RU2461117C1 - Starter device for ac contactless electric motor - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: starter device has a transformer unit for the rotor rotation EMP allocation, the first unit for shaping pulses in-phase with each semi-period of the rotor rotation EMP, the second unit for shaping pulses in-phase with each semi-period of feeding voltage, a unit of boolean summation multiplying the pulses of same name shift of the outputs of the first and the second pulse shaping units; the resultant pulses from the logical summator output are supplied to the AC power tongs input. The rotor initial start-up (prior to counter-EMP origination); pulses from the maximum frequency generator affect the trigger strobing output; further speed0up and synchronous operation of the electric motor are due to the effect of counter-EMP via the trigger asynchronous inputs.

EFFECT: contactless electric motors application field extension, increase of performance factor, cosφ, reduction of weight and dimension indicators.

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Description

The invention relates to electrical engineering and can be used in electrical machines with non-contact switching of the armature winding.

Known schemes of devices [1, 2, 3, and 4] for automatically controlling the start of asynchronous electric motors, which have a main winding and an auxiliary one with a phase-shifting capacitor and triac, connecting the power source at start-up and disconnecting during “synchronous” operation.

The disadvantages of the known devices are dips in the starting moment to the minimum value due to the subtraction in antiphase of the supply voltage from the counter-emf of the electric motor at the time of multiple coincidence of their frequencies in the range from start to "synchronous" operation. This leads to a limitation of the use of asynchronous electric motors under load on the shaft of the type of "dry" friction, which leads to a decrease in efficiency, cosφ and to underutilization of the active parts in the nominal operating mode. The devices also exclude the use of synchronous motors with excitation of the rotor from a permanent magnet, a hysteresis layer, electromagnetic excitation, etc.

The purpose of the invention is to increase the efficiency, cosφ, reduce the overall dimensions of electric motors and expand the scope of synchronous motors in household and industrial equipment.

This goal is achieved by the fact that the starting device of a contactless motor containing "A" - the main one and "B" - an auxiliary winding with a phase-shifting capacitor "C" and a triac "T", turning on and off the voltage "U ~" of the supply winding of the motor; a transformer for isolating the resulting voltage of the counter-EMF of the rotor [5], where the current windings of each phase and the voltage winding are connected in parallel-counter with respect to the supply phase of the voltages, and with respect to the resulting voltage of the rotor EMF, in series according to. As a result, the isolated rotor counter-EMF, together with the introduced functional block-trigger, perform the functions of the rotor position sensor in the optimal angular mode in the frequency range from start-up to synchronous operation. This allows the use of permanent magnet motors on the rotor, hysteresis layer, electromagnetic excitation, etc., as well as the use of toothless stator winding. Confirmation of this is the relatively close basic electromechanical characteristics of the series of collector motors with gear and toothless anchor, where the magnetic flux penetrates the air gap more than two times more than with the gear anchor.

и

.The starting device of FIG. 1 comprises a DC voltage unit 1 supplying logical function blocks; limiter of 2 amplitudes of half-periods of supply voltage "U ~"; the minimum frequency generator 3, necessary for the initial start of the trigger 4 through the gate - counting input, which ensures the initial starting of the rotor; block 5 for isolating the resulting counter-EMF of the rotor, each half-cycle of which through the asynchronous inputs of trigger 4 affects the increase in the rotor speed from start to synchronous operation with continuous monitoring of the optimal angular mismatch between the magnetizing force vectors of the rotor and stator, thanks to the programmed switching of the “T” triac as a logical function adder 6, low-current thyristors which perform the function "And" between the output pulses of the same shift blocks 2 and 4, i.e.

and

.

- эпюры импульсов на выходах формирователя 2; F_min - эпюры импульсов с выхода генератора минимальной частоты 3; которые подаются на стробирующий вход триггера 4, на асинхронные выходы которого соответственно подаются полупериоды противоЭДС, снимаемые с выходной обмотки трансформатора блока 5 - выделения противоЭДС ротора;

и

- это эпюры импульсов с выходов триггера 4 в режиме частот разгона и синхронной работы электродвигателя;

и

- результирующие эпюры положительных и отрицательных импульсов на выходах блока 6; U~ на вых «Т» - результирующие эпюры напряжения на выходе симистора «Т» в виде поочередных переключений серий положительных и отрицательных импульсов при разгоне и поочередном переключении импульсов при синхронной работе.Figure 2 shows the plot voltage at the outputs of the functional blocks: U ~ plot voltage supply; Q ₀ and

- plot of pulses at the outputs of the shaper 2; F _min - plot of pulses from the output of the minimum frequency generator 3; which are fed to the gate input of trigger 4, to the asynchronous outputs of which respectively counter-emf half-cycles are taken, which are removed from the output winding of the transformer of block 5 — the counter-emf of the rotor is isolated;

and

- these are diagrams of pulses from the outputs of trigger 4 in the mode of acceleration frequencies and synchronous operation of the electric motor;

and

- the resulting diagrams of positive and negative pulses at the outputs of block 6; U ~ at the output “T” - the resulting voltage diagrams at the output of the triac “T” in the form of alternating switching of a series of positive and negative pulses during acceleration and alternating switching of pulses during synchronous operation.

, на аноды которых с выходной обмотки блока 2 подаются полупериоды Q₀ и

. В результате симистор «Т» поочередно включает серии положительных полупериодов и серии отрицательных и ротор начинает вращаться с частотой

, затем возникает напряжение противоЭДС, полупериоды которого через асинхронные входы поведут триггер 4 вперед на повышение частоты в функции углового положения ротора вплоть до синхронной работы, т.е. при совпадении с частотой полупериодов напряжения питания U~. Откуда следует еще одно преимущество применения синхронных электродвигателей в противовес асинхронных и универсальных коллекторных в том, что без нагрузки на валу электродвигатель работает в синхронном режиме с минимальным потреблением из сети по причине фазного рассогласования между полупериодами сети и противоЭДС. Этот режим позволит уменьшить сопротивление обмотки статора и повысить КПД и нагрузочную способность электродвигателя.The device operates as follows (Figs. 1 and 2): when the supply voltage U ~ is connected, a DC voltage arises at the output of unit 1, which is supplied to the midpoint of the output winding of the transformer of unit 2, generator 3 and trigger 4, which starts to operate in counting mode from generator 3 and alternately turn on low-current thyristors with a frequency

, on the anodes of which from the output winding of block 2 are fed half-periods Q ₀ and

. As a result, the triac “T” alternately includes a series of positive half-cycles and a series of negative and the rotor begins to rotate with a frequency

, then a counter-EMF voltage arises, whose half-periods through asynchronous inputs lead trigger 4 forward to increase the frequency as a function of the angular position of the rotor up to synchronous operation, i.e. when coinciding with the frequency of half-periods of the supply voltage U ~. From where one more advantage of the use of synchronous motors as opposed to asynchronous and universal collector motors follows from the fact that without a load on the shaft, the electric motor works in synchronous mode with minimal consumption from the network due to phase mismatch between half-periods of the network and the back-emf. This mode will reduce the resistance of the stator winding and increase the efficiency and load capacity of the electric motor.

Information sources

1. Patent No. 3819995 Н02Р 1/44 "Timed-controlled start switches", USA, 1974, June 25, vol. 932, No. 4.

2. Patent No. 3916274 Н02Р 1/44 "Semiconductor control circuit for starting the electric motor", USA, 1975, October 28, Volume 939, No. 4.

3. Patent No. 478278, 4 Н02Р 1/42 “Starting circuit of an electric motor with a cheap hysteresis comparator”, USA, 1988, January 11, Volume 1086, No. 1.

4. Patent No. 38882364 Н02Р 1/44 “Asynchronous electric motor control system”, USA, 1975, May 6, volume 934, No. 1.

5. A.S. SU No. 1617554 A1, H02K 29/12 Electric Drive, Russia, December 30, 90. Bulletin No. 48.

Claims (1)

The starting device of a synchronous electric motor with a rotor made of a permanent magnet and a stator with a main winding and an auxiliary one with a capacitor shift, an alternating current power key connecting and disconnecting the supply voltage of the stator winding of the electric motor, a direct current source supplying the device’s functional blocks, characterized in that, for the purpose of ensuring reliable start-up and synchronous operation of the electric motor, increasing efficiency, cosφ, reducing the overall dimensions of the electric motor, to the starting device additionally introduced: a functional unit for isolating the resulting voltage of the rotor EMF voltage at the transformer output winding, each half-cycle of which affects the corresponding asynchronous inputs of the trigger, the outputs of which

and

in phase to the half-periods of the EMF of rotor rotation; a second pulse shaping unit Q ₀ and

in phase with each half-cycle of the supply voltage, the pulses Q ₀ and

are logically summed through AND elements with impulses of the same shift

and

from trigger outputs, i.e.

and

, the summed resulting pulses through the outputs of low-current thyristors act on the input of the AC power switch, providing control of the angular position of the rotor during acceleration and synchronous operation of the electric motor; the initial starting of the rotor, before the occurrence of counter-EMF, the pulses from the minimum frequency generator act on the gate's trigger input.

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