NTC thermistor produced by EXSENSE Electronic Technology Co., Ltd. has the characteristics of high precision, high reliability and high sensitivity, which plays the role of temperature detection in the IGBT (insulating gate bipolar transistor) module. IGBT module is a relatively expensive component, and over-temperature is one of the main causes of its damage. Currently, many IGBT manufacturers package an NTC thermistor inside the IGBT module to measure the housing temperature of the module. Specifically, the temperature is converted into an electrical signal, which is isolated and transmitted to the processor by the linear optical coupler and other devices to judge and protect module. However, this method is not only expensive, but also susceptible to electromagnetic interference, and can be misjudged sometimes.
In view of the existing technical problems, let’s introduce a temperature detection method for IGBT, this method is strong anti-electromagnetic interference, suitable for application in the electromagnetic interference requirements of high occasions, but also significantly reduce the application cost.
This temperature detection method for IGBT, firstly, NTC thermistor is connected to the power supply through three terminal regulator, and make the current through the NTC thermistor basically 4mA by series connection of resistor partial pressure, then collect the voltage signal on the NTC thermistor; Secondly, the voltage signal is changed to frequency signal through the V-F converting unit with converting chip and peripheral circuit according to proportion of 1V: 1KHz; Thirdly, the frequency signal is converted to optical signal by sending unit first, then transmits the optical signal to the receiving unit through the fiber; Fourthly, the optical signal is restored to the frequency signal by the receiving unit, then frequency signal is then transmitted to the control unit, which includes the DSP chip with the CAP capture interface, CAP capture interface is connected to the receiving unit; Finally, the control unit detects the frequency of the frequency signal and then calculates the temperature of IGBT, the detection is completed.
This temperature detection method for IGBT, using optical fiber transmission signal, having strong anti-electromagnetic interference ability, which is suitable for application in the case of high electromagnetic interference requirements; By collecting the voltage of NTC thermistor to detect temperature of IGBT, plays a role of real-time monitoring , to avoid the overheating and burning of IGBT; The whole method is simple, the low hardware costs can significantly reduce application costs.