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Balanced capacity coupling – Motorola M68HC08 User Manual

Page 36

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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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Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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