RU109356U1 - SINGLE-PHASE-THREE-PHASE TRANSISTOR REVERSE SWITCH LED BY A SINGLE-PHASE NETWORK - Google Patents

Abstract

A single-phase-three-phase transistor reversing switch, driven by a single-phase network, refers to reversible semiconductor switches driven by a single-phase AC network, and is intended for use in an unregulated AC drive for supplying three-phase asynchronous motors from a single-phase network. A transistor is used as each of the two semiconductor switches. The emitter of the first transistor is designed to connect to the phase of the supply network, the collector of the first transistor is connected to the end of the second winding of a three-phase asynchronous motor. The emitter of the second transistor is designed to connect to the phase of the supply network, the collector of the second transistor is connected to the end of the third winding of a three-phase asynchronous motor. The beginning of the first winding of a three-phase asynchronous motor is connected to the phase, and its end to zero of the single-phase AC network. The beginning of the second and third windings are connected to zero single-phase AC network. Reliability and efficiency of the device are increased, as well as its dimensions are reduced.

Description

The proposed utility model relates to reversible semiconductor switches driven by a single-phase AC network, and can be used in an unregulated AC drive to power three-phase asynchronous motors from a single-phase network.

A device is known for supplying a three-phase induction motor from a single-phase network using a capacitor shift in the stator circuit, supplying power from a single-phase network of a three-phase asynchronous motor with windings connected to a star, in which one winding of a three-phase asynchronous motor is connected to a single-phase network through a capacitor to obtain a rotating stator field , and the other two windings - directly to a single-phase network (Voldek A.I. Electrical machines. A textbook for students of higher technical educational institutions tions / A.I.Voldek -. L .: Energy, 1974. - S.612, ris.30-7).

The main disadvantages of the described device for supplying a three-phase asynchronous motor from a single-phase network using a capacitor shift in the stator circuit is the need to use large-capacity paper capacitors, as a result of which the motor torque usually decreases by a factor of three, and the motor power drops to 50% of the nominal value.

The closest to the proposed utility model in terms of technical nature and the achieved result (prototype) - supplying a three-phase asynchronous motor from a single-phase AC network with reverse supply - is a single-phase-three-phase reversing switch containing semiconductor switches that connect the windings of a three-phase asynchronous motor to a single-phase mains alternating current. The beginning of the first winding of a three-phase asynchronous motor is connected to the phase, and its end to zero of the single-phase AC network. The beginning of the second and third windings are connected to zero single-phase AC network. Four lockable thyristors forming counter-parallel pairs are used as semiconductor switches, or four lockable transistors with diode protection forming counter-parallel pairs are used. The first semiconductor switch is connected to the phase of a single-phase AC network and to the end of the second winding of a three-phase asynchronous motor. The second semiconductor switch is connected to the phase of a single-phase AC network and to the end of the third winding of a three-phase asynchronous motor (patent RU 2344540, IPC Н02Р 1/42 (2006.01), Н02Р 25/04 (2006.01), Н02Р 27/16 (2006.01)).

The main disadvantages of the described single-phase-three-phase reversible switch are low reliability, increased dimensions and cost due to the need to use a large number of semiconductor elements forming semiconductor switches - four thyristors or four transistors with four diodes.

The proposed utility model solves the problem of increasing reliability and efficiency, as well as reducing the size of a single-phase-three-phase transistor reversing switch, driven by a single-phase network.

To solve this problem, in a single-phase-three-phase transistor reversing switch, driven by a single-phase network, equipped with semiconductor switches, the beginning of the first winding of a three-phase asynchronous motor is connected to the phase, and its end to zero of the single-phase AC network, the beginning of the second and third windings are connected to zero single-phase AC network, the first semiconductor switch is connected to the phase of the single-phase AC network and the end of the second winding of a three-phase asynchronous motor and the second semiconductor the dongle is connected to the phase of a single-phase AC network and to the end of the third winding of a three-phase induction motor, according to the proposed utility model, transistors are used as semiconductor switches, in which emitters are connected to the phase of the supply network, the collector of the first transistor is connected to the end of the second winding of a three-phase asynchronous motor and the collector the second transistor is connected to the end of the third winding of a three-phase induction motor.

The increase in reliability, efficiency and reduction in the size of a single-phase-three-phase transistor reversing switch, driven by a single-phase network, is due to the property of symmetric transistors to pass current in the key mode in both directions, which is the basis of the introduced semiconductor switch circuit, which are used precisely two transistors.

The proposed utility model is illustrated by drawings, where Fig. 1 shows a circuit diagram of a single-phase-three-phase transistor reversing switch driven by a single-phase network; figure 2 is a vector diagram of a circular rotating field of the stator of the engine, which consists of six fixed positions of the magnetic flux; figure 3 - the direction of the magnetic flux and the flowing current through the windings of the stator of the motor in accordance with the vector diagram shown in figure 2; figure 4 - phase-by-phase voltage change in the stator windings of the motor in accordance with the vector diagram shown in figure 2; figure 5 is a vector diagram of a circular rotating field of the stator of the motor, which consists of six fixed positions of the magnetic flux in the opposite direction of rotation of the motor; in Fig.6 - the direction of the magnetic flux and the flowing current along the stator windings of the motor in accordance with the vector diagram shown in Fig.5; in Fig.7 - phase-by-phase voltage variation in the stator windings of the motor in accordance with the vector diagram depicted in Fig.5.

In addition, the drawings show the following:

- f - phase;

- 0 - zero;

- C1-C6 - the findings of the stator windings of a three-phase asynchronous motor;

- VT1 and VT2 are transistors.

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

- straight lines with arrows - the direction of the magnetic flux vector of the circular rotating field of the stator of the motor;

- U set = f (t) is the change in supply voltage in time;

- straight lines with arrows along the stator windings of the motor - the direction of magnetic flux and current in the stator windings;

- t1-t5 - times of switching transistors.

A single-phase-three-phase transistor reversing switch, driven by a single-phase network, contains the first and second semiconductor switches, which are used as the first and second transistors, respectively. At the same time, the beginning of the first winding of a three-phase asynchronous motor is connected to the phase, and its end to zero of the single-phase AC network, the beginning of the second and third windings are connected to zero of the single-phase AC network. The emitters of both transistors, which are semiconductor switches, are connected to the phase of a single-phase AC network. The collector of the first transistor, which is the first semiconductor switch, is connected to the end of the second winding of a three-phase asynchronous motor. The collector of the second transistor, which is the second semiconductor switch, is connected to the end of the third winding of a three-phase induction motor.

An example of a single-phase-three-phase transistor reversing switch, driven by a single-phase network. The device contains two semiconductor switches, which are used as two transistors. The emitter of the first transistor 1 (VT1), which is the first semiconductor switch, is connected to the phase of the supply network, and the collector of this transistor is connected to the end of the second winding 2 (C4) of the three-phase induction motor. The emitter of the second transistor 3 (VT2), which is the second semiconductor key, is designed to connect to the phase of the supply network, and the collector of this transistor is connected to the end of the third winding 4 (C6) of the three-phase asynchronous motor.

The beginning of the first winding 5 (C1) of a three-phase induction motor is connected to the phase, and its end 6 (C2) is connected to zero of the single-phase AC network. The beginning of the second winding 7 (C3) and the third winding 8 (C5) are connected to zero single-phase AC network.

The operation of a single-phase-three-phase transistor reversing switch, driven by a single-phase network, is as follows. A single-phase alternating voltage is supplied to the stator windings of a three-phase asynchronous motor by switching the corresponding semiconductor switches, which provide a rotating magnetic field of the stator. To ensure the rotation of the magnetic flux vector of the circular rotating field of the stator of the motor in accordance with the vector diagram shown in figure 2, in the sequence I-II-III-IV-V-VI, it is necessary to apply a control voltage to the base of transistors 1 (VT1) and 2 (VT2) in the following sequence:

- at the initial moment of time, an unlocking control voltage is supplied to the base VT1 - 1, the fixed position of the stator field magnetic flux vector;

- at time t1, an unlocking control voltage is applied to the base VT2 - II, the fixed position of the stator field magnetic flux vector;

- at time t2, the unlocking control voltage is removed from the base VT1 - III, the fixed position of the stator field magnetic flux vector;

- at time t3, an unlocking control voltage is supplied to the base VT1 - IV, the fixed position of the stator field magnetic flux vector;

- at time t4, an unlocking control voltage is supplied to the base VT2

- V fixed position of the stator field magnetic flux vector;

- at time t5, the unlocking control voltage is removed from the base VT1 - V1, the fixed position of the stator field magnetic flux vector.

To ensure the rotation of the magnetic flux vector of the circular rotating field of the stator of the motor in accordance with the vector diagram shown in Fig. 5, in the sequence I-II-III-IV-V-VI, it is necessary to apply a control voltage to the base of transistors 1, 2 (VT1, VT2) in the following sequence:

- at the initial moment of time, an unlocking control voltage is supplied to the base VT2 - 1, the fixed position of the stator field magnetic flux vector;

- at time t1, an unlocking control voltage is supplied to the base VT1 - II, the fixed position of the stator field magnetic flux vector;

- at time t2, the unlocking control voltage is removed from the base VT2 - III, the fixed position of the stator field magnetic flux vector;

- at time t3, an unlocking control voltage is applied to the base VT2 - IV, the fixed position of the stator field magnetic flux vector;

- at time t4, an unlocking control voltage is supplied to base VT1

- V fixed position of the stator field magnetic flux vector;

- at time t5, the unlocking control voltage is removed from the base VT2 - VI, the fixed position of the stator field magnetic flux vector.

Thus, the proposed utility model has advantages over known analogues due to higher reliability and economy, as well as smaller dimensions.

Claims (1)

A single-phase-three-phase transistor reversing switch, driven by a single-phase network, equipped with semiconductor switches, the beginning of the first winding of a three-phase asynchronous motor connected to the phase, and its end to zero of the single-phase AC network, the beginning of the second and third windings connected to zero of the single-phase AC network, the first semiconductor switch is connected to the phase of the single-phase AC network and to the end of the second winding of the three-phase induction motor, and the second semiconductor switch is connected to the phase of one phase AC network and the end of the third winding of a three-phase induction motor, characterized in that transistors are used as semiconductor switches, in which emitters are connected to the phase of the supply network, the collector of the first transistor is connected to the end of the second winding of the three-phase induction motor, and the collector of the second transistor is connected to the end of the third winding of a three-phase induction motor.