PWM rectifier with low DC voltage ripple for magnet supply

Control techniques that optimize the behaviour of pulse-width modulation (PWM) rectifiers for magnet supplies are examined. Different control strategies, both with preprogrammed and variable switching patterns, are examined and compared in terms of optimization of the system performance. Optimum digital PWM, multilevel delta modulation, and hybrid PWM/delta techniques are analyzed. The validity of the control methods was verified by simulation and experimental tests on a 60 kW prototype. It was observed that, in practice, digital PWM techniques are better suited for optimizing the AC converter performance, while delta modulation techniques give better results in terms of DC current and voltage distortion.<<ETX>>