Motor controllers are the second most critical component in optimizing for performance. More important than the motors themselves and less than the batteries. AC controllers are referred to as inverters.

DC Motor Controllers

DC motors are inherently simple to control. In the most basic sense you could just use a giant switch to power a DC motor. That would be very dangerous and would certainly cause damage to electrical and mechanical systems almost immediately. Too smooth the application of power, a motor controller works much like a giant dimmer switch, applying a little power at first, then more as desired. Other key features include current limiting, motor speed limiting, and voltage limiting. These are used to protect motors as well as batteries. Due to the simple nature of the DC motor, the controller does not have to be custom matched to the motor. For the most part any motor will work with any controller that is powerful enough to drive it.

Pros:

  • More torque
  • More power
  • Less expensive
  • Lower voltages

AC Controllers

Controllers for AC motors are commonly referred to as inverters.  This is because they do take a DC in (the battery) and output an AC wave. There are three power wires between the motor and inverter. Each of these wires needs to either be positive, neutral, or negative, and constantly changing as the motor turns. If the sequence is out of sync with the rotor, the rotor will not spin.  There is a position sensor embedded in the motor that is also connected to the inverter to enable synchronization. But not all motors use the same sensors and the sensors are not all positioned in the same way.  Because of this, the inverter must be properly programmed for any given motor.  To simplify this, most AC systems are sold with both matching parts.  

Pros:

  • Higher motor speeds
  • Less current
  • Regenerative braking
  • Electric reverse
  • Liquid cooling
  • Better sealed

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