New Load Demand for Electric Vehicles and Its Harmonic Impacts on Power System Distribution Transformers

The growing concern about CO 2 emissions and dependency on foreign oil contributes to the increasing application of electric vehicles (EVs). EV battery chargers are non-linear loads and large-scale application of EVs increases the grid harmonics significantly. The grid harmonics have negative impacts on the components of the power system including distribution transformers. In this thesis, the potentials for EVs to penetrate the transportation market are studied and the additional load demand when EV penetration achieves its full potential is estimated. Loss and thermal modeling of distribution transformers incorporating EV penetration are presented and the impacts of additional EV load demand on load loss, temperature and aging acceleration factor of a sample 100 kVA distribution transformer is estimated. The ability of the existing power system to accommodate the additional EV load demand without threatening the safe operation of distribution transformers (DTs) is evaluated based on the calculation results. To increase the capacity of the existing power system in accommodating the new EV load demand, an optimal charging schedule based on optimization of negative impacts on DTs is proposed. In this regard, EV charging load is formulated as an optimization problem and Newton Method and Karush-Kuhn-Tucker (KKT) optimality conditions are investigated as effective optimization algorithms for solving the developed optimization problem. Using the proposed charging schedule, the impacts of EV penetration on a sample 100 kW distribution transformer is studied and the effectiveness of the proposed charging schedule is validated through a comparative study. Moreover, this thesis investigates application of permanent magnet synchronous motors (PMSMs) in EVs as a second approach for reducing the negative impacts of EV charging on DTs. Controlling PMSMs based on their efficiency maps contributes to increasing the efficiency of EV powertrain and consequently reducing the EV load demand. Considering the significance of accurate modeling in the control of PMSM, this thesis focuses on accurate modeling of PMSM and the sources of error in PMSM steady-state performance estimation. Inaccuracy in the PMSM steady-state performance calculation corresponds to the parameter error and model imprecision. Accurate determination of the PMSM parameters may encounter various complications due to its rotor structure and drive design. Therefore, the PMSM performance calculation is generally vulnerable to inaccuracy because of the parameter error. This thesis studies the effect of parameter error on the inaccuracy of the performance calculations. Several methods for determining the PMSM armature resistance, flux linkage constant and d- and q-axis inductances with varying level of accuracy are proposed. The presented methods are applied to a laboratory PMSM and the sensitivity of the PMSM output power to the equivalent circuit parameters is analyzed based on the experimental results. In addition, this thesis contributes to accurate performance estimations of the PMSM by developing a precise model that incorporates the saturation saliency and core losses. The accuracy of the proposed model is compared with the conventional dq-axis model and its higher accuracy is validated through experimental results

Evaluation Of Available Energy For Regenerative Breaking At The Brazilian Driving Cycle

The purpose of this paper is evaluating the amount of kinetic energy available to be regenerated by a hybrid electric vehicle (HEV) undergoing the Brazilian standardized driving cycle. Improvements on energy efficiency of the cars has become an urgent target of the Brazilian industry since Brazil launched a new automotive regulation imposing the reduction of 15.5% on the fuel consumption of the vehicles to be sold in this country in 2017 comparing to 2011. The HEVs are a possible solution for this situation. They are widely known by the high efficiency, mainly the ones capable to make the regenerative breaking, rescuing an already paid energy. Before the launch of HEVs in Brazil, the feasibility of these vehicles has to be accurately studied and one aspect to be evaluated is how much energy is possible to be rescued in the Brazilian standardized driving cycle. In this paper, a longitudinal vehicle dynamic model is implemented using MATLAB/Simulink® in order to demonstrate the energy balance of longitudinal dynamics of a popular Brazilian car subject to the driving cycle cited before, highlighting the energy available for regeneration. © 2013 SAE INTERNATIONAL.13Tie, S.F., Tan, C.W., A review of energy sources and energy management system in electric vehicles (2013) Renewable and Sustainable Energy Reviews, 20, pp. 82-102Governo anuncia amanhã novo regime automotivo (2012) Folha de São Paulo, , http://www1.folha.uol.com.br/mercado/1163505-governoanuncia-amanha-novo- regime-automotivo.shtml, October 3, (accessed May 18, 2013)Gillespie, T.D., (1992) Fundamentals of Vehicle Dynamics, , Warrendale, PA: Society of Automotive EngineersOleksowicz, S.A., Burnham, K.J., Southgate, A., McCoy, C., Regenerative braking strategies, vehicle safety and stability control systems: Critical use-case proposals (2013) Vehicle System Dynamics, 51 (5), pp. 684-699. , "."Guzzella, L., Sciarretta, A., (2005) Vehicle Propulsion Systems, , New York: Springer-Verlag Berlin HeidelbergEhsani, M., Gao, Y., Emadi, A., (2010) Modern Electric, Hybrid Electric, and Fuel Cell Vehicles: Fundamentals, Theory, and Design, , 2nd ed. Boca Raton: CRC PressJazar, R.N., (2008) Vehicle Dynamics Theory and Applications, , New York: SpringerHeißing, B., Ersoy, M., (2011) Chassis Handbook, , Wiesbaden: Springer FachmedienGenta, G., (1997) Motor Vehicle Dynamics: Modeling and Simulation, , Singapore: World ScientificEckert, J.J., Análise Comparativa entre os Métodos de Cálculo da Dinâmica Longitudinal em Veículos (2013) Msc Diss., , (State University of Campinas)Haim, D., Redução da Inércia Rotacional no Projeto do Trem de Força (2011) Grad Diss., , (University of São Paulo)Chu, L., Yin, J., Yao, L., Wang, W., The method for matching the PMSM's base parameters of the Hybrid Electric Vehicle based on drive cycle (2011) Electronic and Mechanical Engineering and Information Technology (EMEIT), 2011 International Conference on, 6, pp. 3234-3237(2013) 48V MODULES, , www.easby.com/nesscap/manager/uploads/file/Modules_4.pdf, Easby Electronics. (accessed May 15