Page 564 - Mechanical Engineers' Handbook (Volume 2)
P. 564

3 Direct-Current Servomotors  555





















































                           Figure 8 Three-phase brushless motor controller circuit. (From Machine Design, June 9, 1988, p. 140.)



                           back-emf conduction during the zero-voltage portions of the voltage modulation and thereby
                           increases viscous damping. This effect can be eliminated by using a current amplifier rather
                           than a voltage amplifier. 9
                              Figure 9 shows a cross section of a brushless motor developed for use as a fin actuator.
                           Hall effect sensors are used for position measurement.

                           Mathematical Model
                           The mathematical model required to represent a brushless dc motor is identical to that of a
                           brush-type dc motor. Therefore the equations given in Section 3.1 are applicable.
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