Industrial Technology Research Institute (ITRI) has developed two generations of electric scooters (ES) by implementing valve-regulated-lead-acid (VRLA) and nickel-metal- hydride (Ni-MH) batteries respectively. The 1st generation ES has been adopted by Sam-Ever who commenced his production in September 1999, and the 2nd generation one is still under cost-down engineering stage. Although, there already have more that 25 thousands ES on the road in Taiwan, most of ES users are not satisfied the cruise range, vehicle weight, charging time, and vehicle cost. In order to improve the vehicle overall performance to meet the market requirements and support Government ES mandatory sales regulation, ITRI is developing the 3rd generation ES by implementing the lithium-ion (Li-Ion) battery and with higher power-electronic efficiency systems. The engineering targets of the 3rd generation ES are to improve the current production ES performance in terms of 25% of weight, 50% of cruise range, 20% of total energy efficiency, 300% of the longer battery life, and at no price hike after the government subsidy. According to the preliminary customer survey, the developing ES will satisfy most of the current ES users and has very high potential to replace most of 50cc gasoline scooters and becomes one of the best class scooter in Asia. This article will describe the key technical aspects of the development of this 3rd generation ES. It will include the re-design of vehicle structure by implementation the new aluminum-casting frame to replace the steel-welding frame. The Li-Ion battery has selected and equipped with the battery management system to optimize and protect the battery cells. The vehicle performance is upgraded by optimizing the phase angle and flux-weaken of the motor and controller to increase the torque at both low-speed and high-speed regions. A single-stage timing belt transmission is a new design to replace the two-stage gear transmission. The centralized vehicle energy management system is developed to monitor and control the inputs and outputs of the battery energy to increase the total efficiency of the vehicle. Finally, the system bench-test and the vehicle dynamometer-test are planned to validate all engineering targets.
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