System and method for on-line detection of operating junction temperature of IGBT module

Abstract

The invention discloses a system and a method for on-line detection of operating junction temperature of an IGBT module. Under an actually continuous on and off switching operate states of the IGBT module, changeable drive current and collector current generate induced voltage on stray inductance of the IGBT module; the induced voltage occurs twice voltage changes during turn-off, and the interval is recorded as the temperature-sensitive time which is closely related to the operating junction temperature of the IGBT module under a regular voltage and current turn-off condition. According to the system and the method, an IGBT test system is established to extract the temperature-sensitive time at different DC bus voltages, IGBT conducting currents and operating junction temperatures so as to establish an off-line reference database, voltage between a driving emitting electrode and a power emitting electrode of the IGBT module are monitored during the actual operation of an IGBT, and the temperature-sensitive time is extracted to calculate junction temperature on line. Compared with the conventional technology for monitoring the operating junction temperature of the IGBT, the method provided by the invention has higher real-time performance and integration.

Description

technical field [0001] The invention belongs to the technical field of power electronic device detection, and in particular relates to an on-line detection system and detection method for the working junction temperature of an IGBT module. Background technique [0002] The working junction temperature of the IGBT module is an important parameter in industrial power converters such as flexible direct current transmission and wind power generation systems, which provides information on the thermal stress and thermal performance of the IGBT module. Therefore, its working junction Temperature can be used for condition monitoring, assessing IGBT module reliability, predicting remaining service life and analyzing failure mechanisms. [0003] The conventional IGBT module working junction temperature detection method, such as the thermal sensing method, is to place a thermal sensor near the internal chip of the IGBT module. This method needs to open the package of the IGBT module to...

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Problems solved by technology

[0005] Generally speaking, the above IGBT module working junction temperature monitoring technology is not suitable for IGBT module working junction temperature because of expensive measuring instruments, or special requirements for IGBT module packaging that need to open the packaging structure, or junction temperature monitoring has a certain delay. Online Monitoring

[0006] In addition, the behavior of the IGBT module is closely related to its working junction temperature. This is because the semiconductor physical parameters such as carrier concentration and carrier mobility have a strong coupling relationship with temperature, and the electrical properties of the IGBT module The characteristics depend on the semiconductor physical parameters mentioned above, so the temperature-sensitive electrical parameters of the IGBT provide the possibility for the monitoring of the working junction temperature of the IGBT module, such as the threshold voltage, the conduction voltage drop, the maximum change rate of the turn-on current and the change of the turn-off voltage The threshold voltage is to monitor the minimum driving voltage of the MOS channel of the IGBT module at different temperatures, and use the corresponding relationship between the voltage and the working junction temperature to determine the working junction temperature of the IGBT module. However, this parameter and the temperature sensitivity coefficient are low, and the extraction It is more difficult; the conduction voltage drop is to measure the forward voltage drop of the IGBT at different temperatures, and the corresponding relationship between the forward voltage drop and the working junction temperature is used to determine the IGBT working junction temperature, but the detection of the conduction voltage drop requires a high withstand voltage Sensors, and in the high-voltage and high-current switching environment, the tested conduction voltage drop is very small, which is very susceptible to interference; the opening of the IGBT module is often accompanied by the switching off of the power tube that commutates with it. In the inductive load type circuit, when the IGBT module is turned on, when the load current is commutated from the diode to the large IGBT module, the reverse recovery current of the diode will flow through the IGBT module, so the turn-on current of the IGBT module includes the diode The reverse recovery current is not entirely the characteristics of the IGBT module itself; the detection of the turn-off voltage change rate needs to be converted into a signal that is easy to measure directly with the help of additional passive devices (such as capacitors), and the addition of passive devices affects the IGBT module. working status

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