Square-wave flux-weakening control method for permanent magnet synchronous motor

Abstract

The invention provides a square wave lux-weakening control method of a permanent magnet synchronous motor, comprising the following steps: in each sampling period of a DSP chip, the sampled rotor position information and the rotational speed information are sent to an FPGA chip; The discrete rotor position signal is reconstructed in FPGA chip. The FPGA chip shortens the discrete period of the original discrete rotor position signal to generate a new rotor position signal. The reconstructed rotor position signal is considered as an approximate continuous rotor position signal. In each samplingperiod of DSP chip, DSP chip sends voltage phasor angle to FPGA chip. The FPGA chip shifts the phase of the reconstructed rotor position signal according to the voltage vector angle to obtain the phase angle of the square wave driving pulse. FPGA chip generate three-phase drive pulses accord to that phase angle of the square wave drive pulses, and realizes accurate control of the phase of the slave square wave drive pulses. By improving the generation mode of the square wave driving pulse, the invention greatly improves the problem of positive and negative half-cycle asymmetry of the driving pulse of the square wave field weakening control.

Description

technical field [0001] The invention relates to the technical field of permanent magnet synchronous motor control, in particular to a square wave field weakening control method for permanent magnet synchronous motors. Background technique [0002] Compared with asynchronous traction motors, permanent magnet synchronous traction motors have the advantages of high power factor, high system efficiency, high torque density, small frequency converter capacity and strong dynamic response capability. Especially in the last two decades, rare earth permanent magnet materials have developed rapidly, and new permanent magnet materials have the characteristics of high remanence density, high magnetic energy product and high coercive force, which have led to the rapid development of permanent magnet synchronous motors. Especially in rail transit electric traction systems, permanent magnet synchronous traction motors show great application potential. The permanent magnet synchronous moto...

AI Technical Summary

Problems solved by technology

The large switching loss is not conducive to the improvement of the working efficiency of the frequency converter, and it also brings great pressure to the design of the heat sink of the frequency converter, resulting in excessive volume and weight of the device

Especially in the rail transit traction system, the device needs to be miniaturized and lightweight, and the bottom of the vehicle usually does not have water-cooled heat dissipation conditions, which limits the inverter to work only at a lower switching frequency

[0005] The second is that the DC bus utilization rate of the system is not high

If the peak value of the motor port line voltage is close to the DC bus voltage, it will cause the current loop regulator to saturate, resulting in system instability

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