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# EEP301: Dc modular servo motor

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Control Lab experiment EEP301, 5th sem electrical engineering @ IIT Delhi

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### EEP301: Dc modular servo motor

1. 1. EEL301LAB REPORT DC MODULAR SYSTEM 11/5/2010 Group-3 AKSHAY GUPTA AASTHA DUA INDRA BHUSHAN KUMAR SAURAV MEHUL MITTAL UMANG GUPTA VIVEK MANGAL
2. 2. DC MODULAR SERVO MOTOR Assignment 6 Aim: We study the working of the pre-amplifier, PA150C and find out its characteristics. Theory: This Pre-amplifier has two signal inputs and two outputs. If there is a positive voltage on either of its inputs then one of its outputs becomes positive. Also if one of the output becomes negative then the other output becomes positive. Observation Table Fig1. Graph Of V0(3) v/s Vi. 0 2 4 6 8 10 12 -1500 -1000 -500 0 500 1000 1500 Series1
3. 3. Fig2. Graph of V0(4) vs Vi. Fig3. Graph of V0(4-3) vs Vi. 0 2 4 6 8 10 12 -1500 -1000 -500 0 500 1000 1500 Series1 -15 -10 -5 0 5 10 15 -1500 -1000 -500 0 500 1000 1500 Series1
4. 4. Calculations From Fig3 we find the gain of the pre-amplifier by finding out the slope of the straight part of the curve. Slope 1= 1000*(0.59+0.621)/-(59+58.5)= 10.306 Slope 2=1000*(1.706+1.626)/-(166+155.3)=10.6713 Gain= 10.488 Assignment 6.2 Aim: To utilize the error signal output of the operational amplifier to drive the output potentiometer via the pre-amplifier and motor. Theory: When we rotate the input potentiometer then the output potentiometer cursor should rotate to an angle nearly equal to that. If the output cursor stops before arriving at the set position then the system is tolerant to an error and the motor will not respond till the error exceeds a value. Observations Input Output Misalignment 0 5 5 45 42.5 2.5 90 77.5 12.5 135 117.5 17.5 180 220 40 270 260 30 330 313.75 16.25 360 347 13
5. 5. Fig 4. Graph of Misalignment v/s input. Assignment 7 Aim: To show that the improvement that results from closing the loop using feedback instead of using an open loop. Theory: When we use a feedback loop, we compare the actual speed with the required speed. This produces an error signal to actuate the servo amplifier output so that the motor maintains a more constant speed. In this experiment, we simply feed back a signal proportional to the speed, using the tachogenerator. We then compare it with a reference signal of opposite polarity, so that the sum will produce an input signal of the required value. Observations Ref. Voltage(Volts) Tacho Voltage(Volts) Error Voltage(Volts) Speed (r/min) -0.619 0.370 0.122 130 -2.434 1.83 0.478 660 -4.03 3.09 0.844 1120 -5.88 4.51 1.275 1640 -7.41 5.69 1.632 2060 -8.85 6.80 1.962 2470 0 5 10 15 20 25 30 35 40 45 0 50 100 150 200 250 300 350 400 Series1
6. 6. Fig 5. Graph of Error Voltage v/s Speed. Now to find out the effects of loading on speed we use the magnetic break as a load. Brake Position Speed Error 0 2080 1.626 1 2080 1.626 2 2080 1.644 3 2040 1.738 5 1830 2.316 6 1640 2.82 7 1490 3.233 8 1330 3.73 9 1100 4.31 10 860 5.00 0 0.5 1 1.5 2 2.5 0 500 1000 1500 2000 2500 3000 Series1
7. 7. Fig 6. Graph of Error voltage v/s Brake Position. Fig 7. Graph of Speed v/s Breal Position. Now we find the values for a different gain. Brake Position Ref. Volts Error Volts Tacho-generator Volts Speed (r/min) 0 -3.606 0.728 2.75 1000 3 -3.606 0.793 2.69 970 4 -3.606 0.861 2.62 950 0 1 2 3 4 5 6 0 2 4 6 8 10 12 Series1 0 500 1000 1500 2000 2500 0 2 4 6 8 10 12 Series1
8. 8. 6 -3.606 0.971 2.61 910 8 -3.606 1.060 2.42 880 9 -3.606 1.146 2.33 840 10 -3.606 1.243 2.24 810 Fig 8. Error volts v/s Brake Fig 9. Speed v/s Brake 0 0.2 0.4 0.6 0.8 1 1.2 1.4 0 2 4 6 8 10 12 Series1 0 200 400 600 800 1000 1200 0 2 4 6 8 10 12 Series1
9. 9. Now, We have to find the reference Voltage at which the motor just stops. We find this value by slowly tuning the knob and observing the motor. Vref=-320.1 mV N=1010 rpm. Assignment 7.3 Aim: To assemble a simple reversible speed control system. Theory: Because of its importance in speed control, the tacho-generator has become an integral part of the motor. Observations Forward Brake Position Tacho generator Volts Ref. Volts Error Volts Speed (r/min) 0 2.76 -3.145 0.95 1000 5 2.74 -3.153 0.95 990 8 2.72 -3.147 0.95 980 10 2.35 -3.147 0.95 850 Backward Brake Position Tacho generator Volts Ref. Volts Error Volts Speed (r/min) 0 -2.78 2.542 1.697 1000 5 -2.75 2.546 1.697 990 8 -2.73 2.548 1.697 990 10 -2.31 2.548 1.697 840
10. 10. Assignment 8 Aim: To familiarize ourselves with the term deadband and to investigate the effect of gain on deadband and step response. Theory: The deadband is the minimum input signal required to get a system response. So knowing the error factor we can relate the signal input to the degree of misalignment that can occur before there is a corrective response. Observations Gain Rotation Clockwise Rotation Anti- clockwise Total deadband 1 -55 80 135 2 -95 120 215 3 -70 100 170 4 -65 95 160 5 -60 85 145 Fig 10. Total deadband v/s Gain 0 50 100 150 200 250 0 1 2 3 4 5 6 Series1