Research On Single Resistor Sampling Position Sensorless Control Of Permanent Magnet Synchronous Motor In Low Speed Domai

Permanent magnet synchronous motors(PMSMs)are widely used in various fields because of its advantages of high power density,low loss and high reliability.The cost of PMSMs and its control system has become the bottleneck restricting its wide application in the industrial field.This paper presents the method of sensorless control for PMSMs with a DC-Link current sensor at low speed.This method reduces the cost of the current sensor and the possibility of failure.The detailed process of research will be introduced as follows.Firstly,the body structure and control principle of PMSMs are analyzed.The principles of full current sampling and phase current reconstruction are introduced respectively.Then the problems of target voltage vector in the unmeasurable area of current reconstruction is analyzed,and the corresponding method of phase shift is given.Finally,the error of current reconstruction caused by the sampling delay of phase current reconstruction relative to full current sampling is analyzed.Secondly,the equivalent linear modulation wave expression after PWM phase shift is given,and then the Fourier series expansion of PWM phase shift voltage harmonic is given through Fourier series.Then the discrete wavelet transform is used to compare the load voltage after phase shift and before phase shift.Through the analysis results,it can be found that this analysis method can separate the harmonic component generated by phase shift from the fundamental component preferably.Thirdly,the rotated INdirect Flux detection by On-line Reactance Measurement(INFORM)method is proposed,and on this basis,the rotated INFORM method with a DC-Link current sensor is proposed.This proposed method avoids the voltage harmonic problem caused by PWM phase shift.Then,the principle of rotated INFORM method with a DC-Link current sensor is introduced,and the process of sampling current is analyzed.Finally,the simulation results show that the proposed algorithm can obtain better position sensorless observed performance in the steady state,and the three-phase current reconstructed also has better performance.Finally,the proposed rotated INFORM method is experimentally verified on the2.2k W PMSMs coupling experimental platform,and the experimental results verify the feasibility of the proposed method.