How does the DC brushless motor achieve speed regulation?
How does the DC brushless motor achieve speed regulation? This problem is encountered every few days by the electromechanical company. It is a common problem for potential customers who have no need to use brushless motors. Therefore, it is necessary to explain this knowledge to everyone.
The brushless DC motor has no brush wear, the maintenance is relatively simple, and it is more reliable than brush, but a drive (commutation) circuit is required.
The first case of DC brushless motor speed control mode is: mainly by voltage control, the torque is mainly controlled by current, generally with a matching motor driver, changing the output voltage of the driver can control the speed of the motor, if not The driver, if you want to control the motor directly, you need to look at the power and operating current of the motor. If it is a low-power motor, you can use the speed control (not recommended, the method is very simple, you can connect a potentiometer in series, but this method will reduce the efficiency, so it is not recommended), the high-power motor can not use the resistance speed control. Because this requires a small resistance and high power resistor (the motor has a small operating resistance), this resistor is not easy to find and the efficiency of this solution is too low, it is best to find a matching driver.
The second speed regulation mode of DC brushless motor: PWM speed regulation, the PWM speed regulation principle of DC motor is different from the principle of AC motor speed regulation. It does not adjust the speed of the motor by frequency modulation, but adjusts the pulse width of the driving voltage. The way, and with some of the corresponding energy storage components in the circuit, the amplitude of the voltage delivered to the armature is changed, thereby achieving the purpose of changing the speed of the DC motor. Its modulation method is amplitude modulation. There are two ways to control PWM:
1. Use the PWM signal to control the conduction time of the triode. The longer the conduction time, the longer the work time, the higher the motor speed.
2. Use the PWM control signal to control the conduction time of the triode and change the control voltage to achieve
The advantage of the DC brush motor is that the starting torque is large, the speed control system has a simple structure and low price. However, there are many disadvantages such as high noise, easy damage, and replacement of the carbon brush, so it is gradually replaced by a DC brushless motor.
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