Electric motors with variable speed got usual characteristics. Those characteristics would be separated in low speed region and in high speed region. In the low speed region, electric motor has equal or constant torque. On the other hand, on high speed region electric motor got equal or constant power. In vehicle operations requiring low speed, voltage power supply to the electric motor is rising with speed increase.

Variable speed electric motor characteristics

Most basic electric vehicle performances are cruising speed (at its maximum), acceleration and grade ability. Maximum speed for electric vehicle is given by the maximum speed of the motor. It has to be clear that in normal conditions on the road, maximum capabilities are very rare in use. In most of the time while driving, power train got partial load. This load differs from road operating conditions. Uphill or downhill movement, acceleration, deceleration sudden braking and all other outside conditions are appearing with different ratio.

All these different conditions on the road are producing different energy consumption per distance unit. The unit of energy, in electric vehicles, usually is kilowatt hour (kWh). The power consumption per distance unit is kWh/km. That’s how energy consumption is evaluated. Power losses in motor drive and in transmission are known trough their efficiencies ?t and ?m