Fifth, the working principle of the servo motor
As shown in the figure below, it is a servo motor control circuit made of power operational amplifier LM675. The motor uses DC servo motor. As can be seen from the figure, the power operational amplifier LM675 is powered by 15V, the 15V voltage is applied to the non-inverting input of the operational amplifier LM675 via RP1, and the output voltage of the LM675 is applied to the input of the servo motor. A speed signal generator is mounted on the motor for detecting the speed of the motor in real time. In fact, the speed signal generator is a generator whose output voltage is proportional to the speed. The voltage outputted by the speed measuring signal generator G is fed back to the inverting input terminal of the operational amplifier as a speed error signal via the voltage dividing circuit. The voltage value set by the speed command potentiometer RP1 is divided by R1.R2 and applied to the non-inverting input terminal of the operational amplifier, which is equivalent to the reference voltage.
The servo motor uses the letter M to indicate the servo motor and is the source of power for the drive system. Operational Amplifier: Represented by the circuit name, LM675, is an amplifier component in the servo control circuit that provides the drive current for the servo motor.
Speed command potentiometer RP1: Set the reference voltage of the operational amplifier in the circuit, that is, the speed setting. Amplifier Gain Adjusting Potentiometer RP2: Used to fine tune the gain and speed feedback signals of the amplifier in the circuit.
When the load of the motor changes, the voltage fed back to the inverting input of the operational amplifier also changes. That is, when the motor load is increased, the speed is reduced, and the output voltage of the speed measuring signal generator is also lowered, so that the operational amplifier has an inverting input terminal. The voltage drops, the difference between this voltage and the reference voltage increases, and the output voltage of the operational amplifier increases. Conversely, when the load becomes smaller and the motor speed increases, the output voltage of the speed measuring signal generator rises, the feedback voltage applied to the inverting input terminal of the operational amplifier increases, the difference between the voltage and the reference voltage decreases, and the output voltage of the operational amplifier decreases. This will cause the speed of the motor to drop, so that the speed can be automatically stabilized at the set value.
