AN1913 Motorola / Freescale Semiconductor, AN1913 Datasheet - Page 43

• Manufacturer Part Number: AN1913
• Description: AN1913 3-phase BLDC Motor Control with Sensorless Back-EMF ADC Zero Crossing Detection using DSP 56F80x
• Manufacturer: Motorola / Freescale Semiconductor

7.3.4.2 Commutation Control - Starting State
commutation period
No Zero Crossing
get during last
This state is almost entirely serviced by the BLDC Zero Crossing algorithms which are documented in
Motor Control.pdf, Chapter 5, BLDC Motor Commutation with Zero Crossing Sensing). First,
the bldczcHndlr is called with actual time from the Cmt Timer Counter to control requests and
commutation control registers. Other BLDC Zero Crossing algorithms are called, according to the
request flags. The state services are located in the main loop and in the Cmt (commutation) Timer
Interrupt.
The Starting state is as the Running state, see
Calculate Next Commutation
after No Zero Crossing
Corrective Calculation 1.
Zero Crossing Missed
during Per_Toff
BLDC control with BEMF Zero Crossing using ADC
Running - Begin
Preset Next Commutation
settings and timing
Figure 7-9. Substates - Running
commutation period
Detected/Missed during last
Zero Crossing
Calculate Next Commutation
after Zero Crossing Missed
Figure
Corrective Calculation 2.
Zero Crossing Get
7-9.
motor Commutation
Calculate Next Commutation
after Zero Crossing Get
commutation time
(T_Next) expired
Software Design
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