An887, ac induction Motor Fundamentals

FIGURE 24:
DTC BLOCK DIAGRAM
External Torque Reference
Internal
Torque
Reference
Torque
Comparator
Flux
Comparator
Optimal
Switch
Selector
3-Phase
Rectifier
Mains
DC Bus
Switch
Position
DC Voltage
Line 1 Current
Line 2 Current
3-Phase
Adaptive
Motor
Model
Internal
Flux
Reference
Calculated Speed
Flux
Reference
Controller
Torque
Reference
Controller
Torque
Reference
Speed
Reference
Flux Optimization
Flux Braking
Speed
Controller
Inverter
Induction
Motor

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AN887
DS00887A-page 22
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2003 Microchip Technology Inc.
SUMMARY
The AC induction motor drive is the fastest growing
segment of the motor control market. There are various
reasons for this growth. They are:
• Ease of programming
• Low investment cost for development
• Flexibility to add additional features with minimal 
increase in hardware cost
• Faster time to market
• Same VFD for wide ranges of motors with 
different ratings
• Reduced total part count and hence, compact 
design
• Reliability of the end product
• Ease of mass production
• Ever decreasing cost of semiconductors due to 
advancement in fabrication technology
• Energy efficient solution
Microchip has positioned itself to target the motor con-
trol market, where our advanced designs, progressive
process technology and industry leading product
performance enables us to deliver decidedly superior
performance over our competitors, which includes the
best of the industry. These products are positioned to
provide a complete product solution for embedded
control applications found throughout the consumer,
automotive and industrial control markets. Microchip
products are meeting the unique design requirements
of the motion control embedded applications.

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DS00887A-page 23
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2003 Microchip Technology Inc.
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