Overview
Closeup |
A magnetized magnet needs a careful handling at the time of assembling
an IPM motor, so it is useful to magnetize the magnet after placing it
in the motor. Generally, it is desirable the entire magnet is magnetized
completely. So, magnetization conditions, such as the amount of current,
need to be considered before magnetization. In JMAG, Magnetizing Tool is
used to obtain magnetization field which can be later used to produce magnetization
distribution.
This note presents the use of magnetic field analysis to obtain magnetization
fields at different currents, and also to obtain the induced voltage and
cogging torque of an IPM motor when obtained magnetization fields are used
for magnetization of the magnet. |
Magnetization Field Distribution
| Figure 1 shows the magnetization field distributions at the time of magnetizing
the in-site magnet at the current of 1.0 kA, 1.5 kA, 2.0 kA, and 2.5 kA.
The strength of the magnetization field is proportional to the amount of
current. The direction of the magnetization field is the same regardless
of the amount of current. |
Closeup |
Magnetization Distribution inside the Magnet
Closeup |
Figure 2 shows the magnetization distribution inside the magnet when the
whole magnet is uniformly magnetized (ideal magnetization) and when magnetization
fields at the current of 1.0 kA, 1.5 kA, 2.0 kA and 2.5 kA are taken into
account.
In the cases of 1.0 kA and 1.5 kA, the intensity of magnetization in the
whole magnet is smaller. However, in the case of 2.5 kA, the magnetization
distribution is similar to the ideal magnetization. |
Induced Voltage Waveform/ Cogging Torque Waveform
Figure 3 shows the induced voltage waveform of the U-phase. Figure 4 shows
the cogging torque waveform. Both results are obtained when the whole magnet
is uniformly magnetized (ideal magnetization) and when magnetization fields
at the current of 1.0 kA, 1.5 kA, 2.0 kA, and 2.5 kA are taken into account.
Magnetization distributions shown in Figure 2 have an effect on the induced
voltage and the cogging torque. As shown in figures below, when the magnet
is magnetized at more than 2.0 kA, the motor characteristics are similar
to the ideal magnetization. |
Closeup |
Closeup |
|
