Design of Inverter Driven Induction Machines - PowerPoint PPT Presentation

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Design of Inverter Driven Induction Machines

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Material property variation (lot-to-lot) Dimensional variation & shift ... Chopping frequency. Fundamental AC current. Peak transistor frequency. 17. Opportunity ... – PowerPoint PPT presentation

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Title: Design of Inverter Driven Induction Machines


1
Design of Inverter Driven Induction Machines
  • Daniel M. Saban, PE PhD
  • saban_at_ieee.org

2
Overview
  • The induction machine problem
  • Stakeholders design drivers
  • Analysis synthesis challenges
  • Design rules-of-thumb constraints
  • Optimization and/or synthesis
  • Common tools
  • Selected approaches
  • Inverter system consideration
  • Opportunities

3
Induction machine
  • Stakeholders and their perspectives
  • Customers
  • Sales Marketing
  • Manufacturing Engineering Operations
  • Application Engineering
  • Product Development
  • Opportunities
  • Materials improved and exotic
  • Manufacturing processes and process control
  • Design, analysis and optimization tools
  • Size Topology

4
Induction machine
  • Temperature is everything
  • Material limits (life)
  • Insulation system
  • Bearing system
  • Material dependencies (performance)
  • Cooling system
  • Rules-of-thumb in design
  • Cost is everything
  • Operating cost efficiency, power factor
  • Initial cost better material, more material
  • Quality is everything
  • Performance is everything?

5
IM analysis challenges
  • Non-linear saturation, core losses
  • Winding harmonics
  • Rotor/Stator slotting skewing
  • Material property variation (lot-to-lot)
  • Dimensional variation shift
  • Manufacturing/assembly variation
  • Rotor resistance
  • End-leakage (consider frame)
  • High-frequency impedance (bearing currents)

6
Proximity Skin Effect
  • Fundamental current injected into conductors
  • 1 turn per coil 4.0 kW loss/pole
  • 4 turns per coil 2.5 kW loss/pole

7
Slot Ripple Eddy Current
  • Current Sheet used to simulate total air-gap flux
    density
  • No current injected into conductors
  • Loss is due to induced eddy currents
  • Used to analyze effect of wire transposition and
    aspect ratio

8
IM design synthesis
  • Clean sheet
  • Single application
  • Product family
  • Existing laminations
  • Brute Hp vs. finesse

9
IM design synthesis challenges
  • Knowns
  • Full stator slots
  • High conductivity conductors
  • Small gap?
  • Unknowns
  • Rotor stator aspect ratios
  • Slot shape details
  • Discrete values only
  • Pole count
  • Discrete wire sizes, non-linear cost function
  • Winding details number of turns, coils, pitch
  • Integral numbers of slots, rotor/stator
  • Lamination material, grade, thickness

10
Rules-of-thumb
  • Stator current density
  • 620 A/cm2 to 1 kA/cm2
  • Highly dependant on cooling system
  • Revise after thermal modeling
  • Peak flux density of stator teeth, yoke
  • 1.7T, 1.6T
  • Revise upward for more power density
  • Revise lower for higher efficiency
  • Rotor current density
  • Gap flux density 0.5T to 0.8T

11
Common Design Constraints
  • Rotor OD
  • Stator OD
  • Stack length
  • Machine construction
  • Cooling system

12
IM design iteration
Manual Iteration
LP
FE
13
IM design tools
  • In-house
  • Typically only lumped parameter (LP)
  • May be tied to manufacturing or operations
  • Some special versions of commercial software
  • Commercial
  • LP PC-IMD (SPEED), VICA (support?)
  • LPFE PC-IMD/FEA (SPEED), RMxprt (Ansoft)
  • MCM ??
  • FE Magnet (Infolytica), (Flux, Maxwell)
    Ansys/Ansoft
  • System simulation Matlab/Simulink, Simplorer
    (Ansoft), Easy 5

14
IM design optimization
Optimization engine
15
IM design optimization
  • Inverter driven machines
  • Pole count is now a free variable
  • Stator Rotor lamination design optimization can
    be decoupled
  • Skewing penalizes machine
  • Finesse approach
  • Size machine, ignore details discrete values
  • Create response surface narrow search space
  • Optimize rotor and stator separately
  • Second pass takes into account discrete values
  • Requires dedicated code
  • Key design points torque corner point, max
    speed, max torque
  • Best motor will deliver maximum torque for
    maximum drive current

16
IM-Inverter system optimization
  • Max torque-speed envelope (output)
  • different than constant torque/power/slip
  • power factor and efficiency variations
  • Optimal motor leakage
  • Harmonic ripple current
  • Chopping frequency
  • Fundamental AC current
  • Peak transistor frequency

17
Opportunity
  • Simple tools
  • When to apply vs. other technologies (IM vs. PM)
  • Rough sizing stack length, stator od, rotor od
  • Fit of test data for lamination family, or single
    design
  • Models of different manufacturing
    techniques/defects
  • Stray load loss - rotor/stator harmonic
    interaction
  • Stator conductor eddy currents large copper
    cross-section, high frequency
  • Vehicle to adapt academic work into industrial
    setting
  • Open source
  • Widespread use
  • Extensible framework
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