RU2467466C1 - Transistor heteropolar frequency converter that controls speed of synchronous step motor - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention refers to the sphere of electrical engineering. A transistor heteropolar frequency converter that controls speed of a synchronous motor is designed for use in a controlled electric drive with a synchronous step motor, when supplied from a network of AC single-phase voltage. Transistors of each of three reversible transistor switches connected to a source of supply are connected in parallel. A source of supply to reversible transistor switches is a source of AC single-phase voltage. Emitters of the first transistors of each reversible transistor switch are connected to a phase of a supply network. Emitters of the second transistors of each reversible transistor switch are connected to a zero of a supply network. Collectors of transistors of the first reversible transistor switch are combined and connected to the first output of the first control winding. Collectors of transistors of the second reversible transistor switch are combined and connected to the first output of the second control winding. Second outputs of the first and second control windings are combined. Collectors of transistors of the third reversible transistor switch are also combined and connected to combined second outputs of the first and second control windings.

EFFECT: reliability improvement.

Description

The present invention relates to frequency converters operating directly from an AC voltage source, and can be used in a controlled electric drive with a synchronous stepper motor, when powered from a single-phase AC voltage network.

Known four-cycle pulse distributor containing four transistors, each of which feeds the corresponding control winding. Each of the four transistors acts as a switch that supplies voltage to the control windings of a synchronous stepper motor. These transistors are interconnected in parallel and connected to a constant voltage source. The emitters of these transistors are connected directly to the minus of the constant voltage source, and each of the collectors of these transistors is connected to the corresponding control winding and, through the corresponding resistors, to the plus of the constant voltage source. Each base of the corresponding transistor is supplied with a control pulse for opening and closing the transistors (M.G. Chilikin. Discrete electric drive with stepper motors. / Chilikin V.V. - M .: Energy, 1971. - P. 223, Fig. 6-4 )

The disadvantages of this device are the low reliability due to the mandatory presence of a constant voltage source and the inability to use it to work with a two-phase synchronous stepper motor due to the implementation of only unipolar control.

Closest to the proposed invention in terms of technical nature and the achieved result (prototype) is a single-phase voltage inverter powered by a stabilized power source, which is used as a constant voltage source. A single-phase voltage inverter contains two reversible transistor switches, in each of which transistors are connected in parallel. Moreover, each of the switches has two transistors and two diodes. The transistor collectors of the first switch are combined and connected to the plus of the DC voltage source. The emitters of the transistors of the second switch are combined and connected to the negative of the DC voltage source. The emitter of the first transistor of the first switch and the collector of the first transistor of the second switch are combined and connected to the input of the active-inductive load. The emitter of the second transistor of the first switch and the collector of the second transistor of the second switch are combined and connected to the output of the active-inductive load. The anode of each of the diodes shunting the transistors is connected to the emitter, and the cathode is connected to the collector of the corresponding transistor (Yu.K. Rozanov. Fundamentals of power electronics. / Rozanov Yu.K. - M .: Energoatomizdat, 1992. - P.132, fig. .3.15).

The disadvantages of this device are low reliability due to the presence of a stabilized DC voltage source, which is an additional converter link lowering the reliability of the inverter, high cost due to the large number of four transistors and diodes per active inductive load, which can be used as one motor winding .

The present invention solves the problem of increasing the reliability and efficiency of a transistor bipolar frequency converter that controls the speed of a synchronous stepper motor.

To solve the problem in a transistor bipolar frequency converter that controls the speed of a synchronous stepper motor, containing reversible transistor switches connected to a power source, in each of which transistors are connected in parallel, and the collectors of the transistors of the first reversible transistor switch are combined, according to the invention, as a power source of reversible transistor switches used an alternating single-phase voltage source. In this case, the emitters of the first transistors of each reverse transistor switch are connected to the phase of the supply network, the emitters of the second transistors of each reverse transistor switch are connected to zero of the supply network, the collectors of the transistors of the first reverse transistor switch are connected to the first output of the first control winding, the collectors of the transistors of the second reverse transistor switch and connected to the first output of the second control winding. The second outputs of the first and second control windings are combined, and the transistor collectors of the third reverse transistor switch are also combined and connected to the combined second outputs of the first and second control windings.

The increase in reliability of the device is due to the use of an alternating single-phase voltage source as a power source in the absence of a stabilized DC voltage source.

The use of a transistor bipolar frequency converter that regulates the speed of a synchronous stepper motor from a single-phase AC network is determined by the frequency-vector algorithmic switching of transistors. This is possible due to the use of the symmetric structure of the transistors to conduct current in both directions in the key mode, which allows to create various types of stepwise rotating magnetic fields of the stator of a synchronous stepper motor, providing enhanced functionality when adjusting the frequency of the rotating magnetic field of the stator of a synchronous stepper motor, and therefore and motor speed.

The invention is illustrated by drawings, in which Fig. 1 is a circuit diagram of a transistor bipolar frequency converter of the invention that controls the speed of a synchronous stepper motor from a single-phase AC 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 six fixed positions; figure 4 - phase-by-phase change in magnetic flux in the stator windings in accordance with the vector diagram depicted in figure 2; figure 5 - phase-by-phase change in magnetic flux in the stator windings in accordance with the vector diagram depicted in figure 3; in Fig.6 - phase-by-phase change in the magnetic flux in the stator windings in accordance with the vector diagram depicted in Fig.2, for a frequency of 50 Hz, should occur in accordance with the switching cycles of the windings shown in Fig.6.

In addition, the drawings show the following:

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

t is the current time;

F - phase;

0 is zero;

C1-C4 - the findings of the stator control windings of a two-phase synchronous stepper motor;

L1, L2 - control windings;

VT1-VT6 - transistors;

I, II, III, IV, V, VI — successive fixed positions of the magnetic flux vector of a circular rotating field of the stator of a synchronous motor;

straight lines with arrows - direct magnetic flux directions in the stator windings;

dashed lines with arrows - directions of the reverse magnetic flux in the stator windings.

A transistor bipolar frequency converter that controls the speed of a synchronous stepper motor contains three reversible transistor switches connected to a power source, implemented on transistors, which are connected to the mains and stator control windings of the synchronous stepper motor. Each reversible semiconductor switch contains two transistors that are connected together in parallel. An AC single-phase voltage source was used as a power source. In each reversible transistor switch, the emitters of the first transistors are connected to the phase of the supply network, the emitters of the second transistors are connected to zero of the supply network. The transistor collectors of the first reversible transistor switch are combined and connected to the first output of the first control winding. The transistor collectors of the second reversible transistor switch are combined and connected to the first output of the second control winding. The second outputs of the first and second control windings are combined, and the transistor collectors of the third reverse transistor switch are also combined and connected to the combined second outputs of the first and second control windings.

An example of a transistor bipolar frequency converter that controls the speed of a synchronous stepper motor.

A transistor bipolar frequency converter that controls the speed of a synchronous stepper motor contains three reversible transistor switches connected to a power source. As a power source for reversing transistor switches, an alternating single-phase voltage source is used.

In the first reversible transistor switch, the collector of the first transistor 1 (VT1) and the collector of the first transistor 2 (VT2) are combined and connected to the first output 3 of the first control winding 4 (L1); the emitter of the first transistor 1 (VT1) is connected to the phase of the AC mains and the emitter of the second transistor 2 (VT2) is connected to zero of the AC mains.

In the second reverse transistor switch, the collector of the first transistor 5 (VT3) and the collector of the second transistor 6 (VT4) are combined and connected to the first output 7 (C3) of the second control winding 8 (L2); the emitter of the first transistor 5 (VT3) is connected to the phase of the AC mains and the emitter of the second transistor 6 (VT4) is connected to zero of the AC mains.

In the third reversible transistor switch, the collector of the first transistor 9 (VT5) and the collector of the second transistor 10 (VT6) are combined and connected to the combined second output 11 (C2) of the first control winding 4 (L1) and the second output 12 (C4) of the second control winding 8 ( L2); the emitter of the first transistor 9 (VT5) is connected to the phase of the AC mains and the emitter of the second transistor 10 (VT6) is connected to zero of the AC mains.

Thus, the first reverse transistor switch contains parallel-connected transistors 1 (VT1) and 2 (VT2), the second reverse transistor switch contains parallel-connected transistors 5 (VT3) and 6 (VT4), the third reverse transistor switch contains parallel-connected transistors 9 (VT5) ) and 10 (VT6), and the second output 11 (C2) of the first control winding 4 (L1) and the second output 12 (C4) of the second control winding 8 (L2) are combined.

A transistor bipolar frequency converter that regulates the speed of a synchronous stepper motor carries out vectorial-algorithmic control of a synchronous stepper motor when creating several types of rotating stator fields: passing four or six consecutive fixed positions of the magnetic flux vector of a circular rotating field of the stator motor.

To ensure rotation of the magnetic flux vector of the stator field of the synchronous stepper 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 (VT1), 2 (VT2), 5 (VT3), 6 (VT4), 9 (VT5), 10 (VT6) in the following order (Fig. 4):

- in the positive half-period of the supply alternating voltage, at time t ₁ , transistors 1 (VT1), 10 (VT6) turn on and work, providing I a fixed position of the stator magnetic flux when the current flows in the positive direction along winding 4 (L1) shown in figure 4 direction;

- in the negative half-period of the supply alternating voltage, at time t ₂ , transistors 1 (VT1), 10 (VT6) turn off, transistors 6 (VT4), 9 (VT5) turn on and work, providing II a fixed position of the stator magnetic flux when current flows in the positive direction along the winding 8 (L2) in the direction shown in FIG. 4;

- in the positive half-period of the supply alternating voltage, at time t ₃ , transistors 6 (VT4), 9 (VT5) turn off, transistors 9 (VT5), 2 (VT2) turn on and work, providing III a fixed position of the stator magnetic flux when current flows in the negative direction along the winding 4 (L1) in the direction shown in FIG. 4;

- in the negative half-period of the supply alternating voltage, at time t ₄ , transistors 9 (VT5), 2 (VT2) turn off, transistors 10 (VT6), 5 (VT3) turn on and work, providing an IV fixed position of the stator magnetic flux when current flows in the negative direction along the winding 8 (L2) in the direction shown in FIG.

Starting from the next positive half-cycle, at time t ₅ , 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 the synchronous stepper motor in accordance with the vector diagram shown in figure 3, in the sequence I-II-III-IV-V-VI, it is necessary to apply control pulses to the transistors 1, 2, 5, 6 , 9, 10 (VT1-VT6) in the following order (figure 5):

- in the positive half-period of the supply alternating voltage, at time t ₁ , transistors 1 (VT1), 10 (VT6) turn on and work, providing I a fixed position of the stator magnetic flux when the current flows in the positive direction along winding 4 (L1) shown in figure 5 direction;

- in the positive half-period of the supply alternating voltage, at time t ₂ , transistors 1 (VT1), 10 (VT6) remain turned on and transistor 5 (VT3) is turned on, providing II a fixed position of the stator magnetic flux when the current flows in the positive direction along the windings 4 (L1), 8 (L2) in the direction shown in FIG. 5;

- in the negative half-period of the supply alternating voltage, at time t ₃ , transistor 1 (VT1), 10 (VT6), 5 (VT3) turns off, transistors 6 (VT4), 9 (VT5) turn on and work, providing III a fixed magnetic position stator flow when current flows in a positive direction along winding 8 (L2) in the direction shown in FIG. 5;

- in the negative half-period of the supply alternating voltage, at time t ₄ , transistors 6 (VT4), 9 (VT5) turn off, transistors 10 (VT6), 1 (VT1) turn on and work, providing an IV fixed position of the stator magnetic flux during current flow in the negative direction along the winding 4 (L1) in the direction shown in FIG. 5;

- in the positive half-period of the supply alternating voltage, at time t ₅ , transistors 10 (VT6), 1 (VT1) are turned off, and transistors 9 (VT5), 2 (VT2), 6 (VT4) turn on and work, providing V a fixed position the stator magnetic flux when current flows in the negative direction along the windings 4 (L1), 8 (L2) in the direction shown in FIG. 5;

- in the positive half-cycle of the supply alternating voltage, at time t ₆ , transistor 2 (VT2) turns off, and transistors 9 (VT5), 6 (VT4) remain turned on, providing a VI fixed position of the stator magnetic flux when the current flows in the negative direction along the winding 8 (L2) in the direction shown in FIG. 5;

- in the negative half-period of the supply alternating voltage, at time t ₇ , transistors 9 (VT5), 6, (VT4) turn off, and transistors 2 (VT2), 9 (VT5) turn on and work, providing I a fixed position of the stator magnetic flux at current flowing in the positive direction along the windings 4 (L1), 8 (L2) in the direction shown in FIG. 5;

- in the negative half-period of the supply alternating voltage, at time t ₈ , transistors 2 (VT2), 9 (VT5) remain turned on and transistor 6 (VT4) is turned on, providing II a fixed position of the stator magnetic flux when the current flows in the positive direction along the windings 4 (L1), 8 (L2) in the direction shown in FIG. 5;

- in the positive half-period of the supply alternating voltage, at time t ₉ , transistor 2 (VT2), 6 (VT4), 9 (VT5) turns off, transistors 5 (VT3), 10 (VT6) turn on and work, providing III a fixed magnetic position stator flow when current flows in a positive direction along winding 8 (L2) in the direction shown in FIG. 5;

- in the positive half-period of the supply alternating voltage, at time t ₁₀ , transistors 5 (VT3), 10 (VT6) turn off, transistors 9 (VT5), 2 (VT2) turn on and work, providing an IV fixed position of the stator magnetic flux when current flows in a negative direction along winding 4 (L1) in the direction shown in FIG. 5;

- in the negative half-period of the supply alternating voltage, at time t ₁₁ , transistors 9 (VT5), 2 (VT2) are turned off, and transistor 10 (VT6), 1 (VT1), 5 (VT3) turn on and work, providing V a fixed position the stator magnetic flux when current flows in the negative direction along the windings 4 (L1), 8 (L2) in the direction shown in FIG. 5;

- in the negative half-period of the supply alternating voltage, at time t ₁₂ , transistor 1 (VT1) turns off, and transistors 10 (VT6), 5 (VT3) remain on, providing a VI fixed position of the stator magnetic flux when the current flows in the negative direction along the winding 8 (L2) in the direction shown in FIG. 5.

Starting from the next positive half-cycle, at time t _13, the switching cycle of transistors 1 (VT1), 2 (VT2), 5 (VT3), 6 (VT4), 9 (VT5), 10 (VT6) is repeated, providing a circular rotation of the stator field .

Ensuring the rotation of the magnetic flux vector of the stator field of the synchronous stepper motor in accordance with the vector diagram shown in figure 2, in the sequence I-II-III-IV at a frequency of 50 Hz, should occur in accordance with the switching cycles of the windings shown in Fig.6 .

Therefore, changing the sequence of switching on transistors, you can change the speed of the motor in accordance with the change in the frequency (f _reg ) of the voltage supplied to the motor, defined by the formula:

f _reg = f _s / n,

where f _reg - regulatory frequency;

f _with - network frequency;

n is the number of periods of the supply voltage of the AC network used per revolution of the stator's rotating field.

Thus, the present invention can be used to control the speed of rotation of a synchronous stepper motor when powered by a single-phase AC voltage network, with high reliability and efficiency.

Claims (1)

A transistor bipolar frequency converter that controls the speed of a synchronous stepper motor, containing reversible transistor switches connected to a power source, each of which transistors are connected in parallel, and the collectors of the transistors of the first reversible transistor switch are combined, characterized in that a source is used as a power source of the reversible transistor switches alternating single-phase voltage, while the emitters of the first transistors each the reverse transistor switch is connected to the phase of the supply network, the emitters of the second transistors of each reverse transistor switch are connected to zero the supply network, the collectors of the transistors of the first reverse transistor switch are connected to the first output of the first control winding, the collectors of the transistors of the second reverse transistor switch are combined and connected to the second output of the first output control, the second outputs of the first and second control windings are combined, and transi collectors tori third transistor reversing switch also combined and connected to the combined first and second outputs of the second control winding.

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