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Energy management strategies for an electric vehicle (EV) with multiple power sources have been widely described in literature. The investigated energy sources are batteries, ultracapacitors, fuel cells, flywheels and solar panels. The management strategy decides how to combine two or more sources in an optimal way. However, the behavior of these sources and also the behavior of the electric drives depend on their temperature. Moreover, the temperature can have extreme values in automotive applications and affect the energy management task. In this paper, to investigate the temperature effect on battery/ultracapacitor powered EV, temperature dependent models are presented for these storage components, as well as for the drive train components itself: power electronics and motor. The average motor iron loss and ultracapacitor loss tend to decrease with increasing temperature, while the average motor copper loss and power electronics loss tend to increase with increasing temperature. These two opposing trends cause the total loss of the drive train to have a rather small variation with temperature for the considered EV and in the considered temperature range. By consequence, the energy management strategy of the EV does not have to depend on the temperature in order to obtain maximal efficiency. [ABSTRACT FROM AUTHOR]

Abstract: Three types of methods are studied to calculate the shielding efficiency of a cylindrical ferromagnetic shield in Fe–Si steel, i.e. an analytical method, a finite element method and a neural network method. The methods take into account nonlinear hysteretic behaviour in the shield. All of the methods are compared with each other and with measurements: the shielding factor is computed and measured for several shield radii, thicknesses, field amplitudes and frequencies. The mean absolute error rates are calculated for AM, FEM and NN to be 9.16%, 6.45% and 5.54%, respectively. The analytical model is very fast and accurate for materials with mild nonlinearity. In case of highly nonlinear material and a strongly non-uniform field distribution in the shield, the modeling of the nonlinear behavior in the analytical model is not accurate. The FEM is very accurate for all considered shielding configurations if the mesh density is well chosen, but its evaluation time is high. The neural network has the disadvantage that it should be trained. It is, however, a fast method with the additional advantage that it can be used without any knowledge of the shield geometry and material properties if the training is based on measurements. [Copyright &y& Elsevier]

The full and half toroidal CVT have been the subject for many research papers. The efficiency and behavior in steady state of both topologies has already been discussed in detail but until now no special attention has been given to their behavior during ratio variation. Therefore, this paper discusses the comparison of the full and half toroidal CVT during periods of ratio variation focusing on the dynamic response and efficiency. The geometrical constraints for the comparison are as follows: equal output inertia, equal maximum output torque at a speed ratio of 1 and identical radial size. The results of the study are based on a model that describes the behavior of both topologies and an algorithm that determines the optimal ratio variation. The outcome of the study shows that the half toroidal outperforms the full toroidal CVT over the entire operating range in terms of dynamics and efficiency during ratio variation. [ABSTRACT FROM AUTHOR]

This paper investigates the trade-off between efficiency and dynamics of CVT's. Energy efficiently varying the speed ratio of the CVT while maintaining the dynamic requirements is of primordial importance to fully utilize the advantages of the CVT in a drivetrain. Although the toroidal CVT is thoroughly discussed in literature, few articles describe its behavior during ratio variation. Therefore, in this paper a procedure is proposed to achieve optimal ratio variation in terms of settling time and efficiency with a half toroidal CVT. The key concept on which the procedure is based is the expression of the maximum output torque of the CVT. It turns out that the given method offers the fastest possible speed ratio variation for given constraints without excessive increase in slip and thus limited loss in efficiency. The most important constraint proves to be the clamping force which has a profound impact on the resulting dynamics and efficiency of the CVT. The paper indicates that higher clamping forces increase the dynamics of the CVT at a certain cost of loss in efficiency which implies that there is a trade-off between efficiency and dynamics. [ABSTRACT FROM AUTHOR]

• Derivation of power loss scaling laws for planetary reducers. • Fast and accurate generation of efficiency maps of scaled reducers. • High-speed testing of planetary reducers at speed values up to 14,000 rpm. • Experimental characterization of both load-independent and load-dependent losses. • Data-driven modeling of the power loss of planetary reducers. Scaling laws are increasingly recognized as an interesting solution to accelerate the early stages of the development of drivetrains. Concerning gearboxes, prior studies focused on geometric scaling to achieve new desired torque and speed values and to predict mass, volume, and inertia. Power loss scaling laws are still lacking in literature. This paper seeks to bridge this gap by proposing scaling laws for the power loss of high-speed planetary reducers. Due to the lack of reliable information on the losses at high-speed, scaling laws are derived from an experimental campaign of 5 commercial planetary speed reducers. The proposed scaling laws are defined based on high-level specifications of the drivetrain, namely the maximal input speed, output torque, and gear ratio. The results suggest that the derived scaling laws can predict the efficiency and power losses with an average error of less than 1%, and 8% respectively relative to the measurements, considering a torque scaling factor of up to 4, speed scaling factor of up to 0.6 and gear ratio scaling factor of up to 2. [ABSTRACT FROM AUTHOR]

In most applications where a variable transmission is required, either an EVT or a CVT would be viable options. In order to obtain a justified decision between both variable transmissions, the operating range and efficiency should be known better. To be able to pinpoint the pros and cons based on efficiency and operating range, a detailed comparison is necessary. However, to the knowledge of the authors there is no such study reported in literature so far. In this paper a permanent magnet Electrical Variable Transmission (EVT) is benchmarked against a half toroidal Continuously Variable Transmission (CVT) and this during steady state conditions. This paper provides the constraints for the comparison and results based on detailed models of both technologies. Two comparative studies are carried out: on one hand a study based on equal maximum output torque and on the other hand a study based on equal rated power. The outcome of the study shows that the CVT is in favor for high input torques and that the EVT is dominant for high input speeds. [ABSTRACT FROM AUTHOR]

This paper discusses the comparison of two series–parallel hybrid electrical vehicles. The first one is based on the Toyota hybrid system, while the second one is equipped with an electrical variable transmission. The problem with previous comparisons between these two transmissions is the lack of validated data used to support the comparison as well as a comprehensive study on the sizing of the electrical variable transmission for a given vehicle and load cycle. To tackle these issues, a validated model of an electrical variable transmission is used in combination with validated scaling laws to assess design changes. This scalable model is used to determine the optimal design and the impact of sizing on the fuel consumption of the vehicle. To exclude the impact of the chosen control methodology, dynamic programming has been used. This technique is not only used to optimize the operating points of the internal combustion engine, but also to find the optimal DC-bus voltage in order to optimize the system level efficiency. The comparison is performed for multiple driving cycles that all show the added value of the electrical variable transmission based hybrid electrical vehicle. On average, over the different driving cycles, a reduction in fuel consumption of 4.75% is achieved while using an electrical variable transmission. • Detailed comparison between two series–parallel hybrid electrical vehicles. • Optimized energy management based on dynamic programming. • Validated scaling laws to ensure a fair comparison in terms of sizing. • The electrical variable transmission outperforms Toyota hybrid system. • The electrical variable transmission reduces fuel consumption by 4.75%. [ABSTRACT FROM AUTHOR]