| Interior permanent magnet synchronous machines(IPMSMs)have been widely used in national defense,industrial and agricultural applications for merits of simple structure,high efficiency and wide speed range.To reduce the system cost and improve the reliability of machine operation,the sensorless control of IPMSM has gradually become an active area of research in academic and industrial fields.In this paper,a sensorless control scheme is proposed for IPMSM,where a super-twisting sliding mode observer(ST-SMO)is developed to observe the position of rotor,and compensate the inaccuracy of position observation due to the voltage source inverter(VSI)nonlinearity.The mathematical model of the IPMSM is established,and the current and speed double closed-loop control system that adopts PI controllers and a position sensor is designed.To make full use of the reluctance torque caused by the saliency effect of the motor and improve the power density and operating efficiency of the motor,in this paper,the maximum torque per ampere(MTPA)control scheme is designed,and the effectiveness of the MTPA control scheme is verified by simulation studies using MATLAB/Simulink.The work lays a foundation for the design of sensorless control system.A sensorless control system of IPMSM based on the super-twisting sliding mode observer is designed.To reduce the influence of the voltage source inverter nonlinearity on the observation accuracy,in this paper,the nonlinear characteristics of the inverter are considered in the mathematical modeling of the motor,and the 5th and the 7th harmonics caused by nonlinearity can be effectively reduced by the harmonic injection algorithm.The proposed scheme is compared with the conventional scheme based on the first-order sliding mode observer by the simulation studies.The speed fluctuation of the machine is decreased from 21.33r/min to 9.76r/min,and the observed error of the position is decreased from 5.4° to 1.8°.The total harmonic distortion of the system is reduced from 8.69% to 4.07%,and the position estimation error is reduced by 50%.The results demonstrate that the ST-SMO algorithm can effectively solve the chattering issue,suppress the high-frequency oscillation in the control system,and stabilize the observed speed.At the same time,the harmonic suppression algorithm can greatly reduce the system observation error and improve the system performance.Finally,an experimental platform for a coupled PMSM is built,and the proposed dead zone compensation scheme and sensorless control algorithm for PMSM are verified by experiments.The results show that the compensation scheme improves the waveform of the sinusoidal phase currents.The proportion of the 5th harmonics has been decreased from 13.42% to 4.73%,and the proportion of the 7th harmonics has been decreased from 6.11% to 0.92%,and the THD has been decreased from 16.10% to 7.99%.Compared with the conventional SMO and ST-SMO,the speed and position waveform of the proposed algorithm is smoother with the speed error reduced from ±20r/min to ±5r/min,and the position chattering reduced from 12.7° to 4.2°.In summary,the experimental results verify the effectiveness of the proposed position sensorless control algorithm based on ST-SMO. |
