电动汽车用高效宽增益双向直流变换器及其运行控制

In order to solve the issues on efficiency, alternating voltage gains and dynamic response of the bidirectional DC-DC converter for electric vehicle applications based on the hybrid energy sources, the bidirectional DC-DC converter with high efficiency and wide voltage gain and its control methods of balanced operation with rapid dynamic response will be investigated systematically in this project. The two-phase three-level bidirectional converter topology with interleaved parallel at the low voltage side and assembled series connection at the high voltage side is proposed, and the principle of high efficiency and wide voltage gain operation is also investigated; Considering the two-phase parameters difference, the virtual referenced inductor currents under disturbed control can be obtained according to the inductor currents imbalance degree, and the inductor currents balanced control method based on the auxiliary voltage and current loops is also proposed; Because the parasitic parameters difference between power devices, the master – slave balanced control method for the capacitor group is proposed, in term of the master control of the assembled series connection capacitor voltage balance. Even more, the coupled relationship between the capacitor voltage balance and the inductor current balance is decoupled; The direct duty cycle control method is established, its controlled variable and the ones from the two proposed balanced control methods are synthesized, then the rapid dynamic response control strategy for the converter is proposed. Finally, the experiment platform for hybrid energy sources system will be established. This research will not only enrich the theory of establishing bidirectional DC-DC topology with high efficiency and wide voltage gain, and develop the control methods of inductor currents balance, capacitor voltages balance and rapid dynamic response, but also provide the engineering application basis for hybrid energy sources in electric vehicles.

为解决复合能量源电动汽车用双向直流变换器的效率、变增益运行和动态响应问题，将系统地研究一种高效宽增益双向直流变换器及其平稳运行、快速动态响应的控制方法。提出低压侧交错并联、高压侧组合串联的两相三电平双向拓扑，研究其高效宽增益运行的本质机理；考虑两相参数的差异性，根据电感电流不均衡度而扰动虚拟参考电流，提出基于辅助电压电流环的电感电流均衡控制方法；针对功率器件寄生参数的不一致，提出组合串联电容电压平衡为主动控制的电容组电压主从平衡控制方法，并解耦电容电压平衡与电感电流均衡的耦合关系；建立变换器的直接占空比控制方法，并综合电感电流均衡方法和电容组电压主从平衡方法的控制量，提出变换器的快速动态响应控制策略；构建复合能量源系统实验平台。本项目一方面将丰富高效宽增益双向直流变换器拓扑的构建理论、发展变换器均压均流和快速动态响应的控制方法，另一方面也能为复合能量源在电动汽车中的应用提供工程参考基础。

本项目针对电动汽车多源系统的燃料电池、超级电容所需的功率接口存在的效率低、增益运行范围窄、动态响应慢的问题，主要完成了三个方面的主题研究：“燃料电池汽车用宽增益升压直流变换器拓扑研究”、“多源系统电动汽车用宽增益双向直流变换器拓扑研究”、“多源系统功率协同运行控制方法研究”。提出了准Z源三电平宽增益升压直流变换器拓扑、两相交错并联开关电容宽增益升压直流变换器拓扑、准Z源开关电容宽增益升压直流变换器拓扑、二次型开关电容宽增益升压直流变换器拓扑系列，解决了燃料电池汽车的燃料电池因输出特性软，其端电压变化范围宽所导致的与车载高压直流母线电压间动态匹配难的问题。提出了开关准Z源宽增益双向直流变换器拓扑、复合开关准Z源-开关电容宽增益双向直流变换器拓扑、单相开关电容宽增益双向直流变换器拓扑、两相交错并联开关电容宽增益双向直流变换器拓扑、阶梯模块型多相交错并联开关电容宽增益双向直流变换器拓扑、低电流纹波耦合电感宽增益双向直流变换器拓扑系列，解决了电动汽车多源系统中超级电容电压宽范围变化所导致车载高压直流母线间的动态宽增益问题。所提出的宽增益直流变换拓扑，均具有电压应力低而变换效率高的特性。最后，基于宽增益双向直流变换器拓扑，提出了电动汽车多源系统功率协同运行控制方法，解决了电动汽车加减速对动力电池的电流冲击问题，并能保证电动汽车动态响应的前提下延长了动力电池的服役寿命和续航里程。因此，本项目的研究，一方面能丰富高效宽增益直流变换器拓扑的构建理论、发展变换器电感电流均衡与电容电压平衡的解耦方法和快速动态响应控制方法；另一方面能为多源在电动汽车中的应用提供工程参考基础，进而真正意义上延长电动汽车动力电池的使用寿命和续航里程，具有重要的科学意义和广阔的应用前景。