SU921013A1 - Device for stabilizing electric motor speed - Google Patents

Description

C5) DEVICE FOR STABILIZATION OF SPEED

ELECTRIC MOTOR

Claims (2)

The invention relates to electrical engineering, in particular, to electric drives with a controlled speed set by a control signal. A device is known for stabilizing the speed of an EJJectrode, containing a series-connected comparison unit, an amplifier, a motor and a speed sensor, as well as a reference pulse sensor and serially-connected pulse generators, a counter, a memory device and a converter code-voltage II). The disadvantage of the device is an additional error in the stabilization of the engine speed, which is caused by the conversion of digital signals into an analog form, which reduces the stability of the stabilization. The closest to the invention in its technical essence is a device for stabilizing the speed of an electric motor, comprising a series-connected summing amplifier, an electric motor, a speed sensor of an electric motor, a pulse shaper, a differentiating unit, a waiting multivibrator, an integrator and an inverter whose output is connected to the feedback input of the summing amplifier 21. The disadvantage of the device is the low accuracy of the stabilization of the engine speed due to the inconvenience of the duration of the pulses waiting its multivibrator with linear time master circuits. The purpose of the invention is to improve the accuracy of stabilizing the speed of an electric motor. The goal is achieved by estimating that the standby device multivibrator is made on a trigger, a pulse counter and a stable frequency pulse generator, the first trigger input connected to the output of the differentiating unit, the second input to the integrator input and the first pulse counter , the second input of which is connected to the output of a stable frequency pulse generator. FIG. 1 shows a structural diagram of a device for stabilizing the speed of an electric motor; Fig. 2 is a timing diagram explaining its operation. The device contains sequentially connected summations amplifier 1, electric motor 2, motor speed sensor 3, pulse generator k, differentiating unit 5, standby multivibrator 6, integrator 7 and inverter 8, the output of which is connected to the feedback input of summing amplifier 1 The waiting multivibrator b is made on trigger 9, a counter of 10 pulses and a generator of 11 pulses, of a stable frequency. The first input of the trigger 9 is connected to the output of the differentiating unit 5, the second input is connected to the output of the pulse counter 10, and the output to the integrator input 7 and the first input of the pulse counter 10, the second input of which is connected to the output of the generator of stable frequency pulses 11. A device for stabilizing the speed of an electric motor operates as follows. An alternating voltage whose frequency is proportional to the speed of rotation of the output shaft of the electric motor 2, from the output of the sensor 3 of speed (Fig. 2a) is fed to the input of the driver of k pulses, from the output of the driver of 4 pulses for example. The connection (Fig. 26) is fed to the input of the differentiating unit 5 which produces narrow pulses (Fig. 2c). These pulses from the output of the differentiating unit 5 are fed to the input of the trigger 9. On the trigger 9 by means of the counter 10 pulses, pulses of constant duration are formed. A pulse arriving at the first input of trigger 9 from differentiating unit 5 transfers trigger 9 to position 1. Signal 1 from the output of flip-flop E (Fig. 2d) arrives at the first input of pulse counter 10, which starts counting. Stable frequency pulses applied to esro second input from generator 11. When a predetermined number of pulses arrive at the output of counter 10, a pulse is formed (Fig. 2e), which places trigger 9 in position O, and the counting stops. When the next pulse arrives from differentiating unit 5, the cycle is repeated. As a result, the output of the trigger 9 generates a signal (Fig. 2d), which is a sequence of pulses of constant duration, the frequency and duty cycle of which is proportional to the rotation speed of the output shaft of the electric motor 2. The pulses from the output of the waiting multivibrator 6 enter the input of the integrator 7, where they integrate then inverted by inverter 8 and, as si, the negative feedback is fed to the input of summing amplifier 1. Thus, the increase in the accuracy of the stabilization of the motor speed in the described technical whom the decision is obtained by performing a one-shot more precise elements. Apparatus for stabilizing the speed of electric motors, comprising a summing amplifier, an output connected to an electric motor, serially connected speed sensor of an electric motor, a pulse driver, a differentiating unit, a waiting multivibrator, an integrator and an inverter, the output of which is connected to the feedback input of a summing amplifier characterized by that, in order to improve the accuracy of stabilizing the speed of an electric motor, the waiting multivibrator is made on a trigger, the impulse counter a stable frequency and pulse generator, a first trigger input connected to the output of the differentiating unit, the second input - with the output of the pulse counter, and the output to the input of the integrator and the first input of a pulse counter, a second input coupled to an output of the generator of stable frequency pulses. Sources of information taken into account during the examination 1. USSR author's certificate number 5P57, cl. G 05 D 13/00, 1977. 2. US patent If 3970909, “l. H 02 P 5/16, 1976. f /  - ten fui.2