Double-Carrier-Based PWM Theory for Independent Power Control of Dual-Input Three-level Inverters

In this paper, double-carrier-based PWM theory for direct and independent power control for dual-input three-level inverters is proposed. With the proposed PWM strategy, the upper and lower dc bus voltages can be controlled separately in a decoupled manner. These characteristics are crucial in photovoltaic applications (PV) when tracking of maximum power points for two strings of PV panels under different irradiations is required. Independent control of input dc-bus power is achieved by simply decomposing the voltage command of the inverter in proportional to the required dc-bus power. Implementation of the proposed PWM strategy is also simple because it uses double carrier waveforms supported by PWM modules in most hardware. Effectiveness and feasibility of the proposed PWM theory are verified by experiment.