6.5 The motor

I declare: solidlikelyshaky

1. Explain the brushed motor, the brushless and the stepper by what commutates: the commutator, the electronics, the steps.
2. Explain torque, speed, kV and efficiency, and read a motor’s torque-speed curve.
3. Identify a brushless motor’s three phases and its Hall sensors with the multimeter, and measure its phase resistance.
4. Measure a motor’s speed (tachometer, Hall sensor or oscilloscope on a phase) and relate it to voltage.
5. Explain why a stalled motor burns and what the controller does to prevent it.
6. Explain the universal motor (corded tool) and the induction motor (compressor, table saw), and why they aren’t in battery tools.
7. Diagnosis: a brushless motor that vibrates without turning, open phase, dead Hall sensor or phase order; separate them.