Application Catalog
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| 90 - Iron Loss Analysis of an IPM Motor Driven by a PWM Inverter <DP,LS> |
Overview
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For a motor's control circuit, a vector control, such as a PWM control,
is generally used. To obtain more detailed motor characteristics, magnetic
field analysis is necessary in which the carrier harmonics caused by PWM
can be taken into account. In JMAG, there are three ways to input a current
waveform with carrier harmonics caused by PWM; connecting directly to a
circuit/control simulator, using a current waveform obtained from the combination
of JMAG-RT motor model and circuit/control simulator, or using an actual
measurement.
This note presents the use of magnetic field analysis to obtain the iron
loss of an IPM motor using a current waveform calculated by a JMAG-RT motor
model and a circuit/control simulator. |
Iron Loss
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Table 1 lists the iron loss, hysteresis loss, and Joule loss caused by
the PWM inverter drive and by the sinusoidal current drive.
The iron loss of both the rotor core and the stator core is greater with
the PWM inverter drive. The increase of Joule loss is especially greater
among the three losses, as it is increased by 80 percent for the rotor
core and by 30 percent for the stator core. |
Joule Loss
Figure 1 and Figure 2 show the frequency component of Joule loss, and Figure
3 and Figure 4 show the Joule loss density distribution.
The basic frequency of the rotor core is 360 Hz and that of the stator
core is 60 Hz. At their basic frequencies and harmonic components, the
loss is almost the same for both the PWM inverter drive and the sinusoidal
current drive; however, the basic frequency (10 kHz) and harmonic component
of PWM are involved in the PWM inverter drive, as shown in the graph outlined
in green. This result reveals that the increase of the Joule loss with
the PWM inverter drive is caused by the effect of carrier harmonics. To
fully evaluate the motor characteristics, the effect of carrier harmonics
need to be taken into account. |
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Updated: 2011-01-17
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