AN1931D Freescale Semiconductor / Motorola, AN1931D Datasheet - Page 26

• Manufacturer Part Number: AN1931D
• Description: 3-Phase PM Synchronous Motor Vector Control
• Manufacturer: Freescale Semiconductor / Motorola

System Concept
26
A decision must now be made about which phase current should be calculated. The simplest technique
is to calculate the current of the most positive voltage phase. For example, Phase A generates the most
positive voltage within section 0 - 60
In this case, the output voltages are divided into six sectors, as shown in
calculation is then made according to the actual sector value.
Sectors 1 and 6:
PHASE_B
PHASE_A
PHASE_C
Figure 4-11. 3-phase Sinewave Voltages and Corresponding Sector Value
Figure 4-10. Voltage Shapes of Two Different PWM Periods





















Freescale Semiconductor, Inc.
6HFWRU  6HFWRU  6HFWRU  6HFWRU  6HFWRU  6HFWRU 
6HFWRU  6HFWRU  6HFWRU  6HFWRU  6HFWRU  6HFWRU 
3-Phase PM Synchronous Motor Vector Control
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PWM PERIOD
II.
ADC sampling point



I.
I.
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i
A



=
–
i
B
–



i
C



PWM RELOAD
critical pulse width



Quh†rÃ6
Quh†rÃ6
Quh†rÃ6
Quh†rÃ7
Quh†rÃ7
Quh†rÃ7
Quh†rÃ8
Quh†rÃ8
Quh†rÃ8
II.
DQJOH
DQJOH
Figure



4-11. The current
Figure 4-11
MOTOROLA
(EQ 4-5.)