AN2357 Freescale Semiconductor / Motorola, AN2357 Datasheet - Page 13

• Manufacturer Part Number: AN2357
• Description: Sine Voltage Powered 3-Phase Permanent Magnet Motor with Hall Sensor
• Manufacturer: Freescale Semiconductor / Motorola

Speed Ramp
Speed Calculation
MOTOROLA
Sine Voltage Powered 3-Phase Permanent Magnet Motor with Hall Sensor
The new phase increment is α expressed as:
where: C
Position calculation parameters are:
The speed ramp decreases the rate of required speed variation.
The measured speed ω
timer overflow interrupt.
where:
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Freescale Semiconductor, Inc.
For More Information On This Product,
Calculated position resolution 2
Position update 16 kHz
Phase increment resolution 2
C
pairs
T
h
ω
I
is the Hall sensor period
is a constant representing the omega scale and the number of pole
is integral constant of PLL
0
α
ω
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=
Figure 10. Difference Between Motor Position
m
C
=
I
⋅
C
------ -
T
∆α
60
ω
h
m
, reference
T/2
and Generated Sine Wave
120
Generated Sine Wave
Equation
18
180
16
per period
per period
6, is calculated every 5 ms in the
240
∆T – position difference
between expected and
real position
Position Signal from
Hall sensor
300
360
Software Design
Equation 5
Equation 6
AN2357/D
13