RU2166228C2 - Inductor-type reluctance motor noise reduction method - Google Patents

Abstract

FIELD: controlling inductor-type reluctance motors. SUBSTANCE: method involves shaping additional control pulses for opening one of frequency changer switches in shaping reverse-polarity voltage pulses. These voltage pulses are applied to motor winding to organize definite path for motor current thereby actively suppressing unwanted vibrations and noise. EFFECT: reduced acoustic noise. 2 dwg

Description

 The invention relates to electrical engineering, and more specifically to methods of controlling reactive induction motors having a gear stator, on which one or more phase windings are located, each of which is fed by unipolar current pulses from the frequency converter, and a gearless rotor-free rotor.

 A known method of controlling an induction motor (see: the decision to grant a patent for an invention from 2.02.98, application N 95105831/09 (010523) from 04/14/95).

 This source claims a method of controlling an induction motor with a control system based on a microprocessor. This control system implements a method of controlling an induction motor, which consists in generating currents in the phase windings of the motor by applying voltage pulses of normalized duration to the phase winding, during which all the keys of this phase of the frequency converter are opened, which leads to an increase in the phase current. During pauses between pulses, one key of this phase is closed, which leads to a slow decrease in the phase current. At the end of the zone, both keys are closed, providing a rapid decrease in current in the phase winding.

 The disadvantage of this method is the increased acoustic noise of the motor due to a sharp change in the derivative of the motor current during the transition from the simultaneously open key mode, when the current rises, to the simultaneously closed key mode, when the current in the winding decreases sharply.

 There is also a method of controlling an induction motor (see Patent International Application Number PCT / SE90 / 00422 from 06/15/1989, International Publication Number WO 90/16111.

 This source claims the control system of the induction motor, which generates control signals of the converter keys.

 The control system allows you to adjust the intervals on and off keys depending on the speed of the engine. To expand the control capabilities, the system implements a method of simultaneously turning off the keys: before the start of the zone of simultaneously turned off keys, the operating zone of the frequency converter with one key turned on is entered. In this zone, the phase current of the motor drops slowly through an open switch and a reverse diode. The duration of this additional zone can be adjusted. The positive effect of this invention lies in the possibility of controlling the engine speed and in reducing noise due to a smooth transition from the current rise mode to the mode of slow current decay, and then, after turning off the two keys, to the mode of rapid current decay to zero.

 The disadvantage of this method is its lack of flexibility, since with an increase in the duration of the work zone with one key turned on, the engine output is significantly reduced.

 The alleged invention is aimed at increasing the flexibility of controlling a jet induction motor and to reduce acoustic noise.

 A method of reducing the noise of a jet induction motor, which consists in applying one or more voltage pulses to the motor winding, including keys T1 and T2, at the end of the voltage supply zone, turning off the keys T1 and T2 and applying them using diodes D1 and D2 reverse polarity voltage, in which, according to this statement, after turning off the keys T1 and T2, the current decrease is slowed down by turning one of the keys on and off.

The invention is further explained with reference to the accompanying drawings, which show:
- FIG. 1 is a diagram of the power circuits of one phase of the converter;
- FIG. 2a - key control signal T1;
- FIG. 2b - key control signal T2;
- FIG. 2B is the voltage applied to the motor winding;
- FIG. 2g - current phase of the motor;
To generate phase currents in the windings of the induction motor using a frequency converter (see Fig. 1) at time t ₁ , control signals are sent to turn on the keys T1 (see Fig. 2a) and T2 (see Fig. 2b), to the winding the motor OD is applied to the voltage of the power source U (see Fig. 2c) and the current begins to increase in it (see Fig. 2d). When the current reaches a certain level, the key T1 is turned off (time t ₂ ), while the winding current begins to close through the switched on key T2 and diode D1. The winding in this case is shorted by itself, and the current in it slowly decreases. After the key T1 is turned on again (time t ₃ ), the voltage of the power source is again applied to the winding and the current begins to increase in it. At the end of the voltage supply zone (time t ₄ ), both switches T1 and T2 are in the off state, a negative voltage of the power supply is applied to the phase winding of the motor through the reverse diodes D1 and D2 and the current begins to quickly decrease in it. During the current subsidence, the control system generates a control pulse for additional switching on of the key T2 (time moment t ₅ ), the current decrease slows down, since the winding is shorted through T2 and D1. After turning off T2, a negative voltage is again applied to the motor winding through the return diodes D1 and D2, and the current quickly begins to decrease. At time t, an impulse is formed for the next additional switching on of key T2. By selecting the number of additional key control pulses and the ratios of the duration of additional pulses and pauses between them, it is possible to form a form of the phase current of the motor at which the levels of vibration and acoustic noise of the engine will be minimal. The phase current of the motor with additional inclusions of the key T2 is shown in FIG. 2d (curve i ₁ ), and without additional inclusions - in FIG. 2d (curve i ₂ ). As can be seen from FIG. 2d, additional switching on the key drags down the phase-current decay time to zero, since at this time zero voltage is applied to the winding. At times when two keys are turned off simultaneously, a reverse polarity voltage is applied to the winding.

 The technical effect of the present invention is to reduce the acoustic noise and vibration of the motor due to more flexible control of the keys of the frequency converter during the formation of phase currents of a jet induction motor.

Claims (1)

 A method of reducing the noise of a jet induction motor, which consists in applying one or more voltage pulses to the motor winding, including two switches, at the end of the voltage supply zone, turning off these switches and using diodes to apply reverse polarity voltage different to the winding the fact that after turning off the keys slow down the current reduction by turning one of these keys on and off.

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