JPS59169378A - Speed controller of motor - Google Patents

Abstract

PURPOSE:To accurately control the speed of a motor by comparing the detection pulse frequency of a rotating speed with a reference set pulse, and forming a device for controlling the ratio of ON/OFF times of the supplied power to the motor by the output in a full digital type. CONSTITUTION:Up-down counters 10, 12 count pulses from an encoder 3 and a speed setting pulse generator 14 under the control of the reset pulse of a frequency divider 13, the content is inputted to an up-down counter 6, and repeatedly increased or decreased in response to the load of a motor 2. On the other hand, a down counter 8 receives the output of a reference pulse generator 5, down counts the pulse from the division pulse generator 9, the contents of the counters 6, 8 are compared by a comparator 7, and the motor 2 is controlled through a power controller 4. Accordingly, the motor speed can be controlled in full digital type to maintain at the prescribed value, thereby providing stability and high accuracy.

Description

[Detailed description of the invention] The present invention relates to a speed control device for an electric motor.

Conventional speed control for electric motors uses analog comparison methods or analog. Although a digital mixing comparison method was used, if an analog method is mixed, it is inevitable that the rotation speed will be affected by changes in power supply voltage, changes in ambient temperature, load fluctuations, variations in circuit components, etc. In particular, the change in rotational speed due to ambient temperature is large; for example, a temperature change from 00 to lIO00 causes an error of about +LIO% or more, so it is necessary to provide a temperature compensation means. In addition, this type of system has the problem that the ability to follow the set speed is relatively slow due to the presence of overshoot, and it also requires a large number of resistors, capacitors, etc. as circuit components, which limits the service life. Furthermore, due to the presence of capacitors and the like, it is difficult to achieve high-density integration.

Therefore, it is difficult to keep costs below a certain level overall.

The present invention provides a small, low-cost, high-performance electric motor speed control device with excellent stability and reliability by performing speed control through numerical processing using an all-digital method.The present invention has the following characteristics: Rotation speed. A comparison circuit is provided that detects the pulse frequency as a pulse frequency and compares this detected pulse frequency with a set pulse frequency that should serve as a reference, and the ratio of the on time and off time of the supply current to the motor is controlled by the output of the comparison circuit. This is due to the fact that it was configured to do so.

Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. The drawing is a pull diagram of a speed control device for an electric motor according to the present invention, in which 1 is an AC power source, 2 are motors, and 3 is connected to the motor. The pulse encoder G is a power control circuit for the motor 2, and is controlled by the output of a comparator 7, which will be described later. j is a reference pulse generator that generates a pulse at the moment the voltage of power supply l reaches zep volts, and ot is an up/down pulse generator.

A counter, 7 is a comparator, 9 is an up-type or down-type counter, and the reference pulse generator 3 divides the period of the reference pulse into several divisions or more and generates a pulse train that is synchronous or asynchronous with respect to the reference pulse. This is a split pulse generator. Therefore, the counter 7 counts all the pulses from the divided pulse generator q in synchronization with the output pulses of the reference pulse generator S, and the comparator 7 compares the output contents of both counters 6 and 6 to determine the electric power hA. #Controlling the firing or extinguishing position for circuit II. IO is a reset pulse output by the frequency dividing circuit l3, which will be described later.
/3 17) It is an up counter that counts the pulses from the speed setting pulse generator l≠ while being regulated by the read pulse, and the comparator. Rator l/ is both counter 1
By comparing the output contents of 0 and l2, the up/down. The counter provides a switching output for up or down. This is a frequency dividing circuit that divides the output pulse of the 13-divided pulse generator 9 and provides a reset pulse to both counters 10 and /2, and the period of this reset pulse is determined by the output of the motor 1, the moment of inertia, or the electrical time constant. Although the pulse period can be set by considering the above, the pulse period is set to be longer than the pulse period from the reference pulse generator 3. /+ indicates a speed setting pulse generator for generating a pulse train of a frequency corresponding to a desired speed as a speed command, and the up counter /2
is input. Here, the clock input to the up-down counter B is performed through the entire NAND circuit lO, and the clock input to the up-down counter B is performed through the entire NAND circuit lO. ; and an NAliD circuit /6 which receives the pulses of the pulse encoder 3 and the output of the comparator // and the pulses given via the NOT circuit /l'', the output of the comparator // and the output of the speed setting pulse generator llI. Both outputs of the other HAND circuit 17 receiving the signal are given.

In the above configuration, when the motor 2 is operated at a predetermined speed, the speed setting pulse generator llI generates a constant pulse train that commands the speed, and both up counters IO and 12 are connected to the frequency dividing circuit 13. While being regulated by the reset pulse, the pulses from the pulse encoder 3 and the pulses from the pulse generator 11 are each counted in almost synchronization with each other. Since the contents of both counters 10 and 12 advance or lag behind each other by l pulses, the output of comparator 11 repeats H and L each time a pulse from pulse encoder 3 enters one of the counters 10. Therefore, up and down.

The counter t repeatedly increases and decreases around a value corresponding to the load on the motor tacho. Further, the down counter is set to a predetermined numerical value upon receiving the output of the reference pulse generator S, and counts down from, for example, the numerical value λ by the pulses from the divided pulse generator 9 that are subsequently input.

A comparator 7II'i compares the contents of both counters 6 and t, and if the contents of the counter r is smaller than the other counter 6, an off signal is supplied, and if it is larger, an on signal is supplied to the power control circuit l. , power control circuit II
gives power corresponding to the guitar taco load.

In this equilibrium state, when the load increases and the rotational speed of the motor tacho decreases, this control device operates as follows to return the speed of the motor 2 to the set value.

That is, when the rotation speed of the motor 2 decreases, the pulse speed from the pulse encoder 3 decreases, so that the up counter 10 counts slower than the other up counters/2. Therefore, the output of the comparator // is only up, which causes the up and down counters to count up and increase their contents. On the other hand, counter t
Since the counter 6 always counts in the same manner, its contents match the contents of the counter 6 sooner. As a result, the comparator 7 advances the firing timing for the power control circuit II, increases the power supplied to the motor tacho, and increases the power supplied to the motor λ.
, the speed of the pulses output from the pulse encoder 3 increases accordingly, returning to the set speed and entering an equilibrium state.

Up/down, the contents of the counter t will then change to another value that is larger by the amount of the load on the motor 2.

Next, when the rotational speed of the motor 2 becomes faster, the motor 2 enters an equilibrium state through a process reverse to the above operation and returns to the set rotational speed.

As described above, according to the device of the present invention, the rotational speed of the motor is detected by the pulse frequency, and the detected pulse frequency and the set pulse frequency are completely compared to determine the on time and off time of the power supplied to the motor. This is an all-digital control process that controls the ratio of motor rotation speed to a set constant value, so it is not affected by changes in ambient temperature, power supply voltage, or variations in circuit components, etc. It is possible to achieve high-precision speed control with high stability and reliability without fear of damage. In addition, the effects of load fluctuations can be minimized, speed followability is quick with no overshoot, and the required circuits can be highly integrated, making it easy to reduce size and cost. It is possible to provide an excellent speed control device with a long life.

[Brief explanation of drawings]

The drawing is a block diagram showing an embodiment of a speed control device for an electric motor according to the present invention. / AC power supply 6000. Motor 3 , , , Pulse encoder <<
, , , Power control circuit j , , , Reference pulse generator j
,,,,, up down, counter 7, //, +
,,+Connozarator t. 004.・Daunkarantara. 3000 division pulse generator io, tco 0096. Up counter/3 , , , frequency divider circuit

Claims (5)

[Claims] (1) It has a pulse frequency comparison device that compares the detection pulse frequency of the rotation speed and the reference setting pulse frequency, and the ratio of the on time and off time of the power supplied to the motor is regulated by the output of the pulse frequency comparison device. An all-digital electric motor speed control device that is equipped with an ignition position control device that controls the ignition position control device. (2) The pulse frequency comparison device is comprised of two counters that receive the detection pulse and the reference setting pulse separately, and a humparator that compares the magnitudes of the contents of these two counters ( 1) Electric motor speed control device. (3) The above-mentioned pulse frequency comparator is constituted by one up-down counter that receives the above-mentioned detection pulse and reference setting pulse as up input and down input, and compares the magnitude with respect to zet7Fc ( 1
) motor speed control device. (4) The ignition position control circuit determines the ignition or extinguishing position of the power control circuit for the electric motor based on the speed comparison result by the divided pulse generator that time-divides one or a half cycle of the AC power supply and the pulse frequency comparator. A speed control device for an electric motor according to claim 2, further comprising a comparison circuit for increasing or decreasing the speed of the electric motor. (5) The comparator circuit includes an up/down counter that is switched between up and down operations by the output of the pulse frequency comparator and counts either the detection pulse or the reference setting pulse, and the zep volt point of the AC power supply. It consists of an up-type or down-type counter that is set or reset by the reference pulse generated by the pulse generator and counts the pulse output from the divided pulse generator, and a comparator that compares the contents of both counters. A speed control device for an electric motor according to claim (4).