Brushless DC Motor Overview

Your EVsolutions Hub Motor is a brushless, gearless, hub motor. This motor has only one moving part, the motor shell, which rotates around the central portion. The axle is firmly attached to the center section and is used to mount the motor to your bike.

http://en.wikipedia.org/wiki/Brushless_DC_Electric_Motor

The motor has three phases, or power supply wires (think of this as a 3-cyclinder automobile engine.) Each of these phases fires in succession with the others, determined by the "Central Brain", or what is called the "PWM (pulse width modulation) Controller." Inside the motor on the outer perimeter there are many "rare earth magnets". Closer to the center of the motor are the wire coils, also wired in three phases. As a pulse of electricity is sent to the motor from the controller the coils create a strong magnetic field, which repulses them from the magnets and causes the motor to advance (rotate) away from the magnets. The controller then sends another pulse of electricity and the next phase fires, rotating the motor even further. It's helpful to think of our automobile engine example: 3 cyclinders - each firing one after the other.
There are three power (phase) wires going into the hub motor, and five Hall Effects Sensor wires coming out of the hub motor. The Hall Effects wires are used only to help the motor start from a dead stop. If you have a "Pedal First" controller (this controller requires that the bike be moving 3-5 mph before the motor will kick in), the Hall Effects Sensor wires are not needed.

CONTROLLER:

How does the controller determine the speed at which the motor rotates?
The pulses of electricity sent to the hub motor are determined by the throttle, which is mounted on the handlebars of your bicycle. The throttle is actually just a magnet passing by a "Hall Effects Sensor." Power is supplied to the throttle from the battery. The throttle then rations a small amount of power: from 0 to 5 Volts, which it sends to the controller. The amount of voltage sent to the controller is determined by how much the throttle is twisted. As the throttle is twisted, "Hall Effects Sensors" read the amount of voltage, and send this amount of voltage to the controller. 5 volts means the controller does nothing: sends no pulses to the hub motor, 0 volts means the controller sends electrical pulses to the hub motor as fast as it can.