An ANPC-Based Building Block for Medium-Voltage Applications

The cascaded H-bridge (CHB) converter has shown significant potential for integrating several high-power applications into medium-voltage (MV) power grids. While high-voltage (HV) switching devices offer the advantage of reducing the number of MV building blocks (MV-BBs) required in CHB converters, they pose technical and economic challenges. These include low switching frequency, limited current capability, and high cost. This article introduces an innovative MV-BB design based on active neutral point clamped (ANPC) legs. The proposed MV-BB enables the use of switching devices with lower voltage ratings while maintaining the same number of cascaded MV-BBs. Detailed analysis of the configuration and modulation technique highlights the operational characteristics and performance benefits of this approach. Compared to the conventional MV-BB configuration, the proposed one significantly decreases system power losses, volume, and weight. For instance, the power losses of switching devices are reduced by 34%, while the size, volume, and weight of the LCL filter are decreased by at least 50%. To validate the feasibility and performance of the proposed ANPC-based MVBB, a prototype was fabricated and tested at 15 kW.