All topologies require fast switching power switches. The boost stage and the full-bridge conversion stage require fast switching diodes. In addition, switches optimized for low-frequency (100Hz) conversion are also useful for these topologies. For any particular silicon technology, switches optimized for fast switching have higher conduction losses than switches optimized for low-frequency switching applications.

The boost stage is generally designed as a continuous current mode converter. According to the number of solar modules in the array used by the inverter, choose whether to use 600V or 1200V devices. The two options for power switches are MOSFET and IGBT. Generally speaking, MOSFET can work at a higher switching frequency than IGBT. In addition, the influence of the body diode must always be considered: there is no problem in the case of the boost stage, because the body diode does not conduct in normal operating mode. The conduction loss of a MOSFET can be calculated based on the conduction resistance RDS(ON). For a given MOSFET series, this is proportional to the effective die area. When the rated voltage is changed from 600V to 1200V, the conduction loss of the MOSFET will greatly increase. Therefore, even if the rated RDS(ON) is equivalent, the 1200V MOSFET is not available or the price is too high.

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20000 watt pure sine wave ac inverter