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Evaluating performances of real-time strategies for hybrid energy storage systems (HESSs) of electric vehicles (EVs) always requires optimal energy management strategies (EMSs) as offline benchmarks. Dynamic programming (DP) is well-known due to its ability to obtain global optimal solutions based on the numerical searching technique. Nevertheless, DP accuracy depends on the numericalization fineness. Analytical optimal control methods, typically Pontryagin’s minimum principle (PMP), are also frequently used as effective counterparts. However, solving optimal control problems based on these methods often depends on the complexity and the characteristic of the system model; basically, it is sophisticated since there is no general way to solve the issue. This article proposes an alternative approach of using PMP to develop an optimal EMS for battery/supercapacitor HESSs. The novel strategy is based on formulating the problem in terms of power and energy, which forms a state-constrained optimal control problem. PMP is then applied with a penalty function, in which the inequality state constraints are reformulated to deduce a new state-unconstrained problem. The proposed optimal EMS is hundreds of times faster than DP with better results. Moreover, the optimal solution is piecewise constant that could give significant insights to develop real-time strategies in future studies.

This article presents a framework to model and design the longitudinal motion control (LMC) system for electric vehicles (EVs). Thanks to the passivity property of EVs, a hierarchical control configuration including three layers is proposed. In the lower layer, each actuator is provided a disturbance observer (DOB) for locally preventing the wheel slip. A global controller is designed in the upper layer for the cruising purpose. In addition, the middle layer serves as the aggregation and distribution channels.

Electric vehicle (EV) traction drives should be associated with flux-weakening (FW) techniques wide-range speed demands. In this study, the EV performance with an optimal FW strategy is studied in relation to the battery voltage variation caused by cell state-of-charge and temperature changes. The results show that the battery suffers from a voltage reduction by larger internal resistance as the temperature decreases. Moreover, the higher current is required for activating the FW process. However, the inner resistance growth produces more heat inside the cell that affects the battery electrical parameters as well as the system. To assess this effect by simulation, an improved electro-thermal model of lithium-ion battery ls dynamically coupled to the optimal FW strategy. In this model, all the electrical parameters are temperature-dependent deduced from experimental measurements of an off-road EV. The simulation results confirm the effect of the cell self-heating on the battery voltage at sub-zero temperatures. The higher battery voltage can support the FW operation at −10°C for more 1200 s under the modified NEDC driving cycle, whereas the motor drive voltage is saturated after 1118 s by using the simple battery model without thermal effects.

The articles in this special section focus on electric vehicles. In order to face the energy transition challenge, the transport sector should electrify more and more vehicles. The 2016 transport report of the International Energy Agency indicated that, from several scenarios, the number of electrified road vehicles has to move from 1 Million to 100 Millions in only 15 years to keep the global warming under +2 °C. The electrified vehicles can be classified in pure Electric Vehicle (EV, supplied by a battery but also by the electrical grid), Hybrid Electric Vehicle (HEV, combination of electric motors and thermal engine), and Fuel Cell Vehicle (FCV, with H2 as energy source). These disruptive technologies thus require fast development to face this challenge.

Range extension control of in-wheel-motor electric vehicles have been studied for years. However, there is still lack of theoretical results for rigorously stabilizing the overall control system which suffers nonlinear tire-force characteristics. In addition, it is required to locally guarantee safe motion of each driven wheel while globally increase the cruising range per charge. To deal with aforementioned issues, this paper utilizes passivity theory to present a hierarchical range extension control system. Each wheel is provided a local disturbance observer based anti-slip controller. By managing the aggregation of local wheel velocities, the global controller gives the total driving command which is optimally allocated to each wheel. The torque of each wheel is, therefore, the sum of the local control signal and the distributed signal from the global controller. Beside proving the stability rigorously, the effectiveness of the proposed control system is evaluated using Carsim-Matlab co-simulator.

Electric vehicles are considered to be a greener and safer means of transport thanks to the distinguished advantages of electric motors. Studies on this object require experimental platforms for control validation purpose. Under the pressure of research, the development of these platforms must be reliable, safe, fast, and cost effective. To practically validate the control system, the controllers should be implemented in an on-board micro-controller platform; whereas, the vehicle model should be realized in a real-time emulator that behaves like the real vehicle. In this paper, we propose a signal hardware-in-the-loop simulation system for electric vehicles that are driven by four independent electric motors installed in wheels (in-wheel motor). The system is elaborately built on the basis of longitudinal, lateral, and yaw dynamics, as well as kinematic and position models, of which the characteristics are complete and comprehensive. The performance of the signal hardware-in-the-loop system is evaluated by various open-loop testing scenarios and by validation of a representative closed-loop optimal force distribution control. The proposed system can be applied for researches on active safety system of electric vehicles, including traction, braking control, force/torque distribution strategy, and electronic stability program.

Nowadays, Electric Scooters are used more and more, especially in urban because of their flexibility and convenience. Scooters also have requirements for power supply similarly to general electric vehicles, including sizing issues, energy management for hybrid storage system, energy optimization and so on. In this paper, we deal with power distribution for multipack battery of electric scooters by proposing and comparing different voltage and current control schemes. All controllers are designed based on Energetic Macroscopic Representation (EMR) and Inversion-based control. The simulation is carried out for performance validation of proposed control schemes. Results of this paper can be a good recommendation for electric scooters design powered by a multi-pack battery system.

In recent years, Quasi Z Source Inverter (QZSI) has been a promising topology for application in Electric Vehicles (EVs) to deal with the decrease of battery voltage during operation. In EVs using QZSI, the good performance of the traction system requires high quality of dc-link voltage control for the inverter. To this end, it is essential to build-up a design model that captures the dynamics of both battery and Z-source inverter. Unlike almost other previous works which independently modeled the QZSI, this paper suggests a unified model of battery and QZSI. Notice that the battery-QZSI system is always influenced by the change of battery voltage and the load current depending on the operation of the vehicle and environments. In this paper, Internal Model Control (IMC) is employed as a systematic way to improve the robustness of dc-link-voltage control. Moreover, a simulation model that is very closed to the physical system is built in Matlab-Simulink. Using this simulation model, the effectiveness of the proposed model and control scheme is evaluated and compared with the classical Lead-Lag compensator based on the root-mean-square criteria.

Power electronics play a fundamental role for electric transportation, renewable energy conversion and many other industrial applications. They have the ability to help achieve high efficiency and performance in power systems. However, traditional inverters such as voltage source and current source inverters present some limitations. Consequently, many research efforts have been focused on developing new power electronics converters suitable for many applications. Compared with the conventional two-stage inverter, Z-source inverter (ZSI) is a single-stage converter with lower design cost and high efficiency. It is a power electronics circuit of which the function is to convert DC input voltage to a symmetrical AC output voltage of desired magnitude and frequency. Recently, ZSIs have been widely used as a replacement for conventional two-stage inverters in the distributed generation systems. Several modifications have been carried out on ZSI to improve its performance and efficiency. This paper reviews the-state-of-art impedance source inverter main topologies and points out their applications for multisource electric vehicles. A concise review of main existing topologies is presented. The basic structural differences, advantages and limitations of each topology are illustrated. From this state-of-the-art review of impedance source inverters, the embedded quasi-Z-source inverter presents one of the promising architectures which can be used in multisource electric vehicles, with better performance and reliability. The utilization of this new topology will open the door to several development axes, with great impact on electric vehicles (EVs).

An observer-based control (OBC) strategy for dual-active-bridge converters is proposed in this paper. The target is not only to handle the active power transferring between two terminals, but also to regulate the phase difference between the primary voltage and current around specific minimum value. The value is chosen to reduce the conduction loss in the system. A reduced-order observer is developed to estimate the direct and quadrature components of the transmission current for use in a decoupled current control system. Since the dc terminal current is the only input of the observer, a low sampling frequency is enough to ensure an acceptable precision. Experiment results show that the proposed OBC strategy can help improve the dynamic performance compared with that when using a single loop voltage mode system. Furthermore, at the high power range, the efficiency obtained when employing the OBC method is improved by up to 7.2%.

In Dual-Active-Bridge converter control system, high frequency terminal current is usually measured then fed-back to the current mode controller. However, the measurement requires wide bandwidth sensors, fast and precise operational amplifier, and high sampling rate Analog to Digital conversion. This paper proposes a Proportional Integral Observer to estimate such the current to eliminate the need of current sensors. A combined feedforward-feedback control system is then developed to enhance the system dynamics and to regulate the output voltage. The control system needs only the information of terminal voltages. Simulation and experiment results show that the observer performs fast and accurately with acceptable observation error; and the output voltage is well regulated regardless of load changes.

This paper deals with a comparative study between different power train topologies regarding batteries aging index factors for off-road electric vehicle (EV) applications. The studied power train topologies are battery pack supplying the motor- drive directly (original), two-stage inverter motor- drive and embedded quasi-Z-source inverter motor- drive. The comparison is conducted in terms of battery aging performance indexes for an electric vehicle considering the same on-board energy capacity. The modeling and the control design for both topologies are presented and discussed. Simulation investigations are performed to verify the different topologies. It is shown that the embedded quasi-Z-source inverter produces better aging performance index in terms of root-mean-square of the current, average values of the battery currents than other topologies. Embedded quasi-Z- source inverter and two-stage inverter reduce RMS, average values with a slight superiority for embedded quasi-Z-source inverter for standard deviation and variation coefficient. The results demonstrate that under the same operating conditions, the transient and the steady state performances of different topologies are comparable. These results prove that embedded quasi-Z-source inverter is a good candidate topology to be used in multi-source electric vehicle system.

The environmental pollution is becoming an urgent global problem, leading to the dramatically growth of the electric vehicle (EV) market. Permanent magnet synchronous motors (PMSMs) are among the most used in EV traction drives because of their high starting torque and high torque density, especially for urban and small vehicles. It is well-known that flux-weakening strategy is required for motor drives working in extended speed range due to supply voltage saturation. In this paper, the studied surface permanent magnet synchronous motor (SPMSM) is fed by battery DC voltage which varies with different working conditions. Examinations reveal that the battery voltage significantly changes according to the ambient temperature, and hence impacts on the EV operation. This paper proposes a study of the impact of the battery cell temperature on flux-weakening strategy regarding current and torque constraints. Based on a commercial EV, simulation results figure out major effects of the cell temperature on the flux-weakening performance.

The variety of electric vehicle power configurations requires a streamlined and practical energy control strategy. However, many controllers use too complex control methods or only solve a part of the problem. The goals of these studies include increasing the distance and increasing the life cycle of the battery. These two conditions normally be at opposite poles, it is difficult to satisfy both. In this paper, a fuzzy controller combined with a low-pass filter is proposed to find a good point between the two criteria above. The proposal provides an effective and feasible control strategy for applying to the real-time system.

Using Hybrid Energy Storage System (HESS- battery and super capacitor) to extend the lifespan of batteries and travelled distances has been selected by many research laboratories in the world. This is particularly due to the fact that batteries have high energy density but its lifespan is reduced when operating with electric currents with high harmonics. In this paper, we use Fast Fourier transform Analyzer of the traction current as the basis to transfer the suitable current to battery and super capacitor. The algorithm has been simulated in Matlab then implemented in DSP card to control the subject that is emulated in signal Hardware in the loop (S-HIL) HIL402 of Typhoon. Results show that HESS can increase the batteries’ lifetime as well as extend the running distance per charge compared to using only battery.The S-HIL system should be a good and effective tool for further researches on energy management of EVs.

Disturbance Observer-Based Control (DOBC) and Active Disturbance Rejection Control (ADRC) are effective control techniques to deal with disturbances. This paper introduces and applies both DOBC and ADRC to Brushless DC (BLDC) motor drives system. The system is described by Energetic Macroscopic Representation (EMR) method which has recently become powerful approach for the systems related to energy transformation. By using EMR, the system can be described in a comprehensive and visual way, thus the control design becomes simple and easier. The EMR of BLDC motor drives is presented; the inversion-based control system is deduced from EMR; both DOBC and ADRC are employed based on the basis of inversion- based control system to improve performance of motor drive system. The simulation in Matlab/Simulink is realized to evaluate the control effect of DOBC, ADRC and conventional method in some scenarios: an unexpected change load and a parameters variation.

With the rapid development of electric vehicles (EVs), the requirement of enhancement of system efficiency and battery lifetime is put in a high priority. This study introduces an efficient improvement of an all-wheel drive (AWD) system. Modified configurations are proposed to compare effective operation with the original topology of a four-wheel drive (4WD) vehicle. Modeling and control are implemented by using Energetic Macroscopic Representation (EMR) formalism. Based on an e-TESC 4WD off-road platform EV, simulation results figure out an increase of 10% overall efficiency for an adapted WLTC driving cycle in a dual-motor AWD system and a lowest cell battery current stress using a unified DC bus battery supply.

Batteries play the most important role in traveling distance as well as performance of traction motor of every electric vehicle. Noticeably, the battery has a wide voltage range from fully-charged to empty state. However, the traction motor needs an appropriate DC-link voltage value to work with full performance, thus, only a part of the voltage range of the battery is utilized. Under this value, the vehicle is considered to be run out of energy and stopped. In this paper, we propose a solution for such matter by using Bidirectional Quasi-Z-Source inverter instead of conventional one. Applying this solution, the vehicle can take advantage of full voltage range of the battery while still keep the performance of the motor at the highest level. Simulation in Matlab/Simulink with various scenarios has been carried out to validate the effectiveness of the proposed solution.

A new and simple DC bias elimination technique for a Dual-Active-Bridge DC/DC converter is proposed in this paper. The principle is to make the positive and negative volt-seconds of the magnetizing inductance balance when the phase shift changes. This can be done with minimum disruption on the overall control system by some minor modifications on the setting of the PWM modules of the digital signal processor. Thanks to the technique, the DC bias is completely eliminated. Besides, the system dynamics is much improved.

Brushless DC motors are more and more popular in industrial and house appliance application thank to their constructional advantages. Control of these drives in high speed region is however relatively difficult. In order to extend the speed range of the drive, it is common to control the phase-current to lead the phase back EMF by an “advance angle”. It is based on the method of “phase advance approach”, which was first proposed in 1995. The studies in literature have focused on finding the exact advance angle. In general, the previous methods to calculate the advance angle have been complicated. In this paper, the authors propose a new equation that makes the computation of advance angle become simpler. The operation of the drive in high-speed region has been verified by simulation in Matlab/Simulink and the results have demonstrated the validity of the algorithm.

Recently, Traction Control System of vehicles is the vital part of the Active Safety System which enhances the security and comfort of passengers. To realize it, various important states of the vehicle must be measured or estimated, in which slip ratio is a crucial factor. In this paper, we propose a simple but effective algorithm to estimate the slip ratio without using any information of vehicle velocity and dynamic parameters, which are very difficult to be determined. A traction control system using the proposed estimated slip ratio is then presented to illustrate its application. Simulation in Matlab/Simulink as well as experiments on a real electric vehicle and signal hardware-in-the-loop simulation have been carried out to validate the effectiveness of the proposed estimation method.