Modelling characteristics of the impulse transformer in a wide frequency range

Abstract

In the paper, a new compact electrothermal model of the impulse transformer is proposed. This model has a form of a subcircuit dedicated for SPICE and could be used for low power impulse transformers applicable in switch-mode power supplies used in electronics. It takes into account simultaneously electric, thermal, and magnetic phenomena occurring in the considered device and describe nonidealities of the core and windings. The form of the elaborated model and analytical dependences describing all its components are presented. Correctness of this model is verified experimentally in a wide range of frequency and load resistance for selected constructions of transformers. Satisfactory agreement between the results of computations and measurements is obtained K E Y W O R D S compact electrothermal models, impulse transformer, modelling, SPICE

SPICE-Aided Compact Electrothermal Model of Impulse Transformers

“…The values of the temperature T C computed using the new model fit the measurements results well. Differences between them were lower than 5 • C. In contrast, the results of computations obtained using the model from the paper [15] differed visibly from the results of measurements. Such differences reached as far as 50 • C.…”

“…The differences between the measurements and computations results did not exceed 3 °C. In contrast, the results obtained using the model given in [15] differed from the measurements results by 15 °C.…”

“…As one can notice, the computations results obtained using the proposed model were convergent with the measurements results for all the considered transformers in the whole range of R 0 changes. In contrast, the results obtained using the model from [15] fit well the measurements results only for the RTP core, whereas they differed from the results of measurements even by 15% for the other transformers.…”

“…Comparing results presented in Figures 6 and 7, one can observe that using the model described in the paper [15], one can obtain overestimated values of the transformer core and underestimated values of the transformer primary winding. This problem results from omission in the cited paper of an influence of dissipated power on the values of thermal resistances in the transformer model and from omitting differences in temperature of each winding.…”

“…In the figures presented in this section, the results of the computations obtained by means of the proposed model are marked with solid lines, whereas the results of the measurements are shown with points. Additionally, some computation results obtained using the model given in the paper [15] are denoted with a dashed line. In the investigations, the results of which are presented in this section, the transformers operated exceeding their primary winding by sinusoidal signal of frequency f and amplitude V m .…”