Abstract
State-of-the-art methods for determining thermal impedance networks for IGBT (Insulated Gate Bipolar Transistor) modules usually involves the establishment of the relationship between the measured transistor or diode voltage and temperature under homogenous temperature distribution across the IGBT module. The junction temperature is recomputed from the established voltage–temperature relationship and used in determining the thermal impedance network. This method requires accurate measurement of voltage drop across the transistors and diodes under specific designed heating and cooling profiles. Validation of the junction temperature is usually done using infrared camera or sensors placed close to the transistors or diodes (in some cases and open IGBT module) so that the measured temperature is as close to the junction as possible. In this paper, we propose an alternative method for determining the IGBT thermal impedance network using the principles of least squares. This method uses measured temperatures for defined heating and cooling cycles under different cooling conditions to determine the thermal impedance network. The results from the proposed method are compared with those obtained using state-of-the-art methods.
Highlights
Operation of inverters under peak load and frequent thermal transient conditions requires a precise estimation of the junction temperature for effective thermal management
We compared the quality prediction of the temperature of all in a power sources of errors could result from the reconstruction of temperatures from the calibration curve, using direct temperature measurements
We have shown that coefficients of the linear transfer which are laterthe used in the determination of the thermal impedance function from power input to the temperature can be estimatednetwork
Summary
Operation of inverters under peak load and frequent thermal transient conditions requires a precise estimation of the junction temperature for effective thermal management. These conditions are common in inverters used in automotive traction drives operating under low speed and high torque demands such as stop-and-go situations in city driving, off-road/uphill driving, or towing a trailer. IGBT modules are equipped with temperature sensors. Even if much more accurate sensors or those with faster responses were to be used, a sensor will have to be placed close to each diode or transistor in the IGBT module. Depiction of individual diodes and transistor temperatures is necessary [3]
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