SU1716596A1 - Asynchronous-rectifier cascade - Google Patents

Abstract

Usage: regulation of the frequency of rotation of the variable speed electric drive based on power semiconductor frequency converters in the rotor circuit of asynchronous motors. The essence of the invention: an asynchronous valve cascade contains an asynchronous motor 1 with a phase rotor and a thyristor converter 2 frequencies connected between the phase windings of the rotor and the supply network. To the phase windings of the rotor is connected the sensor input 3 of the frequency and phase of the voltage of the rotor. A sensor of 4 frequencies and phases of the supply voltage are connected to the phases of the mains supply. The output of sensor 4 of the frequency and phase of the mains voltage is connected to one of the inputs of the phase-matching unit 5, the output of which is connected to the first input of the two-input multiplication unit 6, the second input of the multiplication unit 6 is directly connected to the output of the frequency and phase 3 sensors the rotor and is also connected to the second input of the phase-shifting unit 5 via an output frequency separator 7 and an intensity adjuster 8. The sensor 3 of the frequency and phase of the voltage of the rotor of the electric motor is made electrically and is composed of a series-connected inductive current filter 10, an electrically isolated node 11, a half-voltage separator 12 of the rotor voltage, a former 13 rectangular pulses, a frequency generator 14 and a rotor voltage phase . 4 il. cl

Description

The invention relates to adjustable AC drives, an advantageous field of use is power semiconductor devices in the rotor circuit of induction motors, which regulate the rotation frequency of the motor according to the principle of an asynchronous valve cascade (AVC). , l:,.

The asynchronous valve cascade is known, which includes an asynchronous motor with a phase-rotor, a thyristor frequency converter with direct coupling, a slip sensor, a low-frequency pulse shaper;

self-contained low-frequency pulse generator, mode switch, driver for unlocking pulse packets, high-frequency pulse sensor, start and overclocking adjuster, tempo adjuster.

The main disadvantage of this AVK is the presence of an electrical slip sensor placed on the shaft of the regulated engine. The design of the sensor depends on the number of poles of the engine; contact rings and brushes are required to remove the signal, which causes a reduction in the processability and reliability of the entire drive. In addition, the engine is started

ABOUT

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using an autonomous low-frequency pulse generator, behind the sensor in start-up and acceleration and a temp master, which ensures starting only at idle.

The purpose of the invention is to increase the reliability of the asynchronous valve operation, cada, and expanding the range of engine speed control.

Figure 1 is a diagram of the asynchronous valve cascade; Fig. 2 shows a potential voltage diagram for individual blocks of a frequency and phase voltage sensor; Fig. 3 shows a filter circuit of a frequency and phase voltage sensor of the rotor; Fig. 4 is a diagram of the galvanic isolation node, the extractor of the half-wave voltage of the rotor, the square pulse former and the frequency generator and phase of the rotor voltage, the frequency sensor and the phase of the rotor voltage.

In the drawings, the following symbols are accepted: UPA, UPB, UPC — phase voltages of the rotor; UVDA is the voltage drop across the diodes of the current filter of phase A of the rotor (on the diodes 16 of FIG. 3); UvT3 UvT4 - signals on transistors 20 (figure 4); wich.1, wil.b are the outputs of the frequency and voltage phase generator of the rotor voltage; UVDA, UVDB. UVDC - current filter output signals 10.

The asynchronous valve cascade contains an asynchronous motor with a phase rotor and a thyristor frequency converter 2 connected between the phase windings of the rotor and the mains, the sensor 3 frequencies and phases of the rotor voltage are connected to the phase windings of the rotor, the frequency 4 sensor is connected to the phases of the power network voltage phases of the supply network. The output of the frequency and voltage supply sensor 4 is connected to one of the inputs of the phase-shifting unit 5, the output of which is connected to the first input of the two-input multiplication unit 6, the second input of which is connected through the output frequency selector 7, the intensity setting unit 8 to the other input of the phase-shifting unit 5 The output of multiplication unit 6 is connected via amplifier 9 to control input of thyristor converter 2 frequencies.

The sensor 3 of the frequency and phase voltage of the rotor of the asynchronous motor 1 is electrically made up of an inductive current filter 10 connected in series, an electrically isolated node 11, a half-voltage separator 12 of the rotor voltage, a 13 rectangular pulse former and a frequency generator 14 and a voltage source 14 wives

the rotor, the output of which forms the output of the sensor 3 frequency and phase voltage of the rotor. The work of AVK is as follows. The sensor has 4 frequencies and voltage phases.

six pulses are generated in the power supply network, each of a 120-degree electrical frequency of the power supply network, the phase of these pulses can be adjusted.

Shift; phase pulses occur in

0 by the phase shifting unit 5 by supplying a direct current control signal (from 2.0 to 3.5 V) to it, formed in intensity sensor 8.

Phase shift required

5 to control the output voltage of the frequency converter 2, i.e. to regulate the additional emf introduced into the rotor circuit.

The voltage taken from the rotor is supplied to the sensor 3 frequencies and phases of the voltage of the rotor.

Sensor 3 frequency and phase, the voltage of the rotor operates as follows.

The voltage-rotor of the engine enters the filter 10 of the sensor 3 frequency and voltage of the rotor.

The voltage taken from the diodes 16 enters the node 11 of galvanic isolation and the extractor 12 half-voltage

0 rotor.

The node 11 of galvanic isolation excludes the possibility of high rotor voltage (up to 1000 V or more) on the microcircuit of the direct current pulse generator 13 and the 14 frequency and phase voltage of the rotor driver.

The operation of the pulse shaper 13 and the shaper 14 of the frequency and phase voltage of the rotor of the frequency sensor and phase of the voltage of the rotor is explained in the diagram shown in Fig. 2 (the diagram is taken using a two-beam electron oscilloscope, so the voltage curves UPA, UPB, UPC have a gear form).

5 Chokes 15 are connected to the rotor circuit. The current in the circuit of each drossel 15 lags behind the corresponding voltage (UPA, UPB, PPC) at an angle of 83-87 e-hail. When current flows in the throttling phases, one of the diodes in the pairs opens.

0 The current through the phase A of the filter is indicated on the UVDA diagram (the currents flowing in the phases B and C of the filter in order to simplify the diagram are not shown). The currents of this phase of the filter flowing through the diodes 16 and

5, respectively, through the optocouplers 18 connected in parallel by it, are shown in the diagram (UvT3, UvT4). When current flows through the optocoupler 18, a transistor 19 (20) closes and appears at terminal 25 (26) through

resistor 23 is a positive voltage of +15 V, indicated below as a signal 1, on a chip 22 shaper 13, 14.

Transistors 19 and 20 serve to amplify the signals of optocouplers. Each of the chips 22 is a logical cell 2I-NOT (if there are signals 1 at the inputs of the cell 1, there is a signal for all other combinations of two signals at the input (1 and O) output is signal 1).

The diagram shown in figure 4, also shows the resistors 17, 24 and the capacitor 21.

In a logical device consisting of microcircuits, the addition of signals of 180 el.grad duration takes place in pairs. over the rotor frequency, with the result that at the output of the logic device six square-wave signals with a duration of 120 electr each are formed, which are fed into a two-input multiplication ball S.

An addition diagram of 180 ° pulses is shown in FIG. :

The continuity of these six signals in transient modes is ensured by the fact that when the rotation frequency changes, the duration of the half-voltage of the rotor also changes (simultaneously), and therefore the duration of the signals supplied to the transistor amplifiers 20 and the switching in the logic circuit. The circuit provides operation at almost any frequency of the rotor voltage, including double synchronous speed (the frequency of the rotor voltage is 50 Hz in the opposite direction to the mechanical rotation of the rotor). The frequency characteristics of the microcircuits make it possible to obtain double or more synchronous speed, however, usually electric machines of medium and high power (from 5 kW and more) are not counted on such high speeds, i

The pulses synchronized with the mains voltage from the phase-shifting unit 5, and the pulses of the frequency and phase of the rotor voltage from unit 3 enter the two-input unit-6 multiplication, on. each of the inputs of which is supplied, one of six pulses. according to the frequency of the mains voltage and one of six pulses according to the frequency of the rotor voltage.

The output signals of unit 6 are supplied to the output amplifier unit.

9, where they are amplified to a value sufficient to transmit them through pulse transformers to the control electrodes of the thyristors of the frequency converter 2.

The asynchronous valve cascade allows to obtain a wide range of adjustment of the frequency of rotation of the motor with a decrease in the mass of the frequency converter, and is also universal for

a large number of different types of sizes and engine power.

Claims (1)

An Asynchronous Valve Cascade, containing a phase-rotor asynchronous motor, a thyristor-frequency converter, equipped with output terminals for connection to the network, and an input connected to the phase leads of the rotor an asynchronous motor, a control input of the thyristor frequency converter is connected to the output of the control unit, a frequency sensor and phases of the induction motor, a frequency sensor and voltage phases network, with an input for connecting to the network, an intensity sensor, characterized in that, in order to extend the frequency control range of the rotational speed and increase reliability, the frequency and phase sensor induction motor is made of electric and is composed of a series-connected inductive current filter, the input connected to the terminals of the rotor winding asynchronous motor, galvanic uncoupling unit, half-voltage separator, square pulse shaper and frequency and rotor voltage phase generator, the output of which forms the output of the frequency sensor and phase of the asynchronous motor, and a phase-shifting unit is inserted with one input connected to the output of the frequency and phase sensor network voltage, and another input - with an output of the intensity setting unit, an output frequency selector connected between the input of the intensity setting unit and the output of the frequency and phase sensor of the asynchronous motor, two Marketing multiplication unit, one input of which is connected to the output phase-shifting unit, the other input - with the output of the frequency detector and phase induction motor and the output of multiplying unit is connected to the input of the control unit thyristor inverter. and “lul gb / control. thyristors Signals dpoaol. - rotational speed Control with orost. Zashchit signals W-J7 k "X ..:. . um % W Uiwl U & one Jl Jt J l R Y / yy zl Upa about-- UpS o ... Uft