Motorola M68HC08 manual Detail of Mutual Inductance Effect, Effect of Mutual Phase Capacitance

Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

BLDC Motor Control

Brushless DC Motor Control Theory

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.

DRM028 — Rev 0		Designer Reference Manual
MOTOROLA	BLDC Motor Control	33
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