Elektriajamite 1. Labor (0)

Tallinn University of Technology
Department of Electrical Engineering
Report on laboratory work 1 on General Course of Electrical Drive
SENSORLESS DRIVE POWER FLEX (ALLEN BRADLEY )
Jüri Lina
666BMW
Group M16 Variant 2
Tallinn 2014
1. Functional Diagram
2. Tables of observations
Task
Operation / Record
Observation
1
Reverse the motor speed . How long does the motor reverse?
Time to reverse was 16 seconds
2
2: Set the screen display an Output Voltage of the inverter . Turning the potentiometer, find accessible minimal and maximal voltages. Stop the drive.
Minimal: 2.8V
Maximal: 166V
3
3 Turn the keypad potentiometer half -way counter -clockwise. Run the drive and reverse it, count the shaft reversing time. Compare with the previous result and explain the difference . Stop the drive.
Reverse time was 7 seconds.
It was less because the motor was running at a lower speed compared to the previous experiment .
4
Set the Stop Mod to coasting (so called freewheel braking). Enable the Flying Start running function . Run the motor to the maximal speed. Then stop and restart it immediately before the motor stops. Observe the motor response. Stop the drive. Disable Flying Start.
The motor restart is very fast and it accelerates at exponential rate .
5
Set the PWM Frequency to the maximal level and run the motor again. Observe and explain the noise. Is it higher or less than before.
Less noise than before.
PWM noise is caused by the voltage inverter switching at a frequency in the audible range.
6
Using Boost Selection , set the variable torque boost to 30.0 VT. Run the motor at very low speed (2-3 Hz). Suspend warily the motor shaft with fingers. Observe the spring effect ( strong or weak ?). Stop the motor.
The spring effect was weak.
4. Solutions of the problems
1.1 What dictates the maximal voltage of the drive? Why is it limited?
Maximal voltage voltage is determined by the drive manufacturer and is usually dictated by the motors ability to dissipate excess thermal energy that comes from the internal resistance of windings.
Applying excessive voltage can cause the motor to run inefficently, components to wear out prematurely or cause permanent damage to the motor from excess heat disspation.
1.2 What parameter sets a mode of the drive operation? What modes exist ?
From the laboratory manual , I found 3 parameters that determine motor operation modes:
Parameter P036 sets Start Source.
Possible values : 0 Keypad 1 Remote panel
Parameter P037 sets the stop (braking) mode.
Possible values: 0 Ramp 1 Coast 2 DC Brake
Parameter A125 sets the Torque Performance mode.
Possible values: 0 V/Hz, 1 Sensorless vector
1.3 Explain the difference between the drive braking modes?
0. Ramp – Power input to the motor is reduced gradually, following a determined ramp path .
1. Coasting –Power is turned off instantly and the rotor is allowed to freely spin until it stops.
2. DC Brake – A DC source from the generates a permanent magnetic field in the stator which creates an EMF in the windings of the rotated rotor, causing the braking current . Interaction of the permanent stator flux and the rotor current produces the braking torque.
1.4 When the sensorless vector control is required ?
Sensorless vector control is beneficial when there is a need to save money on building the drive. With sensorless vector control, costly hardware such as tachometers can be left out from the construction of the drive.
1.5 Call the drive faults you met. How do you avoid and clear these faults?
I met the following faults:
F004 - UnderVoltage
This fault can be avoided by providing a stable source of power to the drive. The manual recommends monitoring the incoming AC line for low voltage or power interruption. Afterwards the error message can be removed by setting parameter A100 Fault Clear to 1
F048 – Params Defaulted
This fault is „intentional” as it is caused by reseting the drive in the end of the lab and commanding it to write the default values to EEPROM . This fault can be cleared by clearing it from the program by setting parameter A100 Fault Clear to 1 or cycling the power to the drive. Afterwards the drive can be reprogrammed to the required parameters.