Automatic Multi-Phase Digital Pulse Width Modulator

Current demands on switched-mode power supplies to deliver higher output power with improved efficiency are leading to an increased use of multi-phase power converters. With an increasing number of phases, special multi-phase digital pulse width modulators (DPWMs) prove advantageous over the parallel use of conventional DPWMs. In this paper a "smart" multi-phase DPWM is presented which incorporates a duty cycle distribution algorithm. This algorithm is based on the fastest execution of the duty cycle input command with respect to the number of switching actions per phase and switching cycle. The system provides good dynamic current sharing during transients and enables the use of "faster" digital loop compensators. Intrinsic support of a variable number of active phases (phase-shedding operation) and improved scalability over conventional designs complete the feature set. The proposed system has been implemented on an FPGA system and tested with a four-phase buck converter.