NTC thermal resistance model of IPM.Infrared IC Vendor

　　The IPM module is the most important power device of the motor drive inverter. In recent years, with the miniaturization of the IPM module, the module Rth(j-c) has become larger, which has brought more and more challenges to the temperature rise; although the chip technology The advancement of junction temperature will reduce the loss of the device and alleviate the temperature rise problem of miniaturization to a certain extent, but the increasingly mature control technology and cost control also require more effective use of the junction temperature evaluation results for flexible protection. In practical applications, one of the most direct and common questions of engineers is: I have detected the temperature of the NTC of the IPM, so what is the real junction temperature of the IGBT & MOSFET inside? This article describes in detail the calculation and test methods of various junction temperatures of IPM modules in actual use, from direct infrared test method, buried thermal test, and case temperature test method, to guide technicians through measurement. The temperature of the Tntc that comes with the module is estimated or the junction temperature of the IPM inverter module is tested, and then the junction temperature is estimated and calibrated for the actual product using the test results of the development prototype to evaluate the reliability of the IPM module operation.

　　Obviously, in the actual product, the temperature information we can detect includes Tntc, Ta, and other information such as system power (or phase current, bus voltage), cooling wind speed (affecting thermal resistance), etc. In the development prototype stage, in addition to Tntc, Ta, can also detect Tc, IPM dissipated power, etc. by certain means, so that Tj can be estimated according to the actual power, thermal resistance parameters, Tc.

　　The actual product and the development prototype need to ensure that the load power, IPM parameters, and system thermal resistance models are consistent, so that the protection limits of the actual product under different working conditions can be set through the calibration test results of the development test prototype. Standard parameters include: actual load information, Ta, Tntc, cooling wind speed, etc.

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