摘要 |
A low noise electronic three phase bridgecontrolled brushless DC motor suitable for whiteware appliance pumps and other appliance applications Back EMF zero crossing sensing is used to determine rotor position and thus stator winding commutation times. Motor torque and speed are controlled by pulse width modulating the operation of that bridge switching device which has just been switched from an OFF state to an ON sta te on each new commutation. All three stator windings have current flowing in each winding commutation to improve motor current waveform and thereby reduce motor noise, but the curre nt in one winding is always terminated before the end of the commutation period to all ow the back EMF in that winding to be sensed for zero crossing.
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