As one of the indispensable core components in new energy vehicles, smart grids and other applications, the operation safety of IGBT modules must be paid attention to. Because the loss generated during IGBT operation will be converted into heat energy, if overheating occurs during the process, it will not only lead to the degradation of IGBT performance, but may even cause failure or permanent damage. In this case, taking advantage of the characteristics of the resistance value of the NTC thermistor that decreases exponentially with temperature changes, which can be used to monitor the operating temperature of the IGBT module in real time and effectively avoid overheating of the module.

NTC thermistor is generally installed on the ceramic substrate of the IGBT module, and is connected to the temperature monitoring module through the terminal to realize the real-time temperature measurement of the IGBT chip. Specifically, when the IGBT starts to run, NTC immediately begins to collect the temperature information of the IGBT chip; Then, the NTC resistance value that matches the temperature value is converted to a voltage by a voltage divider circuit and processed by an operational amplifier; The obtained data is transmitted to the IC chip for A/D and then output as a digital signal; Based on the real-time junction temperature of the IGBT module, the micro controller compares it with a preset temperature threshold, and when the junction temperature is greater than or equal to the threshold, it will send an alarm to the user to quickly take effective countermeasures to prevent IGBT failure or damage caused by excessive temperature. As a result, NTC thermistor plays the following roles in IGBT modules:

First, over-temperature protection: When the thermistor detects the abnormal temperature of the IGBT, NTC can trigger the protection mechanism with the assistance of other components, such as reducing the power output, cutting off the power supply, etc., so as to effectively protect the IGBT;

Second, real-time monitoring and adjustment: Based on the temperature monitoring data of NTC thermistor, user can find potential faults in time and prevent module breakdown caused by abnormal temperature; In addition, the switching frequency and duty cycle can be adjusted according to the real-time temperature data, combined with the IGBT operating temperature and load conditions, effectively reducing power consumption.

Since the internal working temperature of the IGBT module can reach up to 150℃, the GT-T series MELF NTC thermistor produced by EXSENSE Electronics Technology Co., Ltd. is usually used in the module design. The NTC is a glass encapsulation, which can maintain stable operation in high-temperature environments, improving the operational reliability and safety of IGBT. Compared to conventional SMD NTC, MELF thermistor is more sensitive and respond faster during temperature monitoring. Moreover, the MELF NTC thermistor has a leadless structure, which is convenient for the internal integration of the IGBT module and occupies a small installation space.