Abstract:  In order to smooth the power output of the new energy generation system with strong randomness and fluctuation, a current predictive control method of power converter for hybrid energy storage is proposed. Firstly, the complementary characteristics of charging and discharging speeds of lithium batteries and super-capacitors are analyzed, as well as the switching states of their power converters. Then, on the basis of model predictive control, the predictive models of lithium battery, super-capacitor and dual power converter are established. On this basis, a hybrid energy storage control system is designed by using model predictive control. Considering the current tracking errors of lithium batteries, super-capacitor current tracking errors, super-capacitor losses and the number of switches of dual power converter, a multi-objective evaluation function is constructed and the optimal switching mode is solved. After real-time optimization of the control system, the optimal switching mode is output. In this way, not only the high-current and low-frequency variable power tracking of lithium battery, but also the low-current and high-frequency variable power tracking of super-capacitor are realized. Therefore, the balanced energy distribution of hybrid energy storage system is realized. The service life of lithium battery is prolonged. The switching action is reduced, and the overall efficiency of the system is improved. Finally, the correctness of the proposed method is verified by simulation.

Key words:  hybrid energy storage system, model predictive control, dual power converter, multi-objective optimization, optimal switching mode