RU163695U1 - SEMICONDUCTOR REDUCER LED BY A SINGLE-PHASE AC NETWORK - Google Patents

Abstract

A semiconductor reducer driven by a single-phase AC network, containing semiconductor switches, which are transistors connecting the stator windings of an asynchronous three-phase motor connected to a star to a single-phase AC mains, the beginning of the first stator winding of the asynchronous three-phase motor being connected to the phase, the ends three stator windings of an asynchronous three-phase motor are connected to a common zero point, which is connected to zero single-phase supply network of the current, the first transistor is connected to the beginning of the second stator winding of the asynchronous three-phase motor and the phase of the single-phase AC power supply, the second transistor is connected to the beginning of the third stator winding of the asynchronous three-phase motor and the phase of the single-phase AC power supply, characterized in that the field-effect transistors are used, when this, the first terminals of the first and second transistors are connected to the phase of the single-phase AC mains, the second terminal of the first transistor is connected to the beginning of the second the stator winding of an asynchronous three-phase motor, and the second terminal of the second transistor is connected to the beginning of the third stator winding of the asynchronous three-phase motor.

Description

The proposed utility model relates to unregulated frequency converters, driven by a single-phase AC network, and can be used in an AC electric drive to power asynchronous three-phase motors, the stator windings of which are connected to a star.

A device for controlling the rotational speed of an asynchronous three-phase electric motor from a single-phase network, containing semiconductor switches, which are used power elements such as three triacs or six thyristors for switching motor windings, connecting the stator windings of an asynchronous three-phase motor, connected to a star, to a single-phase supply network alternating current. One of the outputs of the triac or thyristor is connected to the phase of a single-phase AC mains, and the other output of the thyristor or triac is connected to the beginning of the corresponding stator winding. In this case, the ends of the stator windings of an asynchronous three-phase electric motor are connected to a common zero point, which is connected to zero of a single-phase AC mains (Glazenko T.A. Semiconductor systems of a pulsed asynchronous electric drive of low power / T.A. Glazenko. - Leningrad: ENERGOATOMIZDAT, 1983. - S. 61, Fig. 2-12, scheme No. 12).

The main disadvantages of the device for controlling the speed of an asynchronous three-phase electric motor from a single-phase network are low reliability and large dimensions due to the use of a large number of semiconductor switches.

The closest to the proposed utility model in terms of technical nature and the achieved result (prototype) is an adjustable single-phase three-phase semiconductor frequency converter driven by a network containing semiconductor switches, which are used bipolar transistors connecting the stator windings of an asynchronous three-phase motor connected to a star to phase of a single-phase AC mains supply. The beginning of the first stator winding of an asynchronous three-phase motor is connected to the phase. The ends of the three stator windings of an asynchronous three-phase motor are connected to a common zero point, which is connected to zero single-phase AC mains. The emitters of the first and second transistors are connected to the phase of a single-phase AC supply network. The collectors of the first and second transistors are connected to the beginnings of the second and third stator windings of an asynchronous three-phase motor, respectively. Bipolar transistors that transmit current in both directions in a pulsed key mode at an adjustable frequency are made on the basis of a symmetric internal structure (patent RU 136265, IPC H03K 17/00 (2006.01), Н02Р 25/04 (2006.01), Н02Р 27/16 (2006.01 ), Н02Р 1/42 (2006.01)).

The main disadvantages of this adjustable single-phase-three-phase semiconductor frequency converter driven by the network are low reliability due to increased heating due to the consumption of control current in the amplifier mode due to the operation of bipolar transistors on alternating current, the complexity of the control system of the device due to the need to take into account the polarity of the voltage passing through transistor at every moment of time and additional energy consumption for creating a control base current.

The proposed utility model solves the problem of improving the reliability and simplification of the control system, as well as reducing energy consumption for controlling the semiconductor keys of the device.

To solve the problem in a semiconductor gearbox driven by a single-phase AC network containing semiconductor switches, which are transistors connecting the stator windings of an asynchronous three-phase motor, connected to a star, to a single-phase AC mains, the beginning of the first stator winding of an asynchronous three-phase motor connected to the phase, the ends of the three stator windings of the asynchronous three-phase motor are connected to a common zero point, which is connected to zero of a single-phase AC mains supply, the first transistor is connected to the beginning of the second stator winding of an asynchronous three-phase motor and a phase of a single-phase AC mains supply, the second transistor is connected to the beginning of the third stator winding of an asynchronous three-phase motor and a phase of a single-phase AC network, according to a utility model transistors, while the first terminals of the first and second transistors are connected to the phase of a single-phase AC supply network, the second terminal is transistor is connected to the beginning of the second stator winding of the asynchronous three-phase motor, and the second terminal of the second transistor is connected to the beginning of the third three-phase stator windings of the asynchronous motor.

Improving reliability, simplifying the control system of the device and reducing energy consumption are due to the use of field-effect transistors as semiconductor switches that transmit current in both directions without the need to take into account the polarity of the voltage passing through the transistors and without applying a base current to the transistors, since the field-effect transistor is controlled electrostatic field created by charges.

The proposed utility model is illustrated by drawings, where in FIG. 1 shows a circuit diagram of a semiconductor gearbox driven by a single-phase AC network; in FIG. 2 is a vector diagram of a circular rotating field of a motor stator, which consists of six fixed positions of the magnetic flux; in FIG. 3-directions of the magnetic flux and current flowing through the stator windings of the motor in accordance with the vector diagram depicted in FIG. 2; in FIG. 4 - phase-by-phase voltage variation in the stator windings of the motor in accordance with the vector diagram depicted in FIG. 2.

In addition, the drawings show the following:

- f - phase;

- 0 - zero;

- A, B, C - stator windings of an asynchronous three-phase motor;

- VT1 and VT2 are field effect 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 network = f (t) - 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 are the times of switching transistors.

A semiconductor gearbox driven by a single-phase AC network contains semiconductor switches, which are field-effect transistors that connect the stator windings of an asynchronous three-phase motor connected to a star to a single-phase AC mains.

The first terminal 1 of the first transistor 2 (VT1) is connected to the phase of the single-phase AC mains, and the second terminal 3 of the first transistor 2 (VT1) is connected to the beginning 4 of the second stator winding B of the asynchronous three-phase motor. The first terminal 5 of the second transistor 6 (VT2) is connected to the phase of the single-phase AC mains, and the second terminal 7 of the second transistor 6 (VT2) is connected to the beginning of the third stator winding C of the asynchronous three-phase motor. Thus, the first transistor 2 (VT1) is connected to the beginning 4 of the second stator winding B of the asynchronous three-phase motor and the phase of the single-phase AC mains, and the second transistor 6 (VT2) is connected to the beginning 8 of the third stator winding C of the asynchronous three-phase motor and the phase of the single-phase supply AC power.

The beginning 9 of the first stator winding A of the motor is connected to the phase of a single-phase AC supply network. The ends of the three stator windings are interconnected to a common zero point 10 stars, which is connected to zero single-phase AC power supply.

The operation of a semiconductor gearbox driven by a single-phase alternating current network occurs as follows. Initially, a voltage is applied to the gates of all transistors, creating an electric field to close them. Vector-algorithmic control is carried out by removing the voltage from the gates of the corresponding transistors in a certain sequence. In order to ensure 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. 2, in the sequence I-II-III-IV-V-VI, it is necessary to carry out the removal of voltage from the gates of transistors 2 (VT1), 6 (VT2) in the following sequence:

- at the initial time, the voltage is removed from the gate of the transistor 6 (VT2) - an I fixed position of the stator field magnetic flux vector is formed;

- at time t1, voltage is applied to the gate of transistor 6 (VT2) - a fixed II position of the stator field magnetic flux vector is formed;

- at time t2, the voltage is removed from the gate of transistor 2 (VT1) - a III fixed position of the stator field magnetic flux vector is formed;

- at time t3, voltage is applied to the gate of transistor 2 (VT1), the voltage is removed from the gate of transistor 6 (VT2) - an IV fixed position of the stator field magnetic flux vector is formed;

- at time t4, voltage is applied to the gate of transistor 6 (VT2) - V fixed position of the magnetic field vector of the stator field is formed;

- at time t5, the voltage is removed from the gate of transistor 2 (VT1) - a VI fixed position is formed, the stator field magnetic flux vector.

Thus, on the basis of the foregoing, we can conclude that the proposed utility model has advantages over known similar devices due to the increased reliability and simplified transistor control system.

Claims (1)

A semiconductor reducer driven by a single-phase AC network, containing semiconductor switches, which are transistors connecting the stator windings of an asynchronous three-phase motor connected to a star to a single-phase AC mains, the beginning of the first stator winding of the asynchronous three-phase motor being connected to the phase, the ends three stator windings of an asynchronous three-phase motor are connected to a common zero point, which is connected to zero single-phase supply network of the current, the first transistor is connected to the beginning of the second stator winding of the asynchronous three-phase motor and the phase of the single-phase AC power supply, the second transistor is connected to the beginning of the third stator winding of the asynchronous three-phase motor and the phase of the single-phase AC power supply, characterized in that the field-effect transistors are used, when this, the first terminals of the first and second transistors are connected to the phase of the single-phase AC mains, the second terminal of the first transistor is connected to the beginning of the second the stator winding of an asynchronous three-phase motor, and the second terminal of the second transistor is connected to the beginning of the third stator winding of the asynchronous three-phase motor.

Images