Improved Switching Scheme to Reduce the Junction Temperature and Power Loss of CHB Inverters

Excessive heating and power loss due to high-frequency switching are always alarming issues in the case of multilevel inverter (MLI) based applications such as solar photovoltaic (PV) systems and industrial drives. Both the heating and power loss of power semiconductor switches significantly rely on the switching pulse width modulation (PWM) scheme employed. This paper proposes an improved switching technique for a solar PV-fed grid-tied 5-level cascaded H-bridge (CHB) inverter, which also reduces the power semiconductor losses of the inverter in relation to several existing switching schemes. The proposed switching scheme employs a modified discontinuous standard mode signal to develop the modulating signal of the proposed method. Level-shifted triangular carrier signals are considered with the proposed switching signal to produce the gate pulses for the 5-level CHB inverter. The performance of the proposed switching scheme is validated through MATLAB/Simulink and PLECS computer simulation environments.