Three-Phase Voltage Boosting Inverter using Single Switched Capacitor

Abstract

This article presents a switched capacitor (SC) voltage boosting inverter and its carrier based modulation strategy. A switched capacitor unit (SCU) is connected to the conventional three-phase bridge inverter to obtain the increased voltage at output. Modified sinusoidal pulse width modulation (SPWM) is used that increases utilization of DC source and the linear operating range of the inverter. Additional references are synthesized for switched capacitor unit modulation. Only single carrier signal is used for comparing and signal generation. Boosting of the inverter can be controlled by manipulating the additional references. Voltage elevation is obtained at intermediate durations resulting in less charging current in capacitor loops. Number of SCUs can be added to conventional voltage source inverter (VSI) for multi-fold voltage augmentation. However, inverter with only one SCU at front end is analysed in this work. Designing of the capacitor is also presented for proposed work. Simulation is performed using MATLAB/SIMULINK and experimental verification is also done. The Switched capacitor inverter helps to get rid of the inductor for boosting the voltage, thus, make the system less bulkier. The proposed work can be retrofitted in existing conventional three phase bridge inverter. The SC-VSI can be used for various low to medium voltage applications,i.e., electric vehicles, photovoltaic, battery energy storage system etc.