Characteristics of a Controlled-Current PWM Rectifier-Inverter Link

Two controlled-current pulsewidth-modulated (PWM) converters have been integrated into rectifier-inverter links of variable-speed ac motor drives. The authors focus on developing a mathematical model of the rectifier-inverter link and presenting experimental justification of the model. The characteristics of the rectifier-inverter system and the constraints imposed by the voltage feedback loop and dc link voltage are discussed. The rectifier-inverter system is made to drive a "selfcontrolled" synchronous motor, thus forming a system for which both the utility and the motor currents are near sinusoidal. The optimized power conversion capability of the motor is now matched by unity power factor operation on the rectifier side. Fast reversal from motoring to regenerative braking capability is demonstrated experimentally.