Demagnetization simulation method of IPM permanent magnet synchronous motor in ANSYS Maxwell R18.1
This case is about the demagnetization of the rotor magnets caused by excessive current. It is necessary to demonstrate the comparison of each opposite electromotive force of no-load operation analysis before increasing the current, and the comparison of each opposite electromotive force of no-load operation analysis after increasing the current. The specific operation steps are as follows :
1. Completely prepared case presentation
The project file name of the completed demagnetization analysis case is “IPM_3 – Demag_Training”. There are a total of 3 cases under this project file, namely “01 Normal_0A”, “02 Source_50A”, and “03 Target_0A”. These 3 cases are respectively “No-load calculation case before increasing the current”, “Calculation case with large current load (50A)”, “No-load calculation case after increasing the current”. The details are shown in Figure 1 below.
2． Calculate Case 1 a) Double-click to open case1, and then open the menu Maxwell 2D→Design properties to display the design properties dialog box as shown in Figure 2. In the Design properties dialog box, set the RMS mean value of the phase current to the “Irms” variable (and set it to 0A), and then set the three-phase winding of case 1 as a three-phase 0 current source, and its A, B, and C three-phase current source functions are:
- PhaseA:Irms*sqrt(2)*sin(2*pi*100*time)；
- PhaseB:Irms*sqrt(2)*sin(2*pi*100*time-2*pi/3)；
- PhaseC:Irms*sqrt(2)*sin(2*pi*100*time+2*pi/3)
，Specifically set up the dialog box shown in Figure 3:
b) The motion attributes, boundary conditions, meshing, and time step settings of Case 1 will not be described in detail. Click “Analyze” directly on this case to run the calculation. After the calculation is completed, the three-phase The no-load reverse electromotive force waveform is shown in Figure 4. The RMS root mean square value of the reverse electromotive force is approximately 114.7V.
3． Set and calculate Case2 a) Copy case1 to get Case 2, and name it “02 Source_50A”, then open the menu Maxwell 2D→Design properties to display the Design properties dialog box as shown in Figure 5. In this dialog box Modify the value of Irms to 50, as shown in Figure 5;
b) Use the mouse to select 2 magnets, then right-click and select the menu Assign Excitation → Set Magnetization Computation, and you will get the demagnetization setting interface as shown in Figure 6 and Figure 7.
Set Demagnetization/Magnetization Computations” selection menu
c) The motion attributes, boundary conditions, meshing, and time step settings of Case 2 remain the same as those of Case 1. They will not be described in detail here. Just click “Analyze” on this case to run the calculation. Wait for After the calculation is completed, the three-phase no-load reverse electromotive force waveform is shown in Figure 8. The RMS root mean square value of the reverse electromotive force is approximately 260.6V.
3． Set and calculate Case 3 a) Copy case1 to get Case 3, and name it “03 Target_0A”, then open the menu Maxwell 2D→Design properties, the Design properties dialog box as shown in Figure 9 will be displayed, check and ensure that Irms The value is 0A;
- b) As shown in Figure 10, select two magnets Mag1_0 and get Mag2_0 and right-click the menu Assign Excitation →Permanent Magnet Field to pop up the “Permanent Magnet Field” dialog box as shown in Figure 11 and select the “Demagnetization” option. card, click the “Setup Link” button in the dialog box, and the “Setup Link” dialog box as shown in Figure 12 will pop up.
- Select “Use This Project”, “02_Source_50A” and “Setup1: Transient” respectively on the “General” tab in the “Setup Link” dialog box, as shown in Figure 12;Then on the “Variable Mapping” tab, keep “Irms” at the default 50A (automatically identify the phase current value of the Case), as shown in Figure 13;
- Then select the two magnets on the “Object Mapping” tab as “Mag1_0” and “Mag2_0” respectively through the drop-down menu in the “Objects in Source Design” column, as shown in Figure 14. This completes the Case 2 pairing. Mapping settings for Case 3.
c) Right-click on the two magnets in Case 3 and select the menu Assign Excitation → Set Magnetization Computation to get the setting interface as shown in Figures 15 and 16.
d) The motion attributes, boundary conditions, meshing, and time step settings of Case 3 remain the same as those of Case 1. They will not be described in detail here. Just click “Analyze” on this case to run the calculation. Wait for After the calculation is completed, the three-phase.
The no-load reverse electromotive force waveform is shown in Figure 17. The RMS root mean square value of the reverse electromotive force is about 31.87V. Compared with the no-load reverse electromotive force of 114.7V before adding a large current of 50A, it has dropped very significantly, indicating that the excitation current of 50A will Cause serious irreversible demagnetization of magnetic steel.
