Six-Step Inverter-Fed Permanent Magnet Synchronous Motor and Brushless DC Motor Drives

Permanent magnet synchronous motor (PMSM) and permanent magnet brushless DC motor (PMBLDCM) drives find wide application as industrial drives and in electric vehicles. These motors are inverter driven and require sensing of rotor position information to generate gate pulse for the inverter to rotate the rotor in the forward direction. The sensing of rotor position can be using sensors which work on Hall effect, phototransistors and disc encoders. Sensorless control by directly sensing the back e.m.f. of motor, input DC voltage and current are also possible. Interactive models for six-step continuous current mode and discontinuous current mode inverter-fed PMSM drive along with laboratory experimental results for the later type inverter-fed PMSM drive are presented in this chapter. Also model for three-phase vector controlled PMSM fed by sine wave voltage source is presented. Case study is presented for a three-phase space vector PWM (SVPWM) inverter-fed vector controlled PMSM drive. In addition models for three-phase inverter-fed BLDCM drive in open loop, with hysteresis current controller in closed loop, are presented. A case study of a three-phase hysteresis current controlled inverter-fed PMBLDCM drive with provision to advance the phase angle of inverter switching to extend the speed above base speed is also presented.