功利用率的提高，關(guān)鍵點(diǎn)在于如何有效的對IGBT單元進(jìn)行合理和有效的散熱。
功率單元在使用兩個FF450R17ME4模塊達(dá)到66%利用率的額定工況時，IGBT輸出頻率50Hz，開關(guān)頻率650Hz，功率因素0.9，單元輸出電流為297A，單個IGBT芯片損耗為78.7W，單個Diode芯片損耗為23.4W。
參考業(yè)內(nèi)針對過載方面的標(biāo)準(zhǔn)，均為每10min內(nèi)可允許120% 過載，過載時間為持續(xù)1min。按1.2倍過載，單元輸出電流為356.4A，單個IGBT芯片損耗為102W，單個Diode芯片損耗為28.9W。
單個IGBT和Diode的封裝熱阻和耐受溫度
單個IGBT和Diode的封裝熱阻和耐受溫度
圖3-單個IGBT和Diode的封裝熱阻和耐受溫度
（3）熱管散熱器仿真設(shè)計
散熱器的材質(zhì)為AL1060，翅片厚度1.2mm，齒間距2.5mm，散熱器整體尺寸為330mm（L）*240mm（W）*93mm（H），熱管采用直徑為9mm的熱管，熱管和散熱器通過Hi-Connector工藝進(jìn)行緊配，如圖4所示。
仿真模型詳細(xì)建模散熱器、熱管及IGBT內(nèi)部封裝，邊界條件為散熱器出風(fēng)口平均風(fēng)速5m/s，環(huán)境溫度40℃，海拔為1000m以下。
散熱器仿真模型
散熱器仿真模型
圖4-散熱器仿真模型
（4）額定穩(wěn)態(tài)仿真結(jié)果
在IGBT穩(wěn)態(tài)運(yùn)行工況下，環(huán)境溫度40℃，進(jìn)風(fēng)風(fēng)速5m/s，IGBT芯片最高Tj=94.6℃，最高Tc=86.7℃，散熱器壓降197Pa。IGBT芯片結(jié)溫均小于工作允許的結(jié)溫Tj=150℃。
IGBT銅基板表面最高溫度Tc
IGBT銅基板表面最高溫度Tc
圖5- IGBT銅基板表面最高溫度Tc
IGBT芯片最高溫度Tj
IGBT芯片最高溫度Tj
圖6- IGBT芯片最高溫度Tj
穩(wěn)態(tài)時芯片溫度曲線 This process is called "top gas". Therefore, the phenomenon of "oxygen leakage" in the removal process can be effectively prevented. In the process of work, a fan should be started. There is also a solenoid valve for adding oxygen to the reservoir.
The oxygenation time set by this product is completed by the micro multi switch on the electronic board in the machine. From the second gear, from left to right, add oxygen respectively: 0.5, 0.5, 1 and 1 minute. The oxygenation time of 0.5 to 3 minutes can be determined by combined addition. The reason why the multi link toggle switch is adopted is that its adjustment is simple and suitable for users to set according to actual needs on site.
In application, the system composed of logo realizes automatic control.
When there is a power on signal, first enter the "regeneration" state. That is, the two three-way solenoid valves are not energized. The fan motor runs. Wait until the set "regeneration" time T1 ends, followed by the first top gas stage with a duration of T2. Then enter the "adsorption" stage with a duration of T3, and finally the second top gas stage with a
