Efficiency Improvement for Regenerative Energy System Using Dynamic Efficiency-SOC-Load Model

The hybrid energy composed of the battery and the supercapacitor can not only provide stable power, but also recover the regenerative energy. Thus, it has been widely promoted in the variable frequency drive system. However, unreasonable energy distribution would lead to a decrease in system efficiency during the process of motoring operation. An energy management strategy based on the dynamic efficiency-SOC-load model was proposed. The equivalent circuit models of the battery and the supercapacitor were constructed and the function relationships between the SOCs and the efficiency were deduced. Afterward, the dynamic efficiency-SOC-load model was established. The maximum efficiency point was dynamically obtained according to the required power of the motor. The dynamic power distribution between the battery and the supercapacitor was realized in real-time. Simulation and experimental verification were carried out. The test results showed that the efficiency of the system was increased by 5.4% compared with the battery power supply.