Shotaro Naito

Semiconductor capacitance-type accelerometer with PWM electrostatic servo technique

Abstract A new semiconductor capacitance-type accelerometer utilizing a pulse width modulation (PWM) electrostatic servo technique has been developed. Highly accurate detection of feeble and low frequency acceleration became possible with the PWM sensing method. The limited air gaps between the movable and fixed electrodes ensured compatibility between high sensitivity and durability, while transverse sensitivity was reduced due to the symmetric structure of the sensing part.

Class 4 Hybrid Electric Truck for Pick Up and Delivery Applications

Pick up and delivery vehicle applications such as parcel handling trucks represent an ideal duty cycle for Hybrid Electric Powertrains. The low speed, frequent stopping and starting operation provides good opportunities for enhancing engine behavior and recovering braking energy by adding an electric drive system to the vehicle. FedEx Express collaborated with the environmental advocacy group Environmental Defense to announce the Future Vehicle Program, with the goal of developing significant improvements in emissions and fuel economy for the familiar FedEx Express W700 parcel delivery vehicle. This paper describes the objectives, development activities, and test results for one of the vehicles submitted to this program. A team led by Eaton Corporation prepared the Direct Hybrid Electric Powertrain system, which received the highest ranking in the Future Vehicle Program evaluation.

The Efficiency Improvement of Electric Vehicles by Regenerative Braking

Generally in electric vehicles regenerative braking is incorporated to increase urban driving range on a single charge and to get the same brake torque as engine brake. An analysis of the regenerative operation by thyristor chopper control is described. Firstly, to clarify regenerative efficiency, the calculation of various losses such as commutation loss and thyristor loss which arises at the braking mode is discussed. The regenerative efficiency calculated from the above losses agrees closely with test results. Secondly, a newly developed automatic field control (AFC) regenerative braking system is introduced. This AFC regenerative control system uses a shunt motor, the field current is controlled inversely proportional to motor speed and regenerative operation is obtainable by low motor speed. This system is suitable for electric vehicles. Thirdly, it is noted that utilizing this AFC regenerative brake control, actual urban driving range can be increased by approximately 16%.