A low-cost low-loss brushless permanent magnet motor drive

In this dissertation, a novel thyristor-based converter topology for a brushless permanent magnet motor is proposed. The proposed drive system is capable of four-quadrant operation, along with built-in current protection. It is believed that the proposed system offers a reliable and low cost solution for the emerging market of home appliance drives. The basic theory for operation of the proposed topology is presented. The operation of a load commutated current source inverter for a trapezoidal back-emf permanent magnet motor is analyzed in detail. A mathematical model for the converter topology including the BPM motor is developed. A simulation program written in MATLAB ® is used to verify the basic operation of the proposed topology. The mathematical model is capable of simulating the steady state as well as the dynamic response of system.; An experimental prototype board for the proposed system is built. A TMS320LF2407 DSP evaluation board is used to implement the closed loop controller that regulates the speed of a three-phase brushless DC motor. An automated setup is used to gather the results of various open loop and closed loop tests. The performance of the system is analyzed in detail to study the effect of various system parameters such as DC link inductor and input voltage on torque ripple, efficiency and power quality of the overall system.