【作者】 张伟；

【导师】 张云；

【作者基本信息】 天津大学 ， 电气工程， 2019， 硕士

【摘要】 纯电动汽车可实现真正的清洁无污染排放,是未来交通运输的发展目标。纯电动汽车的复合能量源由蓄电池和超级电容组成,高比能量的蓄电池作为动力电池通过双向直流变换器建立母线电压,提供母线稳态低频功率,高比功率的超级电容通过双向直流变换器连接直流母线提供瞬态高频功率。复合能量源协同工作,为直流母线提供所需的双向功率。因此研究高效宽增益的双向直流变换器以及复合能量源系统协同运行的控制策略对电动汽车的快速发展、全面应用具有十分重要的意义。本文针对超级电容充放电引起的端电压宽范围变化,提出一种阶梯式模块化双向宽增益直流变换器,该变换器采用开关电容结构和交错并联联结形式,具有电压应力低、低压侧电流纹波低、易拓展等优点,可动态匹配宽范围变化的超级电容电压与固定不变的母线电压。此外为了减小负载突变对动力电池产生的大电流冲击,本文采用复合能量源系统功率分频运行控制策略,实现动力电池吸收释放稳态低频功率,超级电容吞吐瞬态高频功率,有效延长了动力电池的使用寿命。同时动力电池所接变换器以电压源特性运行,用来建立稳定母线电压,超级电容所接变换器以电流源特性运行,可以直接与直流母线并联。最后,为了保证复合能量源系统可以长期稳定工作,提出了基于超级电容电压范围的复合能量源系统分模式运行控制策略,分为七种模式,包括母线功率吸收和母线功率回馈两种状态,有效保证了超级电容不会因为频繁充放电而处于极限电压范围,一直处于正常电压范围可以持续运行工作。更多还原

【Abstract】 Electric vehicles,which can achieve clean and pollution-free emissions,are the development goal for the future transportation.The hybrid energy sources system of the electric vehicles is composed of a battery bank and a super capacitor bank,where the high specific energy battery is used as the power battery to establish the bus voltage through a bidirectional dc-dc converter and provide the steady-state and low-frequency power to the bus,and the high specific power super capacitor provide transient and high-frequency power to the bus through a bidirectional dc-dc converter.The hybrid energy sources work coordinately,servicing the required bidirectional power for the bus.Therefore,it is of great significance to study the high-efficiency and wide-voltage-gain bidirectional dc-dc converter and the coordinate operation strategy of the hybrid energy sources system.In order to match the wide-range voltage of the super capacitor caused by the charging and discharging,a stepped and modular bidirectional dc-dc converter with wide voltage gain is proposed.The converter adopts switched-capacitor structure and interleaved parallel form.It has the advantage of low voltage stresses and low current ripple of the low voltage side and easy to extend.It can also dynamically match a wide-range voltage of super capacitor with a constant bus voltage.In addition,in order to reduce the large surge current impact on the power battery generated by the sudden change of load,the paper adopts the power frequency-division operation control strategy of the hybrid energy sources system to realize that the power battery absorbs and releases the steady-state and low-frequency power,and the super capacitor swallows and spits the transient high-frequency power,which prolongs the life of the power battery.At the same time,the converter connected to the power battery operates as voltage source to establish a stable bus voltage while the converter connected to the super capacitor operates as current source.Finally,a multi-mode operation control strategy based on the super capacitor’s voltage range is proposed to ensure the long-term stable operation of the hybrid energy sources system.The control strategy is divided into seven modes,including bus power absorption state and bus power feedback state.It ensures that the super capacitor will not be in the limit voltage range caused by frequent charging and discharging,and the super capacitor can operate under the normal voltage range continuously.更多还原