The hybrid cascaded inverter with single voltage source

Traditional two-unit H-bridge hybrid inverters need two different voltage sources. This paper adopts capacitances instead of low voltage source, accordingly only high voltage source is needed to achieve 7-level output. With the multi-carrier stacked PWM modulation, the charge status of the capacitance can be controlled by choosing different combination levels. This paper analyses the conditions that control the capacitance voltage to the half value of the high voltage source. Consequently, two factors that determine whether the capacitance voltage is stable are achieved. By comparing the power loss, the optimum scheme is obtained to realize the purpose of holding the capacitance voltage to the half value of the high voltage source. Last, system simulation and experiments verify the proposed strategy. © 2016, The editorial office of Transaction of China Electrotechnical Society. All right reserved.