| With the rapid development of new energy industry, the importance of the energy storage system has become prominent increasingly. The bi-directional DC-DC converter is an important part of energy storage system and numerous types of circuit topology exist in it. And in order to achieve good running of the energy storage system, controlling for bi-directional DC-DC converter is particularly important. In this paper, the research on optimization control for cascaded bi-directional DC-DC converter, interleaved parallel bi-directional DC-DC converter and bi-directional Buck/Boost DC-DC converter which are widely used in various power applications are conducted.The traditional double closed-loop control method of bi-directional Buck/Boost DC-DC converter is relatively mature and its control effect is better, but the setting of PI parameters is a relatively tedious process. The balanced current control method based on model predictive control thought simplifies the control process and optimizes the performance of the system. However, the existence of outer voltage loop is still impact the dynamic performance of the converter to some extent. Therefore, the model predictive control method based on the calculation of reference power is proposed to control the Buck/Boost bi-directional DC-DC converter effectively in this paper. This method has the advantages of simple control process and good control effect, etc. The performance of energy storage system is optimized through the calculation of reference power, the evaluation of performance indicators and the optimization of switching state in this control method.In the method of traditional double closed-loop control for cascade bi-directional DC-DC converter, the number of PI parameters is numerous and it is difficult to set appropriate PI parameters to achieve good performance of the system. Therefore, the study of novel control method for cascaded bidirectional DC-DC converter is necessary. Referencing the model predictive control theory, the optimized control method which combines PI control and model predictive control is proposed in this paper. Combining the advantages of PI control and model predictive control, this method optimal control performance and reduce the amount of calculation and the complexity of control.The conventional phase shift control method is widely used for interleaved bidirectional DC-DC converter. In this method, the number of PI parameters is numerous and two-phase inductors current is unbalance. The control targets of interleaved bi-directional DC-DC converter is balancing two-phase inductors current and reducing the input/output current ripple. Model predictive control method has the advantages of easy to contain constraints and nonlinear characteristics of the system, can be used for multivariable system, and so on. So, the optimized control method based on model predictive control for interleaved bidirectional DC-DC converter is proposed in this paper. This method optimized performances of the system through the building of current prediction models and performance optimization.The proposed control method for the above three topologies were verify by building simulation models and experimental prototypes, the results showed that the model predictive control for bi-directional Buck/Boost DC-DC converter can realize controllable power as needed. Compared with traditional double closed-loop control method, this method can reduce the bus voltage overshoot and make the response speed of battery charge and discharge faster. Optimal control method for cascaded bidirectional DC-DC converter can make static and dynamic performance of the system improved. The computational is reduced by 50% compared with model predictive control. Model predictive control algorithm for interleaved bi-directional DC-DC converter optimized static and dynamic performance of the system, avoided the process of setting many PI parameters effectively, and can achieve balanced two-phase inductors current easily. |
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