Department of Electrical Engineering & Computer Science, Northern Arizona University

1. Yasser Alherz , Mohammed Alsulaiman, Devin Fredrickson, David Glennon, Kamran Sheikh Department of Electrical Engineering & Computer Science, Northern Arizona University performance criteria of an electric vehicle, and our motor controller will be programmed to reflect this. ABSTRACT TORQUE EFFICIENCY MODEL Development of electric vehicles is essential to reducing pollutants and additionally beneficial to reducing transportation costs. Part of the Shell Eco-Marathon was to design the electric systems of such a vehicle, and our goal was to optimize efficiency of the vehicle’s battery usage. To achieve this we programmed a motor control system to improve acceleration efficiency for the SAE-NAU urban concept vehicle. All components were chosen to work together in order to optimize efficiency and reliability based on statistical data gathered about the motor, potentially increasing battery life up to several hours in an urban driving environment. Making electric vehicles more efficient is a key improvement to the world’s economy and environment. For the future on this project, there are plans to implement real time efficiency mapping of the torque curve in Figure 3. This differs from the current auto-acceleration setup in that it is reactive to the drivers input rather that pre-programmed.There is also the potential for construction of a solar charging station for the battery. This would serve as a better model of efficiency for future electric vehicles, and serve as an education research project in energy generation for the vehicle, as well as also serve as a showcase with the vehicle. Efficiency Modeling of an Urban Concept Vehicle The Block diagram in Figure 2 shows the basic layout of the electric subsystems in the vehicle. Power to the accessories from the accessory battery is regulated by switches in the dashboard interface, which also sends signals to the programmable controller, along with the throttle and brake switches. This information, in combination with encoder feedback from the motors is used to regulate efficient power usage by the individual motor controllers Figure 2: Block diagram of the accessory and motor control systems of the electric vehicle SCHEMATICS We are very thankful to Dr. Scott for the opportunity to work on the Urban Concept Project and participate in Shell Eco-Marathon competition. The team appreciates the help from Dr. Tester, who is our client for the whole project. The team would like to thank Dr. Venkatraman, who supported the project in many technical ways, and also Dr. Kipple who was the main advisor for the team. The team also would like to give special thanks for the generous financial help received from our sponsors: • Motor Excellence • NAPA Auto-parts • Architectural & Environmental Assoc • Advanced Digital Solutions International, INC • Encoder Products Co. The graph shown in Figure 3 below shows the power consumption (color) of the motor for an applied torque at a given speed. This information was used to program efficient drive cycles to be implemented by the programmable microcontroller in competition. ACKNOWLEDGMENTS Development Figure 3: Torque Curve The EE Team is responsible for all electrical features for the vehicle. The two major electrical aspects of this project are the critical drive train system and accessories required to make the vehicle viable and efficient. There will be a 12V accessory battery that will power two headlights, two front turn signals, two rear brake lights, windshield wipers, two cooling fans, two rear running lights that will have integral blinkers, and a horn. In addition to the accessories, a crucial part in designing our Shell Eco-Marathon competition vehicle is electrical power control and distribution, Figure 1, specifically, the behaviors of various electrical components. Efficient power usage of the electric subsystems is a key 1 PROJECT OVERVIEW Figure 1: The motor controllers, bottom, and electric subsystem control rack, top, of the Urban Concept EV.