
Copyright © Infineon Technologies 2005. All rights reserved.
Industrial and Multimarket Microcontroller
BLDC MOTOR CONTROL WITH XC866
HOT5:SENSORLESS BLDC
June 2006
Project 2: Motor Start Up Sequence – Variable Inductance

2006-6
IFAP AIM MC IMM
Table of contents
Motor Start Up Sequence – Variable Inductance
Motor Start Up Sequence – Variable Inductance
Demo
Demo
Hands On: Execution of program with motor driver setup
Hands On: Execution of program with motor driver setup
Current Sensor Circuit
Current Sensor Circuit

2006-6
IFAP AIM MC IMM
Table of contents
Motor Start Up Sequence – Variable Inductance
Motor Start Up Sequence – Variable Inductance
Demo
Demo
Hands On: Execution of program with motor driver setup
Hands On: Execution of program with motor driver setup
Current Sensor Circuit
Current Sensor Circuit

2006-6
IFAP AIM MC IMM
Variable Inductance vs Ramp up
Advantages of variable inductance sensing method over ramp up
Works for BLDC motors with different specifications
Can start motors with variable initial load
Disadvantage
Requires additional circuitry
Longer start up time

2006-6
IFAP AIM MC IMM
Initial rotor position is determined based on the variable current generated
when energizing the motor windings.
Each phase (coil winding) is energized in both forward and reverse direction,
each direction generating a different current due to a difference in inductance
of the coil windings.
Difference in inductance and current peaks
phase A
phase B
phase C
DC
B
C
B
B
B
A
Vector sum of
fields B
A
, B
B
, B
C
Vector sum of
fields B
B
and B
C
phase A
energized in
forward direction