brushless motor lab report

# brushless motor lab report - the voltages are 120 degrees...

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Brushless Motors By Joe Doyle Lab Partners: Artem Boyko Ryan Mason Performed on April 7, 2009

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Part A The next page presents the graphs of the waveforms we were able to obtain from the scope captures. I have indicated the time displacement and voltage magnitude at each point where the waveform makes a significant change. These graphs behave as expected. In order to make a brushless motor work, it must be able to switch back and forth from positive to negative flux across each pole pair. By inducing positive voltage to one pole the result is a positive magnetic flux. Inducing a negative voltage to the opposite pole in the pair will result in a negative flux. Using a magnet on the rotor with respective opposite polarities is what produces mechanical output. Observing one graph at a time shows this positive/negative voltage characteristic. Looking at two at a time it can be seen that they are out of phase by 120 degrees. This easily indicates that the motor in the lab has 3 pole pairs because

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Unformatted text preview: the voltages are 120 degrees out of phase. Part B *Note that good data was not able to be recorded between 0-14V for Vm2* Vm2(V) Va(V) n(rpm) no load 15 39.4 2070 18.8 39.4 2610 21.6 39.34 3030 24.78 39.21 3450 27.16 39.19 3780 30.25 39.14 4140 Part C 15VDC 30VDC T(inch/ounce s) n(rpm) 8 2130 10 2010 15 1890 20 1800 25 1500 30 1230 35 1230 T(inch/ounce s) n(rpm ) 7.5 4170 10 4110 13.75 3960 18.75 3840 22.5 3690 27.5 3570 32.5 3390 Part D In order to reverse the direction of this motor the sequence of positive/negative current would have to change to negative/positive current. In essence you would just have to induce opposite polarities of current through the coils, for example pole A/A’ would change from positive/negative to negative/positive. Part E By observing that each sequence is out of phase by 120 degrees it can be determined that this is a 3 pole motor. 360degrees/120degrees=3poles...
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## This document was uploaded on 12/03/2009.

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brushless motor lab report - the voltages are 120 degrees...

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