Optimal Control Method Of Two-Phase Parallel Three-Level Bidirectional Buck/Boost Converter

In order to meet the needs of electric vehicles in applications such as fast charging and bidirectional charging and discharging,it is necessary to develop high-voltage and high-power bidirectional converters to meet the requirements of fast charging station networks.For conductive charge and discharge modules,AC/DC and DC/DC two-stage structures are mostly used.This subject optimizes the control strategy of the two-phase parallel three-level bidirectional Buck/Boost converter in the subsequent structure,which mainly includes three aspects: inductor current balancing control,input voltage balancing control and switching tube out-of-phase control.In order to realize the inductor current balancing,this article introduces a decoupling current balancing loop design.Most of the existing parallel output controllers are single output voltage loops or single output current loops,which are difficult to be applied in medium and high power.Under this high-power issue,the output controller needs to be controlled by dual feedback loops.Therefore,this paper proposes a decoupled average current balancing control method,which can decouple the current balancing loop and the dual feedback loop,so that each control loop can be independently regulated.Based on the decoupled current balancing loop,the traditional duty cycle offset control method and the decoupled average current balancing control method are simultaneously applied to the control system of a two-phase parallel three-level bidirectional Buck/Boost converter.The output control loop,the inductor current balancing loop,and the input voltage balancing loop do not affect each other and are independently regulated,and the design work of each controller can be simplified.In addition,with regard to the proposed voltage equalization/current equalization control method,a reasonable voltage equalization/current equalization controller output limiting range is given,and the voltage equalization range of a two-phase parallel three-level Buck/Boost converter is analyzed.This article also discusses the staggered control method of a two-phase parallel three-level bidirectional Buck/Boost converter.According to the research status investigation,there are four commonly used staggered control methods: non-interleaved,N-type interleaved,Z-type interleaved,and 180° interleaved.Choosing different interleaved methods will affect the inductor current ripple,output current ripple,and common mode.Voltage noise,etc.have different effects.This article comprehensively analyzes the influence of the above four different interleaving methods on the electrical performance of the converter,and compares the advantages and disadvantages of different phase-staggering methods.