Dynamic Temperature Measurements of a GaN DC–DC Boost Converter at MHz Frequencies

Abstract

For reliability predictions, gallium nitride transistors require accurate estimations of the peak operating temperatures within the device. This paper presents a new application of thermoreflectance-based temperature measurements performed on a gallium nitride high electron mobility transistor. The submicron spatial and nanosecond temporal resolutions of the measurement system enables for the first time, the dynamic temperature measurement of a transistor operating up to 5 MHz. The GaN transistor is first biased in class-A and excited with a 1 MHz AC signal to demonstrate the dynamic temperature measurement. The transistor is then incorporated in a 20-40 V DC/DC boost converter to measure the dynamic temperature distributions across the semiconductor die operating under real loading conditions at 1 and 5 MHz switching frequencies. This technique captures the temperature variations that occur during the switching of the transistor and the recorded peak temperatures are 7.4 C higher compared with conventional measurement and simulation approaches. Index Terms-Thermoreflectance measurement, boost converter, gallium nitride, power transistor.

Power Electronics Reliability: State of the Art and Outlook

“…Temperature-Sensitive-Electrical-Parameters (TSEP) are widely studied for temperature estimation, limited to 100 µs temporal resolution [114]. In [113], a non-invasive thermal measurement technique called thermoreflectance thermography is proposed with nanosecond time and sub-micron spatial resolutions. This technique is promising for temperature measurement during short circuits and MHz-level high-frequency converters.…”

“…Thermoreflectance measurement method and an example of the measured temperature profile proposed in[113].…”

Algorithm Execution Time and Accuracy of NTC Thermistor-Based Temperature Measurements in Time-Critical Applications

“…To test the polynomial approach, we chose to use a first-order and sixth-order polynomial for approximation of the temperature vs. voltage curve (as depicted in Figure 8). Firstly, the first-order polynomial (line) was examined, with a line fitted for a limited temperature range from −10 • C to 50 • C. Since the temperature was calculated using a simple notation (12), the expected calculation time for all six temperatures was relatively small. Nonetheless, the total time was 1.31 µs.…”

“…Temperature measurements are also used-often in conjunction with voltage and current measurements-to monitor key components of the device in order to increase the operational safety and reliability of the device in general. A preventive monitoring based on voltage and current measurement to calculate the temperature of a power switch is reported in [10,11], whereas a direct temperature measurement was studied in [12] to prevent power switch failure and efficiency degradation. As for the temperature measurement, there are mainly four types of sensors used in power electronics: thermocouples [13], resistance temperature detectors (RTD) such as the temperature probe PT100 as reported in [14], thermistors [15] and dedicated integrated circuits (IC) [16].…”

Time- and Frequency-Domain Characterization of Switching Losses in GaN FETs Power Converters

“…In this respect, we validate the switching loss measurements through characteristic parameters of the waveforms extracted from the spectrum measurements. The combination of time-and frequency-domain techniques, in conjunction with dynamic temperature assessments presented in [13] comprehends the multiphysics approach developed within the ADVENT project [14], which in this case has been applied to the characterization of the power losses GaN FET power converter applications combining hard switching and high switching frequencies.…”