A Study on General Purpose Position Sensorless PM Synchronous Motor Drives and Its Applications

  • 戚 文駿

Student thesis: Doctoral Thesis

Abstract

Generally in order to implement the drive control of the PM synchronous motor the rotor position information is essential However position sensors may increase the cost and volume of the motor system due to the extra components and wiring Moreover most position sensors are sensitive to change in ambient temperature As a result the reliability of the position sensor based approach is far from satisfactory in some specific applications In order to alleviate the above problem this dissertation develops a general purpose position sensorless method for PM synchronous motor drives This dissertation proposes a sliding-mode current observer based on a general purpose equivalent back-EMF model By using the back-EMF estimated from the sliding-mode current observer one can indirectly obtain the information of the angular position and velocity of the rotor The estimated rotor position is accurate and fast convergence of the observer is guaranteed over a wide speed range Moreover only stator resistance and stator inductances in the q-axis are essential to the calculation of the general purpose equivalent back-EMF which is easy to implement in low-cost microcontrollers In addition the drives of PM synchronous motors capable of electric braking not only allow the motors to smoothly decelerate to a soft stop but also can recover kinetic energy so as to improve the efficiency of energy consumption In order to conduct an in-depth study on this topic this dissertation analyzes and implements three possible position sensorless electric braking commutation strategies based on a general full-bridge motor drive without any additional power switches and bulky passive components For the position sensorless electric braking commutation strategies theoretical analysis on different performance indices such as maximum voltage conversion ratio braking torque energy recovery ratio etc are carried out and compared among each commutation strategy Finally theoretical analysis several experiments and various applications are performed to verify the effectiveness of the proposed methods Experimental results indicate that the proposed position sensorless FOC and electric braking commutation methods are suitable for various speed regulation applications
Date of Award2014 Jul 24
Original languageEnglish
SupervisorMing-Yang Cheng (Supervisor)

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