A Position Sensorless Control Technology for Four-Phase Doubly Salient Motor

Abstract

The invention discloses a position sensor-free control method for a four-phase doubly salient motor. During electric running of the four-phase doubly salient motor, counter potential vectors differ from each other by 90 degrees in sequence in a d-q coordinate system. The control method comprises the following steps of: partitioning N (N is a natural number of more than 2) rotating speed ranges for designing wave filters of corresponding cut-off frequencies, only acquiring the terminal voltages of any two adjacent phases, entering a subtractor for removing direct current bias, judging the rotating speed of a motor according to a potential zero crossing point at a certain moment, deciding to enter a wave filter of a certain cut-off frequency through the rotating speed ranges, and acquiring the waveform of potential passing through the wave filter by using a DSP (Digital Signal Processor); establishing a phase shift angle comparison table of a wave filter which corresponds to a certain range specific to different rotating speeds in the range for performing DSP inquiry and corresponding accurate phase shift; and obtaining a practical phase change position through a zero crossing comparator, performing DSP computation, and outputting a driving signal to a switch tube by using an FPGA (Field Programmable Gate Array) to complete phase change. The four-phase doubly salient motor can work in a wide rotating speed range.

Description

Technical field [0001] The invention relates to a position sensorless control method for a four-phase double salient motor, which belongs to motor control technology. Background technique [0002] With the development of motor design and control technology, accurate detection of rotor position has become one of the research hotspots in the field of motors at home and abroad. There are many kinds of control technologies. The conventional motor position detection technologies include: (1) direct position detection method; (2) conducting phase winding detection method; (3) non conducting phase winding detection method; (4) additional electrical Component detection method; (5) Detection method based on intelligent technology. In these methods, except for the direct position detection method, which directly detects the rotor position through special detection elements such as Hall sensors, the other methods are to find a parameter information that can be obtained to obtain the rotor ...

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Problems solved by technology

Four-phase double-salient motor ("four-phase double-salient motor", Chinese invention patent: 201110062872.7) due to its structure, makes its terminal voltage and THD value of winding back EMF large, and its sine degree is low. The position detection method cannot obtain the exact commutation point

At the same time, because the change of the rotational speed will cause the change of the frequency of the fundamental wave of the voltage, the traditional method is that the collected voltage first enters an RC filter. However, when the cutoff frequency of the filter is lower than the frequency of the fundamental wave, the fundamental wave is directly filtered out; At the fundamental frequency, many harmonics cannot be filtered out

Moreover, an RC filter cannot guarantee that the THD value of the terminal voltage or back EMF meets the detection requirements, and the RC filter will also cause a shift in the potential phase

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