Method for reconstructing phase current of electromotor

Abstract

The invention provides a method capable of reconstructing a three-phase current of an electromotor in full range at any time when the electromotor is driven by a space vector pulse-width modulation mode, which has simple algorithm, high university and relatively good control effects. In the method, an asymmetrical pulse-width modulation (PWM) mode is used for modulation, modulation vectors in a non-observation area are decomposed and one of the decomposed vectors has at least two different non-zero basic space vectors of which the continuous action time is longer than or equal to the action time of a minimal vector in a PWM period; and thus, the non-observation areas are avoided in a space vector PWM process , and the full-time and full-range three-phase current reconstruction and detection of the electromotor are realized, in particular vector distortion is avoided when the electromotor is controlled to be at a low speed. Moreover, the method has the advantages of greatly improving reliability, obviously reducing cost, along with simple algorithm, small code occupation and little increase of current harmonics.

Description

technical field [0001] The invention relates to the technical field of motor phase current reconfiguration, in particular to a motor phase current reconfiguration method based on DC bus current. Background technique [0002] In the AC motor control system, the phase current detection of the motor is a key link. The classic method is to use the current sensor to detect the phase current of the motor, that is, set 3 or at least 2 current sensors at the AC output end to provide the phase current feedback signal. Commonly used current sensors are Hall effect detectors, which are not only expensive but also bulky and difficult to integrate in power electronics. Therefore, in the case that the accuracy does not need to be too high and the cost needs to be reduced, a method of detecting the phase current of the motor by sampling the DC bus current and then reconstructing the phase current of the motor is proposed. [0003] The phase current of the motor is detected by DC bus curr...

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Problems solved by technology

[0008] The existing method of using asymmetric PWM modulation to reconstruct the phase current of the motor in the non-observation area can solve the application problem of the single current sampling technology in the motor to a certain extent, but the control is prone to voltage vector distortion when the motor is controlled at low speed Larger, larger increase in current harmonics, etc., there are deficiencies in realizing the reconstruction of the three-phase current of the motor at all times and in all ranges

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