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Hello everyone, j'm currently working on a project of a brushless motor controller. The idea is to replace a motorola MC33035 motor controller IC, with a Philips P87LPC768 microcontroller. The motor has three windings ad three hall sensors to find the current rotor position. Can someone send me informations and/or links about the theory of handling such motors? Thank you in advance!
Beware the demons of mechanical resonance on brushless motors. What you're doing isn't much different than driving a step motor and like a step motor, for any given constant current and mechanical load on the motor, there will be an RPM where the motor core develops even-numbered harmonic resonance (mechanically). To avoid this an many headaches, either look for an IC solution to act as an interface between the microcontroller and the motor, or be prepared to have precise, fast control of the current in each of the windings. Basically, the ideal is to drive them with pseudo-sinewave output. Thus, (if lacking a single IC solution) each winding will require a DtoA output that controls the current via a chopping FET driver. Chop/cuttoff is determined by feedback from a current sense resistor on each winding. You feed in the desired current to the DtoA and the chopper then controls (on average) to that level.
Thanks everyone fon the hints. Now my holiday is ended (SIGH!) and j put my hands on the job again! Bye