Novel Three and Four Switch Inverters With Wide Input and Output Voltage Range for Renewable Energy Systems

The proposed inverters receive input dc voltage in a wide range and generate output ac voltage in a wide range due to their buck–boost ability. They require only three or four active switches and two inductors. Therefore, the circuit topologies and their operation are simple, and control is easy. The output current of the proposed inverters is continuous, which lowers the output harmonics and filtering capacitor. In the proposed inverters, the output and input voltage sources or capacitors share the same ground, which results in a constant common-mode voltage and negligible leakage current. Of the proposed inverters, an inverter with four active switches and double input voltage sources is analyzed and tested in detail. The circuit operation is discussed, a control strategy is developed, a common-mode voltage analysis is presented, and design guidelines for circuit components selection are given. To verify the theoretical analysis, a 500-W, 40-kHz prototype of the proposed four-switch inverter is designed, fabricated, and tested. An output ac voltage of 110 $\text{V}_{\mathrm {rms}}$ is generated from an input dc voltage of 100–200 V. A peak efficiency of 97.5% is obtained. The proposed inverter obtains high efficiency due to simple circuit operation, few circuit components in the conduction path, and switching of only one switch at high frequency.