A New Method of Separation and Prediction for Iron Losses of Grain

A New Method of Separation and Prediction for Iron Losses of
Grain-Oriented Silicon Steel Sheet under Sinusoidal Excitation
Huiqi Li1, Liansong Zou1, Junjie Zhang2, Hanfang Zhang1, Yangang Yan1
The State Key Laboratory of Alternate Electrical Power System with
Renewable Energy Sources
North China Electric Power University, Baoding, Hebei Province, 071003.
Baoding Tianwei Baobian Electric Company Ltd., Baoding, Hebei Province,
071056, China.
The silicon steel sheet is widely used in the transformer manufacturing, and a
large proportion of transformer losses are iron losses. It has been a complexity
problem of motor and transformer design to calculate the iron losses of
ferromagnetic materials accurately. Based on the Bertotti’s separation model,
the total iron losses (Ptot) could be divided into three parts: the hysteresis losses
(Ph), the classic eddy current losses (Pcl) and the excess eddy current losses (Pex).
It is also a puzzle for the motor design to compute the three loss components
accurately. Some experts and scholars have made contributions to analysis of
the iron losses of the non-oriented silicon steel sheet. In their research work, a
standard 25cm Epstein Frame was adopt as the testing equipment for measuring
the loss of silicon steel sheets, and the parameters of the model have been
obtained by the analyzing experimental data.
In this paper, a new method which separates the total iron losses into three parts
is presented under 50Hz sinusoidal supply. Simultaneously, it can also predict
accurately losses under other frequencies. The method is shown as follow:
1) Pcl is calculated by the classical eddy current losses formula. According to
the methods of measurement of the magnetic properties of electrical steel sheet
and strip by means of an Epstein Frame, Ptot can be measured. That Ptot minus Pcl
is called P2, which includes Ph and Pex.
2) Based on the data of P2, the value of hysteresis coefficients kh, h and excess
coefficient kex can be obtained, by using the mathematics method of nonlinear
regression. With the parameters obtained above, the separation of Ptot is
3) As the losses coefficients are generally considered to be constants with the
change of frequency. According to the parameters (kh, h and kex) obtained above,
the total iron losses Ptot under other frequencies, such as 100Hz and 150Hz, can
be predicted. Comparing the losses curves of the experimental measurements
with predictive value of 100Hz and 150Hz, it is manifested that the predictive
loss values have good agreement with experimental measurements.
In this paper, the new method of iron losses separation and iron losses
prediction of ferromagnetic materials has a very excellent effect. At the same
time, the method is simple, and it is very helpful for the analysis of core losses.
This method has positive referenced value for the design and manufacture of
electric motors and transformers.
The research work is supported by Natural Science Foundation of China
(51577066) and (51307057).