Magnet - PMSM Analysis

7/24/2019 Magnet - PMSM Analysis

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Magnet - PMSM Analysis

Sea Technology

Wang Lei

Date: 2007-11

Note: This note only describes how to operate and may not match the actual motor exist.


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Table of ontents

1Problem Description............................................................................................................................................................... 3

2MAGNET Interface Introduction.......................................................................................................................................... 3

32D Static Magnetic Field Calculation................................................... ................................. ................................. .................. 4

3.1Establish a Geometric Model............................................ ........................................ ......................................... ................... 4

3.2 Material Definition.............................................................................................................................................................. 5

3.3 Physical Model.................................................................................................................................................................... 6

3.3 Coil Setup............................................................................................................................................................................ 9

3.4 Boundary conditions......................................................................................................................................................... 11

3.5 Setting Mesh.......................................................... ......................................... ......................................... ........................... 13

3.6 Solving............................................................................................................................................................................... 13

3.7 After Treatment.................................................. ......................................... ......................................... ............................. 14

4. Back- EMF Calculation............................................... ......................................... ......................................... ........................ 17

4.1 Moving Body........................................ .......................................... ........................................ ......................................... .. 17

4.2 2D Transient with Motion..................................................................... ......................................... .................................... 18

4.3 Results................................................................................................................................................................................ 18

5. Steady Computing........................................... ......................................... ........................................ ..................................... 20

5.1 Power Angle.................................................................... ......................................... ......................................... ................. 20

5.2 Calculations....................................................................................................................................................................... 21

5.3 PMSM Torque-Angle Characteristic ............................... ................................ ................................. ................................ 23

5.4 PMSM Stall Torque Computing............................. ......................................... .......................................... ........................ 26


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1. Problem Description

Model is a three-phase permanent magnet synchronous motor, there are 24 slots on the stator, the rotor magnet built 8, two pairs of

poles, rated speed 1500rpm, specifically to do simulation analysis of the following issues:

1. Two-dimensional static magnetic field of permanent magnet synchronous motor is calculated,

and the flux density harmonic analysis;

2. Permanent magnet synchronous motor load calculated counter electromotive force;

3. Calculate the steady-state performance of permanent magnet synchronous motor;

4. Permanent Magnet Synchronous Motor stall torque.

Professional use Infolytica's magnetic field analysis software MagNet, the model simulation.

2. MAGNET Interface Introduction

1 Drop-Down Menu:

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2 boundary conditions

3 run the script, VBS format

4 linear, circular grid manually partition tool

5 The model view rotation adjustment

6 model view angle adjustment

7 Mobile copy rotation and other operations

8 Electronic components

9 arranged in the electronic component

10 Item Operation Window

11 selection tool

12 draw lines, arcs, circles tool

13 generating entity Tools

14 modeling and display window

15 circuit diagram window

16 Keyboard Input Tools

3. 2D static magnetic field calculation

The basic steps MagNet software. And general finite element CAE software is similar to, an analysis of a project includes the following

steps.

Geometry Material

definition

Electrical

connections

Border

conditions

Mesh Solving Postprocessing

Physical

model

3.1 Establish a Geometric Model

MagNet modeling itself is simple and practical, with its powerful model import and export functions, you can create all kinds of

complex models, this model uses the import and export of the way, first create a pole of permanent magnet synchronous motor model in

AutoCAD, and into MagNet, the specific process is as follows:

1, first established in AutoCAD geometry model, the unit is mm, save as dxf format capture mode while drawing attention to ensure

that the two lines intersect completely, there is no break, the model is as follows:

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2. Open a new MagNet file, set the length in mm in the menu Tools / set units in order to ensure consistency and AutoCAD the unit;

3. Import: menu Files / Import, select the dxf file, previously saved file into dxf can.

4. Set curve smoothness: Select Item Operation window View, select View 1, point right property, jump out the window, the angle of

the curve smoothness angle can be piecemeal, as shown below

3 2 Edit Material

Model of the stator, the rotor yoke material 50w350, neodymium iron boron permanent magnet to 50w350 example, details of

the material definition process: 1, menu Tools / New user material, jump out the window as follows: to define a new material

name (eg 50w350 ), the material color

And a description of the material and use;

2. Click Next, jump out the window as follows, select the need to define material properties, such as the magnetization curve (non-

linear), iron loss curves (do not define, but if you need to calculate the iron loss should be defined), conductivity, permittivity and mass

density;

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3. Continue to click Next, define the magnetization curve;

4, click Next, and then click Define loss curve, conductivity, permittivity and mass density, thus completing the definition of

50w350 of.

3 3 Physical Model

In front of the geometric model are just some of the line segments, and to generate a physical model is now in front of the

geometric model to generate a tensile body, and the material properties of the forming process, the present model specific member

comprising: a rotor yoke, a stator yoke, the permanent magnets, coils, air (air gap layer divided four) to the stator yoke, for example,

specific steps are as follows:

1. Select the object selected

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Select the closed surface structure

2.In the closed surface of the stator yoke structure of any click, as follows:

3. Select the drawing tools, such as this model using linear stretch, as follows:

Straight stretch

Click on the line drawing tool, out of the dialog box as follows: Set the stretched length 65mm, material 50w350, part name

previously defined for stator steel.

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4. Designation of permanent magnet: TypeUniformDirection

(0.86602540378443864676372317075294, 0.5, 0), With the X-axis represents magnetization direction 30 degrees, as

follows

Also a magnetization direction of the permanent magnets, Type: Uniform, Direction:

(0.5, 0.86602540378443864676372317075294, with 60 degrees in X axis direction.

Pay attention to the generation of air gap, generally divided into four layers, layer wrap of the rotor, a stator wrap layer, the gap in

the middle separate into two layers, as shown below:

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ncloses the stator air bag

ntermediate

area between

rotor and

stator that

forms the

remesh area

Wrap rotor air bag

3 3 Coil Setup

1. Select the coil component (for example, press ctrl key to select the following figure component # 4,5,6,15), the menu model /

make simple coil, generating winding coil # 1;

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2. Select the object in the project tree page in coil # 1, point right property, changed its name to coil_A, set the coil type stranded,

turns to 90 turns, set strand area that is single coil in the parameters sectional area of 0.5e-6 meters;

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Coil Type

Turns

Current direction

Set single coil cross-

sectional area

3. Generally adjacent to the motor windings arranged A +, C-, B + (+, - number indicates the current direction), itis set the current direction as shown by


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3 4 Boundary Conditions

MagNetic magnetic field lines in parallel, perpendicular to the magnetic field lines, surface impedance, thin-walled, parity

symmetry several boundary conditions. This model is a pole permanent magnet synchronous motor, so the use of odd symmetry

boundary conditions, loading method is as follows:

1. First select the symmetric boundary conditions need to load the main surface, press ctrl key to select the following four faces

(four faces of the air bag), as shown below:

2. Click on the odd symmetry boundary conditions, out of the dialog box as follows:

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3. Click Set Transformation, pop following dialog: Specify and rotated 90degrees from side to establish odd symmetry relations.

4. Result

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3 5 Setting Mesh

Density affect the accuracy of solving the grid, mesh has both manual and automatic, manual meshing can line, face, body to be

divided, automatic division which uses adaptive mesh mode automatically in the solution process adjust the grid size. This model uses a

simple meshing method, choose a subject, and then set the grid cells of the body. Specific steps are as follows:

1, first select an individual, then right, open the Properties option, open mesh page, as shown below:

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The maximum mesh size

The minimum mesh size

Curvature

2. Set the network of other entities

3. Observe the initial 2D grid: In the menu view / initial 2D mesh

3 6 Solving

First of solving its 2D static magnetic field, you need to set the solution options, such as: solution accuracy, solving the order and

so on. Specific process is as follows:

1. Set the solver options, menus solve / Set Solver Options, as shown below: 0.001% accuracy linear iterative, non-linear iteration

accuracy of 0.01% for the first order to solve the Order;


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2. Using 2D static field solver, menu solve / static 2D

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3 7 Post Processing

1. Magnetic Field


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2, the air gap field harmonic analysis

MagNet software provides a gap field harmonic analysis. Harmonic analysis can easily get the magnetic field at different

locations.

Gap radius of 28mm, to calculate the harmonic component

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Radius 28mm gap at Bx, By, radial Br, tangential Bt flux density amplitude:


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4. Back EMF Calculation

For the calculation of the counter electromotive force requires the use of the transient motion solver, based on the static magnetic

field model, we need to define the moving body, the following first introduced the process of defining the moving body, then using 2D

Transient with Motion solver can solve.

4 1 Moving Body

1. First select the object needs to move, you can use ctrl key to select multiple components, then the menu model / make motion

component, as shown in this example :( moving parts of the rotor yoke, the two magnets, a rotor wrap air bag and close the rotor air gap

layer package):

2. Click make motion component, the dialog box appears as follows, to generate the moving body set: Select the speed, the rotary

motion, the center (0,0,0), the rotation axis (0,0,1) ie z axis.

Set the speed in solution, since the rated speed of 1500rpm, into 9000deg / s, as shown below:

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4 2 2D Transient with Motion

1. For the transient calculation, in addition to solving options, you need to set the time step in the menu solve / set transient

options, starting from 0ms, 65ms end, time step fixed time-step mode, the size of 0.5ms;

2. Select 2D Transient with Motion solver to solve, in the menu solve / transient 2D with motion

4 3 Results

1. Different time field pattern, field fence at the project page you can view the equipotential lines showing various fields amounts of cloud and

Vectors:

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2. Counter electromotive force calculation: open post processing bar in the menu tools, appears below:

1. Selected object need to observe

2. Click this button

Can be obtained following the curve of change with time:

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5 Steady Computing

For non-steady-state simulation of PMSM start function, generally use the load driving simulation is more difficult, this paper

speed drives, in MagNet need to set two points, one is set to start position (ie power angle); the second is to set the speed of the drive, the

speed is synchronous speed.

5 1 Power Angle

1. For the calculation of the load, first established circuit in the menu circuit / new circuit window, as shown below:

Circuit is as follows:

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Coil_A

T1 T2

Coil_B

T1 T2

Coil_C

T1 T2

V1

SINV2

SINV3

SIN

Set voltage V1 to 78V, a frequency of 50Hz, the phase is 0, V2 phase is 120, V3 240 phase,

2. The power angle is calculated for the position 0.After the circuit is set up, we will be the permanent member is set to air, this time only the armature winding is excited, the moving

body is set to speed drives, speed is the synchronous speed 9000deg / s, the time from the beginning to 0ms 10ms, just 180 electricalangle of rotation .

In this way we can consider the power factor angle.

Ff is a permanent magnet excitation MMF alone, Fa is the armature excitation MMF alone, we will set it as a start position coincide,

is about to start moving body position set to about -7.25, power angle is zero.

5 2 Calculations

Circuit diagram above, the permanent magnet or a permanent magnet set, then the combined effect of the armature winding and

the permanent magnet, moving body set up to speed drive. 1, the moving body set

First, the moving body is set to speed drive, and then set the start position and synchronous speed, respectively, as shown below:

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2. Power angle is zero (no load) results

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5.3 PMSM Torque-Angle Characteristic

Using the method in the previous section were calculated steady-state situation is different for the steady-state power angle

(different starting position) when the simulation, you can get torque-angle characteristics of PMSM.

Note: If the power angle is zero start position did not identify, after an angle calculated once per revolution, will

Cause errors accumulate, the next speed is zero power angle 180 degrees) will deviate from the position of an electrical

angle of 180 degrees,

Therefore, you can not consider the power angle, parameterized start position, will get two torque to position 0,

These two points is the power angle is zero for the two combined power angle of 180 degrees, then you can fill the

middle of the power angle.

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1. Start position parameterisation

Using MagNet powerful parametric function can be parameterized start position, get a lot of different simulation

conditions, the specific operation is selected by moving parts (such as motion # 1) in the Project column objects page,

right click to view the properties, then click on the parameter set the start position from -7.25% deg, -2.25% deg,

2.75% deg ......... 82.75% deg, 87.75% deg (mechanical angle) (ie power angle 0 , 10 , 20 , ... 180 , 190 )

(electrical angle), as shown below:

2. Results

Transient motion using 2D solver to solve, calculated as follows: The final position of zero torque should start position for the

power angle of 180 , while there is indeed 190 , which is the accumulation in error.

Cause, the results are as follows:

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Thus, we can be 190 to 180 power angle, the corresponding adjustment will start from 0 to 190 power angle power angle

power angle from 0 to 180 power angle, torque-angle characteristics are as follows:

Torque-angle characteristic

PowerAngle(degrees)

Torque(Nm)

5 4 PMSM Stall Torque Computing

As can be seen from the torque-angle characteristics: PMSM power angle position is greater than the maximum torque of 90 .And this PMSM power angle position is greater than the maximum torque of 90 . And this maximum torque is a PMSM stall torque. Thismodel is about the stall torque 2.7Nm, this time about the power angle 114 .

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Magnet - PMSM Analysis