Modelling and control of sinusoidal PWM rectifiers

PWM rectifiers are promising because they can supply DC power while keeping a sinusoidal AC current with unity in the fundamental power factor. There are two types, a voltage-fed and a current-fed. The former is required to simultaneously control both the fundamental power factor and DC voltage, while the latter does so for both the fundamental power factor and DC current. State feedback control is essentially suited for multi-input and multi-output systems such as these. A discrete-time optimal regulator is applied to their control because it provides a microprocessor-based robust feedback system without steady-state errors in response to a step reference and/or disturbance change. To obtain a mathematical model, only the fundamental component of the rectifier switching function is considered. The obtained nonlinear equations are linearized and then modified in the form that the regulator requires. Finally, the regulator is implemented using a digital-signal-processor. Experimental results demonstrate the validity