STATE-VARIABLE DECOUPLING AND POWER-FLOW CONTROL IN PWM CURRENT-SOURCE RECTIFIERS

Pulsewidth modulated (PWM) current-source rectifiers (CSR), among othe r alternatives, offer marked improvements over thyristor line-commutat ed rectifiers as a source of variable de power, Advantages include red uced line current harmonic distortion and complete displacement power factor control, including unity displacement power factor operation, H owever, due to nonlinearities of the PWM-CSR model, their control has usually been carried out using direct line current control in a three- phase stationary Frame (abc), This paper proposes the application of a nonlinear control technique that introduces more flexibility in the c ontrol of the rectifier and results in a more straightforward approach to controller design, The proposed technique is based on a nonlinear state variable feedback approach in the rotating frame (dq), The appro ach allows the independent control of the two components of the line c urrent (active and reactive) with the same dynamic performance, regard less of the operating point, The control strategy also eliminates the need for input damping resistors and rejects the effect of supply volt age variations, Furthermore, a space vector modulation (SVM) technique is used to maximize the supply voltage utilization, This paper includ es a complete formulation of the system equations and a controller des ign procedure, Experimental results on a 2-kVA digital-signal-processo r controlled prototype confirm the validity of theoretical considerati ons.