Battery Balance and AC Output Based on Dynamic Series Structure of Battery Pack
Battery has been the main energy st orage system of electric vehicles.How to improve the reliability of output waveform and improve the inconsistency of battery has become the key issue of automotive battery research.An improved battery cell structure is proposed,which can realize the series connection of any battery cell and adjust the number of batteries in series.It can not only output stable sine wave,but also effectively realize battery equalization.Compared with other multilevel structures,its structure is simple,the device cost is low,the control mode is simpler and easy to implement,and it has higher efficiency and lower waveform distortion rate.The control strategy of the inverter output uses the area equivalent principle to make the output waveform equivalent to the sine wave to the maximum extent and effectively reduce the harmonic content.In the equalization strategy,the dynamic equalization strategy based on this structure is designed to achieve the rapid balance between the battery units.The results show that the circuit structure can stably provide 220 V/50 Hz AC voltage,and the harmonic content of the output waveform is only 2.37%.Compared with the traditional inverter circuit,the topology structure has the function of battery equalization when the inverter works,and the equalization effect is good.Finally,the effectiveness and reliability of the circuit are proved by the test of the physical prototype,which provides a new scheme for the inverter output and equalization control of electric vehicles.
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