Motorola M68HC08 manual Commutation Control Stages, Alignment

Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

BLDC Motor Control

Used Control Technique

position is known, and can be used to calculate the speed and processing of the commutation in the running state.

START MOTOR

ALIGNMENT

ALIGNMENT TIME	NO
EXPIRED?
YES
STARTING
(BACK-EMF ACQUISITION)
MINIMAL CORRECT	NO
COMMUTATIONS DONE?

YES

RUNNING

Figure 3-14. Commutation Control Stages

3.3.1.1 Alignment

Before the motor starts, there is a short time (depending on the motor’s electrical time constant) when the rotor position is stabilized by applying PWM signals to only two motor phases (no commutation). The current controller keeps current within predefined limits. This state is necessary in order to create a high start-up torque. When the preset time-out expires then this state is finished.

DRM028 — Rev 0		Designer Reference Manual
MOTOROLA	BLDC Motor Control	39
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