Comparative Analysis of TSD and NTC-Based Temperature Measurement for Power Semiconductor Modules

Abstract

Accurate temperature estimation is essential for ensuring the reliability and performance of power semiconductor devices. This paper presents various techniques used in the industry and focuses on a comparative analysis of two temperature measurement methods: temperature sensing diodes (TSD) and negative temperature coefficient (NTC) resistors. TSDs provide direct and fast junction temperature (Tj) measurements, while NTCs, being external to the junction, can approximate steady-state Tj through calibration. An experimental test bench based on a back-to-back topology is developed to evaluate both methods under real operating conditions. The paper analyzes the performance of TSD under constant current pulses, demonstrating its ability to represent the transient thermal behavior, with a response time of 5 ms after the pulse. Furthermore, the study investigates the ability of NTC and TSD to detect thermal ripple at different fundamental frequencies, revealing that NTC fails to capture thermal dynamics, while TSD accurately tracks temperature fluctuations across all tested frequencies. The findings highlight the strengths and limitations of each method, providing insights into the selection of an appropriate temperature measurement approach for power electronic applications.