【作者】 张晓峰；

【导师】 吕征宇；

【作者基本信息】 浙江大学 ， 电气工程， 2009， 博士

【摘要】 汽车工业可以说是一个国家的重要支柱产业,但是由汽车带来的环境污染日益恶化,同时地球上化石燃料的储存量与消耗量的矛盾越来越突出。目前的迫切需要是找到快捷、有效、可行的途径来解决或者缓解汽车对化石燃料的依赖和对环境的严重污染。新能源汽车,尤其是混合动力车被证明是一种非常行之有效的途径。混合动力技术已成为能够使用于所有燃料的关键技术,同时它也是目前能满足排放要求和节能目标且有利于市场化的实用技术。本文正是基于电力电子功率变换技术在混合动力车中所占有的重要技术地位而进行研究和探讨,以小型混合动力试验样车为载体,开展对混合动力电力驱动装置的关键技术研究。主要所做的研究工作包括：(1)通过对混合动力车的各种动力结构进行总结和对比,结合作者所研究课题的目标重点,提出了小型HEV试验样车中的动力组成结构方案。选用了铅酸蓄电池+超级电容的混合电力储能源组合方案,可以使得小型HEV对电力储能单元的比能量和比功率要求分离开。并且把两种混合电力储能源在小型HEV电力驱动装置内的不同电气连接方式及特点做了分析,指出了铅酸蓄电池、超级电容模组和无刷直流电机逆变器三者通过两个双向DC／DC变换器实现的级联结构,具有的灵活性、合理性和整体高效性。然后对比了各种不同的实用型双向DC／DC变换器在所用功率器件的数量、对器件的电气应力要求、损耗等方面的性能参数指标,并且结合小型HEV的实际运行工况,对比了不同拓扑在完成此方面功能的局限性,最终给出了适应小型混合动力车实际运行工况的拥有多模态工作方式的高效率双向DC／DC变换器的拓扑结构选定依据。(2)结合所采用的小型HEV的混合电力储能源组成结构,研究了新型的双向DC／DC变换器的拓扑和相应的控制技术。首先是针对小型混合动力车的具体运行工况,进一步提高级联型Buck-boost双向DC／DC变换器在特殊情况下的电能转换效率,提出了利用单一电流采样电阻实现双向平均电流控制,以及较好地实现同步整流断续工作模式等关键技术方法。再是在该车电力驱动装置中采用了一种基于“3-L”结构的新型双向软开关DC／DC变换器,而且通过理论推导、分工作阶段说明了其电路的有益效果在于：保证器件承受的电压和电流应力并没有增加的情况下,通过“3-L”换流电路实现开关的零电压或者零电流开通、零电压关断和续流二极管的零电流关断,降低变换器的开关损耗,尤其解决了续流二极管反向恢复这一主要损耗来源,可以显著提高变换器的效率,更加适合较大功率变换器的效率提升。(3)以提高整车的电力驱动性能和驾驶舒适度为研究目的。首先通过对无刷直流电机和相匹配的DC／AC三相逆变器结构为分析对象,详细分析了BLDCM实际的等效数学模型,提出了在HEV中选用BLDCM的原则。再是全面分析了无刷直流电机的两类转矩脉动的本质,其中对无刷直流电机的传导区电磁转矩脉动,利用能量单元分析法对其进行定量的理论推导,并在此基础上结合小型混合动力车电力驱动系统,提出了一种新的控制策略,理论上可以消除BLDCM在传导区内的电磁转矩脉动；同时针对换流区转矩脉动提出了一系列解决问题的新方法和新思路；此外由于所设计的小型HEV电力驱动装置样机系统中,采用了多级电路结构,可以方便的实现BLDCM高速区域内的恒功率控制。本课题研究的意义在于：当前混合动力汽车的核心技术多数掌握在几个汽车制造大国,如美国、日本和德国等,而我国要实现新能源汽车产业走在世界的最前端,必须尽早的掌握其中的核心和关键技术。本文正是基于这个目的,结合所学专长而展开研究,虽然以小型混合动力车为具体研究和方案实施对象。但是所设计的动力组成结构、电力驱动装置以及控制方法,完全适合转化到混合动力电动轿车或者混合动力电动客车的电力驱动系统中,可为广大的工程技术人员提供设计参考和研究思路,具有一定价值的借鉴意义。更多还原

【Abstract】 Automotive industry has been the mainstay industry for a country, but the problem between need of fossil fuel and environmental pollution is becoming more and more serious, because of motor vehicle in life using. The one effective mean to resolve this contradiction must be found now. Fortunately, new energy vehicle, specially hybird electric vehicle(HEV) has been proven a kind of practical and fast-developing vehicle in the latest years. Based on the power electronics being the core part for HEV technology development, this dissertation focuses on the key technologies of electric drive equipment in the minitype HEV system.These are three aspects to research as follows.(1) The power structure of minitype HEV’s prototype is proposed by the comparion between different power structures, likely series HEV, parallel HEV and combined HEV. Based on the selected structrue, the lead-acid battery mixed with super capacitor is adopted as hybrid electric engergy storage mode. Because this mixture can exert the advantages of lead-acid battery and super capacitor. In the proposed minitype HEV’s electrical structrue, the lead-acid battery, super capacitor and BLDCM’s inverter are cascaded by two bi-directional DC/DC converters. This electrical structure has some characteristics:flexibility, rationality and overall efficiency. Aimed to realize proposed electrical structure efficiently under different minitype HEV’s operating modes, this dissertation have compared the seven topologies with bi-directional DC/DC converter fuction, mainly through number of the devices, electrical stress of active and passive devices, volume and dissipation of devices.Then as requirement of different minitype HEV’s operating modes, it gives the selection basis and characteristic of bi-directional DC/DC converter used in minitype HEV.(2) This dissertation focuses on the most important aspects of the bi-directional DC/DC converter in the minitype hybrid electric vehicle for the project applications.The different operating modes of converter are introduced under all HEV’s work conditions. Based on summarization, the demerits including low efficiency at light load and the uncontrolled discontinuous current are derivated. Through theoretical and mathematical analysis, a new algorithm of average current controlling and digital control method in discontinuous synchronous rectifier mode with a single current sensor resistance are proposed to realize the multi-mode bi-directional cascade Buck-boost DC/DC converter. At the same time, the prototype using proposed technology is implemented to verify the operational principles and advantages that improved synchronous rectifier inverse-boost converter light load efficiency. And then, a new kind bi-directional DC/DC converter with the characteristics of soft-switching based on "3-L" structure is proposed to use in minitype HEV. This bi-directional DC/DC converter has many advantages:low electrical stress of active devices, high efficiency, simple structure and so on.(3) Aimed to improve the drive performance and comfort. Firstly, the actual BLDCM’s mathematical model and mechanical characteristic are analyed based on pratical DC/AC inverter with power MOSFET and anti-parallel diode. This dissertation presents a comprehensive research on torque ripples of brushless dc motor drive in conduction region and commutation region.The phenomenon of torque ripples of conduction exists because of diode freewheeling happened under the conventional PWM schemes.Through new proposed energy unit theoretical analysis, a new method for reducing the torque ripple in brushless dc motor with a single current sensor has been proposed under the minitype HEV’s electrical sturcture. So in such drives, torque ripples are theoretically eliminated in conduction region. For torque ripple in the commutation region, a series of new methods are proposed and analyed to reduce this kind torque ripple, including of single-stage and two-stage modulation strategy. Effectiveness and feasibility of the proposed control method are verified through experiments.Nowadays, the key technologies of HEV have been mastered by several great automobile manufacturers, likely Toyota, Ford, GM, Honda and so on. But if our motherland wants to belong to first group in new energy vehicle, the key technologies of HEV must be researched and mastered as soon as possible. So this dissertation has been finished with this background and prospect. Although the all kinds of new methods are realized on minitype HEV’s prototype, the proposed system analysis and method implementation are valuable for project application and design.更多还原