This is integrated to obtain a reference waveform for outputting a voltage inversely proportional to a load current. A comparator CMP compares a sawtooth wave obtained from 0-cross time point compared waveform at a power terminal position with a reference waveform to obtain a rectangular wave of a duty ratio proportional to the load capacity. The gate of the triac TRIC is controlled by this rectangular wave to control the power consumption of the motor proportionally to the work amount of the load operation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for controlling power proportional to load on a motor, such as an induction motor, connected to an AC power source.

[Prior Art] Conventionally, as a power control method for an induction motor connected to an AC power supply, the power factor is generally detected from the phase difference between voltage and current, and then the impedance of the load circuit is adjusted to reduce the phase difference. In addition to controlling the power factor and improving the power factor,
In this case, the power loss of induction lightning II for load operation is reduced, but in this case, even if the power loss is reduced, the power is not controlled according to the degree of load applied to the induction motor, so when the load is light, It consumes more power than the work of the load, and as a result, the induction motor consumes the same amount of power even at no load or light load as when operating at rated load, increasing the power consumption of the induction motor. This had the disadvantage that it did not change even if the power factor was improved.

[Problems to be Solved by the Invention] The present invention aims at effective use of electric power by controlling the power consumption of an induction motor in proportion to the workload of load operation.
The purpose is to prevent unnecessary power consumption.

[Means for Solving the Problems] The present invention provides anti-AC control of the motor to control voltage changes in a load circuit when controlling the power of a motor connected to an AC power supply via an AC control element in response to load fluctuations. The waveforms detected at the element side power supply terminal position and the AC control element position are added, and both waveforms are compared at the zero cross point to obtain an added waveform with a duty ratio inversely proportional to the load current, and the added waveform is integrated. While obtaining a reference waveform that outputs a voltage inversely proportional to the load current, a duty ratio proportional to the load capacitance obtained by comparing the reference waveform with the sawtooth wave obtained from the 0902 point comparison waveform at the power supply terminal position. A method of controlling power for an electric motor, characterized in that the gate of the AC control element is controlled by a rectangular wave of.

[Function] When the voltage change in the load circuit is detected in the operating state of the motor at the power supply terminal position on the anti-AC control element side of the motor and at the AC control element position, a rectangular wave corresponding to the voltage phase is obtained at the power supply terminal position. , a rectangular wave corresponding to the power phase is obtained at the AC control element position, and these two waveforms are
By adding the waveforms compared at this point, you can obtain an added waveform with a duty ratio inversely proportional to the load current, and
The addition waveform is integrated to obtain a reference waveform that outputs a voltage inversely proportional to the load current, while a sawtooth wave having the same phase as the voltage waveform is obtained from the waveform compared at the 0-cross point of the power supply terminal position. The wave and the reference waveform are compared to obtain a rectangular wave with a duty ratio proportional to the load capacity, in this case, the actual load capacity applied to the motor during load operation, that is, the amount of work. Controls the gate of the g-flow control element.

[Example] Next, the configuration of an embodiment of the present invention will be explained with reference to the drawings.

FIG. 1 is an electrical circuit diagram of this embodiment, in which an AC power source is connected to an AC power source via a triac TRIC as an AC control element.
Induction motor IIM connected to single phase AC ACl 00V
The voltage waveform of the load circuit detected at the anti-TRIAC TRIC side power supply terminal position , e, + and - side comparator circuits X+CMP to obtain C waveforms.

Input to X-CMP1Y+CMP, Y-CMP, each comparator circuit X+CMP, X-CMP, Y+CMP,
Output from Y-CMP (alb, e, C waveforms in Figure 2)
is input to the adder circuit ADD for phase detection of voltage and current, as well as the + side and - side comparator circuits X+CMP, X-C
The output from MP (waveforms a and b in Figure 2) is the differential circuit DF.
It is input to F.

On the other hand, the addition waveform with a duty ratio inversely proportional to the load current obtained by inputting it to the adding circuit ADD, the 9 waveform in FIG. 2, is inputted to the integrating circuit INT to obtain the h waveform in FIG. A rectangular wave with a proportional duty ratio is input to the reference value terminal of the comparator CMP to obtain the J waveform in Figure 2, and the differential waveform (C waveform in Figure 2) obtained by inputting it to the differentiator circuit DFF is a sawtooth waveform. The sawtooth wave synchronized with the voltage waveform is input to the wave generating circuit RGC, and the d waveform in FIG. 2, and the rectangular wave is input to the back 7 amplifier AMP, and is then input to the triac T.
It is input to the gate terminal of RIC, and it is also input to the buffer amplifier A.
A soft start signal for applying voltage to the induction motor M at a time 90 degrees shifted from the time 0902 when the induction motor M is started is input from the differentiation circuit DFF to the MP via the soft start signal generation circuit SSC.

Next, the operation of this embodiment will be explained.

In the power control circuit configured in this way, the induction motor 1
When power is supplied to 1M and load operation is performed, the voltage change in the load circuit is detected at the power supply terminal position X on the side of the repulsion flow control element of the induction motor M and the triac TRIC position Y, and both waveforms, X in Fig. 2, A waveform obtained by comparing the Y waveform at time 0902, a waveform a, b, e, and f waveforms shown in Fig. 2 are added to obtain the sum waveform with a duty ratio inversely proportional to the load power, and the 9 waveforms shown in Fig. 2 are obtained. The reference waveform that outputs a voltage inversely proportional to the load current by integrating the added waveform, the h waveform in Figure 2, is obtained, while the comparator waveform at 0902 at the power terminal position X, the a and b waveforms in Figure 2 The sawtooth waveform obtained from (waveform d in Figure 2) and the reference waveform (waveform h in Figure 2)
A rectangular wave (waveform j in Fig. 2) with a duty ratio proportional to the load is obtained by comparing the two, and this rectangular wave (waveform j in Fig. 2) is input to the gate terminal of the triac TRIC. , the induction N motive M is supplied with electric power proportional to the load.

The above has described the case where single-phase alternating current is supplied to the induction motor M, but when three-phase alternating current is supplied to the induction motor M, the above steps are performed for each phase.

[Effects of the Invention] When the present invention controls the power of a motor connected to an AC power supply via an AC control element in response to load fluctuations, the voltage change in the load circuit is controlled by the position of the terminal on the opposite AC control element side of the motor. The waveforms detected at the AC control element position and compared at the O-cross point are added together to obtain an added waveform with a duty ratio inversely proportional to the load current, and the added waveform is integrated to generate a voltage inversely proportional to the load current. While obtaining a reference waveform for outputting, the AC control is performed using a rectangular wave with a duty ratio proportional to the load capacity obtained by comparing the reference waveform with the sawtooth wave obtained from the 0902 time point humbular rate waveform at the power terminal position. By controlling the gate of the element,
The power consumption of the induction motor can be controlled in proportion to the workload of load operation, which makes it possible to use power effectively and prevent wasteful power consumption.

[Brief explanation of drawings]

FIG. 1 is an electric circuit diagram of an embodiment of the present invention, and FIG. 2 is a waveform diagram thereof. M...Induction motor TRIC...Triac CMP...Comparator ADD...Addition circuit OFF...Differentiating circuit ADD...Integrator circuit RGC...Sawtooth wave generation circuit △MP...Buffer 7 Ambient

Claims (1)

[Claims] 1. When controlling the power of a motor connected to an AC power source via an AC control element in response to load fluctuations, voltage changes in a load circuit are controlled by the position of a power supply terminal on the opposite side of the AC control element of the motor. The waveforms detected at the AC control element position and compared at the zero-cross point are added together to obtain an added waveform with a duty ratio inversely proportional to the load power, and the added waveform is integrated to generate a voltage inversely proportional to the load power. While obtaining a reference waveform for outputting, a square wave with a duty ratio proportional to the load capacitance obtained by comparing the reference waveform with a sawtooth wave obtained from the 0-cross time point comparison waveform at the power supply terminal position is obtained. A power control method for an electric motor, comprising controlling a gate of an AC control element. 2. A power control method for an electric motor according to claim 1, wherein the electric motor is an induction motor.