DC Motor Positioning - Lab Report Example

Lab Report Student’s Name Course Title: Date: Abstract The report is shows DC Motor Positioning, DC motor speed control and AC synchronous motor control that power can bed efficiently by ac motor as compared to Dc motor. For analog dc motor positioning voltage was set +10 and the reference voltage was 1.76 withvoltage gain was 14.7V while in PWM Dc motor positioning the waveform ratio was 0.5 and voltage change of ∆VO = 14V was measured. In DC Motor speed control analog maintained a speed of 50rpm/V with motor torque of -0.55 mNm while Pulsed Speed Control of Dc motor had dissipation power of 120mW. AC Synchronous Motor Control showed that Variable Frequency Control AC motors are turning and subjected to adjustment ac motor is generated -1.73 Vdc +-0.05Vdc this gave rpmdc=100 which was . a 1/3 of the dc motor’s 300 rpm. Table of contents Abstract 2 Nomenclature 4 Introduction 5 Theory 5 Experiment set and procedure 6 Results and discussion 11 Conclusion 14 References 15 Nomenclature A.C Alternating Current D.C Direct Current V Voltage PWM pulse-width modulation RPM Revolutions per minute PFM pulse-frequency modulation Introduction The aim of the report is to perform various operations relating to DC Motor Positioning, DC motor speed control and AC synchronous motor control. In Dc motor positioning the report will cover both Analog Dc motor Positioning and PWM Dc motor Positioning while in DC motor speed control, Analog Speed Control of a Dc motor and Pulsed Speed Control of a Dc motor will analysed. In AC synchronous motor control, both Variable Frequency Control and The Tachometer Generator will be covered. The report will be of valuable importance as it will help in determining how to control the motor both direct current and PWM. A direct current motor circuit block on motors will be used as well as control circuit board and motor generators in the analysis. Objectives The objective of this report is to provide information of operations of analog and pulse width modulated position systems and this will require the use of equipments such as generators and controls circuit block on the motors generators, DC motor circuit block on the motors, controls circuit board and oscilloscope to confirm the results. The other objective will be to provide report on the use of proportional position control for DC motor positioning as well as understand pulsed and analog Dc motor speed regulation. The last objective will to provide details of factors that affect the performance of AC motor and generator and how to control speed of the two-phase synchronous motor with an AC generator. Theory DC motor positioning and control as well as AC synchronous motor control are critical in generation of power and its efficiency in use. Pulse-width modulation and analog signals affect the control and positioning of DC motor while Variable Frequency Control and the Tachometer Generator have effects on AC synchronous motor control. Experiment set and procedure DC Motor positioning In the experiment proportional feedback control circuit is used in providing power that is to drive both direct current motor module and analogue circuits. A voltage of +12v, +5v and -12v will be employed. in order to have analog position, banana connectors will be connected to the Multimetre in order to measure. Oscilloscope, dual trace, generator, sine wave and motors will be other equipments that necessary to the experiment The procedure for this exercise will involve the connecting of five components as show in the diagram where the position set diagram are connected to positive and negative voltage respectively. In the connection summing up junction becomes the centre of the two where they will be added then it will be amplified by the amplifier before being connected to the DC motor. The DC motor helps in controlling because it has a belt and a pulley. This is closed loop system since the only comparison is the comparison between reference signal and feedback signal. In case there is an error in the signal it will be amplified to the point that it is useable in running the motor in a direction which will reduce the error signal. Exercise 1:- Analog Dc motor positioning- The equipment will be connected as the shown in the diagram below The position set signal will be set at 1.5V and the input error voltage will be measured. Then the two-post connector will be removed with the aim of disabling the Dc motor. Then it will be connected to oscilloscope channel and analog servo jack so that position set will be set at +10V and ±1V then varied and the results will be recorded. The voltage gain will be calculated. Exercise 2:- PWM Dc motor positioning- The aim is to use pulse with modulated position systems to determine positions of a motor. In the case we will need generators, control circuit block, direct current , motor circuit block, and control circuit. The block diagram will be as (http://www.ee.nmt.edu/~wedeward/EE443L/FA99/EE443_lab5.pdf) The steps or procedure for the experiment will be as Connect the oscilloscope to PWM servo jack and start varying the position set. the oscilloscope is also connected to triangle test point to observe the wave form. It is also connected to square wave test point to observe the frequency which is observed and recorded Then, two connectors are removed to measure the input voltage When oscilloscope is connected to the resistors, position set is made 7V0.1V then it is moved to PWM servo jack The multimetre will be used to record the voltage DC MOTOR speed control In this case the results will entail regulation of speed of Dc using various parameters in Analog and Pulsed circuits. This will assist in understanding relationship between armature current and torque in a dc motor as well as relationship between armature voltage and rpm in a dc motor. Exercise 1:- Analog speed Control of a Dc motor here the DC motor will be driven and observation for the motor drive input VIN and output VOUT will be recorded from oscilloscope. The following block diagram will represent layout for the experiment The procedure that will be followed in accomplishing the exercise will as follows; The switches are set to drive dc motor with analog voltage input as well produce analog speed feedback from the generator output. VIN will choice analog motor drive input and tachogenerator will facilitate analog speed feedback output. Drive the shaft at 500 rpmf500 = 100 Hz Record all the voltages and Exercise 2:- Pulsed Speed Control of Dc motor: in determining how pulse mode control can save power. The equipment will be arrange as shown as in block diagram of the circuit below to generates the PWM control signals From the diagram it can be stated that the input voltage which sets rotation direction thus giving analog speed signal. The oscillated is connected to give to record frequency and determine the modulation depth. The speed of the motor will be set at full rate after fitting drive belt between the dc and ac motors. There is a connection of DVM to measure the driver output voltage with respect to GND. Then analogue seed is varied for -10 Vdc +- 0.2Vdc at the driver output (VA) and results are taken. Determination of the duty factor at the driver output and effective dc voltage (Va) driving the motor is calculated. Lastly measurement of tach is taken. AC Synchronous Motor Control The objective of this report is demonstrated that AC motors and generators are affected by variation of frequency. Exercise 1:- Variable Frequency Control - alternative current motor rpm is always 1/3 of the dc motor and drives the dc motor. In essence it means that a reduction of ac motor drive frequency will lead to reduction of synchronous speed. The following procedure will be employed:- There will a connection from ac motor to input, ac motor to PHASE 2 output and ac motor to PHASE 1 output. Phase shifter direction is set and switched to CW then ac motor speed control is adjusted. Next is to connect the positive lead of a DVM to dc motor and the negative DVM lead to GND. Adjust the ac Motor to control speed and the results is recorded Then connect CH1 TO PHASE 1 and CH 2 to PHASE 2 and measurement of frequency are taken Lastly phase shifter is switched to the direction of CW, then the PHASE 2 and measurement taken. Exercise 2:- Tachometer Generator - in this case the procedure that will be used will be 1. The equipment will connected to incorporate connectors at dc motor and analog speed leading to setting of speed controls. 2. the DMM is used to measure the resistance of the PHASE 2 stator winding 3. Connection of CH1 to PHASE 1 and PHASE 2. Adjust the scope to display several cycles of the two waveforms, the two sine waves 900 out of phase. 4. Read oscilloscope values of frequency. 5. Measurement for peak output voltage from the generator’s CH 1 with the generator will be taken Results and discussion DC Motor positioning Exercise 1:- Analog Dc motor positioning During the experiment, the position sense signal was sent at -1V and the position set signal was 1.V and it produced an error of 5V which was used to run the motor reducing the error. This was done by removing two post connectors to disable the DC motor. When Oscilloscope was connected to analog servo jack and the voltage was set +10 for position set and 1V for oscilloscope, the reference was recorded to be 1.76 and voltage gain was 14.7V. during the variations of reference signals were recorded as 0.5V and 1.76 V with output voltage of 10.73V It can be concluded that voltage gain is the change in output voltage divide by the change in input voltage that result and deviation at the output voltage. This means that the analogy positioning creates too much time which makes it unstable thus making it oscillate. Exercise 2:- PWM Dc motor positioning – After the experiment it was discovered that waveform ratio was 0.5 with a frequency of 20Hz. The feedback voltage was measured initially as -7 V and when it was adjusted it was measured as -6V thus giving a calculated output voltage change of ∆VO = 14V. The change in input voltage was 8V which gave voltage gain of the pulse width modular amplifier circuit as Av = ∆VO / ∆VF = 14V/8V = 1.75. Various measurement was considered and each was measurement were used to calculated and it was discovered that the error signal modulates the width of the pulse signal. It is also amplified together with triangle wave determine the slope of voltage gain. It was noted that at a wave form of 50% ratio the signal error was zero. DC Motor speed control In this case the results will entail regulation of speed of Dc using various parameters in Analog and Pulsed circuits. This will assist in understanding relationship between armature current and torque in a dc motor as well as relationship between armature voltage and rpm in a dc motor. Exercise 1:- Analog speed Control of a Dc motor - in this case the frequency of the Dc motor output is recorded as 100 Hz while the measured voltage was found to be -10 Vdc, maintaining a speed of 50rpm/V. When the ouput voltage was -8.0 Vdc and VTO = -8 Vdc the current was IA = -0.01 A this gave motor torque of -0.55 mNm It has been observed that VIN and VOUT are not equal in some measurement. It can be concluded that Dc motor rpm decrease when the torque (T) increased because increased current (IA) increased the motors IR voltage drop. Exercise 2:- Pulsed Speed Control of Dc motor: PWM speed control uses switches control movement of Dc motor to have power efficiency. In Dc motor control sinusoidal current waveforms are created during displacement of motor. After the connections it was found that Dc motor average current. Ia=-20mA and the power amplifier had a -15 Vdc while the motor had -9Vdc at -20 mA. The calculated amplifier output transistors dissipation power was 120mW. The oscilloscope measured the amplitude of the driver output pulses to be -14Vdc. It can be deduced that pulse width modulated speed controllers uses less electricity as compared to analog speed controllers. AC Synchronous Motor Control Exercise 1:- Variable Frequency Control - the aim was to show the effect of varying frequency of ac motor on speed control of a two-phase synchronous motor by using an AC control as a generator. The results show that when AC motors are turning and subjected to adjustment ac motor is generated -1.73 Vdc +-0.05Vdc this gave rpmdc=100. This is 1/3 of the dc motor’s 300 rpm. The frequency was similar with dc motor of 20 Hz and had 24 poles. It can be concluded AC motor synchronous speed is determined by the stator poles per phase and the frequency of the ac supplied and it runs at synchronous speed. Exercise 2:- Tachometer Generator - the aim of this experiment was to demonstrate that AC generation from tachometer runs at synchronous speed and can be controlled. Phase 2 stator winding had resistance Rt2. Rt2=200ohm, Rt1=200ohm as measured by DMM. the oscilloscope measured generator’s output frequency as 20 Hz with a speed of speed=500rmp. The constant generator’s speed was measured as 70rpm/Vpk. From these results it can be confirmed that output frequency is proportional to rpm for synchronous generator. Conclusion From dc motor positioning the voltage gain is the change in output voltage divide by the change in input voltage that result and deviation at the output voltage. In dc motor control rpm decrease when the torque increases because increased current (IA) increased the motors IR voltage drop. At the same time in pulse width modulated speed controllers uses less electricity as compared to analog speed controllers. AC motor synchronous speed is determined by the stator poles per phase and the frequency of the ac supplied and it runs at synchronous speed while in Tachometer results show that output frequency is proportional to rpm. References EE443L Lab 5: DC Motor Position Control. Accessed from University of California (2007).ME 104 Sensors and Actuators- Laboratory 6a Closed Loop Analog Control Of DC Motor Velocity. Department of Mechanical Engineering University of California. Read More