An electric wheelchair control system is adapted to control a wheelchair and comprises a sensing assembly, an inertial sensor, a controller, a motor driver, and a three-phase AC motor. The sensing assembly is configured to detect an external force applied to the wheelchair and generate a first sensed signal based thereon. The inertial sensor is configured to detect an inclination of the wheelchair and generate a second sensed signal based thereon. The controller selectively outputs a PWM braking signal to the motor driver according to the first sensed signal and the second sensed signal, and the PWM braking signal includes an upper arm braking signal and a lower arm braking signal, wherein the upper arm braking signal and the lower arm braking signal have the same duty cycle and when the upper arm braking signal is at a high level, the lower arm braking signal is at a low level.
