From Unofficial Zero Manual
The motor controller takes power from DC battery bus, encoding three-phase sine waves to match the motor's position sensor to apply torque precisely to the motor.
- Gen2 motor controllers are all Sevcon Gen4 motor controllers, mostly Size 4 (S/DS) and Size 6 (SR/DSR), with Size 2 for the older XU model.
- The sine waves are constructed by power transistors operating in a pulse-width modulation (PWM) capacity.
- The power is applied to the motor in synchronization with the current speed and position of the rotor.
- Controller alignment (motor commissioning) is the process of tuning all of this for maximum efficiency and to avoid any slippage.