SU1069113A2 - Device for adjusting rotational speed of asynchronous motor - Google Patents

Abstract

DEVICE FOR REGULATING THE SPEED OF ROTATION OF AN ASYNCHRONOUS ENGINE in auth.St. No. 681532, characterized in that, in order to improve the mass and size parameters, a logic block is introduced into the converter control circuit, composed of serially connected counter with a conversion factor of three, and a decoder, while the logic block input is connected to the output of the mode switch, and the output - with the input of the phase distributor. (La: so with

Description

The invention relates to electrical engineering and is used predominantly in frequency controlled drives of lifting mechanisms with intermittent modes of operation. According to the main bus; No. 681532, a device for controlling the speed of a multi-winding asynchronous motor on a stator, containing a power supply, a colo-imptive elements in a stator winding circuit, connected in series between switching elements and a power source, a thyristor frequency converter with direct connection, whose control circuit consists of series-connected low-frequency sensors, a scaler, a mixer connected to the high-frequency sensor and output keys, A series-connected mode switch and phase distributor, the mode switch is connected to the high frequency sensor and mixer, and the phase controller is connected to output switches and the high frequency sensor, the device allows the thyristor converter to work in the frequency converter mode, as well as in current-free conductor mode, due to which the size of the drive is reduced ij The disadvantage of the known device is that in the power supply mode of the 50 Hz motor from 18 thyristor in the converter operates only schest which should be designed to pass the full capacity dvigs1tel that improves the weight and size parameters directly to the frequency converter and the entire unit as a whole. The purpose of the invention is to improve the mass parameters. The goal is achieved by introducing into the device for controlling the rotational speed of the asynchronous motor bodies a logic block composed of a serially connected counter with a scaling factor equal to three, the decoder, while the input of the logic block is connected to the output of the mode switch, and the output is with the input of the phase distributor. Fig. 1 shows a device for controlling the speed of an eragzen asyn engine; in FIG. 2 is a variant of the logic block. The device contains a thyristor frequency converter 1 with direct connection, including the power part 2 and the control system 3. The control system 3 consists of a low-frequency sensor 4 connected to the counting device 5. You 6 sensor; low frequency through the mixer 7 is connected to the inputs of the output keys 8. The high frequency sensor 6 input is connected to the output of the 9 mode switch, the output of which is connected to the phase the distributor 10 and the logic unit 11, and the second output - to the mixer 7. The input terminals of the thyristor converter 1 are designed to be connected to the network via a line contactor 12, and the output terminals - through the current-free contactors 13 and 14 to the windings are two-winding asynchronous motor 15. Logic block (figure 2} consists of a counter 16 with a conversion factor of three, connected to the decoder 17. The power part 2 of the frequency converter 1 contains thyristors 18-35. The device works as follows. Depending on the switch command 9 modes The frequency converter operates either in the frequency converter mode or in the contactless switch mode. In the first mode, the frequency is controlled from zero to about 1/3 of the power frequency, and the second mode of the motor winding directly connected to the network. In the proposed device, an additional (logical unit 11, which in the second mode changes the sequence of commands of the phase distributor 10 depending on the sequence number of the signal from the mode switch. In the 18-thyristor frequency converter circuit, the signals from the logic unit 11 to the phase distributor 10 are repeated for each direction of rotation of the motor through three signals from the switch of the switch. Each signal from the logic unit 11 provides the output from the phase to distribute He ate 10 trigger pulses on a certain six thyristors so that the six thyristors alternate all the time when operating at a frequency of 50 Hz. For example, after the first start of the engine, the thyristors 18, 21, 25, 28, 32 and up 35 thyristor converter 1, after the second switching on - thyristors 19, 22, 26, 29, 30 and 33, etc. The signals from the switch 9 modes, corresponding to the inclusion of linear contactors 12 and 13 in the ascent or descent modes, go to counter 16 the outputs of which are connected to the decoder 17. Combi aci signal decoder 17 varies with each signal from the mode switch 9

And changes the combination of the output signals of the phase distributor 10.

With intermittent modes of operation, which is typical of most lifting mechanisms, the heating of all thyristor sixes is evened out. Due to this, there is no need to install

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six of the thyristors with increased i rating currents, which as a result leads to a decrease in the mass and dimensions of the converter, and consequently to an improvement in the weight and size of 5 indicators of the device for controlling the rotational speed of an induction motor.

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Claims (1)

DEVICE FOR REGULATING THE ROTATION SPEED OF AN ASYNCHRONOUS MOTOR according to ed. No. 681532, characterized in that, in order to improve the overall dimensions, a logic block is made up of the converter control circuit composed of series-connected meters with a conversion factor of three and a decoder, while the input of the logic block is connected to the output of the mode switch, and the output - with input of phase ♦ distributor. SU, 1069113