Motorola M68HC08 - Manual (Page 36)

BLDC Motor Control
Designer Reference Manual DRM028 — Rev 0
36 BLDC Motor Control MOTOROLA
Figure 3-11. Balanced Capacity Coupling
NOTE: The configuration of the phase windings end-turns has significant
impact; therefore, it needs to be properly managed to preserve the
balance in the mutual capacity. This is important, especially for prototype
motors that are usually hand-wound.
CAUTION: Failing to maintain balance in the mutual capacitance can easily
disqualify such a motor from using sensorless techniques based on the
back-EMF sensing. Usually, the BLDC motors with windings wound on
separate poles show minor presence of the mutual capacitance. Thus,
the disturbance is also insignificant.
3.2.5 Back-EMF Sensing Circuit
An example of the possible implementation of the back-EMF sensing
circuit is shown in
Figure 3-12 .
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