How to control the speed of the stepper motor
Stepper motors are widely used in automatic control equipment, such as industrial robotic CNC machine tools, small to ordinary printer fax machines, and so on. The stepping motor for air conditioning to adjust the wind direction is a relatively simple one in the application.
As the name suggests, the stepper motor has a set of pulse currents (phase difference 120 degrees) composed of three different phases, and the rotor rotates by one angle. The more precise the equipment requirements, the smaller the angle.The initial phase angle of the motor rotor is fed back to the CPU processor via the signal line. It is assumed that the motor is designed to rotate at a degree of rotation of a group of pulsed motors,the motor needs 360 group pulse current to be supplied by the processor-controlled servo circuit for one revolution. The program for adjusting the wind direction of the air conditioner built-in machine is set by the chip factory. It is assumed that a certain brand air conditioner wind direction control requires the motor to rotate 180 degrees. The stepping motor is designed to rotate once in a group of pulses.The processor will convert 180 sets of pulse currents and then transform the phase of one of the pulse currents to provide 180 sets of pulse currents in opposite phases to return the motor to the initial phase angle position. The motor speed is determined by the pulse frequency.
Stepper motors used in industrial control have a variety of control methods. The stepper motor used for air conditioning is not well understood, but from the point of view that it is simple to control and mainly requires inexpensive, it should be the pulse control method used.
The basic principle of pulse control does not need to be understood too deeply. From this figure, you can see several elements of its control method: frequency and quantity.
Then, the number of pulses determines the angle at which it rotates, and the frequency of the pulse determines how fast it rotates.