Guillermo A. Magallan

Maximization of the Traction Forces in a 2WD Electric Vehicle

A new control strategy for obtaining the maximum traction force of electric vehicles with individual rear-wheel drive is presented. A sliding-mode observer is proposed to estimate the wheel slip and vehicle velocity under unknown road conditions by measuring only the wheel speeds. The proposed observer is based on the LuGre dynamic friction model and allows the maximum transmissible torque for each driven wheel to be obtained instantaneously. The maximum torque can be determined at any operating point and road condition, thus avoiding wheel skid. The proposed strategy maximizes the traction force while avoiding tire skid by controlling the torque of each traction motor. Simulation results using a complete vehicle model under different road conditions are presented to validate the proposed strategy.

Vehicle dynamics using multi-bond graphs: Four wheel electric vehicle modeling

This work addresses the development of a 4-wheels vehicle model capable to reproduce the complete dynamical behavior. The modeling task is firstly performed by the separated 3-D representation on the Dymola environment of the chassis, suspensions, tires and joints using the library for multi-bond graphs in 3-D mechanics. Secondly, these parts are connected to form the complete vehicle model. The compactness and resemblance with a real vehicle assembling is shown.The main contribution of this paper is to provide a model applicable to electric or hybrid vehicles where the complete dynamics can be simulated. The simulation results obtained illustrate ordinary situations where the inclusion of traction control and ABS are essential for the vehicle safety and stability.

A neighbourhood-electric vehicle development with individual traction on rear wheels

A simple traction control implementation of a Neighbourhood Electric Vehicle (NEV) is presented in this paper. An electronic differential traction control is performed using two independent field-oriented controlled Induction Motors (IMs) mounted in the rear wheels. In order to reproduce a mechanical differential behaviour, an equal-torque traction control is carried out using only the IMs currents and speeds measurements. A basic self-blocking control is introduced to avoid uncontrolled wheel acceleration during equal-torque control action. The traction system allows energy recovery for batteries during vehicle braking through the IMs regenerative braking. Standard industrial IMs are rewound to operate on safe low voltage (28 Vrms) and to use standard DC-Link 42V, while maintaining the original motor power. Two three-phase MosFet inverters are built for these motor power requirements. The whole system is controlled using a single digital signal processor, TMS320F2812. Experimental results for different vehicle manoeuvres are presented to validate the right traction control operation.

Modeling of electric vehicles dynamics with Multi-Bond Graphs

The construction of a model that represents the behavior of an Electric Vehicle is studied in detail. The contribution of this work is twofold. On one hand an efficient and compact way to model dynamical systems is introduced. On the other hand, the power interchange between the electrical and mechanical sub-models allows a deep understanding of the dynamics involved in electrically driven vehicles. The approach used to model the mechanical parts (chassis, suspension, wheels) and the induction motors is the Multi-Bond Graph based in models discussed in recent literature. Then these models are integrated in order to form the complete model that simulates the whole system dynamics. Simulation results are aimed to illustrate the electromechanical interaction (ABS, regenerative braking, etc) as well as the evolution of certain variables during a risky situation. Conclusions are obtained based on these results.

Simulation of Electric Vehicles Combining Structural and Functional Approaches

In this paper the construction of a model that represents the behavior of an Electric Vehicle is described. Both the mechanical and the electric traction systems are represented using Multi-Bond Graph structural approach suited to model large scale physical systems. Then the model of the controllers, represented with a functional approach, is included giving rise to an integrated model which exploits the advantages of both approaches. Simulation and experimental results are aimed to illustrate the electromechanical interaction and to validate the proposal.

Eliminación de Interferencia Armónica para la Detección de Fallas en Motores Eléctricos

Resumen En este trabajo se presentan diferentes tecnicas de filtrado o cancelacion de interferencia armonica en senales de medicion para la deteccion de fallas en motores electricos. El objetivo es eliminar de las senales de medicion aquellas componentes producidas por la red electrica, dejando unicamente las componentes utiles para el diagnostico de fallas. Para dicha aplicacion se evalua el diseno de filtros en el dominio de la frecuencia (tipo comb) y de tecnicas multirate, de procesamiento digital en el dominio temporal.

Experimental evaluation of different semi-active configurations for battery-ultracapacitor hybrid energy storage system (HESS)

This paper presents the implementation of a Hybrid Energy Storage System (HESS) for electric vehicles. Two semi-active configurations are analyzed: semi-active Ultracapacitor (UC) and semi-active Battery. Control of the energy of one of the storage elements is performed by a bidirectional non-isolated DC-DC converter. The control strategy is based on the separation of the dynamic components of the power required by the load. Namely, while the UC provides fast dynamic power components efficiently, the complement is provided by the battery bank. The separation of the required power into two components is performed by a filter with variable bandwith depending on UC voltage, which allows obtaining an efficient HESS. Experimental results verifying the HESS control strategies for both semi-active configurations are presented, using a pulsating load to represent the demands of a traction drive system.

Electric vehicle stability control under limit adherence situations in curved paths

In this paper a stability control system for a rear-wheel drive (2WD) Electric Vehicle (EV) with differential traction is proposed. The control strategy ensures vehicle stability in maneuvers near grip limit. Additionally, conditions where the vehicle reaches the limit of cornering stability even using a Direct Yaw Control (DYC) are analyzed. From these bases, a first approach of a brake control that increases vehicle stability region is introduced in order to improve the safety under risky maneuvers.

Longitudinal velocity estimation of an electric vehicle usind fuzzy logic as data fusion technique

A longitudinal velocity estimation scheme is analyzed in this paper. Besides, its adaptation for being used in a rear-wheel drive (2WD) Electric Vehicle (EV) is evaluated. The velocity estimation is based on the fusion of the available measurements, which are the vehicle longitudinal acceleration and angular velocities on each wheel. The aim of this analysis is to obtain an accurate longitudinal-velocity estimation based on the knowledge of the weight of credibility that each sensor has at different operations points. Fuzzy logic is used as the information processing tool. In order to validate the strategy, a hybrid simulation platform is used, which involves CarSim software for the vehicle dynamic model simulation and Simulink to implement the data fusion strategy.

Estrategia de estimación de la condición de suelo para el control de tracción en vehículos eléctricos

Design and implementation of a Luenberger nonlinear observer to estimate the road condition in a 4-wheel electric vehicle is presented in this paper. Knowledge of the road condition allows controlling the force transmitted to the road by traction wheels, thus preventing slippage even in low-traction surfaces. This is done to improve vehicle control and prevent loss of stability that may be risky. The proposed observer is based on a rotational dynamic model of the wheel and a Dugoff force model. The proposal is validated by simulation using a full vehicle model on Simulink/CarSim platform.