A high power PWM quadrature booster phase-shifter based on a multi-module converter

This paper analyses a PWM quadrature booster phase-shifter based on a multi-module converter to attain high voltage levels and improve the harmonic spectrum and the speed response. The modules are based on a nonconventional three-phase PWM AC-AC converter that requires only four force-commutated switches and is controlled by duty cycle variation. The PWM technique is carrier based and the individual modules are gated through phase shifted triangular carriers. As a result, harmonic cancellation take place in the input current and output voltage, yielding an improved harmonic spectrum in both order and magnitude of the line injected harmonics. An additional operating mode with negligible harmonic generation and step-like control is identified. The feasibility and advantages of the proposed phase-shifter are demonstrated by digital simulations