Explanation the principle of action of servo amplifier
The function of the servo amplifier is to combine and amplify a plurality of input signals and feedback signals, and output corresponding signals according to the polarity of the integrated signal to control the servo motor to rotate forward or reverse.
When the input signal and the feedback signal are balanced, the servo motor stops rotating and the output shaft of the actuator is stabilized at a certain position.
The servo amplifier group is composed of a pre-magnetic amplifier, a flip-flop, a thyristor main circuit, and a power supply, and its composition is as shown in the following figure.
To accommodate the need for complex multi-parameter adjustments, the servo amplifier is configured with three input signal channels and one position feedback signal path. Therefore, it can input three input signals and one at the same time position feedback signal. In a single-parameter simple adjustment system, only one of the input and feedback channels is used.
In the servo amplifier, the pre-amplifier combines the three input signals and one feedback signal into a deviation signal and amplifies it into a voltage signal U22-21 output. This output voltage is simultaneously triggered by the trigger1 (or 2) is converted into a trigger pulse to control the thyristor conduction of the thyristor main circuit 1 (or 2), thereby applying an AC 220V power supply to the two-phase servo motor winding to drive the two-phase servo motor turn. When △1 is greater than 0, U22-21 is greater than 0, trigger 2 and main circuit 2 are working, and two-phase servo motor is rotating forward; when △1 is less than 0, trigger 1 and main circuit 1 are working, and two-phase servo motor is reversed.The circuit composition and parameters of the two sets of flip-flops and the two sets of thyristor main circuits are exactly the same, so when the input signal is balanced with the position feedback current If, the output of the pre-magnetic amplifier is U22-21≈0,the two triggers have no trigger pulse output, the thyristors in the main circuits 1 and 2 are blocked, the power of the two-phase servo motor is disconnected, and the motor stops rotating.
It can be seen that the servo amplifier is equivalent to a three-position non-contact relay and has a large power amplification capability.