Motor Drives and Inverters
Technical Dialogue Session
Motor Drives II
Cascaded H5, cascaded h-bridge, converter efficiency, multilevel converter, mixed switching frequency, pulse width modulation
Multilevel converter generally consists of more switching devices than the conventional two-level converter topology. The performance of these multilevel converters tends to increase by using high switching frequency which may also increase the switching loss that is the largest dominating loss of a power converter. This paper proposed a novel modulation strategy with a mixed switching frequency scheme that uses both high and low switching frequency to overcome this problem. Different multilevel converter topology such as Cascaded H-Bridge (CHB), Cascaded H5 (CH5), Neutral point Clamped (NPC), and Flying Capacitor Converter (FCC) topologies are presented for the validation of using proposed mixed switching frequency scheme. The level shifted modulation technique is used for all topologies except for CH5 topology which doesn't allow level shifting operation. Moreover, it is observed that the zero-voltage state occurs for the CH5 topology during mixed switching condition which may result in reactive power flow from load/grid to the photovoltaic solar panel. Hence a new modified H5 topology is proposed to avoid the reactive power flow.