Thermal-network parameter identification method based on IGBT junction temperature information

Abstract

The invention provides a thermal-network parameter identification method based on IGBT junction temperature information.The thermal-network parameter identification method includes the steps that an equivalent thermal-network model is built according to the performance parameter of an IGBT module and the performance parameter of a radiator; according to the equivalent thermal-network model, any one pair of measurable thermal resistance and thermal capacity in a thermal network is changed, and constraint equations of two sets of different IGBT thermal-network parameters are built; two lowered temperature curves of the thermal resistance and thermal capacity before and after changes in the equivalent zero-input state are measured respectively; the lowered temperature curves are fitted, the two sets of corresponding time constants are obtained, and the IGBT thermal-network parameters are obtained through the constraint equations of the IGBT thermal-network parameters according to the measurable thermal resistance and thermal capacity.The thermal-network parameter identification method can be applied to the equivalent zero-input input state such as normal machine switching during working of a power conversion device, the thermal-network parameters of an IGBT can be accurately, effectively and simply identified without disassembling the IGBT module, the IGBT aging state is monitored, the service life is estimated, safe operation of the power conversion device is guaranteed, and operation and maintenance cost is reduced.

Description

technical field [0001] The invention relates to the field of electric power, in particular to a thermal network parameter identification method based on IGBT junction temperature information. Background technique [0002] With the development of power electronics technology, IGBT has been widely used in various power conversion devices such as converters due to its advantages of simple drive module, high power level, and low power consumption. However, most of its application conditions are harsh. At the same time, the IGBT is required to have high reliability. Studies have shown that when the IGBT module is turned on and off repeatedly during work, the conduction loss and switching loss will cause the temperature of the internal chip to rise, and the different material layers in the module will suffer due to the difference in thermal properties. different thermal stresses. Under the cyclic impact of external power, the materials of each layer are also subjected to repeate...

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Problems solved by technology

There are many forms of similar methods, including PRBS and TRAIT, etc., and their essence is to identify parameters according to the port impedance response of the network; because this method imposes a constant loss on the IGBT module, the loss in the actual power conversion device is affected by many factors. Due to the influence of various factors, it is difficult to measure accurately, and the loss model is difficult to establish accurately, so there is a certain difficulty in its realization

[0005] 2. According to the physical parameters and dimensions of the materials of each layer inside the IGBT module, the thermal network parameters are obtained by direct calculation or finite element (FEA) simulation; this method is calculated based on the initial thermal parameters of the materials of each layer inside, and does not calculate And in actual work, the materials of each layer of IGBT will produce fatigue effects and cause thermal parameters to change, so the accuracy of its identification is difficult to guarantee, so it cannot be applied to IGBT modules that are in the aging process

[0006] 3. Measure the cumulative structure function of the IGBT power device according to the JESD standard, and then stratify the cumulative structure function according to the principle of the same heat transfer properties of the same material, and finally obtain the Cauer type thermal network parameters; this method not only needs to be applied to the IGBT module Constant loss, and the structure function method involves complex mathematical transformations, and has very strict requirements on the measurement conditions, so there are certain difficulties in its implementation

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