Acceleration and Deceleration Ramps

Acceleration and deceleration ramps are a central part of the function of a motor speed controller. Without a controller, if you connect a battery directly to a motor, there will be a sudden torque spike as the motor instantly tries to accelerate to its top speed. We have seen this torque spike be strong enough to strip gears or even tear a motor off its mountings.

When a controller is fitted, this spike does not occur as the motor is accelerated at a controlled rate. The ‘winding up’ of the speed is not only done by the operator slowly turning up the demand motor speed control, but there is also a wind-up rate built into the controller, so even if the operator turns up the demand speed suddenly, the controller will still wind up the motor at a more controlled rate. This ‘winding up rate’ is called an ‘acceleration ramp’. There is also a ‘deceleration ramp’ to control the winding down.

At point A the demand speed control is suddenly turned to full speed, the motor will follow the acceleration ramp up to full speed at point B. At point C the demand speed is suddenly reduced to zero and the motor speed follows the deceleration ramp down to zero at point D.