Generalized Phase-Shift PWM for Active-Neutral-Point-Clamped Multilevel Converter

The multilevel active-neutral-point-clamped (ANPC) converters have more control freedoms compared to the conventional neutral-point-clamped topology due to increased switching redundancies. However, the device utilization of level-shift pulsewidth modulation (PWM) is inherently low, and the scalability of space-vector-based PWM is challenging to realize for high-level (e.g., four-level or five-level) topologies. In this article, a novel phase-shift PWM and the design approach for ANPC converter are proposed to handle these two problems simultaneously. The proposed idea enables the modular phase-shift PWM design based on the switch group concept. In such a way, the complexity in the PWM design process can be significantly reduced with enhanced scalability for both the general and simplified ANPC topologies. Moreover, compared with conventional level-shift PWM, the proposed PWM schemes can fully utilize the devices for better loss distribution and higher equivalent switching frequency. Study cases have been done regarding output features, device utilizations, loss distributions, etc., through experimental verification and thorough discussions.