This post was last edited by Li Shilong on 2018-9-27 16:23 I am a newbie in electric control and have been obsessed with motor control for a few years. From today on, I will give you some tips on motor control. One is my own interest, and the other is for communication and learning. Please give me more advice. Regarding the control of electric motors, the three-phase six-arm full-bridge drive circuit is a commonly used drive circuit on the market. This circuit adopts a three-phase six-arm full-bridge drive method, which can reduce current fluctuations and torque pulsations, so that the motor outputs a larger torque. Six power field-effect transistors are used in the motor drive part to control the output voltage. As shown in the figure, the power supply voltage of the drive circuit is 12 V, Q1~Q3 uses IRFR5305 (P channel) from IR, and Q4~Q6 is IRFR1205 (N channel). The field-effect tube has a built-in freewheeling diode to provide a current path when the field-effect tube is turned off to avoid reverse breakdown of the tube. As can be seen from the figure, A1~A3 provide the gate drive signal of the upper arm of the three-phase full bridge, and are connected to the hardware PWM drive signal of the LKS32MC061 microcontroller, and the motor speed control is realized by changing the duty cycle of the PWM signal; B1~B3 provide the gate drive signal of the lower arm, which is directly provided by the I/O port of the microcontroller, and has two states: on and off. The drive control adopts a three-phase six-state control strategy. The power tube has six trigger states. Only two tubes are turned on at a time, and the direction is changed every 60° electrical angle. If the AB phase is turned on at a certain moment, the C phase is turned off and there is no current output. The microcontroller uses the switching characteristics of the MOSFET according to the detected motor rotor position to realize the power-on control of the motor. For example, when Q1 and Q5 are turned on, the AB phase is turned on. At this time, the current flows from the positive pole of the power supply → Q1 → winding A → winding B → Q5 → negative pole of the power supply. Similarly, when the MOSFETs are turned on in the order of Q1Q5, Q1Q6, Q2Q6, Q2Q4, Q3Q4, Q3Q5, the brushless DC motor can be operated continuously as long as the commutation is performed accurately at the right time. If you make a little progress every day, you will eventually become a god. I am a newbie in electronic control. See you next time.
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