How to control the speed of a brushless DC motor?

　　Many customers who have just started to use brushless motors asked this question. With the widespread application of brushless motors in medical, automation equipment, robotics, automobiles and other fields, in order to achieve different transmission control requirements, there are many questions about the speed, forward and reverse rotation of the control of the brushless DC motor. Let me share with you three methods to control the speed of brushless motors:

　　Speed control methods of brushless DC motor:

　　Method 1: Use voltage to control speed. Torque is mainly controlled by current. Generally, a matching motor driver is provided. Changing the output voltage of the driver can also control the speed of the brushless motor. If you don't have a driver and you want to directly control the motor yourself, you need to look at the power and working current of the motor.

　　Method 2: PWM speed control. The PWM speed control principle of DC motor is different from the principle of AC motor speed control. It does not use frequency modulation to adjust the speed of the motor, but adjusts the pulse width of the driving voltage, and cooperates with some corresponding energy storage components in the circuit. It changes the amplitude of the voltage delivered to the armature, so as to achieve the purpose of changing the speed of the brushless DC motor. Its modulation method is amplitude modulation. There are two methods of PWM control:

　　1. Use the PWM conduction signal to control the conduction time of the transistor. The longer the conduction time, the longer the work time and the higher the motor speed.

　　2. Use the PWM conduction signal to control the conduction time of the transistor and change the control voltage to achieve.

　　Method 3: If it is a low-power motor, resistor can also be used to control the speed (it is not recommended, the method is very simple, just connect a potentiometer in series, but this method will reduce efficiency, so it is not recommended). High-power motors cannot use resistors to control speed, because this requires a small resistance but high-power resistor (the motor working resistance is very small). This resistor is not easy to find and the efficiency of this solution is too low. It is better to find one matching brushless DC motor driver.

　　The above are three commonly used methods of brushless DC motor control and speed regulation. Hoping they can give you some help and enlightenment.