Optimal control and appropriate pulse width modulation for a three-phase voltage DC-link PWM converter

Novel control strategies are presented which use all allowed switching operations of the three-phase voltage DC-link pulse width modulation (PWM) converter such that the converter has a line-friendly performance from the point of view of the utilities or the consumer. In the case of an ideal converter and a distortion-free supply network, the power factor becomes equal to unity under steady-state conditions and the dynamic characteristics of the control system are sufficient. In order to reach this line friendly performance with an existing converter and to keep the expenditure for the line-side filter low, appropriate PWM at a high switching frequency (>10 kHz) is necessary. The theory of the control strategies and appropriate PWM are presented. Practical results obtained with an insulated-gate bipolar transistor (IGBT) converter illustrate the dynamic and steady-state performance of the new control system in both energy-flow directions