Politecnico di Torino - Corso Duca degli Abruzzi, 24 - 10129 Torino, ITALY

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Affidabilità e prognosticaCTENEXTDiodi di ricircoloElettronica di potenzaFree-wheeling diodesGestione termicaJunction temperature estimationPower electronicsReliability and prognosticStima della temperatura di giunzioneThermal management


The junction temperature of power devices is a vital intimate state very hard to measure. The invention relates to a method and a system for characterizing the junction temperature of the power diodes of a voltage source inverter (VSI) as a function of the forward current and voltages of the device. The method is valid for a variety of switching converters types, including all converters using anti-parallel diodes.

Technical features

The present invention is an expansion of the methodology for the thermo-electrical mapping and for the estimation of the junction temperature of power semiconductors described in the patent application 102020000012100. This patent extends the same concept allowing to estimate also the junction temperature of the diodes in antiparallel to the power switches. The solution is applicable to all converters that use free-wheeling diodes. The invention proposes a method and a system for the thermo-electrical mapping of the diodes and for the estimation of the junction temperature during the operation of the converter. With a modest additional cost it is possible to obtain an accurate estimate of the junction temperature in order to increase the peak current and the reliability of the converter. Moreover, aging of components becomes predictable allowing for advanced prognostics.

Possible Applications

  • Applications with frequent overloads like automotive and servo-drives;
  • Safety critical applications like medical and aerospace;
  • Applications were the downtime is costly (industrial processes, oil & gas);
  • Extreme power density applications;
  • Harsh ambient temperature conditions.


  • Individual temperature map calibration for each device of the converter;
  • Temperature detection is precise;
  • Does not affect the operations of the converter;
  • Has a fast dynamic response;
  • No complex computation required;
  • Hardware modifications are minor and low cost.