Effect Of Non-ideal Factors On High Frequency Pulsating Signal Injection In PMSM

Permanent magnet synchronous motors are widely used in production and life because of its high power density and small size.Among them,the accurate acquisition of rotor position of permanent magnet synchronous motor is one of the important conditions for its accurate control.In general,the motor requires rotor position signals from the mechanical position sensor.However,the mechanical position sensor increases the volume and cost of the system,and reduces the reliability of control in some harsh environments.To avoid these problems,the sensorless control method has become the current research focus.Based on the low-speed sensorless control algorithm “high frequency pulsating signal injection”,this paper studies the influence of machine parameter asymmetry and inverter nonlinearity for the observation of rotor position and proposes the corresponding compensation strategy.In view of the influence of machine parameter asymmetry,this paper theorizes and concludes that the position observed both have secondary harmonic component because of machine parameter asymmetry.This paper uses the notch filter to suppress the second harmonic component.Since f(Δθ)used for position observation contains second harmonics,and its amplitude is related to the frequency of injected high-frequency signal.Therefore,choosing the optimal injection frequency has an important impact on improving the accuracy of position observation.In this paper,the optimal injection frequency of high frequency signal can be found by observing the size of the second harmonic component in the q-axis current continuously.This paper theorizes that the q-axis current used for position observation contains six harmonic components because of inverter nonlinearity.This component will make the position observed contain the sixth harmonic error.In this paper,the PR regulator and PI regulator are connected in parallel in the current loop to suppress the sixth harmonic component and then the error will be reduced.Aiming at the three research points mentioned above,this paper established relevant simulation models through MATLAB/Simulink and carried out simulation verifications.And the hardware control platform based on TMS320F28335 and the corresponding software program were built in this paper for experimental verification.Simulation and experimental results verify the influence of non-ideal factors on position observation and the effectiveness of the corresponding compensation strategy.