Brushless dc motor speed controller 2013-02-14

alec_t submitted a new article:

Brushless DC Motor Speed Controller - A simple, cheap, BLDC motor controller using readily-available components is described.
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A simple, cheap, BLDC motor controller using readily-available components is described.
Most previously-published speed controllers for BLDC motors either (1) reduce the supply voltage across the motor by a linear or asynchronous PWM control method, or (2) require access to the individual coils of the motor to vary the coil drive, and involve either dedicated ICs or microcontrollers together with optical or back-emf rotor-position sensing arrangements. Here is a simple alternative, using what...

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Again... Very nice work Alec_t.

I would just like to highlight to any on lookers that this circuits primary advantages over simpler circuits of similar efficiency (PWM circuits) is this circuits synchronous nature. With synchronous control, one is never supplying a highly noisy "out of step" signal to a motor that will have an internal frequency of it's own. This prevents any miscommutations inside the motor that could potentially be damaging, especially for larger brushless motors.

It really is quite cleaver. As I had said, this gets you inside the motor without having to open it. It reminds me of smart card hacking through power use analysis. Very cool trick.