Research On Interior PMSM Self-sensing Vector Control Technique

At present, interior permanent magnet synchronous motor (IPMSM) has beenwidely used in the fields of national economy, science and technology for its strongoverload ability and fitness for flux-weakening control. For high performanceinterior permanent magnet synchronous motor vector controlled drive system, itusually needs to install the position sensor, like photoelectric encoder, to get theinformation of motor speed and position. However, the installation of the positionsensor not only increases the cost, but also reduces the reliability. In addition, theIPMSM can produce magnetic resistance torque due to the structure asymmetric ofrotor magnetic circuit. If the magnetic resistance torque is fully utilized, it canimprove the overload output capacity of the motor. Therefore, interior permanentmagnet synchronous motor self-sensing control method and maximum torque perampere control strategy were researched in this paper.In order to realize self-sensing control operation of the IPMSM, the rotorposition estimation based on sliding-mode observer theory adopting extendedelectromotive force model was studied. The information of the rotor position couldbe completely separated from the inductance matrix through an equivalenttransformation of the voltage equation. The concept of extended electromotive forceis introduced, so the sliding-mode observer could be structured. On that basis, theinformation of observed position was obtained by the software phase lock loop, toovercome the influence of the noise. To analyze the dynamic response androbustness to load disturbance of the IPMSM drive system, the structure andparameter of the position observer based on software phase lock loop was designedthrough the pole assignment method.An IPMSM maximum torque per ampere (MTPA) online control strategyadopting current vector angle self-adjusting method was proposed. The currentvector angle is adjusted online according to the stator current sampling values. TheFourier analysis and real-time comparing current vector amplitudes of differentvector angles were adopted, in this way the optimal current vector angle whichcould produce the minimum current amplitude was achieved to realize the MTPAcontrol. The cause of the stator current distortion and its negative effects on thesystem were analyzed. A dead-time effect compensation method based on saturationfunction was researched and realized.On the basis, experiments were carried out through the experimental platformof2.2kW interior permanent magnet synchronous motor drive system. Thehardware and software were designed. The experimental results show that the sliding-mode observer adopting the software phase lock loop could estimate therotor position accurately and realize self-sensing control of the system. In addition,the self-sensing IPMSM drive system has good dynamic response and robustness tothe load disturbance. The proposed online maximum torque per ampere controlmethod can track the ideal maximum torque per ampere operation trajectoryeffectively.