飞轮储能系统的集成性能分析——ELPH车辆 外文翻译.doc

Integration and Performance Analysis of Flywheel Energy Storage System in an ELPH VehicleI. INTRODUCTIONConventional Internal Combustion Engine (ICE) vehicles bear the disadvantages of poor fuel economy and environmental pollution. Basis of poor fuel economy are (i) Operation of engine in lower efficiency region during most of the time in a drive cycle and (ii) Dissipation of vehicle kinetic energy during braking . Electric battery operated vehicles have some advantages over theICE driven vehicles, but their short range is a major lacuna in their performance. The shortcomings of both of these can be overcome by using a Hybrid Electric Vehicle (HEV). An HEV comprises conventional propulsion system with an on-board Rechargeable Energy Storage System (RESS) to achieve better fuel economy than a conventional vehicle as well as higher range as compared to an Electric Vehicle. HEVs prolong the charge on RESS by capturing kinetic energy via regenerative braking, and some HEVs also use the engine to generate electricity through an electrical generator (M/G) to recharge the RESS.An HEVs engine is smaller and may run at various speeds, providing higher efficiency. Reference suggests that HEVs allow fuel economy and reduced emissions compared to conventional ICE vehicles by:1. Allowing the engine to stop under vehicle stop condition,2. Downsizing the engine for same peak load requirements, as the motor will assist the engine forsuch higher loads, and3. Allowing regenerative braking, not possible in conventional vehicle. In urban drive conditions,about 30% of the fuel can be saved through regenerative braking because of the frequent stop andgo conditions .Series and Parallel hybrids are the two major configurations of the HEVs. Even in Parallel Configuration of Hybrid Vehicles, there are several possibilities in which an arrangement between the engine, motor and transmission can be made to achieve the desired performance from the vehicle. In general there are two methods to couple the energy of the engine and motor namely, (i) Speed Coupling, and (ii) Torque Coupling. In Speed Coupling the speeds of engine and motor areadded in appropriate fractions to achieve the final speed of the drive, whereas in Torque Coupling the torque from the engine and motor are summed up in Torque Coupler, which can be either an epicyclic gear train or simply the rotor of the electric machine (motor). In latter case the rotor of the electric machine is integrated with the shaft from the engine through a clutch. The parallel hybrid is considered for the present analysis because of its significant advantages over the series hybrid, such as lower emissions, improved efficiency, simpler configuration and better performance. The configuration considered for the analysis is Pre-transmission torque coupled parallel hybrid drive train . There are various candidates for onboard RESS. So far lead acid batteries have dominated the industry because of their compactness, easy availability and low cost. However, batteries have a number of disadvantages, such as limited cycle life, maintenance and conditioningrequirements, and modest power densities . To overcome these shortcomings, research activities have focused upon other alternatives of Energy Storage System (ESS). FESS is a prominent candidate for ESS applications in HEVs. Flywheels in particular offer very high reliability and cycle life without degradation, reduced ambient temperature concerns, and is free of environmentally harmful materials .Flywheels offer many times higher energy storage perkilogram than conventional batteries, and can meet very high peak power demands. Power density, which is a crucial parameter for ESS in HEVs, of an FESS is much higher as compared to a chemical battery. Deeper depth of discharge, broader operating temperature range adds to the advantages of using an FESS over batteries. The FESS employed for the present analysis is an Integrated Flywheel Energy Storage System with Homopolar Inductor Motor/Generator and High-Frequency Drive . The use of integrated design has various benefits over other contemporary FESS designs. Some of these advantages are reduced system weight, lower component count, reduced material costs, lower mechanical complexity, and reduced manufacturing cost.II. SYSTEM DESCRIPTIONThe arrangement used for analysis consists of an Electrically Peaking Hybrid Electric propulsion system that has a parallel configuration . Through the use of a parallel configuration the engine has been downsized as compared to the engine required for a similar conventional ICE vehicle. A small engine of power approximately equal to the average load power is used in the model. An AC induction motor is used to supply the excess power required by the peaking load. The electric machine can also absorb the excess power of the engine while the load power is less than the peak value. This power, along with the regenerative braking power, is used to charge the FESS to maintain its State-Of-Charge (SOC) at a reasonable level. Fig. 1 shows a schematic diagram of the complete vehicle configuration illustrating the pre-transmission torque coupling, and the other major components of the drive The operation of the vehicle is managed by a vehicle controller. It sends control signals to the motor controller, engine controller (throttle) and FESS controller depending upon the control strategy and the input signals. Basically the input signals are from theacceleration pedal and brake pedal. With the electrically peaking principle, two control strategies for the drive have been used . The first one is called MAXIMUM BATTERY SOC control strategy, which in particular aims at maintaining a particular range of SOC in the battery at any instant. In this SOC range, the battery is having maximum efficiency and thus, the best performance of the vehicle which is employing a chemical battery, can be achieved through this strategy. Under this strategy the engine and electric motor are controlled so that the battery SOC is maintained at its appropriate level for as much duration as possible. This control strategy may be used in urban driving, in which repeated acceleration and deceleration is common and high battery SOC is absolutely important for normal driving. This control strategy, which basically aims at thebest performance of the chemical battery, is employed in the analyzed model comprising FESS, so that a direct comparison can be drawn over the performance level of an FESS as compared to a chemical battery, working in its best efficiency range. The other control strategy developed is called ENGINE TURN-ON AND TURNOFF control strategy. Under this, the engine is turned on and off depending upon the instantaneous SOC of the RESS. This strategy can be used during highway driving. An integrated flywheel system is one in which the energy storage accumulator and the electromagnetic rotor are combined in a single-piece solid steel rotor. This allows the housing of the motor to comprise a large part of the vacuum and burst containment of the flywheel, enabling significant savings in total system weight and volume. By using an integrated design, the energy storage density of a high power steel rotor FESS can approach that of a composite rotor system, but the cost and technical difficulties associated with a composite rotor are avoided. High efficiency, a robust rotor structure, low zero torque spinning losses, and low rotor losses are the key requirements for an FESS electrical machine. PM motors are currently the most commonly used motors for flywheel systems . However PM rotors tend to be more temperature sensitive, mechanically complex, and costly. Homopolar inductor motors present an attractive alternative with a low-cost rotor, machined from a single piece of steel, which is more robust and less temperature sensitive than PM rotors. In addition, a homopolar inductor motor with a slotless stator and six-step drive eliminates the stator slot harmonics and maintains low rotor losses while also allowing operation at unity (or any desired) power factor . As discussed in previous sections, it is quite clear that employment of FESS in place of chemical battery will lead to a better performance of hybrid vehicles. A scan of the available literature, to the best of authors knowledge, indicates that very few efforts have been aimed at replacing the chemical batteries with FESS altogether. Thus, to bridge the gap in this field, this work has been carried out. The work presented in this paper uses the simulation results of the discussed ELPH propulsion system based vehicle, as obtained in using V-ELPH computer simulation package, developed at Texas A&M University. The paper provides various plots depicting the performance of various components of the vehicle.The simulation results are mathematically treated and are combined with the results of the practical testing as well as the simulated results of the FESS considered . A SIMULINK model (Fig. 2) is used to perform these mathematical operations for two particular drive cycles namely (i) FTP-75 Urban Drive, and (ii) FTP-75 Highway Drive. The figure illustrates the various components of the SIMULINK model, which are used to perform various operations, mentioned in the following text.飞轮储能系统的集成性能分析ELPH车辆1、引言传统的内燃机（ICE）车辆具有贫困燃油经济性和环境污染的缺点。燃油经济性差的基础是：（一）引擎运转过程中，在驱动器周期及（ii）车辆损耗动能在制动过程中大部分时间在低效率的地区。电动电动车驾驶的车辆在冰面上的一些优势，但他们的短距离是一大空白，其性能研究。这些可以通过使用一个缺点克服，两者在混合动力电动汽车（HEV）。戊型肝炎病毒由一个具有板上充电储能系统（快速膨胀法），提供比传统汽车的燃油经济性更好以及更高的远程常规推进系统相比，一个电动车。混合电动汽车通过捕捉动能延长对快速膨胀法通过再生制动充电，有的还使用混合电动汽车通过发电机（男/ G）的充电的快速膨胀法的发动机来发电。一种混合动力汽车的发动机更小，可以运行在不同的速度，提供更高的效率。混合电动汽车的参考建议，使燃油经济性和降低排放比传统内燃机车辆：1。让发动机停止车辆停止状态下，2。瘦身负荷要求，发动机同样的高峰期，由于汽车发动机的负荷将协助这些较高，3。允许再生制动，而不是在传统的车辆可能。在城市驾驶条件下，约30的燃料可以节省通过再生制动，因为经常走走停停的条件。串并联混合动力车的混合电动汽车的两个主要的配置。即使在混合动力汽车并行配置，其中有一个引擎之间的安排，电机和传动，可实现从车辆所需的性能几种可能性。一般有两种方法来夫妇的发动机和电动机的能量，即（一）速度耦合，以及（ii）扭矩耦合。在汽车发动机转速和速度的耦合的分数将在适当的实现发动机和电动机的扭矩最后在驱动器的速度，而转矩耦合的总结，在转矩耦合器可用于任何一个行星齿轮火车或简单的异步电机（马达转子）。在后一种情况下，在电机转子集成了从发动机轴通过离合器。并联式混合动力被认为是由于其具有明显的优势分析目前在系列杂交，比如降低排放，提高效率，更简单的配置和更好的性能。在分析中考虑的配置是预传动扭矩耦合并联混合动力列车。用于板载快速膨胀法有不同的候选人。到目前为止铅酸电池为主，因为体积小，容易获得，成本低的产业。然而，电池的缺点，例如有限的生命周期，保养和调节，要求，而温和的功率密度。为了克服这些缺点，研究活动主要集中在能源储存系统（ESS）的其他选择。鼻内镜在混合电动汽车是一个突出的候选人ESS的应用。飞轮提供特别的高可靠性和循环退化，失去生活，降低环境温度的关注，并免费对环境有害的材料。飞轮提供了许多倍，比传统电池的能量储存每公斤，可满足高峰电力需求非常高。功率密度，这是一个ESS的关键参数的混合电动汽车的鼻内镜手术，大大提高相比，化学电池。更深的深度放电，宽工作温度范围内增加了对电池的使用鼻内窥镜手术的优点。目前分析的鼻内镜采用的是一个高调速综合飞轮储能系统的单极感应电动机