SU764081A1 - Dc electric drive - Google Patents

Description

(54) DC POWER ELECTRIC DRIVE

  one

The invention relates to electrical engineering and can be used to control the speed of engines used in machine tool industry, mechanical engineering, home appliances, etc.

A device for controlling the speed of an electric motor is known,. containing .thyristor and choke in the motor circuit, which sets the potentiometer and diode in the yapI avl CL circuit of the thyristor LP. The operation of the known device is based on comparisons of the counter-emf of an electric motor with a reference voltage.

The disadvantage of this device is the unstable operation of the engine at various speeds.

The closest to the invention to the technical essence is a direct current drive containing an electric motor connected in series with a thyristor, serially connected first resistor p, one output of which is connected to the thyristor anode, potentiometer and first diode, capacitor, second resistor and second diode, anode which is connected to the potentiometer slider, and the cathode is connected to the first terminal of the aforementioned capacitor 2. In this electric drive, a capacitor connected in parallel with the downstream potentiometer provides t unlocking angle of thyristor more than 90 °

The described electric drive is unstable at low speeds. If it is necessary to increase the stability of the rotational speed of the motor, the capacitor capacitance, the power of the potentiometer and the resistor, and, consequently, the dimensions of the drive circuit of the electric drive thyristor are enlarged.

Claims (2)

The purpose of the invention is to improve the weight and size parameters and increase the stability of the rotational speed. electric motor at low speeds. 3 The goal is achieved by the fact that an additional diode and an autotransformer equipped with an additional voltage winding are inserted into the electric drive, while the autotransformer is switched on parallel to the thyristor and the coil of the electric motor. The winding of the additional voltage is connected by one lead to the cathode of the first diode, the anode of which is connected to the second lead of the capacitor and one lead of the second resistor. The other terminal of the second resistor is connected to the second terminals of the motor core, and the winding of the additional voltage of the autotransformer, and an additional diode is connected between the control electrode of the thyristor and the cathode of the second diode. The drawing shows a schematic diagram of the drive. The armature of motor 1 is connected to the AC mains through thyristor 2. The reference voltage is removed from potentiometer 3 and is supplied to the control electrode of thyristor 2 through diodes 4 and 5. The potentiometer is turned on for mains voltage in series with two resistors 6 and 7 in parallel with part of the potentiometer 3 and diode 4, capacitor 8 is turned on. Potentiometer 3 and capacitor 8 are connected to a resistor 7 that shunt the winding of the overvoltage of the auto transformer 9 Through diode 10. The drive operates as follows. If voltage is lower from potentiometer 3 than the voltage on the additional winding of the auto-format 9, then in the first half of the positive half-wave capacitor 8 is charged along the circuit: resistor 6, part of potentiometer 3, diode 4, diode 10. The voltage on the capacitor reaches maximum in the middle of the half-wave of the supply voltage and for some time remains unchanged, since there is no discharge of the capacitor (diodes 4 and 5 are locked). In the second half of the half-period, when the potential of point A becomes greater than the potential of point B, the capacitor is 8 times through the open diode 5, the control electrode of the thyristor 2, the core circuit of the motor 1 and the resistor 7, the thyristor opens and passes current through the motor measles. So, at low driving voltages x 1 corresponding to low speeds of the electric motor (low counter-emf), autotransformer 9, diode 10 and resistor 7 hold the capacitor 8 in a charged state for some time and then due to its energy the thyristor turns on in the second half half-wave network voltage (unlock angle more). In this case, the thyristor transmits small portions of electrical energy and ensures stable operation at low speed with small dimensions of the control circuit. With a large setting voltage, the thyristor is unlocked in the first half of the positive half-wave when the potential of point A becomes greater than the potential of point B. Invention A direct current drive containing an electric motor connected in series with a thyristor connected in series with a first resistor, one output of which is connected to the thyristor anode, a potentiometer and the first diode, a capacitor, a second resistor and a second diode, the anode of which is connected to the potentiometer slider, and the cathode is connected to the first terminal, mentioned of the capacitor, and a m l h chayuschiys in that, in order to improve weight and size and stability povshgeni skoroe- minute at low motor rotation speeds, it introduced an additional diode and an autotransformer. provided with an additional-on-i, coil winding, the autotransformer is turned on, parallel to the thyristor and the electric motor's core winding, the additional-voltage winding is connected to the cathode of the first by one output. a diode whose anode is connected to the second capacitor terminal and one terminal of the second resistor, the other terminal of which is connected to the second terminals of the motor core and the winding of the additional voltage of the autotransformer, and an additional diode is connected between the control electrode of the thyristor and the cathode of the second diode. Sources of information taken into account at the first examination. 1. GCGP author's certificate No. 452905, cl. And 02 R 7/06, 1972.. 2. Thyristors. Technical reference book ed. V.A. Labuntsova. M., Energie, 1971, p. 252 (prototype) .. 0- ten } l 0 -i-s