An Investigation into Regenerative Braking Control Strategy for Hybrid Electric Vehicle

Energy regeneration during braking is an important technique for hybrid electric vehicle (HEV) to improve their fuel economy and extend their driving range. Due to the effect of regenerative braking torque which is added by electric motor, the braking torque distribution between front and rear axles should be changed and the control logic of anti-lock braking system (ABS) ought to be adjusted according to the regenerative braking torque. This paper put forward a braking control strategy for hybrid electric vehicle; the control strategy is implemented with eight DOFs (Degree-of-Freedom) nonlinear vehicle forward simulation model which is built under the environment of Matlab/Simulink. Based on target wheel slip ratio, a fuzzy logic approach was applied to maintain the optimal target slip ratio so that best compromise between hydraulic torque and regenerative torque can be obtained for the vehicle.

Design and Analysis of Electro-mechanical Hybrid Anti-lock Braking System for Hybrid Electric Vehicle Utilizing Motor Regenerative Braking

Braking on low adhesion-coefficient roads, hybrid electric vehicle＇s motor regenerative torque is switched off to safeguard the normal anti-lock braking system （ABS） fimction. When the ABS control is terminated, the motor regenerative braking is readmitted. Aiming at avoiding permanent cycles from hydraulic anti-lock braking to motor regenerative braking, a novel electro-mechanical hybrid anti-lock braking system using fuzzy logic is designed. Different from the traditional single control structure, this system has a two-layered hierarchical structure, The first layer is responsible for harmonious adjustment or interaction between regenerative system and anti-lock braking system. The second layer is responsible for braking torque distribution and adjustment. The closed-loop simulation model is built. Control strategy and method for coordination between regenerative and anti-lock braking are developed. Simulation braking on low adhesion-coefficient roads with fuzzy logic control and real vehicle braking field test are presented. The results from simulating analysis and experiment show braking performance of the vehicle is perfect, harmonious coordination between regenerative and anti-lock braking function, significant amount of braking energy can be recovered and the proposed control strategy and method are effective.

Driving and Braking Control of PM Synchronous Motor Based on Low-resolution Hall Sensor for Battery Electric Vehicle

Resolvers are normally employed for rotor positioning in motors for electric vehicles, but resolvers are expensive and vulnerable to vibrations. Hall sensors have the advantages of low cost and high reliability, but the positioning accuracy is low. Motors with Hall sensors are typically controlled by six-step commutation algorithm, which brings high torque ripple. This paper studies the high-performance driving and braking control of the in-wheel permanent magnetic synchronous motor （PMSM） based on low-resolution Hall sensors. Field oriented control （FOC） based on Hall-effect sensors is developed to reduce the torque ripple. The positioning accuracy of the Hall sensors is improved by interpolation between two consecutive Hall signals using the estimated motor speed. The position error from the misalignment of the Hall sensors is compensated by the precise calibration of Hall transition timing. The braking control algorithms based on six-step commutation and FOC are studied. Two variants of the six-step commutation braking control, namely, half-bridge commutation and full-bridge commutation, are discussed and compared, which shows that the full-bridge commutation could better explore the potential of the back electro-motive forces （EMF）, thus can deliver higher efficiency and smaller current ripple. The FOC braking is analyzed with the phasor diagrams. At a given motor speed, the motor turns from the regenerative braking mode into the plug braking mode if the braking torque exceeds a certain limit, which is proportional to the motor speed. Tests in the dynamometer show that a smooth control could be realized by FOC driving control and the highest efficiency and the smallest current ripple could be achieved by FOC braking control, compared to six-step commutation braking control. Therefore, FOC braking is selected as the braking control algorithm for electric vehicles. The proposed research ensures a good motor control performance while maintaining low cost and high reliability.

Energy-Optimal Braking Control Using a Double-Layer Scheme for Trajectory Planning and Tracking of Connected Electric Vehicles

Most researches focus on the regenerative braking system design in vehicle components control and braking torque distribution,few combine the connected vehicle technologies into braking velocity planning.If the braking intention is accessed by the vehicle-to-everything communication,the electric vehicles(EVs)could plan the braking velocity for recovering more vehicle kinetic energy.Therefore,this paper presents an energy-optimal braking strategy(EOBS)to improve the energy efficiency of EVs with the consideration of shared braking intention.First,a double-layer control scheme is formulated.In the upper-layer,an energy-optimal braking problem with accessed braking intention is formulated and solved by the distance-based dynamic programming algorithm,which could derive the energy-optimal braking trajectory.In the lower-layer,the nonlinear time-varying vehicle longitudinal dynamics is transformed to the linear time-varying system,then an efficient model predictive controller is designed and solved by quadratic programming algorithm to track the original energy-optimal braking trajectory while ensuring braking comfort and safety.Several simulations are conducted by jointing MATLAB and CarSim,the results demonstrated the proposed EOBS achieves prominent regeneration energy improvement than the regular constant deceleration braking strategy.Finally,the energy-optimal braking mechanism of EVs is investigated based on the analysis of braking deceleration,battery charging power,and motor efficiency,which could be a guide to real-time control.

A Novel Braking Control Strategy for Hybrid Electric Buses Based on Vehicle Mass and Road Slope Estimation

Proper braking force distribution strategies can improve both stability and economy performance of hybrid electric vehicles,which is prominently proved by many studies.To achieve better dynamic stable performance and higher energy recovery efficiency,an effective braking control strategy for hybrid electric buses(HEB)based on vehicle mass and road slope estimation is proposed in this paper.Firstly,the road slope and the vehicle mass are estimated by a hybrid algorithm of extended Kalman filter(EKF)and recursive least square(RLS).Secondly,the total braking torque of HEB is calculated by the sliding mode controller(SMC),which uses the information of brake intensity,whole vehicle mass,and road slope.Finally,comprehensively considering driver’s braking intention and regulations of the Economic Commission for Europe(ECE),the optimal proportional relationship between regenerative braking and pneumatic braking is obtained.Furthermore,related simulations and experiments are carried out on the hardware-in-the-loop test bench.Results show that the proposed strategy can effectively improve the braking performance and increase the recovered energy through precise control of the braking torque.

Electro-mechanical Braking Method in Hybrid Electric Vehicles Based on Feedback Control Theory

In this paper, the hybrid electric vehicle braking process is researched, by using variables consists of HEV speed, motor speed, and state of charge established, fimctions of mechanical braking force, regenerative braking force and efficiency of energy recovery are constructed, and the control goal is to maximization the energy recovery efficiency. Under the feedback control strategy, with the constrain condition of braking strength and braking stability, combining experiments in ADVISOR, in different experiments of different working conditions, we can see that in UDDS Cycle, the regenerative braking efficiency is the best. What＇s more, compared with strategies in ADVISOR, strategy proposed in this paper is obviously better.

永磁无刷直流电机PWM调制方式研究

分析了永磁无刷直流电机电动运行时不同PWM调制方式对电枢电流的影响,得出了采用全桥载波时电流波动最小,转矩脉动最小的结论。又提出了一种能量回馈制动的方法,实现了电机制动时能量的回馈。

PWM调制方案对无刷直流电机电动汽车再生ABS的影响

为研究PWM调制方案对无刷直流电机电动汽车再生ABS的影响,在分析单、双管PWM调制方案下的无刷直流电机再生制动原理基础上,通过调节占空比的方法来防止再生制动时驱动轮抱死。建立了单轮车辆再生制动动力学模型,设计了再生ABS双闭环控制系统,外环控制滑移率,内环控制制动电流。以系统在结冰路面上再生制动为例,对系统在单、双管PWM调制方案下的防抱死制动性能进行了仿真试验。结果表明:与单管调制相比,双管调制时系统的制动距离短,回收能量多。

一种用于无刷直流电机回馈制动的PWM调制方式

在能量回馈制动原理的基础上,分别指出无刷直流电机(brushless DC Motor,BLDCM)回馈制动时半桥和全桥脉宽调制(Pulse-Width Modulation,PWM)的优缺点,并在此基础上详细分析了BLDCM的半桥PWM回馈制动原理。针对现有的半桥PWM会在BLDCM回馈制动中引起非导通相续流,从而影响电机运行特性的问题,通过原理分析及数学推导,提出一种PWM-OFF-PWM调制方式,采用该调制方法可消除非导通相续流电流,改善电流波形,减小电磁转矩脉动,在制动过程中获得更大更稳定的制动转矩,进而实现高效回馈制动。仿真和试验分析表明该方法具有比传统半桥PWM调制更优良的特性。

基于智能PWM控制的机车制动控制单元的设计

针对目前机车上难以实现对制动机精确制动的情况,开发了基于智能PWM精确控制机车制动机气缸的制动控制单元。着重讨论了系统的整体结构、模糊PID控制器的设计、软件实现等。现场调试表明,控制精度可达±0.5 kPa,具有良好的静、动态特性,能满足机车制动控制的需要。

带制动装置气缸的PWM位置控制系统

目的分析传统气动位置控制系统存在的问题，提出一种新的位置控制系统．方法采用新的执行机构——内藏制动装置和位移传感器的新型气缸．系统的位置控制采用ＰＷＭ方法和模糊控制算法实现，当气缸达到目标位置后，利用制动装置来实现气缸的位置保持．结果实验研究表明，系统的刚性得到明显提高，定位精度达到０．１５ｍｍ．与不同带制动装置气缸定位系统相比，本系统无大的定位冲击和磨损．结论气动位置控制系统解决了传统气动位置控制系统存在的问题。

城市轨道交通车辆再生制动能量回馈系统PWM整流器容量计算方法

在现有城市轨道交通供电系统的基础上,构建能馈式牵引供电系统的方案,从根本上改善传统牵引供电系统能量的单向流动性引起的系列问题,解决再生制动能量的回馈与利用。以概率论理论为基础提出了一套确定PWM(脉宽调制)整流器容量的计算方法。

双PWM变频器在船舶上的应用前景

因为船舶用电设备的谐波标准日益提高,而现阶段船用变频器会给船用电网注入大量的谐波,为此,PWM整流技术的研究,新型单位功率因数变流器的开发引起广泛的关注。

蓄电池式矿用电机车PWM斩波调速控制系统的研制

针对工作在煤矿井下恶劣环境中的电机车在换向和调速方面的不足,研制了一种新型矿用电机车直流斩波调速系统。该系统以STC15W4K32S4为控制核心,配合基于HCPL-316J的H桥式IGBT驱动电路,在实现电机车调速和换向的同时完成对硬件电路的各种保护功能。系统通过采集电机电枢端电压和电流瞬时值算法对无速度传感器直流电机进行转速控制,并加入回馈制动功能,可以有效延长蓄电池的使用时间,提高电机车工作效率。实验室数据表明该控制系统操作简单,换向稳定,调速过程平滑无振动,运行安全可靠,应用价值较高。

基于模糊控制的纯电动汽车再生能量回收技术

针对车辆低速行驶的制动能量回收率低,频繁充放电影响动力电池寿命的问题,提出以电池荷电状态(state of charge,SOC)、制动强度、车速和制动间隔时间为输入,再生制动力分配系数为输出的纯电动汽车模糊控制再生制动策略。同时,采用遗传算法对控制参数进行优化。在Simulink中搭建控制策略模型,并在不同测试工况下与CarSim联合进行仿真,结果表明,相比于仅以电池SOC、制动强度和车速为输入的模糊控制再生制动策略,所提策略减少了制动能量回收次数,提高了制动能量回收率。该策略不仅可以改善对动力电池的损害情况,而且可以获得更多的制动能量。

抑制过压的PWM整流器功率因数调节方法

本文提出了一种通过调节PWM整流器功率因数,来抑制交流传动的列车处于再生制动时因受电弓处电压过高而导致再生失效的方法。分析了列车再生制动时,为了抑制受电弓电压升高,所需的PWM整流器功率因数角调节的范围,给出了在PWM整流器的预测电流控制的基础上改进策略并实现其功率因数调节的方案。在考虑无功传输导致的线路功率损耗的情况下,计算了抑制受电弓电压上升所需要的PWM整流器功率因数角调节的大小,并通过仿真验证了方案的可行性。

Evaluation of regenerative braking based on single-pedal control for electric vehicles

More than 25%of vehicle kinetic energy can be recycled under urban driving cycles.A single-pedal control strategy for regenerative braking is proposed to further enhance energy efficiency.Acceleration and deceleration are controlled by a single pedal,which alleviates driving intensity and prompts energy recovery.Regenerative braking is theoretically analyzed based on the construction of the single-pedal system,vehicle braking dynamics,and energy conservation law.The single-pedal control strategy is developed by considering daily driving conditions,and a single-pedal simulation model is established.Typical driving cycles are simulated to verify the effectiveness of the single-pedal control strategy.A dynamometer test is conducted to confirm the validity of the simulation model.Results show that using the single-pedal control strategy for electric vehicles can effectively improve the energy recovery rate and extend the driving range under the premise of ensuring safety while braking.The study lays a technical foundation for the optimization of regenerative braking systems and development of single-pedal control systems,which are conducive to the promotion and popularization of electric vehicles.

航空无刷直流电动机四象限PWM驱动PI控制方法研究

分别对无刷直流电动机在Ⅰ,Ⅲ象限以及Ⅱ,Ⅳ象限运行时三相绕组的导通及续流过程进行了分析,推导了驱动电路占空比与绕组电流的函数关系,提出了适用于电机四象限PWM驱动的变参数可重置PI控制方法。实验结果表明该控制方法可以使电机在四象限下良好地运行,且具有较好的电流和转速限踪精度。

Operation control strategy of series-parallel hydraulic hybrid vehicle

A series-parallel hydraulic hybrid system applied to public buses is put torwaro, ano parameters of key components are analyzed and determined. Energy management strategy based on logic thresh- old is designed which is aimed at efficient operation of the overall system considering the operational characteristic of the components and taking the curves of engine, hydraulic pump/motor and hydrau- lic pump as the main design basis; regenerative control strategy which makes regenerative brake sys- tem and frictional brake system work harmoniously is designed to raise recovery rate of regenerative brake energy. System dynamic modeling and simulation results show that the energy control strategy designed here is able to adapt system to changes of working condition and switch the operating mode reasonably. The regenerative braking control strategy is effective in raising the utilization of energy and improving fuel economy.

PWM变流器在城市轨道交通再生制动中的应用

城市轨道交通机车制动时产生的制动能量,除一部分被正在取流的机车利用外,剩余的则会导致直流牵引网压升高。现阶段,由于普遍采用的是电阻制动,剩余的能量全部由电阻消耗,这样不仅造成了再生制动能量的利用率低,还会增加散热通风系统的负担。本文分析了将PWM变流器应用于城市轨道交通再生制动能量吸收,建立了系统数学模型,并在Matlab/Simulink环境下搭建了系统仿真模型。仿真结果验证了方案的可行性,并且具有功率因素较高、系统动态响应快和直流侧电压稳定性好等特点。