DC motor – speed regulation principle DC motor speed regulation: the so-called speed regulation, that is, the required torque is obtained by adjusting the motor speed. The DC (brush) motor can adjust the speed by adjusting the voltage, connecting the resistance in series, and changing the excitation, but it is actually the most convenient and most commonly used to adjust the voltage. At present, the main use of PWM speed regulation, PWM is actually through high-speed switching to achieve DC Voltage regulation, in one cycle, the longer the ON time is, the higher the average voltage is, and the longer the OFF time is, the lower the average voltage is. It is very convenient to adjust. As long as the switching speed is fast enough, the harmonics of the power grid will be less, and the current will be more continuous.