RU2403671C1 - Semiconductor single-phase two-winding induction motor speed setter - Google Patents

Abstract

FIELD: electricity. ^ SUBSTANCE: reversible semiconductor switches are mounted on semiconductor keys which are connected to direct current mains, connected with stator windings of a single-phase two-windings induction motor. A diode bridge is connected to a phase and a zero point of alternating mains. Each of four reversible semiconductor switches represents a pair of transistors. Commutators of even transistors are connected to a plus point of rectified double-wave voltage of the diode bridge. Emitters of the even transistors are connected to the commutators collectors of odd transistors. The emitters of the odd transistors are connected to a minus point of the rectified double-wave voltage of the diode bridge. A junction midpoint of the commutator of the odd transistor and the emitter of the even transistor of each pair is connected to a corresponding lead of the stator windings of the single-phase two-winding induction motor. The device provides power supply of the single-phase two-winding induction motor from the double-wave direct current mains with enabled vector-algorithm rotation speed setting of the electric motor both under, and above the nominal. ^ EFFECT: simplified control system of the transistor switching, higher reliability and efficiency. ^ 9 dwg

Description

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

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 . - S.20, Fig. 78).

The main disadvantages of the described device are low reliability, high cost and increased dimensions due to the use of a paper capacitor to provide capacitive locking of thyristors and a smoothing power reactor, which reduces the ripple of the rectified DC voltage.

The present invention solves the problem of increasing reliability and efficiency, as well as reducing the dimensions of the device by providing power to a single-phase two-winding induction motor from a half-wave DC network with the possibility of low-frequency regulation of the rotation speed of the electric motor while simplifying 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, containing reversible semiconductor switches made on semiconductor switches that are connected to a DC power supply 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 four reversible semiconductor switches is made on a pair of transistors. In this case, the collectors of even transistors are connected to the plus of the rectified half-wave voltage coming from the diode bridge, the emitters of the even transistors are connected to the collectors of the odd transistors, the emitters of the odd transistors are connected to the minus of the rectified two-half-voltage, coming from the diode bridge, and the midpoint of the connection of the collector of the odd collector an even transistor of each pair is designed to connect to the corresponding output of the stator winding of a single-phase d uhobmotochnogo induction motor.

Improving the reliability, efficiency and reducing the dimensions of the device are provided due to the simplification of its power part in the absence of the use of a smoothing power reactor and a locking paper capacitor.

The use of the proposed semiconductor device for controlling the speed of a single-phase two-winding induction 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 control of the rotating stator magnetic field.

The invention is illustrated in the drawing, where figure 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 drawing shows the following:

- Ф - phase of the power source;

- 0 - zero power source;

- U _pit (t) - network power;

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

- L1, L2 - stator windings;

- VT1-VT8 - transistors;

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

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

- straight lines with arrows - current directions in the stator windings of a single-phase two-winding asynchronous motor.

The semiconductor device for controlling the speed of a single-phase two-winding induction motor contains a diode bridge connected to the phase and zero of the AC mains, as well as four reversing semiconductor switches made on semiconductor switches that are connected to the DC mains and are designed to connect to the stator windings of a single-phase two-winding induction motor. Each of the four reversible semiconductor switches is a pair of transistors that are used for vector-algorithmic switching of the windings of a single-phase two-winding asynchronous motor. The diode bridge introduced into the device is connected to the phase and zero of the AC mains. The collectors of even transistors are connected to the plus of the rectified half-wave voltage coming from the diode bridge, the emitters of the even transistors are connected to the collectors of the odd transistors, the emitters of the odd transistors are connected to the minus of the rectified half-wave voltage coming from the diode bridge. The middle point of the connection of the collector of the odd transistor and the emitter of the even transistor of each pair is designed to connect to the corresponding output of the stator winding of a single-phase two-winding induction motor.

Thus, the semiconductor device for controlling the speed of a single-phase two-winding asynchronous motor contains transistors 1, 2, 3, 4, 5, 6, 7, 8 (VT1-VT8) connected counter-parallel to two transistors in each of the four reversing semiconductor switches, and diode bridge 9 connected to the phase and zero of the AC mains.

In the first reversible semiconductor switch, the emitter of transistor 1 (VT1) is connected to the minus of the diode bridge 9, and the collector of transistor 1 (VT1) is connected to the emitter of transistor 2 (VT2), and their common output is designed to connect to the first output 10 (C1) of the winding L1 . The collector of transistor 2 (VT2) is connected to the plus of diode bridge 9. In the second reverse semiconductor switch, the emitter of transistor 3 (VT3) is connected to the minus of diode bridge 9, and the collector of transistor 3 (VT3) is connected to the emitter of transistor 4 (VT4), and their common the output is intended for connection with the second output 11 (C2) of the winding L1. The collector of transistor 4 (VT4) is connected to the plus of the diode bridge 9.

In the third reversible semiconductor switch, the emitter of transistor 5 (VT5) is connected to the minus of the diode bridge 9, and the collector of transistor 5 (VT5) is connected to the emitter of transistor 6 (VT6), and their common output is designed to connect to the first output 12 (C3) of the L2 winding . The collector of transistor 6 (VT6) is connected to the plus of diode bridge 9. In the fourth reverse semiconductor switch, the emitter of transistor 7 (VT7) is connected to the minus of diode bridge 9, and the collector of transistor 7 (VT7) is connected to the emitter of transistor 8 (VT8), and their common the output is intended for connection with the second output 13 (C2) of the winding L2. The collector of transistor 8 (VT8) is connected to the plus of the diode bridge 9.

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

The operation of the semiconductor device for controlling the speed of a single-phase two-winding induction motor is as follows.

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 2, in the sequence I-II-III, it is necessary to apply control pulses to transistors 1, 2, 3, 4, 5, 6, 7, 8 (VT1-VT8) in the following order:

- in the first half-wave of the supply voltage (I of Fig.6), transistors VT1, VT3 are turned on and operate, providing current flow through the winding L1, forming I fixed position of the stator magnetic field (Fig.2);

- in the second half-wave of the supply voltage (II of FIG. 6), transistors VT1, VT3 turn off, transistors VT2, VT4, VT5, VT8 turn on and work, providing current flow through the windings LI, L2, forming II a fixed position of the stator magnetic field (figure 2 );

- in the third half-wave of the supply voltage (III of FIG. 6), transistors VT5, VT8 are turned off, transistors VT7, VT6 are turned on and working, providing current flow through the windings L1, L2, forming III a fixed position of the stator magnetic field (FIG. 2).

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, 7, 8 (VT1-VT8) in the following order:

- in the first half-wave of the supply voltage (I of Fig. 7), transistors VT7, VT6 are turned on and operate, providing current flow through the winding L2, forming I a fixed position of the stator magnetic field (Fig. 3);

- in the second half-wave of the supply voltage (II of FIG. 7), transistors VT7, VT6 turn off, transistors VT1, VT3 turn on and work, ensuring the flow of current through the winding L1, forming II a fixed position of the stator magnetic field (figure 3);

- in the third half-wave of the supply voltage (III of FIG. 7), the transistors VT1, VT3 are turned off, the transistors VT5, VT8 are turned on and working, providing current flow through the winding L2, forming a III fixed position of the stator magnetic field (FIG. 3);

- in the fourth half-wave of the supply voltage (IV of Fig. 7), transistors VT5, VT8 are turned off, transistors VT2, VT4 are turned on and work, providing current flow through the winding L1, forming an IV fixed position of the stator magnetic field (Fig. 3).

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 4, in the sequence I-II-III-IV-V-VI, it is necessary to apply control pulses to the transistors 1, 2, 3, 4 , 5, 6, 7, 8 (VT1-VT8) in the following order:

- in the first half-wave of the supply voltage (I of Fig. 8), transistors VT1, VT3, VT7, VT6 are turned on and working, providing current flow through the windings L1, L2, forming I a fixed position of the stator magnetic field (Fig. 4);

- transistors VT7, VT6 are turned off in the second half-wave of the supply voltage (II of Fig. 8), ensuring the flow of current through the winding L1, forming II a fixed position of the stator magnetic field (Fig. 4);

- in the third half-wave of the supply voltage (III of Fig. 8), transistors VT5, VT8 are turned on and operate, providing current flow through the windings L1, L2, forming III a fixed position of the stator magnetic field (Fig. 4);

- in the fourth half-wave of the supply voltage (IV of Fig. 8), transistors VT1, VT3 turn off, transistors VT2, VT4 turn on and work, providing current flow through the windings L1, L2, forming an IV fixed position of the stator magnetic field (Fig. 4);

- in the fifth half-wave of the supply voltage (V of Fig. 8), transistors VT5, VT8 are turned off, providing current flow through the winding L1, forming a V fixed position of the stator magnetic field (Fig. 4);

- in the sixth half-wave of the supply voltage (VI of Fig. 8), transistors VT7, VT6 are turned on and operate, providing current flow through the windings L1, L2, forming a VI fixed position of the stator magnetic field (Fig. 4).

To ensure rotation of the magnetic flux vector of the stator field of the 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 the transistors 1, 2, 3, 4, 5, 6, 7, 8 (VT1-VT8) in the following order:

- in the first half-wave of the supply voltage (I of Fig. 9), transistors VT7, VT6 are turned on and operate, providing current flow through the winding L2, forming I a fixed position of the stator magnetic field (Fig. 5);

- in the second half-wave of the supply voltage (II of Fig. 9), transistors VT1, VT3 are turned on and operate, providing current flow through the windings L1, L2, forming II a fixed position of the stator magnetic field (Fig. 5);

- in the third half-wave of the supply voltage (III of FIG. 9), transistors VT7, VT6 are turned off, providing current flow through the winding L1, forming a III fixed position of the stator magnetic field (FIG. 5);

- in the fourth half-wave of the supply voltage (IV of Fig. 9), transistors VT5, VT8 are turned on and operate, providing current flow through the windings L1, L2, forming an IV fixed position of the stator magnetic field (Fig. 5);

- in the fifth half-wave of the supply voltage (V of Fig. 9), transistors VT1, VT3 are turned off, providing current flow through the winding L2, forming a V fixed position of the stator magnetic field (Fig. 5);

- in the sixth half-wave of the supply voltage (VI of Fig. 9), transistors VT2, VT4 are turned on and operate, providing current flow through the windings L1, L2, forming a VI fixed position of the stator magnetic field (Fig. 5);

- in the seventh half-wave of the supply voltage (VII of FIG. 9), transistors VT5, VT8 are turned off, providing current flow through the winding L1, forming VII a fixed position of the stator magnetic field (FIG. 5);

- in the eighth half-wave of the supply voltage (VIII of Fig. 9), transistors VT7, VT6 are turned on and operate, providing current flow through the windings L1, L2, forming VIII a fixed position of the stator magnetic field (Fig. 5).

In addition, for each type of rotating field, it is possible to perform both high-frequency switching of transistors to increase the speed of rotation of the electric motor, switching transistors in the same order, but with a higher frequency, and 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 half-wave DC network, 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 four reversible semiconductor switches nen on a pair of transistors, the even-ness transistor collectors connected to the plus of the rectified half-wave voltage coming from the diode bridge, the even-numbered transistor emitters connected to the odd transistor collectors, the odd-numbered transistor emitters connected to the minus of the rectified half-wave voltage coming from the diode bridge, and the middle point the odd transistor and the emitter of the even transistor of each pair is designed to connect to the corresponding output stator th winding of a single-phase double-winding induction motor.

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