双向直流变换器控制方法

Control Methods for Bi-directional DC/DC Converters

双向直流变换器配合蓄电池或超级电容等化学储能元件应用在具有直流母线支撑的系统中时,其主要控制目标为结合储能元件的荷电状态实现负载的稳定工作。当负载功率大于主供电功率时,控制储能元件释放能量以满足负载功率需求;当负载功率小于主供电功率时,控制储能元件吸收能量以避免母线电压上升。归纳和总结了现有的双向控制方法,详细分析了储能系统中变换器两端均为直流源的应用场合时双向直流变换器的双向切换原理,重点研究了采用带有方向信息的电感电流平均值作为电流内环、直流母线电压作为电压外环的双向控制方法。针对该控制方法中存在的母线电压波动和电池频繁充放电的问题,阐述了相应的优化措施。

The main control target of bi-directional DC/DC converters is to achieve the steady state of the load while considering the state of charge of the chemical storage unit in the energy storage system.When the load power demands more or less than the main power supply provides,the bi-directional DC/DC converter should be controlled to release or absorb energy to make the load work normally.The existing bi-directional control methods are summarized,and the principle of bi-directional switching is introduced.Especially,the double-loop control strategy which has a dc bus voltage outer loop and makes use of the average inductor current with direction information as the inner loop is introduced.Aiming at the problems of the fluctuation of the dc bus voltage and damages done to the batteries when the converter charges or discharges frequently in the constant voltage control method,the corresponding optimizing solutions are expounded.