This is the "magic box" between your battery and your motor. Regular 24V DC electricity goes into the two controller battery wires and "pulse width modulated" 24V DC electricity comes out the three motor power wires to power the motor.
This is not AC, but in certain basic terms has a similar function. This is the reason many electric bike motors have three power wires coming out of them, even though they are called brushless "DC" motors. You may be familiar with simple DC electric motors that only have two wires. These motors are also technically DC motors, but the pulse modulation split up over three power wires has advantages of making them more efficient.
250 Series Controller
Rated voltage: 24v
Max current: 15A
Rated current: 7A
Low voltage shutoff: 20.5v
Motor control: Pre-wired for simple on/off motor operation when plugged into our Grip Switch Cable set (see Related Products at bottom of page).