| SELF-COMMUTATION OF BRUSHLESS DC MOTORS WITHOUT ENCODERS | ||||||
| Author(s) | M. Jufer | |||||
| Abstract | The brushless DC motor phases are normally switched by a rotor position detector. Usually, it is constituted by 3 Hall sensors, excited by the PM rotor flux density. If this solution is relatively simple, its main limitation is the invariant switching position. In order to keep an optimum torque characteristic, this position must normally vary in a range of ± pi/2 (electric angle). Different alternatives for this solution are presented, mainly related to the back EMF detection: - the direct back EMF detection through a particular winding or a non-supplied phase; - the indirect back EMF detection in an analogical way; - the indirect back EMF detection by a numerical sample method; - the third harmonic voltage detection. The two last solutions are presented, applied to the same motor and compared to the Hall sensor technique. |
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| Type | Members Only | |||||
| Date | Last modified 2021-03-10 by System | |||||
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