AN1911 Freescale Semiconductor / Motorola, AN1911 Datasheet - Page 16

• Manufacturer Part Number: AN1911
• Description: 3-Phase AC Motor Control with V/Hz Speed Open Loop Using DSP56F80X
• Manufacturer: Freescale Semiconductor / Motorola

Software Design
16
where PWMA, PWMB and PWMC are calculated duty cycles passed to PWM driver and Amplitude
determines the level of Phase voltage Amplitude.
The process is performed in a PWM reload callback function pwm_Reload_A_ISR and is accessed
regularly at the rate given by the set PWM reload frequency. This process has to be repeated often
enough compared to the wave frequency in order to generate the correct wave shape. Therefore for
16kHz PWM frequency it is called each 4th PWM pulse and thus the PWM registers are updated in
4kHz rate (each 250 sec).
Figure 6-5
Amplitude is 1 (100%).
Figure 6-6
Amplitude is 0.5 (50%).
Figure 6-5. 3-ph Sine Waves with 3rd Harmonic Injection, Amplitude = 100%

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PWMA
PWMB
PWMC
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shows the dutycycles generated by the mcgen3PhWaveSine3rdHIntp function when
shows the dutycycles generated by the mcgen3PhWaveSine3rdHIntp function when
=
=
=
------ - Amplitude
------ - Amplitude
------ - Amplitude
1
1
1
3
3
3
Indirect Power Factor Correction Using DSP56F80X
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
sin
sin
sin
+
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1
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6
120
240
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0
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6
1
-- -
6
+
sin
sin
0.5
3
3
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0.5
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