Sersonless Control Of High Power Traction PMSM Based On Low Switching Frequency

In the modern electric drive industry,the position sensorless vector control algorithm has gradually become a research hotspot.In this paper,a permanent magnet synchronous motor vector control system based on low switching frequency and position sensorless is designed for high power traction permanent magnet synchronous motor,which can achieve great motor control performance in full speed range.Firstly,this paper designs a multi-mode synchronous modulation strategy for low switching frequency conditions.According to the motor operating frequency,the carrier ratio is adjusted and the vector sequence is optimized,which improves the quality of current and the system performance.Secondly,this paper designs a double closed-loop vector control system for permanent magnet synchronous motor,and gives three kinds of stator current control strategies.Based on this,in the case that the output of the inverter is limited and the rotational speed cannot be increased,a flux-weakening control algorithm that does not change the vector control structure is proposed,and the utilization of the output capability of the inverter is further improved.Then,this paper uses the model reference adaptive method for velocity and position solution in the medium and high speed region.At the same time,this paper creatively proposes a voltage reconstruction technique at low switching frequency,which solves the problem of inaccurate stator voltage acquisition at low switching frequency and improves the stability and accuracy of the MRAS algorithm.In the lowspeed region,two high-frequency injection algorithms are analyzed in this paper,and the rotor initial position polarity judgment strategy is designed.For the application of high-frequency voltage signal injection method and model reference adaptive method,this paper combines two algorithms and designs a composite position sensorless algorithm.Finally,this paper constructs a hybrid control system for permanent magnet synchronous motor without position sensor in the whole speed range based on low switching frequency.The possibility of the proposed algorithm is verified on the Simulink simulation platform and the actual experimental platform,and the experimental analysis is carried out.Compared with the performance,it is verified that the relevant theoretical algorithm is proposed.