| The energy crisis and environmental pollution caused by the excessive exploitation and use of fossil fuels are getting more and more attention.Lithium-ion batteries have the characteristics of large energy density,wide operating temperature range,no memory effect,fast charge and discharge,and environmental friendliness.They are widely used in portable electronic equipment,industrial machine tools,aerospace,electric vehicles,hybrid vehicles and energy storage devices of renewable energy system and other fields.Groups of lithium-ion battery cells have to be arranged to comprise a series string to obtain a high voltage output since each cell has a nominal voltage of around 3.6V.To increase the capacity of the system,cells can also be paralleled.The battery pack with series and parallel connected battery cells becomes the centralized energy source in the battery energy storage system.However,the inconsistency between single-cell lithium-ion batteries can cause over-voltage and under-voltage of single-cell batteries during the use of lithium-ion battery packs.The battery pack energy balance system can solve the problem of battery overcharge and over discharge.The traditional battery energy balance converters are hard switches,which will cause a large amount of energy loss and reduce the energy transmission efficiency of the battery pack energy balance system.In order to improve the problems of the traditional battery energy balance converter,this paper takes a bidirectional Cuk DC-DC converter applied to battery balancing as the research object,and designs a zero current(Zero Current Switch,ZCS)PWM bidirectional converter.And the main work is as follows:(1)This article analyzes in detail the working principle,working timing and waveforms of key parameters of ZCS PWM bidirectional Cuk DC-DC converter working in forward boost and reverse buck modes.The conditions for soft switching of converter switch are deduced.(2)In order to verify the correctness of the theoretical analysis of the converter proposed in this paper,this paper builds a ZCS PWM bidirectional Cuk DC-DC converter simulation circuit through MATLAB/Simulink software,and conducts the converter in boost mode and buck mode.The simulation initially verified the correctness of the converter circuit analysis and the feasibility of the converter application.(3)The parameters of each component of the converter are calculated in detail,and the component selection is completed.Through the design of the converter hardware and software,a 30 W STM32-based ZCS PWM bidirectional Cuk DC-DC converter experimental platform was built,and the experimental results of the converter working in the boost mode were analyzed to verify the proposed the correctness of the circuit analysis and simulation research of the converter.The efficiency of the ZCS PWM bidirectional Cuk DC-DC converter proposed in this paper is fully verified by comparing with the efficiency of the ordinary bidirectional Cuk DC-DC converter.In summary,the paper proposes a ZCS PWM bidirectional Cuk DC-DC converter that replaces the battery energy balance circuit,and has been simulated and experimentally demonstrated.The results show that the converter proposed in this paper can effectively improve the energy transmission efficiency,and has certain effectiveness and practicability. |
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