AN2357 Freescale Semiconductor / Motorola, AN2357 Datasheet - Page 15

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

MOTOROLA
Sine Voltage Powered 3-Phase Permanent Magnet Motor with Hall Sensor
The voltage limit is:
where:
Since the ratio omega and voltage U
depends on rotor flux and motor parameters,
where:
The constants C
application the angle between the rotor position and the voltage are not
constant, and the motor field is weakened in dependency on the motor speed.
In this case, the constants C
speed. The used motor characteristics were measured experimentally (see
Figure
A 64 point table was created from measured constants, and used in formulating
the algorithm for torque limitation.
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Freescale Semiconductor, Inc.
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t
U
C
C
LIM
12).
ef
Z
φ
U
U
C
is a constant, representing rotor flux [Wb]
is a constant, representing stator impedance [Ω]
is motor voltage [V]
is required torque limit [Nm]
LIM
LIM
G
=
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=
=
------- - C
U
ω
Figure 12. Constants for Torque Limitation
G
ef
C
m
t
--------------------- - C
LIM
and C
G
⋅
U
t ⋅
⋅
ef
Z
LIM
ω
m
Φ
+
⋅
motor speed [rpm]
depend on motor parameters. In the designed
C
Z
φ
G
+
⋅
and C
ω
C
m
φ
⋅
ω
m
Φ
ef
are changed according to the motor
can be replaced by a constant, which
Equation 9
can be simplified to:
C
C
Software Design
Equation 10
Equation 11
G
Φ
Equation 9
*ω
AN2357/D
15