The UNAM project for designing and constructing a battery-powered electric minibus is being implemented by the Engineering Institute in Mexico City. If used widely, such a vehicle could rapidly become popular in the Mexico City metropolitan area, and greatly improve the area's air quality. As in all modern electric vehicles, the drive motor also acts as an electric generator to recharge batteries during braking. An unusual feature of the UNAM minibus is its secondary hydro-pneumatic drive system, which includes a variable displacement hydraulic motor that can operate as a pump or motor. The minibus's electric motor is a squirrel cage induction motor. A sealed lead-acid battery of advanced design is used; there are 28 12V of advanced design is used; there are 28 12V batteries, giving a total power of 32.93kWh. The electric minibus must provide equivalent service to minibuses with internal combustion engines. Thus its operating specifications are: 30 passengers capacity, 40kph cruising speed, 60kph top speed, initial acceleration 0.9m/second squared, acceleration to 40kph in 14s, climbing speed 15kph up a 10% slope, 7.5m turning radius, and 100km range. The bodywork was designed for maximum passenger safety, stability, and strength, combined with light weight.
Abstract