来源：http://www.jnmcd.com 发布时间：2019-06-04 浏览：次
The stator of brushless DC motor is armature of coil winding and the rotor is permanent magnet. If only a fixed DC current is applied to the motor, the motor can only produce a constant magnetic field, and the motor can not rotate. Only by real-time detecting the position of the motor rotor, and then according to the position of the rotor, corresponding current is given to the motor to make the stator produce a rotating magnetic field with uniform change in direction, the motor can rotate with the magnetic field.
如图2所示为无刷直流电机的转动原理示意图，为了方便描述，电机定子的线圈中心抽头接电机电源 POWER，各相的端点接功率管，位置传感器导通时使功率管的 G极接 12V，功率管导通，对应的相线圈被通电。由于三个位置传感器随着转子的转动，会依次导通，使得对应的相线圈也依次通电，从而定子产生的磁场方向也不断地变化，电机转子也跟着转动起来，这就是无刷直流电机的基本转动原理——检测转子的位置，依次给各相通电，使定子产生的磁场的方向连续均匀地变化。
Fig. 2 shows the schematic diagram of the brushless DC motor's rotation principle. For convenience of description, the coil center of the motor stator is tapped to the motor power supply POWER, the end points of each phase are connected to the power tube, the G pole of the power tube is connected to 12V when the position sensor is turned on, and the corresponding phase coil is turned on. As the three position sensors turn on in turn with the rotation of the rotor, the corresponding phase coils turn on in turn, so that the direction of the magnetic field generated by the stator is constantly changing, and the rotor of the motor rotates with it. This is the basic rotating principle of brushless DC motor, which is to detect the position of the rotor, turn on the power to each phase in turn, and make the direction of the magnetic field generated by the stator continuously uniform. Land change.
The stator windings of the motor are mostly made into three-phase symmetrical star connection, which is very similar to the three-phase asynchronous motor. In order to detect the polarity of the motor rotor, a position sensor is installed in the motor. The driver is composed of power electronic devices and integrated circuits. Its functions are: to receive the starting, stopping and braking signals of the motor to control the starting, stopping and braking of the motor; to receive the position sensor signals and the positive and negative rotation signals to control the switching on and off of the power transistors of the inverting bridge and to generate continuous torque; to receive speed instructions and speed feedback signals for control and adjustment. Speed; Provide protection and display, etc.
DC motor has fast response, large starting torque, and can provide rated torque from zero to rated speed. But the advantage of DC motor is just its disadvantage. For DC motor to produce constant torque performance under rated load, the armature magnetic field and rotor magnetic field must be maintained at 90 degrees, which needs carbon brush and rectifier. Carbon brushes and rectifiers produce sparks and powders when the motor rotates. Therefore, in addition to causing damage to components, their use is limited. AC motors have no carbon brushes and rectifiers. They are maintenance-free, robust and widely used. However, complex control techniques are needed to achieve the performance equivalent to that of DC motors. Nowadays, with the rapid development of semiconductor, the switching frequency of power components has been accelerated a lot, which improves the performance of driving motors. The speed of microprocessor is also faster and faster. It can control AC motor in a rotating two-axis rectangular coordinate system and properly control the current component of AC motor in two axes, so as to achieve the similar control of DC motor and have the same performance as that of DC motor.
此外已有很多微处理机将控制电机必需的功能做在芯片中，而且体积越来越小；像模拟/数字转换器(analog-to-digital converter，adc)、脉冲宽度调制(pulse wide modulator，pwm)…等。直流无刷电机即是以电子方式控制交流电机换相，得到类似直流电机特性又没有直流电机机构上缺失的一种应用。
In addition, many microprocessors have made the necessary functions to control motors in chips, and the size is getting smaller and smaller; such as analog-to-digital converter (adc), pulse width modulator (pwm)... And so on. Brushless DC motor is an application that controls the commutation of AC motor electronically and obtains the similar characteristics of DC motor without the absence of DC motor mechanism.
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