Smart Integrated NTC Temperature Sensor

　　As one of the most ideal switching devices in the field of power electronics, IGBT has three characteristics of high voltage, high speed and high current, and is widely used in household appliances, transportation, power engineering, renewable energy and smart grids and other fields. At present, the IGBT device has developed from the first generation to the fourth generation, its operating frequency can reach 200KHz, and the power capacity has developed from a single tube of low power (80-300A/500-1200V) to a super power (1000-1200A/2500- 4500V) modules, forming a series of products, the product coverage is very wide.

　　One of the most important parameters in IGBT applications is the temperature of the chip. However, to measure the temperature directly, a temperature sensor needs to be installed on the IGBT chip or as a part of the chip, which will occupy a certain space in the module and reduce the current passing through the chip. effective area of ability. Another possible way to measure the die temperature is to calculate the junction temperature through a thermal model and use the measured substrate temperature as the base data. In the products of major IGBT manufacturers around the world, most of the IGBT modules are integrated with a thermistor (Negative Temperature Coefficient, NTC), and the NTC is used as a temperature detection element inside the IGBT to accurately measure the temperature. In this paper, for the internal thermistor of IGBT, based on the design and application principle of NTC, its use method in application is given, including isolation measures, temperature acquisition method and related application details.

　　1.1 The installation position of the internal integrated NTC In order to obtain a closer temperature of the IGBT silicon chip, the NTC is generally installed near the silicon chip, so that a tight thermal coupling can be obtained. Depending on the IGBT module, the NTC is either mounted on the same ceramic-based copper clad board (DCB) as the silicon chip, or mounted on a separate substrate. The installation position should be as close as possible to the silicon chip that generates heat due to the flow, and the volume should be as small as possible without affecting the thermal coupling effect and flow capacity. In addition, it must meet the safety requirements of the application.

　　1.2 Insulation isolation design IGBT chips generally undertake the function of power conversion in power electronic circuits, and will withstand high voltage and large current, and belong to the primary high voltage side in safety regulations. The NTC that detects the temperature of the IGBT is generally located on the secondary side of the low voltage in the power electronic circuit. The position of the IGBT chip in the module is relatively close to the NTC. Therefore, when obtaining the IGBT temperature through the NTC, a necessary isolation design is required. Inside most IGBT modules, outside where the NTCs are located, is covered with an isolation glue that fills the module. This is sufficient for isolation under any normalized working conditions. In order to ensure the quality of insulation and isolation, IGBT module manufacturers implement the safety standard EN50187, and conduct insulation tests according to the corresponding safety standards during the production process.

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