How It Works...
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 cylinders - 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.
The controller determines 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.
The battery pack is the power supplier for your kit. You must look after SLA battery packs carefully. SLA batteries need to be recharged
immediately after EVERY use. They hate to be left in a discharged state, even if they are only slightly discharged. So, if you forget to recharge your batteries, leaving them
drained for even one day, you WILL damage them, and they will soon begin to give you poor performance. LiFePO4 battery packs offer much more convenience and do not require charging immediately after use. Click HERE for more information on Deep Cycle Sealed Lead Acid (SLA) & LiFePO4 electric bike battery packs offered by E-BikeKit™.
How does a brushless electric motor work?
Brain, Marshall. "How does a brushless electric motor work?." 15 December 2006.
HowStuffWorks.com
In a typical DC motor, there are permanent magnets on the outside and a spinning armature on the inside. The permanent magnets are stationary, so they are called the stator. The armature rotates, so it is called the rotor.
 The armature of a typical DC motor
The armature contains an electromagnet. When you run electricity into this electromagnet, it creates a magnetic field in the armature that attracts and repels the magnets in the stator. So the armature spins through 180 degrees. To keep it spinning, you have to change the poles of the electromagnet. The brushes handle this change in polarity. They make contact with two spinning electrodes attached to the armature and flip the magnetic polarity of the electromagnet as it spins.
This setup works and is simple and cheap to manufacture, but it has a lot of problems:
- The brushes eventually wear out.
- Because the brushes are making/breaking connections, you get sparking and electrical noise.
- The brushes limit the maximum speed of the motor.
- Having the electromagnet in the center of the motor makes it harder to cool.
The use of brushes puts a limit on how many poles the armature can have.
With the advent of cheap computers and power transistors, it became possible to "turn the motor inside out" and eliminate the brushes. In a brushless DC motor (BLDC), you put the permanent magnets on the rotor and you move the electromagnets to the stator. Then you use a computer (connected to high-power transistors) to charge up the electromagnets as the shaft turns. This is how the E-BikeKit™ brushless hub motor is made.
The E-BikeKit™ brushless DC motor (BLDC) system has all sorts of advantages:
- Because a computer controls the motor instead of mechanical brushes, it's more precise. The computer can also factor the speed of the motor into the equation. This makes brushless motors more efficient.
- There is no sparking and much less electrical noise.
- There are no brushes to wear out.
With the electromagnets on the stator, they are very easy to cool.
- You can have a lot of electromagnets on the stator for more precise control.
 The poles on the stator of a two-phase BLDC motor used to power a computer cooling fan. The rotor has been removed.
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