RU2403670C1 - Network driven adjustable transistor reducer with explicit direct current link - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: single-phase bridge self-excited inverters / frequency converters are presented on semi-conductor keys connected to a power direct-current mains wherein stator windings are connected to the midpoints of the series semiconductor keys. One alternating voltage output of a connected diode bridge is connected to a mains phase, the other alternating voltage output of the diode bridge is connected to mains zero. A positive direct voltage output of the diode bridge is connected to commutators of the transistors being the semiconductor keys and used with base lock. The negative direct voltage output of the diode bridge is connected to emitters of these transistors. The rotation under frequency of the electromagnetic field generated by a stator is enabled by vector-algorithm switching of the corresponding network-driven transistors.

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 with a pronounced DC link 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 lack of low-frequency regulation of the rotational speed 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 motor windings is regulated, containing single-phase bridge autonomous frequency inverters-converters made on semiconductor switches connected to a direct current supply network, as well as a smoothing power reactor, and a locking paper capacitor connected in parallel but the stator winding of the motor. Each single-phase bridge autonomous inverter-frequency converter is made on thyristors, which are four semiconductor switches. Stator windings are connected to the midpoints of the series-connected semiconductor switches. One output of the smoothing power reactor is connected to the plus of the DC supply network, and the second output is connected to the anodes of the two thyristors. The cathodes of these thyristors are connected to the stator winding of the motor, respectively, as well as to the anodes of another pair of thyristors. The cathodes of the last pair of thyristors are connected to the minus of the DC supply network. The first and second capacitor plates are connected to the first and second terminals of the stator winding of the motor, respectively (Labuntsov V.A. Autonomous thyristor inverters / V.A.Labuntsov, G.A. Rivkin, G.I.Shevchenko. - M - L .: “ Energy ”, 1967. - p.20, Fig. 7c).

The main disadvantages of the described device are low reliability, high cost and increased dimensions due to the use of paper capacitors to provide capacitive locking of thyristors and a smoothing power reactor, which reduces the ripple of the rectified DC voltage, as well as a complex control system for switching thyristors of inverters, providing control by pulse-width modulation .

The present invention solves the problem of increasing reliability and efficiency, as well as reducing the dimensions of the device while providing vector-algorithmic control.

To solve this problem, an adjustable transistor gearbox with a pronounced DC link, driven by a network, containing single-phase bridge autonomous frequency inverters-inverters, made on semiconductor switches connected to a DC supply network, in which windings are connected to the midpoint of the series-connected semiconductor switches stator, according to the invention, a diode bridge is introduced, in which one AC output is connected to the phase of the supply network, the other output is the alternating voltage is connected to zero of the mains supply, the positive output of the constant voltage is connected to the collectors of transistors, which are semiconductor switches and used to lock on the base, and the negative output of the constant voltage is connected to the emitters of the transistors, when the rotation frequency of the stator electromagnetic field is reduced by vector-algorithm switching transistors driven by the network.

The use of an adjustable transistor reducer with a pronounced DC link driven by the network in a single-phase network causes the creation of a rotating stator magnetic field by means of algorithmic switching of transistors, which allows one to obtain not only the required current direction in the stator windings, but also a reduced frequency of the stator rotating magnetic field.

Improving the reliability, efficiency and reducing the size of the device are ensured by simplifying both the power part of the device and the control system for switching transistors in a single-phase bridge autonomous inverter-frequency converter.

The invention is illustrated by drawings, where in Fig.1 shows a circuit diagram of an adjustable transistor gearbox with a pronounced DC link driven by the network; figure 2 is a vector diagram of the rotation of the magnetic flux of the stator field, consisting of four fixed positions; figure 3 is a vector diagram of the rotation of the magnetic flux of the stator field, consisting of eight 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 three fixed positions; figure 6 - phase-by-phase change in magnetic flux in the stator windings in accordance with the vector diagram shown in figure 2; in Fig.7 - phase-by-phase change in the magnetic flux in the stator windings in accordance with the vector diagram shown in Fig.3; on Fig - phase-by-phase change in the magnetic flux in the stator windings in accordance with the vector diagram depicted in figure 4; figure 9 is a phase-by-phase change in the magnetic flux in the stator windings in accordance with the vector diagram depicted in figure 5; figure 10 - phase-by-phase change in the magnetic flux in the stator windings for high-frequency speed control in accordance with the vector diagram shown in figure 2; figure 11 - 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; on Fig - phase-by-phase change in magnetic flux in the stator windings in accordance with the vector diagram depicted in figure 5.

In addition, the drawings show the following:

- f - phase;

- 0 - zero;

- t ₁ -t ₈ - time intervals;

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

- L1, L2 - stator windings.

- V1-V8 - transistors;

- VD1-VD4 - diodes;

- 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;

- π, 2π, 3π, 4π, 5π, 6π, 7π, 8π, 9π - half-periods of the rectified voltage;

- arcuate lines with an arrow - the direction of rotation of the stator magnetic field;

- U _vyp. = f (t) is the change in the rectified voltage in time.

An adjustable transistor gearbox with a pronounced DC link driven by the network contains single-phase bridge autonomous frequency inverters-converters, made on semiconductor transistors, which are semiconductor switches and are used with locking on the base, connected to the DC power network. In single-phase bridge autonomous frequency inverters-inverters, stator windings are connected to the midpoint of the series-connected transistors. In the diode bridge introduced into the device, one AC output is connected to the phase of the supply network, the other AC output is connected to zero of the supply network, the positive DC output is connected to the transistor collectors, and the negative DC output is connected to the emitters of these transistors. In this case, a non-smoothed single-phase two-half-wave rectified rectified voltage of the power source is used, and the frequency of the rotating electromagnetic field of the stator is reduced by vector-algorithm switching of the corresponding transistors driven by the network.

An example of an adjustable transistor gearbox with a pronounced DC link driven by the network. An adjustable transistor gearbox with a pronounced DC link contains two single-phase bridge autonomous inverters-frequency converters, each of which has four semiconductor transistors 1, 2, 3, 4 (V1-V4) and 5, 6, 7, 8 (V5- V8), and also contains a diode rectifier bridge formed by diodes 9, 10, 11, 12 (VD1-VD4). One AC output of the diode bridge, i.e., the anode of the diode 12 (VD1) and the cathode of the diode 11 (VD2), is connected to the phase of the DC supply network, and the other AC output, i.e. the anode of the diode 9 (VD3) and the cathode of the diode 10 (VD4 ) are connected to zero DC power supply.

Four transistors 5, 6, 7, 8 (V5-V8) are connected to the winding 13 (L1) of the stator of a single-phase two-winding induction motor, connected in two in series in each branch - transistors 5, 6 (V5, V6) and transistors 7, 8 ( V7, V8) - and connected in parallel in two branches - transistors 5, 8 (V5, V8) and transistors 6, 7 (V6, V7). In this case, the winding 13 (L1) is connected to the midpoints of the series-connected transistors 5, 6 (V5, V6) and 7, 8 (V7, V8).

Four transistors 1, 2, 3, 4 (V1-V4) are connected to winding 14 (L2) of the stator of a single-phase two-winding induction motor, connected in two in series in each branch - transistors 1, 4 (V1, V4) and transistors 2, 3 ( V2, V3) - and connected in parallel in two branches - transistors 3, 4 (V3, V4) and transistors 1, 2 (V1, V2). In this case, the winding 14 (L2) is connected to the midpoints of the series-connected transistors 1, 4 (V1, V4) and 2, 3 (V2, V3).

Thus, to the midpoints of two pairs of semiconductor transistors formed by transistors 1, 4 and 2, 3 (V1-V4), a winding 14 (L2) with terminals 15, 16 (C3-C4) of the stator of a single-phase two-winding asynchronous motor is connected. The midpoints of two pairs of semiconductor transistors formed by transistors 5, 8 and 6, 7 (V5-V8) are connected to winding 13 (L1) with the terminals 17, 18 (C1-C2) of the stator of a single-phase two-winding induction motor.

The emitter of transistor 4 (V4) and the collector of transistor 1 (V1) are connected to terminal 15 (C3) of the stator winding. The emitter of transistor 3 (V3) and the collector of transistor 2 (V2) are connected to terminal 16 (C4) of the stator winding. The emitter of transistor 6 (V6) and the collector of transistor 7 (V7) are connected to terminal 18 (C2) of the stator winding. The emitter of transistor 5 (V5) and the collector of transistor 8 (V8) are connected to terminal 17 (C1) of the stator winding.

The emitter of transistor 7 (V7) and the emitter of transistor 8 (V8) are connected to the emitter of transistor 1 (V1) and the emitter of transistor 2 (V2), as well as to the minus of the diode bridge. The collector of transistor 5 (V5) and the collector of transistor 6 (V6) are connected to the collector of transistor 4 (V4) and the collector of transistor 3 (V3), as well as to the plus of the diode bridge.

Transistors 1, 2, 3, 4, 5, 6, 7, 8 (V1-V8) can have either an “n-p-n” or a “p-n-p” structure.

Using an adjustable transistor gearbox with a pronounced DC link, a vectorial-algorithmic control of a single-phase two-winding asynchronous electric motor is performed when creating several types of rotating stator fields: passing through or four successive fixed positions of the magnetic flux vector of a circular rotating field while simultaneously turning on only one of the stator windings of the motor, or eight consecutively fixed positions of the magnetic flux vector circle of the rotating stator field of the motor stator, while turning on one or two stator windings, or six consecutively fixed positions of the magnetic flux vector of the circular rotating field of the stator motor, also with two or one simultaneously turned on stator winding, or three sequentially fixed positions of the magnetic flux vector of the circular rotating field stator.

Vector control of a single-phase two-winding asynchronous motor when passing four consecutive fixed positions of the stator magnetic flux vector per engine revolution while simultaneously turning on only one stator winding of the 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-IV, it is necessary to apply control pulses to transistors 1, 2, 3, 4, 5, 6 , 7, 8 (V1-V8) in the following order (Fig.6):

- in the first half-cycle of the supply voltage, transistors 6, 8 (V6, V8) are turned on and operate, providing current flow through the winding 13 (L1) in the shown direction in Fig. 6 and forming an I fixed position of the magnetic flux of the stator field;

- in the second half-cycle of the supply voltage, transistors 2, 4 (V2, V4) turn on and work, ensuring the flow of current through the winding 14 (L2) in the shown direction in Fig.6 and forming II a fixed position of the magnetic flux of the stator field, while transistors 6, 8 (V6, V8) are disabled;

- in the third half-cycle of the supply voltage, transistors 5, 7 (V5, V7) are turned on and operate, providing current flow through the winding 13 (L1) in the shown direction in Fig. 6 and forming III a fixed position of the magnetic flux of the stator field, while transistors 2, 4 (V2, V4) are disabled;

- in the fourth half-cycle of the supply voltage, transistors 1, 3 (V1, V3) turn on and work, providing current flow through the winding 14 (L2) in the shown direction in Fig. 6 and forming an IV fixed position of the magnetic flux of the stator field, while transistors 5, 7 (V5, V7) are disabled.

- in the fifth and subsequent half-periods, the process is repeated starting from the first half-period.

.With the above-described transistor switching sequences, this adjustable transistor gearbox with a pronounced DC link driven by the network allows the motor to operate at a frequency

.

To ensure rotation of the magnetic flux vector of the stator field of a two-phase asynchronous electric motor in accordance with the vector diagram shown in figure 3, 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 (V1-V8) in the following order (Fig.7):

- in the first half-cycle of the supply voltage, transistors 6, 8 (V6, V8) are switched on and operate, providing current flow through the winding 13 (L1) in the shown direction in Fig. 7 and forming an I fixed position of the magnetic flux of the stator field;

- in the second half-cycle of the supply voltage, transistors 2, 4 (V2, V4) are turned on and transistors 6, 8 (V6, V8) are turned on, providing current flow through the windings 13, 14 (L1, L2) in the direction shown in FIG. 7 and forming a fixed position II of the magnetic flux of the stator field;

- in the third half-cycle of the supply voltage, transistors 2, 4 (V2, V4) continue to operate, providing current flow through the winding 14 (L2) in the shown direction in Fig. 7 and forming III a fixed position of the magnetic flux of the stator field, while transistors 6, 8 (V6, V8) are disabled;

- in the fourth half-cycle of the supply voltage, transistors 2, 4 (V2, V4) continue to operate and transistors 5, 7 (V5, V7) are turned on, providing current flow through the windings 13, 14 (L1, L2) in the direction shown in Fig. 7 and forming IV a fixed position of the magnetic flux of the stator field;

- in the fifth half-cycle of the supply voltage, transistors 5, 7 (V5, V7) continue to operate, providing current flow through the winding 13 (L1) in the shown direction in Fig. 7 and forming a V fixed position of the magnetic flux of the stator field, and transistors 2, 4 ( V2, V4) are disabled;

- in the sixth half-cycle of the supply voltage, transistors 1, 3 (V1, V3) turn on and work, and transistors 5, 7 (V5, V7) continue to operate, providing current flow through the windings 13, 14 (L1, L2) in the direction shown in FIG. 7 and forming a V1 fixed position of the magnetic flux of the stator field;

- in the seventh half-cycle of the supply voltage, transistors 1, 3 (V1, V3) continue to operate, providing current flow through the winding 13 (L1) in the shown direction in Fig. 7 and forming the VII fixed position of the magnetic flux of the stator field, and transistors 5, 7 ( V5, V7) are disabled;

- in the eighth half-cycle of the supply voltage, transistors 1, 3 (V1, V3) continue to operate and transistors 6, 8 (V6, V8) are turned on, providing current flow through the windings 13, 14 (L1, L2) in the direction shown in Fig. 7 and forming a VIII fixed position of the magnetic flux of the stator field;

- in the ninth half-cycle, the repetition of the first half-cycle begins and so on, similar to the description above.

.With the above-described transistor switching sequences, this adjustable transistor gearbox with a pronounced DC link driven by the network allows the motor to operate at a frequency

.

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 transistors 1, 2, 3, 4, 5, 6, 7, 8 (V1-V8) in the following order (Fig. 8):

- in the first half-cycle of the supply voltage, transistors 6, 8 (V6, V8) are switched on and operate, providing current flow through the winding 13 (L1) in the shown direction in Fig. 8 and forming an I fixed position of the magnetic flux of the stator field;

- in the second half-cycle of the supply voltage, transistors 2, 4 (V2, V4) turn on and work, and 6, 8 (V6, V8) are turned on, providing current flow through the windings 13, 14 (L1, L2) in the direction shown in Fig. 8 and forming II a fixed position of the magnetic flux of the stator field;

- in the third half-cycle of the supply voltage, transistors 2, 4 (V2, V4) continue to operate and transistors 5, 7 (V5, V7) are switched on, providing current flow through the windings 13, 14 (L1, L2) in the direction shown in Fig. 8 and forming III a fixed position of the magnetic flux of the stator field, and transistors 6, 8 (V6, V8) are disabled;

- in the fourth half-period of the supply voltage, transistors V5, V7 continue to operate, providing current flow through the winding L1 in the shown direction in Fig. 8 and forming an IV fixed position, the transistors V2, V4 are turned off;

- in the fifth half-cycle of the supply voltage, transistors 1, 3 (V1, V3) are turned on and transistors 5, 7 (V5, V7) are turned on, providing current flow through the windings 13, 14 (L1, L2) in the direction shown in FIG. 8 and forming a V fixed position of the magnetic flux of the stator field;

- in the sixth half-cycle of the supply voltage, transistors 1, 3 (V1, V3) continue to operate and transistors 6, 8 (V6, V8) are turned on, providing current flow through the windings 13, 14 (L1, L2) in the direction shown in Fig. 8 and forming VI a fixed position of the magnetic flux of the stator field, and transistors 5, 7 (V5, V7) are turned off;

- starting from the 7th half-cycle, the transistor control is repeated as described, starting from the first half-cycle.

.With the above-mentioned sequences of switching on transistors, this adjustable transistor gearbox with a pronounced DC link driven by the network allows the motor to work at a frequency

.

To ensure rotation of the magnetic flux vector of the stator field of a two-phase asynchronous electric motor in accordance with the vector diagram shown in figure 5, in the sequence I-II-III, it is necessary to apply control pulses to transistors 1, 2, 3, 4, 5, 6, 7, 8 (V1-V8) in the following order (Fig.9):

- in the first half-cycle of the supply voltage, transistors 6, 8 (V6, V8) are switched on and operate, providing current flow through the winding 13 (L1) in the shown direction in Fig. 9 and forming an I fixed position of the magnetic flux of the stator field;

- in the second half-cycle of the supply voltage, transistors 2, 4, 5, 7 (V2, V4, V5, V7) turn on and work, providing current flow through the windings 13, 14 (L1, L2) in the direction shown in Fig. 9 and forming II a fixed position of the magnetic flux of the stator field, while the transistors 6, 8 (V6, V8) are turned off;

- in the third half-cycle of the supply voltage, transistors 1, 3 (V1, V3) are turned on and transistors 5, 7 (V5, V7) are turned on, and currents flow through the windings 13, 14 (L1, L2) in the direction shown in FIG. 9 and forming III a fixed position of the magnetic flux of the stator field, while the transistors 2, 4 (V2, V4) are turned off.

- starting from the fourth half-cycle, the process of turning on the transistors is repeated similarly to the above description.

.With the above-mentioned transistor switching sequences, this adjustable transistor gearbox with a pronounced DC link driven by the network allows the electric motor to operate at a frequency

.

In addition, during each half-cycle, 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.

For example, 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-IV, it is necessary to apply control pulses to transistors 1, 2, 3, 4, 5 , 6, 7, 8 (V1-V8) in the following order (figure 10):

- at time t ₁ , transistors 6, 8 (V6, V8) turn on and work, providing current flow through the winding 13 (L1) in the shown direction in Fig. 10 and forming an I fixed position of the magnetic flux of the stator field;

- at time t ₂ , transistors 2, 4 (V2, V4) turn on and work, providing current flow through the winding 14 (L2) in the shown direction in Fig. 10 and forming II a fixed position of the magnetic flux of the stator field, while transistors 6, 8 (V6, V8) are disconnected;

- at time t ₃ , transistors 5, 7 (V5, V7) turn on and work, providing current flow through the winding 13 (L1) in the shown direction in Fig. 10 and forming III a fixed position of the magnetic flux of the stator field, while transistors 2, 4 (V2, V4) are disconnected;

- at time t ₄ , transistors 1, 3 (V1, V3) turn on and work, providing current flow through the winding 14 (L2) in the shown direction in Fig. 10 and forming IV a fixed position of the magnetic flux of the stator field, while transistors 5, 7 (V5, V7) are disconnected;

- then the process of turning on the transistors is repeated starting from time t ₁ .

With the above-mentioned transistor switching sequences, this adjustable transistor gearbox with a pronounced DC link driven by the network allows the electric motor to operate at a frequency of 2 · f of the _network .

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-V-VI-VII-VIII, it is necessary to apply control pulses to the transistors 1, 2 , 3, 4, 5, 6, 7, 8 (V1-V8) in the following order (Fig. 11):

- at time t ₁ , transistors 6, 8 (V6, V8) turn on and work, providing current flow through the winding 13 (L1) in the shown direction in Fig. 11 and forming an I fixed position of the magnetic flux of the stator field;

- at time t ₂ , transistors 2, 4 (V2, V) 4 are turned on and transistors 6, 8 (V6, V8) are turned on, providing current flow through the windings 13, 14 (L1, L2) in the direction shown in FIG. .11 and forming a fixed position II of the magnetic flux of the stator field;

- at time t ₃ , transistors 2, 4 (V2, V4) continue to operate, providing current flow through the winding 14 (L2) in the shown direction in Fig. 11 and forming III a fixed position of the magnetic flux of the stator field, while transistors 6, 8 (V6, V8) are disconnected;

- at time t ₄ , transistors 2, 4 (V2, V4) continue to operate and transistors 5, 7 (V5, V7) are turned on, providing current flow through the windings 13, 14 (L1, L2) in the direction shown in FIG. 11 and forming IV a fixed position of the magnetic flux of the stator field;

- at time t ₅ , transistors 5, 7 (V5, V7) continue to operate, providing current flow through the winding 13 (L) in the direction shown in Fig. 11 and forming a fixed position of the magnetic flux of the stator field, and transistors 2, 4 ( V2, V4) are disconnected;

- at time t ₆ , transistors 1, 3 (V1, V3) turn on and work, and transistors 5, 7 (V5, V7) continue to operate, providing current flow through the windings 13, 14 (L1, L2) in the direction shown in FIG. 11 and forming a VI fixed position of the magnetic flux of the stator field;

- at time t ₇ , transistors 1, 3 (V1, V3) continue to operate, providing current flow through the winding 13 (L1) in the shown direction in Fig. 11 and forming VII a fixed position of the magnetic flux of the stator field, while transistors 5, 7 (V5, V7) are disconnected;

- at time t ₈ , transistors 1, 3 (V1, V3) continue to operate and transistors 6, 8 (V6, V8) are turned on, providing current flow through the windings 13, 14 (L1, L2) in the direction shown in FIG. 11 and forming VIII a fixed position of the magnetic flux of the stator field.

- then the process of turning on the transistors is repeated starting from time t ₁ .

With the above-described transistor switching sequences, this adjustable transistor gearbox with a pronounced DC link driven by the network allows the motor to operate at a frequency of 2 · f _network .

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 transistors 1, 2, 3, 4, 5, 6, 7, 8 (V1-V8) in the following order (Fig. 12):

- at time t ₁ , transistors 6, 8 (V6, V8) turn on and work, providing current flow through the winding 13 (L1) in the shown direction in Fig. 12 and forming an I fixed position of the magnetic flux of the stator field;

- at time t ₂ , transistors 2, 4 (V2, V4) are turned on and transistors 6, 8 (V6, V8) are turned on, providing current flow through the windings 13, 14 (L1, L2) in the direction shown in FIG. 12 and forming a fixed position II of the magnetic flux of the stator field;

- at time t ₃ , transistors 2, 4 (V2, V4) continue to operate and transistors 5, 7 (V5, V7) are turned on, providing current flow through the windings 13, 14 (L1, L2) in the direction shown in Fig. 12 and forming III a fixed position of the magnetic flux of the stator field, and transistors 6, 8 (V6, V8) are turned off;

- at time t ₄ , transistors 5, 7 (V5, V7) continue to operate, providing current flow through the winding 13 (L1) in the direction shown in Fig. 12 and forming an IV fixed position of the magnetic flux of the stator field, and transistors 2, 4 ( V2, V4) are disconnected;

- at time t ₅ , transistors 1, 3 (V1, V3) are turned on and transistors 5, 7 (V5, V7) are turned on, providing current flow through the windings 13, 14 (L1, L2) in the direction shown in FIG. 12 and forming a V fixed position of the magnetic flux of the stator field;

- at time t ₆ , transistors 1, 3 (V1, V3) continue to operate and transistors 6, 8 (V6, V8) are turned on, providing current flow through the windings 13, 14 (L1, L2) in the direction shown in Fig. 12 and forming VI a fixed position of the magnetic flux of the stator field, and transistors 5, 7 (V5, V7) are turned off;

- then the process of turning on the transistors is repeated starting from time t ₁ .

With the above-mentioned transistor switching sequences, this adjustable transistor gearbox with a pronounced DC link driven by the network allows the electric motor to operate at a frequency of 2 · f of the _network .

To ensure rotation of the magnetic flux vector of the stator field of the two-phase induction motor in accordance with the vector diagram shown in figure 5, in the sequence I-II-III, it is necessary to apply control pulses to the transistors 1, 2, 3, 4, 5, 6, 7, 8 (V1-V8) in the following order (Fig.13):

- at time t ₁ , transistors 6, 8 (V6, V8) turn on and work, providing current flow through the winding 13 (L1) in the shown direction in Fig. 13 and forming an I fixed position of the magnetic flux of the stator field;

- at time t ₂ , transistors 2, 4, 5, 7 (V2, V4, V5, V7) turn on and work, providing current flow through the windings 13, 14 (L1, L2) in the direction shown in Fig. 13 and forming II a fixed position of the magnetic flux of the stator field, while the transistors 6, 8 (V6, V8) are turned off;

- at time t ₃ , transistors 1, 3 (V1, V3) are turned on and transistors 5, 7 (V5, V7) are turned on, providing current flow through the windings 13, 14 (L1, L2) in the direction shown in FIG. 13 and forming a III fixed position of the magnetic flux of the stator field, while the transistors 2, 4 (V2, V4) are turned off;

- then the process of turning on the transistors is repeated starting from time t ₁ .

With the above transistor switching sequences, this adjustable transistor gearbox with a pronounced DC link driven by the network allows the motor to operate at a frequency of 2 · f _network . Similarly, you can form the work of an asynchronous electric motor at higher speeds, while to increase the frequency of rotation of the electric motor, you can completely skip two, three, four and so on times the vector diagrams shown in figure 2-5, as well as a fractional number of times .

Thus, the present invention can be used for wide control of the rotation speed of a single-phase two-winding asynchronous electric motor when powered by an alternating voltage of a single-phase network, with high reliability and cost-effectiveness and small dimensions.

Claims (1)

An adjustable transistor gearbox with a pronounced DC link driven by a network, containing single-phase bridge autonomous frequency inverters-inverters, made on semiconductor switches connected to a DC supply network, in which stator windings are connected to the midpoints of the semiconductor switches connected in series, characterized in that that a diode bridge is introduced, in which one AC output of which is connected to the phase of the supply network, another AC output is connected to zero the mains supply, the positive DC output is connected to the collectors of transistors, which are semiconductor switches and used to lock on the base, and the negative output of the DC voltage is connected to the emitters of these transistors, while decreasing the frequency of rotation of the stator electromagnetic field by vector-algorithm switching of the corresponding transistors driven by a network.

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