48V brushless DC motor, because brushless, motor itself can not complete the commutation of current, must rely on external control circuit to achieve commutation. Therefore, there is no conventional DC control mode, the external control circuit to complete the commutation is through the switch tube to achieve, due to the flexibility of the switch circuit, can be convenient to achieve more functions than the simple commutation, so, the Chopper DC control mode is used to control the motor.
To get the 48V brushless DC motor to turn, the control unit must turn on (or off) the power transistors in the converter in the order in which the stator is wound, based on the current position of the motor rotor, the upper arm power transistor and the lower arm power transistor make the current flow through the motor coil to produce a forward (or reverse-RRB- rotating magnetic field, and interact with the magnet of the rotor so that the motor can rotate clockwise/reverse. When the motor rotor rotates to a position where another set of signals is induced, the control part turns on the next set of power transistors, the circulating motor can continue to rotate in the same direction until the control part decides to turn off the power transistor (or only turn on the lower arm power transistor) when the motor rotor is stopped To reverse the motor rotor power transistors turn on in the opposite order.
According to the commutation mode of stator windings, the relationship between the status of signal H1, H2, and H3 of three rotor magnetic steel position sensors and six power tubes is found firstly, in the form of a table in the single-chip EEPROM. According to the states from H1, H2, and H3, the 8751 can find the corresponding power tube and send it out through the p 1 port to realize the commutation of the 48V brushless DC motor.
Speed control in the normal operation of the 48V brushless DC motor process, as long as the control of the output voltage of the digital-to-analog converter U0, you can control the current of the 48V brushless DC motor, and then control the current of the motor. That is, the 8751 single chip computer calculates the speed of the motor through the period of the sensor signal and compares it with the given speed. If the speed is higher than the given speed, the output value of the P 2 port will be reduced, and the motor current will be reduced, to achieve the goal of reducing its speed. On the contrary, it increases the output value of p 2, thus increasing the speed of the motor.
PWM control speed control can also be achieved through PWM mode.
Variable structure control when the 48V brushless DC motor is in the starting state or the adjustment process, the 48V brushless DC motor is adopted to realize the dynamic corresponding fast, once the speed of the motor is near the given value, immediately put it into the synchronous motor operation mode to ensure its speed accuracy. At this time the computer only needs to control the motor by a certain frequency commutation, at the same time, the computer through the signal period of the position sensor, to measure its speed, and judge whether it falls out of sync. As soon as the cloth is lost, switch to the 48V brushless DC motor and pull it back into sync.
Dewo Motor is a company specializing in 48V brushless DC Motor, products are widely used in printing equipment, engraving machines, textile machinery, computer external equipment, medical equipment, stage lighting equipment, robots, CNC machine tools, and other automatic control systems. If you need the 48V brushless DC motor, please feel free to contact us.