Current Sharing Strategy of Cascade Capacitive Interlaced Parallel DC-DC Converter Based on Current Model Prediction

With the gradual depletion of conventional fossil fuel resources, the development and utilization of renewable energy sources has become a critical imperative for sustainable development. However, when photovoltaic power generation and wind power generation are connected to the grid, there are intermittency and volatility problems, which require high-performance DC-DC converters. The cascade capacitive interlaced parallel high-gain DC-DC converter plays an important role, but it can only achieve phase current sharing in a specific duty ratio range. In this paper, a new current sharing strategy is proposed for four-phase cascade capacitive interleaved parallel high-gain boost converters. Firstly, the operating modes in the uneven current region are analyzed. The total change of inductance current in a period is obtained by superimposing the inductance current change of each mode in the uneven current region, which is discretized to obtain the inductance current prediction model. Then the cost function is designed with the goal that the four-phase inductance current is equal. The optimal duty ratio is obtained by setting the partial derivative of the cost function about the duty ratio is zero. Ultimately, the simulation verifies the strategy’s capability to reach current balance over the complete span of duty ratios.