The Design of High-Speed High-Power Density Machines

1
The Design of High-Speed High-Power Density
Machines

• Liping Zheng

2
Tasks

• Design two kinds of motors (1kW and 3kW) using
  sizing equations combined with FEM simulation and
  calculate the machine parameters and performance.
• Consider both axial flux and radial flux
  structure to compare the performance.
• To design radial flux motor, use the same rotor
  and stator diameter for two motors to reduce the
  manufacture cost.

3
Sizing Equations

• Four types of sizing equations are available
  which link the motor torque to the motor size.

4
The Sizing Equation

• Provides many relations between physical
  dimensions and density-like quantities and is
  well adaptive to produce a design that is
  geometrically compatible from the start.

5
Electrical Constraints

• Current density
• Induced voltage
• Output power
• Output torque

6
Maximizing the Coefficient

• Specify current density J110000A/in
• flux density at stator Bt1.8T,
  Bc1.4T
• flux density at airgap Bg0.8T
  
• Get the maximum value of
• Select the number of slots and the winding
  structure to meet the induced voltage and input
  current requirement.

7
Rotor Design

• Design the rotor structure using magnetic
  equivalent circuit method.
• 4 poles.
• High energy PM NdFeB (Neodymium-iron-boron).
• Design airgap length.
• Design permanent magnetic structure.

8
FEM Analysis

• Calculate flux density in airgap, rotor and
  stator core.
• Calculate back emf and inductance.
• Calculate torque and torque ripple.
• Calculate losses.

9
Performance Analysis

• All performance must meet the required
  specification.
• Thermal consideration.
• Tradeoff may be necessary for the best
  performance.

10
Estimated Results Using Sizing Equations
Estimated Design Size for 40Krpm Motor (Case not
included)
Output Power (W) Output Power (W) 1000 3000
Radial Flux Motor Stator Outer Diameter (in) 1.95 1.95
Radial Flux Motor Length (in) 0.608 1.823
Axial Flux Motor Rotor Outer Diameter (in) 1.442 1.898
Axial Flux Motor Length (in) 1.406 2.217
Axial flux motor size parameters are calculated
according to the same airgap surface and stator
volume as those of the radial flux motor.