双有源桥DC/DC变换器输出电压优化控制策略

Optimal Control Strategy for Output Voltage of Dual-active-bridge DC/DC Converters

基于电压控制的双有源桥(DAB)DC/DC变换器是直流微电网中控制直流母线电压的核心变流器装置,电容电压反馈控制作为DAB控制中的常用策略存在着控制系统增益与传输功率耦合的问题,并且控制性能受恒功率负载的负阻抗特性的影响较大。为优化DAB的控制性能,在充分分析耦合问题产生的原因、恒功率负载的负阻抗特性的影响的基础上提出了一种基于电容能量反馈解耦的优化控制策略。通过电容能量反馈控制消除DAB控制性能与恒功率负载的耦合;结合基于模型的解耦移相控制得到对应的移相控制信号,解除传输功率对控制系统闭环增益的耦合,实现了以DAB为核心的直流微电网控制性能的优化。理论分析与试验结果验证了所提控制策略的有效性。

The dual-active-bridge(DAB)DC/DC converter under the operation of voltage source is used as the core device to control the DC bus voltage in the DC microgrid.The capacitor voltage feedback control strategy is a common DAB voltage control strategy,but it has the problem of coupling between the control system gain and the transmission power,and it also does not consider the influence of the negative impedance characteristics of the constant power load.In order to optimize the control performance of DAB,an optimized control strategy based on capacitive energy feedback decoupling is proposed on the basis of fully analyzing the causes of coupling problems and the negative impedance characteristics of constant power loads.Through capacitor energy feedback control,the coupling between DAB control performance and constant power load is eliminated.Combined with model-based decoupling phase shift control to obtain the corresponding phase shift control signal,the closed-loop gain of the control system and the transmission power are also eliminated.The optimization of DC microgrid control performance with DAB has been realized.Theoretical analysis and experimental results verify the effectiveness of the proposed control strategy.