AN1914 Freescale Semiconductor / Motorola, AN1914 Datasheet - Page 43

• Manufacturer Part Number: AN1914
• Description: 3-Phase BLDC Motor Control with Sensorless Back EMF Zero Crossing Detection Using DSP56F80x
• Manufacturer: Freescale Semiconductor / Motorola

7.3.4.4 Commutation Control - Set Starting
7.3.4.5 Commutation Control - Set Stop
7.3.4.6 Commutation Control - Set Alignment
This state is used to set the start of the motor commutation.
The following actions are performed in this state:
In this state:
In this state BLDC motor is set to Alignment state, where voltage is put across 2 motor phases and
current is controlled to be at required value. The following actions are provided in Set Alignment state:
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T_Actual = Cmt Timer Counter
setting new commutation parameters and initialized commutation with bldczcHndlrInit
algorithm
initialization of computation with bldczcComputInit algorithm
Commutation initialized to start commutation step and required direction
2 additional motor commutations are prepared (in order to create starting torque)
setting commutation parameters and commutation handler initialization by
bldczcHndlrInit algorithm
first action from bldczcHndlrInit algorithm (for commutations algorithms) is timed by
Output Compare Timer for Commutation timing control (OC Cmt)
PWM is set according the above prepared motor commutation steps
Zero Crossing is initialized by bldcZCrosInit
Zero Crossing computation is initialized by bldczcComputInit
Zero Crossing is Enabled
supply
PWM set according to Align_Step_Cmt variable status
current controller is initialized
PWM output is enabled
Alignment Time is timed by Output Compare Timer for Speed and Alignment
bldczcHndlrStop algorithm is called
PWM output pad is disabled in order to stop motor rotation and switch off the motor power
DSP56F80x MC PWM Module in Motor Control Applications
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SW Design
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