The document discusses strategies for achieving energy savings through the effective selection and configuration of AC drives in various applications. Key methods include using a common DC bus architecture, retrofitting older DC drives with AC systems, and utilizing active front-end (AFE) technology for improved efficiency. It emphasizes the importance of optimizing designs and auto-tuning capabilities in modern AC drives for enhanced performance and reduced mechanical losses.

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Energy Savings Using AC Drives
Drive Selection level
Presentation by
Prashob P K
in.linkedin.com/in/prashob7

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Introduction
Energy Savings is getting more and more importance in
current scenario
We have to effectively configure suitable drives with
adequate configuration
Selection and configuration of suitable drives based on
application or load is also critical

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Design and Selection
Savings can be achieved by :
• Use of common DC bus architecture
• Utilizing AFE [Active Front End]
• Use of Direct drives thereby reduce mech. Loss
• Optimizing and Tuning
• Retrofitting Older DC drives
• Use of energy efficient and inverter duty motors

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AC/AC Coordinated Drive Line Up
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Fuses
Line Reactor
Contactor
AC Drive
Regenerating
Resistor
AC Motor
Ac power supply
Explanation in next slide

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AC/AC Coordinated Drive Line Up
• Implemented in multi axis coordinated drive
system
• Individual drive connected to ac line with
separate protective components
• Losses are high.
• In some cases Pseudo-Common DC bus
created , but its costly and inefficient

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Common DC Bus Coordinated Drive Line Up
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Common DC Bus
AC Line
Inverters
Rectifier
[Infeed]
Regen.
Resistor
Fuses
Line Reactor
Contactor
Explanation in next slide

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Common DC Bus Coordinated Drive
Line Up
• Shared Rectifier used for all drives, losses are less
• Rectifier sized based on max current drawn of the
system, not the summation of individual motors
• Power sharing now possible between each drive sections
• More optimized and effective design possible for line
components,

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AFE: Active Front End Technology
• AFE is IGBT based rectifier that
controls/regulates DC bus level for both over
and under voltage
• AFE allows input voltage and current
waveform to be sinusoidal, thereby reduce
harmonics being regenerated to the line
• AFE improves the power factor to great
extend

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Line current diode bridge vs. AFE rectifier
motoring generating
DC link
Auto Transformer
Line Current Line Current
DC link
Conventional rectifier system AFE Rectifier system

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Eliminating Mechanical Losses
• Energy mainly lost through friction and mechanical
inefficiency
• Losses can be reduced by eliminating gearboxes with direct
Drive Torque motors
• High ratio multistage gear system can be completely replace
by shaft mounted torque motors
• Replacement of pneumatic, electromechanical tension
controls brake with AC drives are now common

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Retrofit of DC drives with AC/Servo
Drives
• Now that advanced speed control options are
available for AC motors, Existing old DC drive systems
can be replaced
• DC motors are bulky, and requires maintenance for
brushes and all.
• With servo drives constant and precise speed control
now achievable.

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Optimization and Adaptive tuning
• New age AC drives are capable of auto tuning
• Auto tuning helps in improving internal closed
control loop gain and thus more stable and
efficient will the operation of the drive
• Certain drives are capable of adaptive tuning
where the gain is continuously adjusted to
meet the load requirements while running

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THANK YOU
Reference
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