AN2519 Freescale Semiconductor / Motorola, AN2519 Datasheet - Page 6

• Manufacturer Part Number: AN2519
• Description: 3Sin with Dead-Time Correction - XOR version TPU Function Set
• Manufacturer: Freescale Semiconductor / Motorola

AN2519/D
6
3Sin with Dead-Time Correction – XOR version TPU Function Set (3SinDtXor)
notifies the CPU that the reload values have been read and new values can be
written by clearing the LD_OK parameter.
The TPU function rotates the Stator Reference Voltage Vector by dTheta angle
each period so that the TPU can drive the motor with constant amplitude and
constant speed independently of the CPU. The CPU can adjust the Ampl
parameter to change the Stator Reference Voltage Vector amplitude, the
dTheta parameter to change the rotation speed. The CPU can also set the
absolute value of Stator Reference Voltage Vector angle Theta. To notify the
TPU that the Theta parameter should be loaded instead of using the buffered
value, the CPU must set LD_OK = $8001 instead of $0001.
The following equations describe how the 3-phase sine wave PWM signal high-
times ht
The function cos is calculated using a table of 32 values from the first quadrant
of one cosine wave period. The function parameter is mirrored in the first
quadrant. The function value is obtained by linear interpolation between the two
closest table values.
calculation. The maximum error is 7 in the amplitude range <–32768, 32767>,
that is 0.021%.
Theta
s
s
s
A
B
Freescale Semiconductor, Inc.
C
For More Information On This Product,
cos
cos
A
, ht
s
Theta
Theta
Theta
A
B
, ht
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C
s
B
and transition times t
dTheta
Figure 3
120
shows the error of the cosine function value
trans
of each channel are calculated:
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