Rotor Initial Position Detection Of Permanent Magnet Synchronous Motor Based On Current Response Envelope

Permanent magnet synchronous motor(PMSM)is widely used for its high power density,high power factor and high efficiency.PMSM high performance control requires accurate rotor position information.However,the mechanical position sensor,such as the rotary encoder and the encoder,makes the cost and reliability of the PMSM system lower,therefore,sensorless technology has received great attention,and the rotor initial position is the most important problem to be solved.In this paper,a new initial position detection method of permanent magnet synchronous motor rotor based on d-axis and q-axis current response envelope is proposed to solve the disadvantages of PMSM rotor initial position detection technology that are necessary to inject multiple signals and design filters and integrators,sensitive to changes in motor parameters and complex detection system structure and so on.First of all,a fluctuating high-frequency voltage signal is injected into the estimated two-phase rotating coordinate system,which rotates at a low frequency,the relationship between the characteristics of the direct axis inductance and the injection signal is analyzed based on the saturation effect of PMSM,it provides a theoretical basis for the new method of detecting rotor initial position based on current response envelope.Secondly,the expression of PMSM signal injected into the d-q axis current response was deduced,according to the characteristics of the definition of response envelope quadrature direct axis current,and gives the positive expression and envelope extraction method,through the analysis of positive envelope and the injected signal,gives a method of detecting the rotor initial position : the rotor initial position is estimated by extracting the reference value of the coordinate system,which corresponds to the maximum value of d-axis current positive envelope curve and the minimum value of q-axis current positive envelope curve.Thirdly,the relationship between the frequency and amplitude of the injected signal and the detection accuracy of the PMSM rotor initial position detection method is deduced,application of Ansys Maxwell software to establish the simulation model of motor finite element simulation,and to determine the range of frequency and amplitude of signal injection.Finally,the hardware system structure,experimental platform and software design are given,and the feasibility of the rotor initial position detection method is verified by experiments.