A Pulse-Width Phase-Shift Triangle Modulation (PSTM-PWM) Technique to Reduce Transformer Heating

Power transformers are fundamental devices in electrical power transmission and distribution
systems as they regulate voltage levels, which helps reduce system losses. However,
their operation can be affected by temperature, with increases in temperature causing a
decrease in their efficiency and lifetime. In addition, the presence of harmonics in the
electrical current can cause overheating and distortions in transformer performance. A
significant proportion of these harmonics are caused by the increasingly widespread use of
DC renewable energies. To control such renewable sources, power inverters are used, which
generate harmonics and cause overheating in transformers connected to the grid. One
solution to this problem is to reduce the harmonic content generated by these converters
to avoid transformer overheating and improve their lifetime. In this work, a modulation
technique for H-bridge multilevel inverters is presented with the aim of reducing both
harmonics and transformer heating. To test the technique’s effectiveness, the recommendations
of a standard have been followed, which include the use of a dry transformer
prototype for temperature measurements. The proposed technique has been compared
with classical techniques for H-bridge multilevel inverters, and the experimental results
indicate a reduction in the hottest-spot temperature.