Dynamic driving/braking force distribution in electric vehicles with independently driven four wheels

A novel algorithm for the dynamic driving/braking force distribution is proposed for electric vehicles (EV) with four in‐wheel motors. In such EVs, the vehicle lateral motion can be controlled by a yaw moment, generated by the torque difference between wheels. This method is known as DYC (Direct Yaw moment Control) in ordinary engine vehicle engineering; however, the torque difference can be generated more directly with in‐wheel motors. One problem of DYC is its instability on slippery roads, such as wet or snowy asphalt. To achieve high stability, the loads of wheels are preferably equal. The load on each wheel can be evaluated as the square root of the sum of squares of driving/braking force and side force. Therefore, the driving/braking forces, or motor torques, should be distributed depending on the side forces of the wheels, to minimize the load imbalance between wheels. The proposed algorithm can solve this optimization problem approximately with little calculation cost, and thus this method can be applied for real‐time calculation within a control period. Approximate solutions obtained with the proposed method are evaluated by comparison with numerical solutions that require much calculation time. The difference between these solutions is shown to be negligible, indicating the effectiveness of the proposed method. © 2001 Scripta Technica, Electr Eng Jpn, 138(1): 79–89, 2002     

Methods to control wheel locks and wheel spins on low friction coefficient roads for front and rear wheel independent drive type electric vehicles (FRID EVs)

Wheel lock and spin control methods suitable for front and rear wheel independent drive type electric vehicles (FRID EVs) are studied here. Wheel locks and spins occur easily when braking and driving operations such as deceleration and acceleration are performed on bad roads with low friction coefficient such as wet or frozen roads. The methods studied here are characterized by using the structural feature of FRID EVs which can freely distribute the driving and braking torques to front and rear wheels according to running and road surface conditions. These wheel locks and spins occurring when braking and driving on bad roads are controlled by properly distributing the braking and driving torques to front and rear wheels in consideration of the load movement caused by braking operations and slip ratios of the front and rear wheel sides. The effectiveness of the wheel lock and spin methods studied here is verified through simulations and experiments on various roads with a low friction coefficient using a prototype EV with the FRID structure. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Optimal slip ratio estimator for traction control system of electric vehicle based on fuzzy inference

In this paper we propose an optimal slip ratio estimation method based on fuzzy inference. One of the major advantages of electric vehicles is the quick and precise torque response of the electric motor, which realizes a novel traction control system. To prevent skidding, optimal slip ratio control has been successfully developed. It maintains the slip ratio at the optimum value that gives the maximum driving force. The remaining problem is how to generate the optimal slip ratio command sent to the controller. First we show that effective estimation of the optimal slip ratio is difficult to perform by the simple gradient method, which is a well‐known optimization method. But various experimentally obtained data can be easily incorporated into fuzzy inference, and therefore its estimation performance can be easily improved by the accumulation of human experience. This is a major advantage in the nonlinear estimation of real road‐tire characteristics. The effectiveness of the proposed estimation and control methods is confirmed by numerical simulation. © 2001 Scripta Technica, Electr Eng Jpn, 135(3): 56–63, 2001     

Assisted Control of Step Passage Motion and Its Comfort Evaluation in Two‐Wheel Wheelchair Systems

Two‐wheel wheelchair systems have been attracting attention because their mobility is better than that of conventional four‐wheel wheelchair systems. However, two‐wheel wheelchair systems must achieve stabilization control in the presence of disturbances caused by modeling error or the road situation, since these systems are underactuated systems similar to the inverted pendulum. In this investigation, step passage motion in two‐wheel wheelchair systems is considered. A reaction torque observer was employed to estimate the pitch angular interaction torque and the pure external wheel disturbance. Repulsive compliance control was employed to determine the optimal pitch angle command to compensate for the center of gravity of the user and to assist the whole step passage motion. Experimental results are evaluated in terms of user comfort by utilizing the ISO 2631‐1 generalized index.     

基于混合动力电动公交车的能量优化管理研究

利用电动公交车行驶路径固定、道路信息确定的特点,提出基于下一时段路况信息的超级电容、蓄电池电动公交车能量优化管理方法。在行驶过程中针对加速和制动2种工况设计了加速、减速2种模糊控制器对公交车进行能量实时优化;在公交车停站时刻,还可根据下一路况所需的平均功率,通过模糊控制器提前对超级电容和蓄电池进行功率预分配,以充分发挥2种电源的互补特性。数值仿真表明,所述方法能够大幅降低蓄电池放电峰值功率,明显提高能量回收效率,有效提高电动公交车的动力性能和经济性。     

Adaptive model predictive control for co‐ordination of compression and friction brakes in heavy duty vehicles

In this paper, an adaptive model predictive control scheme is designed for speed control of heavy vehicles. The controller co‐ordinates use of compression brakes and friction brakes on downhill slopes. Moreover, the model predictive controller takes the actuator constraints into account. A recursive least square scheme with forgetting is used in parallel with the controller to update the estimates of vehicle mass and road grade. The adaptation improved the model predictive controller. Also online estimation of the road grade enhanced the closed‐loop performance further by contributing through feedforward control. Simulations of realistic driving scenarios with a validated longitudinal vehicle model are used throughout this paper to illustrate the benefits of co‐ordinating the two braking mechanisms and influence of unknown vehicle mass and road grade. Copyright © 2006 John Wiley & Sons, Ltd.     

Balancing control for dispersed generators considering torsional torque suppression and AVR performance for synchronous generators

Electric utility deregulation enabled PPSs (Power Producers and Suppliers) to enter the electricity market. PPSs are supposed to achieve 30‐minute balancing control for stable power supply of electric power. In addition, load rejection and instantaneous voltage drops greatly affect turbine shafting, that is, torsional torque oscillation. Therefore, PPSs must consider a reduction of torsional torque in order to prevent generator shaft damage. This paper proposes a control system which allows the achievement of both 30‐minute balancing control and reduction of torsional torque by using an H_∞ controller. The effectiveness of the proposed controller is validated by using MATLAB. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(1): 16–25, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20868     

Evaluation of changes in power wheelchair maneuver induced by a downhill turning prevention control on cross sloped surfaces

In order to improve direction stability of a power wheelchair on a cross‐sloped surface, a downhill turning prevention control (DTPC) has been developed by some researchers and wheelchair suppliers. The DTPC‐induced effect on wheelchair maneuver, however, has not been well clarified. In this study, we quantitatively assessed DTPC‐induced changes in joystick control strategies during a driving task on a cross‐sloped test course. Among several evaluation measures calculated from the joystick inputs during the test trials, the x‐axis joystick displacement amount was found to be significantly decreased by the DTPC. This result suggests that the DTPC can save wheelchair users from the burden of compensation control on cross‐sloped surfaces. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

混合动力汽车用异步电动机驱动系统研究

针对混合动力汽车用异步电动机能量需要双向流动的特点,基于TMS320F2812数字信号处理器对电机驱动系统进行了设计,采用基于空间矢量PWM的直接转矩控制策略控制电机转矩,且能够有效的控制电机处于电动运行和发电运行状态,电机速度控制精度高.针对控制策略进行了必要的仿真,仿真和试验结果验证了系统的有效性.     

Evaluation and discussion of disturbance observer‐based anti‐slip/skip readhesion control for electric train

The improvement of adhesion characteristics is very important for electric trains. The drive system of electric trains must have fine anti‐slip and anti‐skid readhesion controls. In order to achieve the required adhesion, we have already proposed an anti‐slip/skid readhesion control system based on disturbance observer and sensorless vector control. Moreover, we have already applied the proposed method to actual electric multiple unit trains Series 205‐5000. In this paper, using the experimental results of Series 205‐5000 and the numerical simulation results, we evaluate the proposed anti‐slip/skid readhesion control system and confirm that the system has the desired driving wheel torque response. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 169(4): 55–64, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20834     

Development of a new sensorless vector‐controlled and transmissionless electric vehicle using a permanent‐magnet synchronous motor

One of the most important technologies for electric vehicles (EVs) will be drive control technology for the main motor. It is desired that the drive control technology have the following characteristics. (1) It does not require a position/speed sensor for controlling motor drive, which has been mounted on the rotor shaft. (2) It has vector controls that can produce torque quickly, efficiently, and/or precisely. (3) It has wide driving‐range and allows developing EVs with no variable transmission. This paper proposes new drive control technologies for such EVs using a permanent‐magnet synchronous motor as a main motor, and verifies its usefulness through development of an actual EV that can drive on public roads. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(3): 83–94, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20459     

Optimization of Electric Power Leveling Systems by Taper‐Off‐Reflectance Particle Swarm Optimization

It has become desirable to develop energy control technologies for environmental issues such as global warming and exhaustion of fossil fuel. Power fluctuations in large power consumer facilities may cause instability of electric power systems and increase the cost of the electric power facilities and electricity charges. Developing electric power leveling systems (EPLS) to compensate power fluctuations is necessary for future electric power systems. EPLS with an SMES has been proposed as one countermeasure for use in electric power quality improvement. SMES is superior to other energy storage devices in response and storage efficiency. The authors have proposed EPLS based on fuzzy control with SMES. For this practical implementation, optimizing the control gain and SMES capacity is an important issue. This paper proposes a new method for optimization of the EPLS. The proposed algorithm is a novel particle swarm optimization based on taper‐off reflectance (TRPSO). The proposed TRPSO optimizes the design variables of the EPLS efficiently and effectively. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(3): 10–18, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22472     

Control strategy for motor drive system of electric vehicle

An induction motor drive system is widely used in electric vehicles (EVs). However, most control strategies of these EVs focus only on control of the induction motor without considering the switching of different driving conditions and the changing of motor parameters. The upper limits of the torque generated by the motor are different under different motor parameters and driving conditions, which may lead to the fluctuation of the driving torque and affect the comfort and safety of the driver. This paper proposes a vector‐control‐based flexible control strategy to deal with this problem. First, the threshold values of the automatic speed regulator (ASR) and the automatic voltage regulator (AVR) could change with respect to the state variables of the motor including the change in driving conditions and some motor parameters; second, a backward proportional integral controller, which has a dynamically adjustable threshold, is added to the output of the ASR and AVR to achieve the flexibility of driving torque. Finally, a calculator that has threshold value is added to the input of the ASR and AVR controller. The results of simulation show that the designed flexible control strategy can achieve the stability of motor current, torque, and speed during the switching of different driving conditions. © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

永磁同步电机两种工作模式的切换控制策略

电动汽车有巡航模式和非巡航模式2种行驶工况,相应的车用驱动电机有转矩模式和转速模式2种工作模式。首先,针对传统PI速度调节器会使驱动电机转速出现超调和波动问题,通过采用主动阻尼二自由度PI转速调节器实现了电动汽车巡航模式下的无超调控制,改善了车辆乘坐的舒适性;其次,针对驱动电机2种工作模式的切换问题,采用零转矩模式的切换策略作为驱动电机2种工作模式的过渡,实现了驱动电机2种工作模式的有效切换。仿真分析结果表明:所提策略可以有效实现电动汽车的无超调控制,以及驱动电机2种工作模式的有效切换。电动汽车的无超调控制策略及驱动电机的零转矩模式切换策略具有一定的实际应用价值。     

Range Extension Autonomous Driving for Electric Vehicle Based on Optimal Vehicle Velocity Profile in Consideration of Cornering

Electric vehicles (EVs) have been intensively studied in the last decade due to their environment‐friendly characteristics. However, the miles‐per‐charge of EVs is less than that of internal combustion engine vehicles. To improve the miles‐per‐charge, the authors’ group proposed a Range Extension Autonomous Driving (READ) system that minimizes consumption energy by optimizing the velocity profile. However, conventional systems can be applied to driving on only straight roads. Therefore, this study extends READ system to be applied to driving not only on straight roads but also on curved roads by modeling the vehicle rotation motion and the cornering resistance. The effectiveness of the proposed method is verified by simulations and experiments.     

Position control for ultrasonic motors using backstepping control and dead‐zone compensation with fuzzy inference

The ultrasonic motor has comparatively high nonlinearity which varies with driving conditions, and possesses a variable dead zone in control input associated with the applied load torque. The dead zone is a problem for industrial applications and it is important to eliminate the dead zone in order to improve control performance. This paper proposes a new position control scheme for ultrasonic motors to overcome the dead zone. The dead zone is compensated by fuzzy inference, and backstepping control performs accurate position control. Compared with model reference adaptive control, which uses an augmented error, backstepping control can analyze a transient response. Mathematical models are formulated and experimental results show the effectiveness of the proposed position control scheme. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 149(1): 69–77, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20016     

开绕组无刷双馈风力发电机最大功率点跟踪直接转矩模糊控制研究

基于风力发电机最大功率点跟踪原理,结合无刷双馈电机无电刷和集电环的特殊结构及采用双定子磁场调制使得所需变流器容量更小的特点,提出了一种由双两电平变流器拓扑构造三电平馈电的开绕组策略,阐述了无刷双馈风力发电机最大功率点跟踪、开绕组策略及直接转矩控制、模糊控制等各部分工作原理,进而利用Matlab/Simulink仿真软件,搭建了无刷双馈风力发电机控制绕组采用双两电平SVPWM变流器馈电实现最大功率点跟踪的开绕组直接转矩模糊控制模型,并进行了详细的性能仿真,最后,通过无刷双馈电机半实物仿真实验平台,证实了所提开绕组策略的正确性和可行性,为进一步研发半实物仿真实验平台及相关控制策略提供了良好的参考与借鉴。     

一种基于模糊逻辑的直接转矩控制算法

介绍了一种新颖的基于模糊逻辑的直接转矩控制算法,该算法利用电机转矩偏差和定子磁链偏差,运用模糊逻辑控制器动态地得到所期望的空间电压矢量,再结合空间矢量调制技术实现对异步电机的控制.该算法结构简单,可大大减小转矩脉动和磁链脉动.仿真结果证实了该算法的有效性.     

无刷直流电机直接转矩模糊控制研究

为简化无刷直流电机控制系统的结构同时又能使其具有较快的转矩响应速度,论文提出一种新颖的控制方案,将直接转矩控制和模糊控制相结合应用于无刷直流电机控制系统中。直接转矩控制省掉了复杂的矢量变换,使系统结构简单且响应迅速,但是转矩脉动相对较大;而模糊控制鲁棒性强,根据转矩偏差和转矩偏差的变化率,模糊调节电压矢量作用时间,减小转矩脉动。新型的控制策略不仅具有良好的动态特性和简单的结构,其它性能也可与传统的无刷直流电机控制系统相媲美。利用MATLAB对系统进行了仿真,并对两种不同控制方法的实验结果进行比较。通过比较可以看到模糊直接转矩控制方法实现了对转矩和电流的有效控制,更优于传统的控制方法。     

Electric Vehicle Range Extension Control System Based on Front‐ and Rear‐Wheel Sideslip Angle and Left‐ and Right‐Motor Torque Distribution

In this paper, a range extension control system based on the least‐squares method is proposed for electric vehicles with in‐wheel motors and front active steering. We propose a method that distributes the front and rear‐wheel sideslip angles and the difference in the driving force between the left and right motors resulting from the lateral force and yaw moment. The proposed method allows a reduction in the driving resistance generated due to the front steering angle. In practice, the mileage per charge is increased to about 200 m/kWh. Simulations and experiments confirm the effectiveness of the proposed method.