Thermal Analysis of IPM Motorexamples|products|Murata Software Co., Ltd.

Example1 Thermal Analysis of IPM Motor

General

  • Temperature and torque characteristics of IPM motor (Interior Permanent Magnet Motor) are analyzed when the electricity is applied.
    The model is a permanent magnet synchronous motor with magnets built in a rotor.

  • The analysis is coupled with the external circuit.

  • The homogenizing method is applied to simulate the layer structure of the electromagnetic plates of steel for the core.

  • Fast stabilizer is employed to make the magnetic field reach the steady state in short calculation time.

  • Temperature, torque and magnetic flux density are solved.
     

  • Unless specified in the list below, the default conditions will be applied.
     

Analysis Conditions

Item

Setting

Solver

Magnetic Field Analysis [Luvens]

Thermal Analysis [Watt]

Analysis Type

Magnetic field analysis: Transient Analysis

Thermal analysis: Steady-State Analysis

Unit

mm

Options

Select External Circuit Coupling.

Select Rotating machinery.

 

[Conversion]

Model Thickness: 30×10^-3[m]

Select Partial Model.

Number of Divisions of the Whole Model: 4

Circuit Configuration Number of Series: 1

Circuit Configuration Number of parallels: 1

Select Convert the result to the whole model and output it.

 

The Rotating Machinery tab is set as follows.

Tab

Setting Item

Setting

Rotating Machinery

Rotational Movement

Select Constant Velocity.

Number of Rotations: 1800[r/min]

Rotor’s Initial Rotation Position: 0[deg]

Number of Slide Mesh Divisions

Circumferential Division Angle: 1.0[deg]

Rotation per Step: 1[mesh]

Number of Slide Mesh Layers: 3

 

External circuit is as follows.

60[Hz] three-phase AC voltage is applied.

 

Set the Mesh Tab as follows.

Tab

Setting Item

Setting

Mesh

Meshing Setup

Automatically set the general mesh size: Deselect

General mesh size: 4[mm]

Ambient Air Creation

Select Create ambient air automatically.

Ambient Air Scale: 1.2

 

The Transient Analysis tab is set up as follows.

With the settings as below, number of steps is 450, circumferential division angle is 1.0[deg], and rotation per step is 1[mesh], the rotation up to 450 degrees (=450*1.0*1) is analyzed.

The steps are set until the magnetic field reaches the steady state.

Tab

Setting Item

Setting

Transient Analysis

Time step

Automatic

Table

Number

Calculation steps

Output steps

1

450

1

 

 

Fast stabilizer is set up as follows to make the magnetic field reach the steady state in short calculation time.

Tab

Setting Item

Setting

Fast Stabilizer

Correction Method

Simplified Three-Phase AC TP-EEC Method

Coil Name on the External Circuit

U Coil: Circuit_Coil1

V Coil: Circuit_Coil2

W Coil: Circuit_Coil3

Graphical Objects

A rotor core and magnet are placed in the center. A stator and coils are placed around them.

This is a 3D model analysis. By utilizing the symmetry of the model, it is made to be a quarter model.

Half period rotation boundary (symmetry) is set.

“Ambient Air Creation” is selected.

Adiabatic boundary condition is set on the shaft and the gap between stator and rotor.

Body Attributes and Materials

Body Number/Type

Body Attribute Name

Material Name

28/Solid

coil_1

Cu

34/Solid

coil_2

Cu

35/Solid

coil_3

Cu

36/Solid

coil_4

Cu

37/Solid

coil_5

Cu

38/Solid

coil_6

Cu

55/Solid

mag

mag

45/Solid

stator_core

core

47/Solid

rotor_core

core

 

The body attribute is set up as follows.

For the core, the homogenizing method is selected to simulate the layered steel plates.

Body Attribute Name

Tab

Setting

coil_1

Current

Waveform: External Circuit Coupling

Coil Name on the Circuit: Circuit_Coil1

Turns: 35[Turns]

Direction: Specify Inflow/Outflow Faces

Stator/Rotor/Air

Stator

coil_2

Current

Waveform: External Circuit Coupling

Coil Name on the Circuit: Circuit_Coil1

Turns: 35[Turns]

Direction: Specify Inflow/Outflow Faces

Stator/Rotor/Air

Stator

coil_3

Current

Waveform: External Circuit Coupling

Coil Name on the Circuit: Circuit_Coil2

Turns: 35[Turns]

Direction: Specify Inflow/Outflow Faces

Stator/Rotor/Air

Stator

coil_4

Current

Waveform: External Circuit Coupling

Coil Name on the Circuit: Circuit_Coil2

Turns: 35[Turns]

Direction: Specify Inflow/Outflow Faces

Stator/Rotor/Air

Stator

coil_l5

Current

Waveform: External Circuit Coupling

Coil Name on the Circuit: Circuit_Coil3

Turns: 35[Turns]

Direction: Specify Inflow/Outflow Faces

Stator/Rotor/Air

Stator

coil_6

Current

Waveform: External Circuit Coupling

Coil Name on the Circuit: Circuit_Coil3

Turns: 35[Turns]

Direction: Specify Inflow/Outflow Faces

Stator/Rotor/Air

Stator

mag

Direction

Vector: X=1, Y=1, Z=0

Stator/Rotor/Air

Rotor

rotor_core

Layer

Select Take layer into account

Space: 97[%]

Layer Direction Vector: X=0, Y=0, Z=1

Stator/Rotor/Air

Rotor

stator_core

Layer

Select Take layer into account

Space: 97[%]

Layer Direction Vector: X=0, Y=0, Z=1

Stator/Rotor/Air

Stator

 

The material properties are set as follows.

Material Name

Tab

Properties

Cu

Conductivity

Conductivity Type: Conductor

Conductivity: 5.977×10^7[S/m]

Thermal Conductivity

Thermal Conductivity: 398[W/m/deg]

mag

Relative permeability

Material Type: Permanent Magnet

Magnet

Magnetization Characteristic Type: Linear

Magnetization Strength: 1.25

Relative Permeability: 1.05

Thermal Conductivity

Thermal Conductivity: 1[W/m/deg]

core

Electric Conductivity

Conductivity Type: Conductor

Conductivity: 1.7 x10^6[S/m]

Permeability

Magnetization Characteristic Type: Select B-H curve

B-H Curve Table

Magnetic Field [A/m]

Magnetic Flux Density [T]

0 0
58 0.42
90 0.8
180 1.19
380 1.37
1100 1.48
2000 1.55
3000 1.608
11000 1.81
20000 1.91

Thermal Conductivity

Thermal Conductivity: 10[W/m/deg]

Boundary Conditions

“Natural convection (automatic calculation)” is set on the outer boundary condition (surrounding the motor in the case of the thermal analysis).

Half period symmetric boundary is set.

Adiabatic boundary condition is set on the shaft and the gap between stator and rotor.

Boundary Condition Name/Topology

Tab

Boundary Condition Type

Setting

Outer Boundary Condition *

Thermal

Heat Transfer/Ambient Radiation

Natural convection (automatic calculation)

Room temperature: 25[deg]

shaft

Thermal

Adiabatic

 

rotor

Thermal

Adiabatic

 

stator

Thermal

Adiabatic

 

Symmetry

Symmetry/Continuity

Periodic

Rotation Period (Half Period)

 

To set Outer Boundary Condition, go to the [Model] tab
 


 

and click [Outer Boundary Condition] .

Results

The distribution of the magnetic flux density at 450 calculation steps.

 

The diagram below shows time-torque characteristics.

Transient state becomes stable at around 20[ms].

About 0.5[N*m] of torque is obtained.

 

The diagram below shows the temperature distribution of the stator.

In the steady state, it is around 100[deg].