A novel hybrid power configuration and its power distribution strategy for electric vehicles

To improve the operation efficiency of hybrid power in electric vehicle and ensure the safety of its batteries, a novel hybrid power configuration is proposed, which can achieve the function of ultra-capacitors/batteries (UC/Batteries) and batteries/UC (Batteries/UC) configurations of hybrid power by controlling selector switches and DC-DC converter. On this basis, seven operation schemes of hybrid power is devised, and the parameter matching of hybrid power system is fulfilled according to the effective operation voltages of lithium batteries and motor and the power demand characteristics of motor in SD-EV test vehicle. Then the power distribution strategies for different operation schemes are put forward based on power balance control rule with considerations of the efficiency of DC-DC converter and the SOCs of lithium batteries and UC. The results of simulation with Matlab/Simulink show that the novel hybrid power can operate with many schemes, effectively enhance the efficiency of hybrid power and ensure the charging-discharging safety of lithium batteries, while the results of verification test with tester built indicate that the overall efficiency of novel hybrid power is 9% and 4% higher than that of UC/Batteries hybrid power and Batteries/UC one respectively.