Fig 1Brushless PM motorHover or tap a part · Space holdsθe 0° · A +1.00 B −0.50 C −0.50
Phase APhase BPhase CRotor magnets, N light and S darkThis is a 12-slot, 8-pole motor with buried magnets, the kind that drives many electric cars. The inverter switches battery DC into three sine-wave currents 120° apart. Each phase feeds every third coil, so the field round the stator turns, and the magnets are pulled along 90 electrical degrees (half a pole) behind it. With four pole pairs, the rotor turns once every four electrical cycles: at 12,000 rpm the currents run at 800 Hz. The figure runs at half a cycle a second. Space holds the motor; when it is held, ← and → step the current by 15°.