EEP301: Ac position control
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This document summarizes an experiment on AC position control. The aim was to investigate the effects of loop gain and velocity feedback changes on the dynamic characteristics. Various equipment was used including an AC motor, synchro transformers, and an oscilloscope. Observations showed that reducing the brake setting caused instability, while increasing velocity feedback and loop gain improved step and following performance. Applications include power amplifiers, servo potentiometers, and speed or position configurations.
EEP301: Ac position control
- 1. EEP 301 - Control Lab Cycle 2 Experiment 2 Ac Position Control System Submitted By: Aastha (2009EE50052) Akshay Gupta (2009EE50275) Indra Bhushan (2010EE50548) Kumar Sourav (2009EE50796) Mehul Mittal (2010EE50553) Umang Gupta (2010EE50564) Vivek Mangal (2010EE50566)
- 2. AIM: The effects of loop gain and velocity feedback changes on the dynamic characteristics of an A.C position control are investigated. EQUIPMENT REQUIRED: AU150B–Attenuator Unit SA150D–Servo Amplifier PS150E‐Power supply LU150L‐Loading unit ST150R‐Synchro Transformer ST150T‐Synchro Transmitter ACM150U‐AC motor PA150V‐AC pre‐Amplifier Unit GT150X‐Reduction Gear Techno Unit Oscilloscope THEORY: To make a position control servo using an a.c motor the following two components are required: 1. A position demand transducer. 2. An output position sensing transducer of a type that will produce an error signal which is an alternating voltage. The rotor of ST150T is energised by the reference voltage and the two stators are coupled together, the rotor signal of ST150R will be an a.c signal which becomes zero in amplitude when the two rotors are aligned. Synchro Pair ST150T transmitter ST150R control transformer
- 3. General Layout of the a.c position control:
- 4. Setting Up: Set the potentiometer to zero, apply full break. Remove the connection to the motor. Tx and Rx should have 20 degree difference. It looks like a circle on Cathode Ray Oscilloscope The upper potentiometer is set to 2.5 OBSERVATIONS: 1) Observed circle on the oscilloscope by adjusting the phase knob of PA150U. 2) Observe the effect of tacho feedback on response & graph The system is almost sure to become unstable and oscillate continuously .This can be stopped by re‐applying the brake but change to the gain potentiometer setting only after the frequency and amplitude of oscillation. (a) Keep the gain at 2, vary gain in the step of 2 Gain=2, brake =2
- 5. Gain=4, brake =2 Gain=6, brake =2 Gain=8, brake =2
- 6. Gain=10, brake =2 (a) Keep the gain at 2.5, vary brake in the step of 2 Gain=2.5, brake =0 Gain=2.5, brake =2
- 7. Gain=2.5, brake =4 Gain=2.5, brake =6 Gain=2.5, brake =8
- 8. Gain=2.5, brake =10 Gain=2.5, Tacho = 2 Gain= 5, Tacho=3
- 9. Gain= 5, Tacho=5 Gain= 5, Tacho=7 Gain= 5, Tacho=9
- 10. CONCLUSIONS: (1) Observed the effect of loop gain and velocity feedback changes on the dynamic characteristics of the system. (2) When the brake setting is reduced to 0 and the demand shaft ST150T is given a small displacement then the system becomes unstable and oscillates continuously. (3) Reasonably good step and following performance can be achieved using only position and velocity feedback. (4) When the tacho setting is increased, the error signal increases APPLICATIONS OF AC POSITION CONTROL: (1) Power Amplifier for driving. (2) Servo potentiometer type error detector. (3) Speed or position configuration may be built.