| In recent years, with the development of power electronics technology and speed control theory. AC-DC-AC variable-frequency system has been widely used in various fields of national economy. While the super-capacitor energy storage system is used in AC-DC-AC variable-frequency system, the reliability, stability, energy saving and other characteristics of the variable-frequency system were improved, for the breaking energy to be collected, the DC bus voltage to be balanced and the power to be compensated.Firstly, based on classic RC series model, the differential equations of super-capacitor voltage, current and the charge and discharge efficiency changes related with time were deduced. With the help of MATLAB image processing function, the correlation curves were drawn, and the advantages and disadvantages of different charging and discharging modes were analyzed and discussed.Secondly, combined with the practical production, the operating conditions of AC-DC-AC variable-frequency system were analyzed. On the one hand, to stabilize the DC voltage in AC-DC-AC variable-frequency system, the DC voltage control strategy of super-capacitor energy storage system was proposed; On the other hand, to avoid the power supply overload in AC-DC-AC variable-frequency system, the load power control strategy of super-capacitor energy storage system was presented.The correctness and feasibility of the two control strategies were verified in PSIM simulation software.Again, with the help of predictive control theory in the advanced control technology, the dynamic matrix predictive control (DMC) and traditional PI control were combined as the series predictive control strategy of DMC-PI. It was applied in the DC voltage control strategy of energy storage system, to improve the system control speed and anti-disturbance performance.Finally, the main circuit parameters of the super-capacitor energy storage system were designed. The CPU PCB board and the sampling PCB board were projected, in which TMS320F28335 was selected as the core controller.Through the experiment, while the proposed strategies were used, the energy storage system can be safely cut-in, cut-out and switched between each other according to different operating demand. The super-capacitor energy storage system control effect on stable DC voltage is verified. |
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