Motor Characteristics

MAE156A – Winter 2014, measuring motor characteristics, due Jan 28th

Go to office hours and use the experimental setup provided for you in the Design Studio (on the workbench across from the LaserCAMM room).

The high-speed motor used in the experiment has a half-clear, half-opaque acrylic disk on the motor shaft to trigger an optical sensor which counts revolutions.

The variable power supply has a switch and a knob on the right side to vary the voltage between 2V - 20V. For this experiment, measure values between 2V - 12V only.

The precision resistor is in series with the motor, as seen in the circuit above. The resistance (R_s) is printed on the housing.

Two Digital Multimeters are wired to probe the circuit. One DMM is used to measure the voltage across the precision resistor (V_s). The second DMM is used to measure the voltage across the high-speed motor (V_i).

CHECK THE WIRING BEFORE PROCEEDING.

To measure an approximate the motor speed, dial in the desired voltage level on the power supply. Wait until the motor has reached a constant speed. Using a timer, start measuring the time while resetting the optical counter. After a time duration, record the time elapsed and the motor revolutions.

Record the DMM voltages and motor speeds for two voltages.

POWER OFF the OPTICAL COUNTER, POWER SUPPLY and BOTH DMMs before leaving.

After making the appropriate measurements then calculate:

Km, Ke, R, I1, I2, ω1-max, ω2-max, I1-max, I2-max, T1-max, and T2-max

Plot efficiency of the actual motor as a function of ω for both cases measured. Do not assume ideal conditions, internal resistance torque needs to be included.