Square wave field weakening control method for permanent magnet synchronous motor

Abstract

The invention provides a square wave field weakening control method for a permanent magnet synchronous motor, comprising the following steps: in each sampling cycle of a DSP chip, sending the rotor position information and rotational speed information obtained by sampling to the FPGA chip; The obtained discrete rotor position signal is reconstructed; 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 to be an approximate continuous rotor position signal; each sampling period of the DSP chip Inside, the DSP chip sends the voltage phasor angle to the FPGA chip; the FPGA chip performs phase-shift processing on the reconstructed rotor position signal according to the voltage vector angle to obtain the square wave drive pulse phase angle; the FPGA chip uses the square wave drive pulse phase angle Generate three-phase drive pulses to achieve precise control of the phase of drive pulses from a square wave. The invention greatly improves the asymmetrical problem of positive and negative half cycle of the driving pulse of the square wave field weakening control by improving the generation mode of the square wave driving pulse.

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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