SU1248023A1 - A.c.electric drive - Google Patents

Abstract

The invention relates to electrical engineering and can be used in automation. The purpose of the invention is to improve the weight and dimensions. The device contains a two-phase asynchronous motor (BP), a pulse converter, a control circuit made on the S block saw voltage, comparison block 9, block 10 of the absolute value of the input signal. An input signal indicator 11, a logic operation block, and a galvanic isolation and control signal gain block are introduced into the control circuit. BP control is based on the pulse-width formation of voltages in the phase windings of the stator of the BP with a shiroto $ (L 4 00 o to 00

Description

but-pulse quarter-wave modulation of sinusoidal power supply. In the device, by eliminating the phase shift of the capacitor, it is possible to reduce the dimensions of the control equipment while simultaneously increasing the body. The invention relates to electrical engineering and can be used in electromachine counting automation systems.

The aim of the invention is to improve the weight and size parameters.

FIG. 1 shows the power circuit of an alternating current electric drive; in fig. 2 and 3 — control circuit blocks; in fig. 4 shows a table with a switching algorithm of a diode-transistor switch. A pulse semiconductor converter; in fig. 5 - voltage diagrams in electric drive blocks.

The AC electric drive (Fig. 1) contains a two-phase asynchronous electric motor 1 with two windings 2 and 3 pulsed semiconductor converter 4, consisting of two connected in series and equipped with leads for connecting a single-phase power supply network of transistor diodes 5 and 6, parallel to each of which The corresponding phase winding of the synchronous motor 1 is connected, the control circuit 7, two outputs of which are connected to the control inputs of the diode-transistor switches 5 and 6.

The control circuit 7 (Fig. 2) consists of a sawtooth voltage block 8 connected in series and a comparison block 9, an input signal absolute value generating block 10, an input signal polarity indicator 11, a logic block 12 and a power isolation unit 13. control j, and the inputs of the absolute value formation unit 10 of the input signal and indicator 11 of the p-field, the input signal are combined and provided with a terminal for connecting

bones of mechanical and linearity of the adjustment characteristics of the engine. This increases the speed of precision instruments and the accuracy of automatic adjustment, 5 Il.

sensor input signal, the input unit 10 forming the absolute value of the input signal is connected to two other inputs of the comparison unit 9, the input unit 8 of the sawtooth voltage is equipped with pins for connecting the single-phase supply network, the third, second and first inputs of the logical operation unit 12 are respectively connected to the output the input polarity indicator 11 and the two outputs of the comparison unit 9, the outputs of the logic operation unit 12 are connected to two inputs of the galvanic isolation unit 13 and the control signal gain.

Block 12 of logical operations (Fig. 3) consists of four two-input logic elements AND 14-17, four two-input logic elements AND NOT 18-21, two two-input elements HIMSET 22 and 23, one input of the first logical elements AND 14 and AND-18 are combined and form the first input of the block 12 logical operations, one inputs of the second logical elements AND 15 and AND-NOT 19 are combined and form the second input of the block 12 logical operations, other inputs of the first and second logical elements AND 14 and 15 and two the input of the third logical element AND-NOT 20 combined s and form the third input of the block 12 logical operations, the output of the third logical element AND-NOT 20 is connected to other inputs of the first and second logical elements AND-NOT 18 and 19, the output of the second logical element AND 15 is connected to one input of the first logical element EXCLUSIVE SHSh 22, the other input of which is connected to the output of the first logical element NAND 18, the output of the first logical element

And 14 is connected to one input of the second. logical element EXCLUSIVE OR 23, the other input of which is connected to the output of the second logical element AND-NOT 19, the outputs of the first and second logical 5 elements EXCLUSIVE OR 22 and 23 are connected to the inputs of the fourth logical element AND-NOT 21 and to the same inputs of the third and the fourth logical elements AND 16 and 17, the other inputs of which are connected to the transceiver of the fourth logical element AND-NOT 21, and the codes of the third and fourth logical elements AND 16 and 17 form the outputs of the logical operations block 12.

FIG. 5 denotes a voltage input 24; output voltages 25 and .26 of block 8 of the sawtooth voltage; output voltages 27-28 of the comparison unit; voltages 29 and 30 at the outputs of the block 12 logical operations; voltages 31 and 32 at the outputs of the galvanically isolated and amplified control signals 13; voltages 33 and 34 on the phase windings 2 and 3 of the asynchronous electric motor.

Sawtooth block 8 includes an input operational amplifier (OA) that converts a sinusoidal voltage to a square RZ of the same frequency. The amplitude-limited signal from the op amp is fed to the inputs of two integrators with a reset, performed on two op amps. and field effect transistors. The integrator outputs are connected to two inverters to produce two sawtooth voltages 25 and 26 (Fig. 5).

The absolute value formation input unit 10 (Fig. 2) 40 is implemented on the operational amplifier and implements the Ug function when there is a common point with other units of the control circuit.

The polarity indicator 11 of the input signal 45 is made at the operational amplifier, the output of which is connected to the first input of the block 12 logic operations through the signal level limiter. 50

Comparison block 9 consists of two identical circuits. The inverting inputs of the operational amplifiers are supplied with voltage from block 10, and to the non-inverting inputs to the reference voltages 55 and 26 (Fig. 5). As a result of the addition of input signals at the output of block 9, rectangular pulses of positive polarity 27 and 28 are formed (Fig. 5), the duty cycle of which is proportional to the value of the input signal.

The logic logic unit 12 is performed on integrated circuits of TTL-logic and ensures the distribution of a sequence of rectangular pulses over two control channels of power diode-transistor switches 5 and 6 in accordance with the sign and value of the input signal and protection from through short circuits of the converter 4 If the maximum input level is exceeded.

The unit 13 for galvanic isolation and amplification of control signals consists of two identical parts, each of which includes an input optical coupler and a key amplifier on a single transistor. For active locking of power transistors im. pulse converter 4 uses diode-resistive circuits to automatically offset the output voltages 31 and 32.

The control of the reversible asynchronous motor 1 from a single-phase alternating voltage source is based on the pulse-width formation of voltages in the phase windings 2 and 3 of the stator of the electric motor 1. Since the phase-shift capacitor is not used, the angle of the phase shift between voltages required for normal operation of the motor 1 The mi (currents) of the stator windings 2 and 3 are created by using pulse-width-quarter-wave modulation of the sinusoidal power voltage.

The drive works as follows.

In the absence of an input signal (I. 0) at the output of the indicator 11 of the polarity of the input signal, the signal O is generated, the zero signal will be also at the output of the unit 10 to form an absolute value of the input signal. As a result, at the output of the unit: 9 comparisons, two voltages with a voltage equal to one are formed. These two voltages and the signal O are fed to the inputs of the block 12 logical operations. At the output of block 12, signals O are formed, which, after passing the optocoupler pairs of block 13, galvanic isolation and amplification

the transistors of the pulse amplifiers are inverted and unlocked. As a result, the n diode-transistor switches 5 and 6 are supplied with a negative (locking) bias voltage. The keys 5 and 6 are locked and the stator windings 2 and 3 of the engine 1 are connected in series to the mains. Since the voltages (currents) of the stator windings 2 and 3 coincide in phase, a pulsating magnetic field arises in motor 1 with a zero input signal, which ensures effective dynamic braking of the rotor.

If there is an input signal of positive polarity (H g 0), signal 1 is formed at the output of block 11, and at block 9 output two rectangular voltages 27 and 28 are shifted in phase in accordance with the reference voltages 25 and 26 and having the same duty cycle, determined by the input signal level 24. In the time interval 35-36 (Fig. 5), the thirds and the first inputs of block 12 receive signals from one output of block 9 and output of block 11, signals 28 and 24 equal to 1 and to the second input there is a sigt over 27 equal to O. As a result of the operation of block 12, its first output has a signal 1, and on the second, O. After the passage of these signals through the block 13, the key 5 closes and the key 6 opens. As a result, in the considered time interval (-39-35 and J39-37), the stator winding 2 is short-circuited, and the supply voltage is applied to the winding 3. In the time interval 35-36 and 37-38, all three inputs of block 12 receive signals 1, thus forming signals equal to O at its output. At the same time, the keys 5 and 6 are locked and a supply voltage is applied to the sequentially connected windings 2 and 3. Engine 1 develops a damping torque that increases the linearity of the mechanical and adjustment characteristics. In the time interval 36-40, 38-40, signals 1 are received at the first and second inputs of block 12, and signal O is received at the third input. As a result of block 12, the signal O is at its first output, and 1. is at the second output. signals through the block 13, the key 5 is opened, and the key 6 is closed. As a result in

The considered time interval of 36-40 and 38-40 to the starting windings 2 and 3 are applied voltages 33 and 34 (Fig. 5). During the next half-wave of the supply voltage, the processes in the electric drive are repeated and negative stator voltage pulses are generated in windings 2 and 3. The values of stator voltages and the phase shift angle of the first harmonic components depend on the importance of the output signal of the block 9.

With an increase in the absolute value of the input signal from zero to a maximum, the phase shift angle of the first harmonic components of the stator voltage (current) increases from zero to a limit value close to. The rotating electromagnetic moment of the asynchronous motor also increases from 0 to the maximum value. The maximum duration of the conductive states of the keys 5 and 6 liters is equal to a quarter of the period of the supply voltage. With a further increase in the duration of the conductive states of the keys 5 and 6 in the power circuit, the through short circuit mode appears, to eliminate which in block 12 there is a protection node locking the key control channels 5 and 6 with input signals that exceed the maximum allowable values at which The outputs of the logical elements EXCLUSIVE STI 23 and 22 simultaneously appear signals 1.

This drive provides reverse control of the electric motor 1. When the polarity of the input signal changes in time intervals 40-36 and 40-38 (Fig. 5), the first and second inputs of block 12 receive signals O, and the third input receives signal 1. In the first code of block 12, the signal O appears, and in the second, 1, i.e. opposite., that were at Ugj 0. Signals change to opposite and in time intervals of 36-40 and 38-40 (Fig. 5), which leads to a reverse order of the following phases of stator voltage and reverse of asynchronous electric motor 1.

By eliminating the phase-shifting capacitor, the mass

and dimensions of motor control equipment, while simultaneously increasing the mechanical stiffness and linearity of the control characteristics of the engine, which has a positive effect on the accuracy and speed of precision automatic control instrumentation systems.

The invention provides high reliability and manufacturability of assembly and assembly works.

Claims (1)

Invention Formula An AC electric drive containing a two-phase asynchronous electric motor, a pulsed semiconductor converter and a control circuit composed of a series of sawtooth voltage and a comparison block, a galvanic isolation and amplification of control signals, the outputs of which are connected to the control inputs of a pulsed semiconductor converter, and a control input The saw-tooth voltage is provided with leads for connection of a single-phase power supply network, characterized in that Improvements in May, along with the dimensions, the input signal polarity indicator, the input signal absolute value forming unit and the logic operation block, consisting of four two-input logic elements AND, two-input logical elements, are introduced into the control circuit. elements EXCLUSIVE OR OR one inputs of the first AND and AND NAND logic elements are combined and form the first input of the logical operation block jprii, one inputs of the second AND AND AND AND NOT logic elements are not combined and processed comfort second input logic operation unit, the other inputs of the first and second AND gates and two inputs of the third AND gate AND-combined and formed o five 0 five The third input of the logical operations block is output, the output of the third NAND logical element is connected to other inputs of the first and second NAND logic elements, the output of the second AND logical element is connected to one input of the EXCLUSIVE OR logic element, the other input of which is connected. the logical element AND-NOT, the output of the first logical element AND is connected to one input of the second logical element EXCLUSIVE OR, the other input of which is connected to the output of the second logical element AND-NOT, the outputs of the first and second of the logical element EXCLUSIVE OR connected to the inputs of the fourth logical element AND-NOT and to one input of the third and fourth logical elements AND, the other inputs of which are connected to the output of the fourth logical element AND-NOT, the outputs of the third and fourth logical elements AND form the outputs of the logical block operations, a pulsed semiconductor converter is made in the form of two diode-transistor keys of alternating current connected in series and equipped with leads for connecting one of the mains supply, parallel to each diode-transistor. the key is connected to the corresponding phase winding of the asynchronous electric motor, the inputs of the input signal polarity indicators and the absolute value input unit are combined and provided with a terminal for connecting the input signal sensor, the output unit of the absolute value input signal is connected to two two comparator inputs, two the output of which and the output of the polarity indicator of the input signal are connected respectively to the third, second and first inputs of the block of logical operations, two you odakotorogo connected ksootve- favoring vhodambloka galvanic decoupling iusileni Fib control signals T FIG. 3 FIG.