The working principle of brushless motor
The MCU only outputs the six-channel PWM to control the signal through the equipment register. The maximum voltage is only 5V, and the motor cannot be directly driven. Instead, the motor is operated by the switch of the power tube. The drive circuit is generally a drive bridge and motor composed of multiple MOSFETs. The drive axle power tube is constructed. The commutation of the brushless motor is based on the detection of the rotor orientation. The sensing method is to detect the rotor orientation using the Hall sensor. The non-inductive driving method is to detect and calculate the current in the rolling process of the brushless motor. Changes in voltage, voltage, etc., estimate the rotor orientation, and then commutate.
1, the principle of commutation
The internal device of the brushless motor has a Hall sensor, which can distribute the condition according to different magnetic field directions in different directions of the rotor, and gives an output signal of 1 or 0, and the three sensors are evenly arranged, and the attack is performed 6 times on the 360-degree television point. The flip level, each time a difference of 60 degrees TV point, according to the signal encoding of the three sensors to measure the orientation of the rotor, this is the commonly used sense drive method. In addition, the non-inductive driving method is to detect and calculate the parameters such as current and voltage in the rolling process of the brushless motor, estimate the rotor orientation, and then perform commutation.
2, the principle of the drive circuit operation
Q1 to Q6 are power FETs. When the demand phase AB is turned on, it is only required to open the Q1 and Q4 tubes, and the other tubes are kept off. At this moment, the current flow path is: positive → Q1 → coil A → winding B → Q4 → negative. The MCU gives the gate of Q1 a PWM signal, and the gate of Q4 is a normally open signal, so you can manipulate the useful voltage of the drive motor by manipulating the duty cycle of the PWM signal at the Q1 input. The same is true of the other five-step tour guide.
