RU2403669C1 - Semiconductor single-phase two-winding induction motor speed setter - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: in a semiconductor speed setter, three reversible semiconductor switches are mounted on semiconductor keys connected to direct current mains and used to be connected to the stator windings of a single-phase two-winding induction motor. A diode bridge is connected to a phase and a zero point of alternating mains. Each of three reversible semiconductor switches is mounted on two transistors. Commutators of odd transistors of each semiconductor switch are connected to a plus of the rectified double-wave voltage mains. Emitters of the odd transistors are connected to the commutators of the even transistors, and the emitters of the even transistors are connected to a minus of the rectified double-wave voltage mains. A common junction midpoint of the odd and even transistors of the first reversible semiconductor switch is connected to joint inputs of the stator windings of the single-phase two-winding induction motor. A common junction midpoint of the odd and even transistors of the second reversible semiconductor switch is connected to an output of the first stator winding of the motor. A common junction midpoint of the odd and even transistors of the third reversible semiconductor switch is connected to an output of the second stator winding of the single-phase two-winding induction motor.

EFFECT: simplified control system of the transistor switching, higher reliability and efficiency of the device and downsizing.

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Description

The present invention relates to frequency converters and can be used in a controlled AC drive for power from a single-phase network of a single-phase two-winding asynchronous electric motor.

A single-phase capacitor motor is known in which the first output of the first winding is connected to zero of the supply network, and the second output of the first winding is connected to the first output of the second winding and to the phase of the supply network. The second output of the second winding is connected to the first lining of the paper capacitor. The second lining of the capacitor is connected to zero of the supply network (IP Kopylov Electric machines: a textbook for high schools / IP Kopylov. M .: Higher school, 2006. - P.343, Fig. 3.96).

The disadvantages of this device are the inability to control the speed of rotation of the electric motor and the increased dimensions, as well as low reliability due to the need to use paper capacitors of large capacity and the unpredictability of the direction of rotation of the electric drive.

The closest to the proposed invention in terms of technical nature and the achieved result (prototype) is a single-bridge current inverter circuit with which the frequency of the voltage supplied to each of the windings of a single-phase two-winding asynchronous motor is controlled, which contains reversible semiconductor switches made on semiconductor switches that are connected with a direct current supply network and are intended for connection with stator windings of a single-phase two-winding th asynchronous motor and power smoothing reactor and locking paper capacitor, connected in parallel to the motor winding. Each reversible semiconductor switch is made on four thyristors. One output of the smoothing power reactor is connected to the plus of the direct current network, and the second output is connected to the anodes of the two thyristors. The cathodes of these thyristors are connected to the motor winding and capacitor plates, respectively, as well as to the anodes of another pair of thyristors. The cathodes of the last pair of thyristors are designed to connect to the minus of the DC network (V. Labunts. Autonomous thyristor inverters / V. A. Labuntsov, G. A. Rivkin, G. I. Shevchenko. - M.-L.: Energy, 1967 . - C.20, Fig. 7c).

The main disadvantages of the described device are the increased dimensions, high cost, and low reliability due to the use of locking paper capacitors to ensure capacitive locking of the thyristors and the danger of not closing the thyristors when the current flow direction changes along the stator winding and, as a result, the inverter breaks, i.e., a short short circuit of a direct current source.

The present invention solves the problem of reducing the dimensions, increasing the efficiency and reliability of the device by reducing the number of semiconductor switches in the absence of the need to use locking paper capacitors and a smoothing reactor in the power part of the device.

To solve the problem, in a semiconductor device for controlling the speed of a single-phase two-winding induction motor, which contains reversible semiconductor switches made on semiconductor switches that are connected to a DC power network and are designed to connect to the stator windings of a single-phase two-winding asynchronous motor, according to the invention, a diode bridge connected to phase and zero of the AC mains, each of the three reversible half Vodnikova switches formed on the two transistors, the collectors of transistors each odd semiconductor switch connected to the positive full-wave rectified mains voltage, the emitters of the odd transistors are connected to the collectors of transistors of even and odd emitters of transistors are connected to negative full-wave rectified mains voltage. The common midpoint of the connection of the odd and even transistors of the first reversing semiconductor switch is designed to connect to the combined inputs of the stator windings of a single-phase two-winding asynchronous motor. The common midpoint of the connection of the odd and even transistors of the second reversing semiconductor switch is for connecting to the output of the first stator winding of the motor. The common midpoint of the connection of the odd and even transistors of the third reversing semiconductor switch is designed to connect to the output of the second stator winding of an asynchronous single-phase two-winding motor.

The use of a semiconductor device for controlling the speed of a single-phase two-winding asynchronous motor causes the creation of various types of rotating stator magnetic fields by means of algorithmic switching of transistors, which makes it possible to obtain not only the required current direction in the stator windings, but also the frequency of the stator rotating magnetic field and, therefore, the speed of the electric motor.

The invention is illustrated by drawings, where Fig. 1 shows a circuit diagram of a semiconductor device for controlling the speed of a single-phase two-winding induction motor; figure 2 is a vector diagram of the rotation of the magnetic flux of the stator field, consisting of three fixed positions; figure 3 is a vector diagram of the rotation of the magnetic flux of the stator field, consisting of four fixed positions; figure 4 is a vector diagram of the rotation of the magnetic flux of the stator field, consisting of six fixed positions; figure 5 is a vector diagram of the rotation of the magnetic flux of the stator field, consisting of eight fixed positions; figure 6 - phase-by-phase change of the magnetic flux in the stator windings in accordance with the vector diagram depicted in figure 2; figure 7 - phase-by-phase change in magnetic flux in the stator windings in accordance with the vector diagram shown in figure 3; on Fig - phase-by-phase change in magnetic flux in the stator windings in accordance with the vector diagram depicted in figure 4; in Fig.9 - phase-by-phase change in the magnetic flux in the stator windings in accordance with the vector diagram depicted in Fig.5.

In addition, the drawings show the following:

- U _network - voltage coming from an AC voltage power source;

- U _rect - rectified voltage;

- t is the current time;

- f - phase;

- 0 - zero;

- C1-C4 - conclusions of stator windings of a two-phase asynchronous motor;

- L1, L2 - stator windings.

- VT1-VT6 - transistors;

- I, II, III, IV, V, VI, VII, VIII - sequential fixed positions of the magnetic flux vector of a circular rotating field of the stator of an induction motor;

- arcuate lines with arrows - directions of rotation of the stator magnetic field;

- straight lines with arrows - directions of the magnetic flux in the corresponding stator winding.

The semiconductor device for controlling the speed of a single-phase two-winding induction motor contains three reversible semiconductor switches made on semiconductor switches, each of which consists of two transistors connected to a diode single-phase two-half-wave bridge providing a rectified two-half-wave voltage that is used for vector-algorithmic single-phase asynchronous asynchronous switching engine. The semiconductor switches are connected to the DC supply network and are intended for connection with the stator windings of a single-phase two-winding induction motor.

So, the first reversible semiconductor switch is made on the odd and even transistors 1 (VT1) and 2 (VT2), the second reversible semiconductor switch is made on the odd and even transistors 3 (VT3) and 4 (VT4), and the third semiconductor switch is made on the odd and even transistors 5 (VT5) and 6 (VT6). Transistors 1, 2, 3, 4, 5, 6 (VT1-VT6) are connected in two transistors counter-parallel.

In the first reversible semiconductor switch, the collector of the odd transistor 1 (VT1) is connected to the plus of the diode bridge 7, that is, to the plus of the supply network of the rectified half-wave voltage, and the emitter of the odd transistor 1 (VT1) is connected to the collector of the even transistor 2 (VT2). The average common connection point of the odd transistor 1 (VT1) and the even transistor 2 (VT2) is designed to connect with the combined inputs 8 (C2), 9 (C4) of the first 10 (L1) and second 11 (L2) stator windings of an asynchronous single-phase two-winding motor. The emitter of the even transistor 2 (VT2) is connected to the minus of the diode bridge 7, that is, to the minus of the supply network of the rectified half-wave voltage.

In the second reversible semiconductor switch, the collector of the odd transistor 3 (VT3) is connected to the plus of the diode bridge 7, that is, to the plus of the supply network of the rectified half-wave voltage, and the emitter of the odd transistor 3 (VT3) is connected to the collector of the even transistor 4 (VT4). The average common connection point of the odd transistor 3 (VT3) and the even transistor 4 (VT4) is designed to connect with the output 12 (C1) of the first 10 (L1) stator winding of an asynchronous single-phase two-winding motor. The emitter of transistor 4 (VT4) is connected to the minus of the diode bridge 7, that is, to the minus of the supply network of the rectified half-wave voltage.

In the third reversible semiconductor switch, the collector of the odd transistor 5 (VT5) is connected to the plus of the diode bridge 7, that is, to the plus of the power supply network of the rectified half-wave voltage, and the emitter of the odd transistor 5 (VT5) is connected to the collector of the even transistor 6 (VT6). The average common connection point of the odd transistor 5 (VT5) and the even transistor 6 (VT6) is designed to connect to the output 13 (C3) of the second 11 (L2) stator winding of an asynchronous single-phase two-winding motor. The emitter of transistor 6 (VT6) is connected to the minus of the diode bridge 7, that is, to the minus of the supply network of the rectified half-wave voltage.

Using a semiconductor device for controlling the speed of a single-phase two-winding induction motor, it is possible to carry out vector-algorithmic control of a single-phase two-winding asynchronous motor, creating several types of rotating stator fields: the passage of three, or four, or six, or eight consecutive fixed positions of the magnetic flux vector of a circular rotating field of the motor stator .

To ensure rotation of the magnetic flux vector of the stator field of a two-phase asynchronous motor in accordance with the vector diagram shown in figure 2, in the sequence I-II-III, it is necessary to apply control pulses to transistors 1, 2, 3, 4, 5, 6 (VT1 -VT6) in the following order:

- in the first half-period of the rectified voltage, transistors 5 (VT5) and 2 (VT2) turn on and work, providing I a fixed position of the stator magnetic flux when current flows along the stator winding 11 (L2) in the direction shown;

- in the second half-period of the rectified voltage, transistors 5 (VT5) and 2 (VT2) turn off, transistors 1 (VT1), 4 (VT4) and 6 (VT6) turn on and work, providing II a fixed position of the stator magnetic flux when current flows through the stator windings 10 (L1) and 11 (L2) in the direction shown;

- in the third half-period of the rectified voltage, transistors 1 (VT1) and 4 (VT4) turn off, transistors 3 (VT3) and 6 (VT6) turn on and work, providing III a fixed position of the stator magnetic flux when current flows through the stator windings 10 (L1) and 11 (L2) in the direction shown.

Starting from the fourth half-cycle, the switching cycle of the transistors is repeated, providing a circular rotation of the stator field.

To ensure rotation of the magnetic flux vector of the stator field of a single-phase two-winding induction motor in accordance with the vector diagram shown in figure 3, in the sequence I-II-III-IV, it is necessary to apply control pulses to transistors 1, 2, 3, 4, 5, 6 (VT1-VT6) in the following order:

- in the first half-period of the rectified voltage, transistors 3 (VT3) and 2 (VT2) turn on and work, providing I a fixed position of the stator magnetic flux when current flows along the stator winding 10 (L1) in the direction shown;

- in the second half-period of the rectified voltage, the transistor 3 (VT3) turns off, the transistors 5 (VT5) and 2 (VT2) turn on and work, providing II a fixed position of the stator magnetic flux when current flows through the stator winding 11 (L2) in the direction shown;

- in the third half-period of the rectified voltage, transistors 5 (VT5) and 2 (VT2) turn off, transistors 1 (VT1) and 4 (VT4) turn on and work, providing III a fixed position of the stator magnetic flux when current flows through the stator winding 10 (L1) in direction shown;

- in the fourth half-period of the rectified voltage, transistor 4 (VT4) turns off, transistors 1 (VT1) and 6 (VT6) turn on and work, providing an IV fixed position of the stator magnetic flux when current flows through the stator winding 11 (L2) in the direction shown.

Starting from the fifth half-cycle, the switching cycle of the transistors is repeated, providing a circular rotation of the stator field.

To ensure rotation of the magnetic flux vector of the stator field of a single-phase two-winding induction motor in accordance with the vector diagram shown in figure 4, in the sequence I-II-III-IV-V-VI, it is necessary to apply control pulses to transistors 1, 2, 3, 4, 5, 6 (VT1-VT6) in the following order:

- in the first half-period of the rectified voltage, transistors 3 (VT3) and 2 (VT2) turn on and work, providing I a fixed position of the stator magnetic flux when current flows through winding 10 (L1) in the direction shown;

- in the second half-period of the rectified voltage, transistor 3 (VT3) turns off, transistors 5 (VT5) and 2 (VT2) turn on and work, providing II a fixed position of the stator magnetic flux when current flows through winding 11 (L2) in the direction shown;

- in the third half-period of the rectified voltage, transistor 2 (VT2) turns off, transistors 5 (VT5) and 4 (VT4) turn on and work, providing III a fixed position of the stator magnetic flux when current flows through windings 10 (L1) and 11 (L2) in the shown direction;

- in the fourth half-period of the rectified voltage, the transistor 5 (VT5) turns off, transistors 1 (VT1) and 4 (VT4) turn on and work, providing an IV fixed position of the stator magnetic flux when the current flows through winding 10 (L1) in the direction shown;

- in the fifth half-period of the rectified voltage, transistor 4 (VT4) turns off, transistors 1 (VT1) and 6 (VT6) turn on and work, providing V a fixed position of the stator magnetic flux when current flows through winding 11 (L2) in the direction shown;

- in the sixth half-period of the rectified voltage, transistor 1 (VT1) turns off, transistors 3 (VT3) and 6 (VT6) turn on and work, providing a VI fixed position of the stator magnetic flux when current flows through windings 10 (L1) and 11 (L2) in the shown direction.

Starting from the seventh half-cycle, the switching cycle of the transistors is repeated, providing a circular rotation of the stator field.

To ensure rotation of the magnetic flux vector of the stator field of a single-phase two-winding induction motor in accordance with the vector diagram shown in Fig. 5, in the sequence I-II-III-IV-V-VI-VII-VIII, it is necessary to apply control pulses to transistors 1, 2, 3, 4, 5, 6 (VT1-VT6) in the following order:

- transistors 3 (VT3), 2 (VT2) turn on and work in the first half-period of the rectified voltage, providing I a fixed position of the stator magnetic flux when current flows along the stator winding 10 (L1) in the direction shown;

- in the second half-period of the rectified voltage, transistors 2 (VT2), 3 (VT3) and 5 (VT5) turn on and work, providing II a fixed position of the stator magnetic flux when current flows through the stator windings (10) LI and (11) L2 in the direction shown ;

- in the third half-period of the rectified voltage, transistor 3 (VT3) turns off, transistors 5 (VT5) and 2 (VT2) turn on and work, providing III a fixed position of the stator magnetic flux when current flows through the stator winding 11 (L2) in the direction shown;

- in the fourth half-period of the rectified voltage, transistor 2 (VT2) turns off, transistors 5 (VT5) and 4 (VT4) turn on and work, providing an IV fixed position of the stator magnetic flux when current flows through the stator windings 10 (L1) and 11 (L2) in direction shown;

- in the fifth half-period of the rectified voltage, the transistor 5 (VT5) turns off, transistors 1 (VT1) and 4 (VT4) turn on and work, providing a V fixed position of the stator magnetic flux when current flows along the stator winding 10 (L1) in the direction shown;

- in the sixth half-period of the rectified voltage, transistors 1 (VT1), 4 (VT4) and 6 (VT6) turn on and work, providing a VI fixed position of the stator magnetic flux when current flows through the stator windings 10 (L1) and 11 (L2) in the direction shown ;

- in the seventh half-period of the rectified voltage, the transistor 4 (VT4) turns off, transistors 1 (VT1) and 6 (VT6) turn on and work, providing VII a fixed position of the stator magnetic flux when current flows along the stator winding 11 (L2) in the direction shown;

- in the eighth half-period of the rectified voltage, transistor 1 (VT1) turns off, transistors 3 (VT3) and 6 (VT6) turn on and work, providing VIII a fixed position of the stator magnetic flux when current flows through the stator windings 10 (L1) and 11 (L2) in direction shown.

Starting from the ninth half-cycle, the switching cycle of the transistors is repeated, providing a circular rotation of the stator field.

Thus, changing the algorithm for turning on transistors, you can change (decrease) the engine speed in accordance with the formula:

Where

ω is the engine speed;

f _c - network frequency;

f _reg - adjusting frequency;

n is the number of half-periods involved in organizing a full 360 ° rotation of the stator's rotating magnetic field;

p is the number of pole pairs.

In addition, for each type of rotating field, high-frequency switching of transistors can be performed to increase the speed of rotation of the electric motor, switching transistors in the same order, but with a higher frequency, as with low-frequency switching of transistors.

Thus, the present invention can be used to control the speed of rotation of a single-phase two-winding induction motor when powered from a network of a half-wave rectified voltage, with high reliability and efficiency and small dimensions.

Claims (1)

A semiconductor device for controlling the speed of a single-phase two-winding induction motor, comprising reversible semiconductor switches made on semiconductor switches that are connected to a DC power network and designed to connect to the stator windings of a single-phase two-winding asynchronous motor, characterized in that a diode bridge connected to the phase and zero AC mains, each of the three reversible semiconductor switches is made on two transistors, with the odd transistor collectors of each semiconductor switch connected to the plus of the power supply network of the rectified half-wave voltage, the emitters of the odd transistors connected to the collectors of even transistors, and the emitters of the even transistors connected to the negative of the power network of the rectified two-wave voltage, and the common and even odd connection point transistors of the first reversible semiconductor switch designed to connect to the combined the stator windings of a single-phase two-winding induction motor, the common midpoint of the connection of the odd and even transistors of the second reversing semiconductor switch is designed to connect to the output of the first stator motor winding, the common midpoint of the connection of the odd and even transistors of the third reversing semiconductor switch is used to connect to the output of the second stator winding asynchronous single-phase two-winding motor.

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