Motorola M68HC08 - Manual (Page 33)

BLDC Motor Control
Brushless DC Motor Control Theory
DRM028 — Rev 0 Designer Reference Manual
MOTOROLA BLDC Motor Control 33
Figure 3-8. Detail of Mutual Inductance Effect
3.2.4.4 Effect of Mutual Phase Capacitance
The negative effect of mutual inductance is not the only one to disturb
the back-EMF sensing. So far, the mutual capacitance of the motor
phase windings was neglected in the motor model, since it affects
neither the phase currents nor the generated torque. Usually the mutual
capacitance is very small. Its influence is only significant during PWM
switching, when the system experiences very high
du/dt.
The effect of the mutual capacitance can be studied using the model
shown in
Figure 3-9 .
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Freescale Semiconductor, Inc.
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