本文選題：脈沖晶閘管 + 熱特性��； 參考：《華中科技大學(xué)》2015年碩士論文

【摘要】：高壓脈沖晶閘管作為一種耐壓高、通流大的半導(dǎo)體開關(guān)被廣泛應(yīng)用于脈沖功率領(lǐng)域。本文主要研究脈沖晶閘管的熱特性,包括基于瞬態(tài)熱阻抗網(wǎng)絡(luò)晶閘管結(jié)溫計算,有限元仿真分析晶閘管結(jié)溫不均勻分布和晶閘管結(jié)溫的實驗測量。論文推導(dǎo)了晶閘管熱阻抗網(wǎng)絡(luò)模型與電路模型之間的等效過程,求解了晶閘管的熱阻抗參數(shù),在此基礎(chǔ)上求解了不同脈沖電流下晶閘管結(jié)溫響應(yīng)曲線,同時計算了考慮結(jié)溫對晶閘通態(tài)壓降的反饋影響下的結(jié)溫響應(yīng)曲線。計算結(jié)果表明,流過晶閘管的脈沖電流其峰值對結(jié)溫的影響比脈寬對結(jié)溫的影響顯著,考慮結(jié)溫對晶閘管通態(tài)壓降反饋影響后計算的結(jié)溫要比不考慮反饋影響下的結(jié)溫要大。論文分析了脈沖晶閘管開通過程中導(dǎo)通區(qū)域的擴(kuò)展過程,建立了晶閘管耗散功率密度的不均勻分布數(shù)學(xué)模型,結(jié)合晶閘管傳熱有限元模型,求解晶閘管不均勻溫度分布。仿真結(jié)果表明,晶閘管在流過脈沖大電流時,熱量開始時主要集中在門極附近,隨后開始逐漸往周圍陰極區(qū)域擴(kuò)散。熱量擴(kuò)散速度的快慢主要取決于導(dǎo)通區(qū)域的擴(kuò)展速度。同時由于硅片和鉬片的導(dǎo)熱系數(shù)都比較小,所以晶閘管閥片上的熱量主要集中在硅片上,從硅片往兩側(cè)鉬片上擴(kuò)散的熱量很小,而擴(kuò)散到鉬片外側(cè)銅基座上的熱量就更少。晶閘管的溫度不均勻分布導(dǎo)致局部溫度高達(dá)數(shù)百至一千攝氏度,達(dá)到晶閘管閥片缺陷點的熔點,造成閥片熔化,導(dǎo)致晶閘管熱擊穿和損壞。論文基于熱敏參數(shù)法的基本原理,針對熱敏參數(shù)法測量脈沖晶閘管結(jié)溫所存在的技術(shù)難點,設(shè)計了合理的實驗方案,通過在待測晶閘管兩端并聯(lián)一個恒流源支路,提前觸發(fā)待測晶閘管導(dǎo)通,這樣待測晶閘管在整個實驗測量過程中兩端電壓都維持在幾伏至十幾伏之間,因而可以采用普通示波器探頭精確測量晶閘管通態(tài)壓降,進(jìn)而根據(jù)熱敏曲線計算結(jié)溫。通過實驗驗證了該方案的可行性。測量了晶閘管在200A直流電流下的熱敏曲線,同時測量了脈寬為400μs,峰值分別為12.48kA,26kA,39.2kA的脈沖電流流過晶閘管后晶閘管的結(jié)溫升,其結(jié)溫升分別為56.9℃,74.3℃和100.6℃。
[Abstract]:High voltage pulse thyristor is widely used in pulse power field as a kind of semiconductor switch with high voltage and high current. In this paper, the thermal characteristics of pulse thyristors are studied, including the calculation of thyristor junction temperature based on transient thermal impedance network, the finite element simulation analysis of the non-uniform distribution of thyristor junction temperature and the experimental measurement of thyristor junction temperature. In this paper, the equivalent process between the Thyristor thermal impedance network model and the circuit model is derived, and the thermal impedance parameters of the thyristor are solved. On this basis, the temperature response curve of the thyristor junction under different pulse currents is solved. At the same time, the junction temperature response curve considering the effect of junction temperature on the on-state pressure drop of the gate is calculated. The calculated results show that the peak value of the pulse current flowing through the thyristor has more influence on the junction temperature than the pulse width on the junction temperature, and the junction temperature calculated after considering the influence of junction temperature on the on-state pressure drop of thyristor is greater than that without considering the feedback effect. In this paper, the expanding process of the conduction region in the process of pulse thyristor opening is analyzed, and the mathematical model of non-uniform distribution of the dissipation power density of thyristor is established, and the non-uniform temperature distribution of thyristor is solved by combining with the finite element model of thyristor heat transfer. The simulation results show that when the thyristor flows through the pulse high current, the heat is mainly concentrated near the gate pole at the beginning, and then diffuses gradually to the cathode region around it. The speed of heat diffusion mainly depends on the speed of expansion in the conduction region. At the same time, because the thermal conductivity of silicon wafer and molybdenum wafer are small, the heat on thyristor valve is mainly concentrated on silicon wafer, and the heat diffused from silicon wafer to both sides of molybdenum wafer is very small, and the heat diffused to copper base outside molybdenum wafer is even less. The uneven distribution of the temperature of the thyristor leads to the local temperature of hundreds to 1000 degrees Celsius, which reaches the melting point of the defect point of the thyristor valve, causes the melting of the valve sheet, and leads to the thermal breakdown and damage of the thyristor. Based on the basic principle of thermistor parameter method, a reasonable experimental scheme is designed for measuring the junction temperature of pulse thyristor by means of thermo-sensitive parameter method, and a constant current source branch is connected at the two ends of the thyristor to be measured. The thyristor conduction is triggered in advance, so that the voltage at both ends of the thyristor is kept between several volts and ten volts in the whole process of experimental measurement, so the on-state voltage drop of thyristor can be accurately measured by ordinary oscilloscope probe. Then the junction temperature is calculated according to the thermal sensitivity curve. The feasibility of the scheme is verified by experiments. The thermal sensitivity curves of the thyristor at 200A DC current were measured, and the junction temperature rise of the thyristor with pulse width of 400 渭 s and peak value of 12.48 Ka / 26kA / 39.2 Ka was measured respectively. The temperature rise of the thyristor was 56.9 鈩，

本文編號：1944210