新材料打開電源轉換設計的選擇

　　旨在提高能源效率的開關電源設計人員面臨著一些權衡，這些問題往往涉及到成本和復雜性的增加，或者如果與傳統(tǒng)的硅功率器件相匹配，則會降低功率密度。寬帶隙材料，如碳化硅（SiC）提供了一個新的自由度在功率轉換器的設計，尤其是在高功率額定需要。

　　寬禁帶和臨界電場導致較高的擊穿電壓：比硅高十倍。這使得可以制造更薄和更小的器件，這樣即使SiC的載流子遷移率比硅的差，但它可以攜帶更少損耗的更多電流。最重要的是，高得多的熱導率會大大提高功率密度。碳化硅器件可以在150℃以上的結溫下可靠地運行，有助于節(jié)省散熱片和包裝成本。

　　該技術仍在發(fā)展，并沒有一個完整的設備組合，但有越來越多的二極管和第一個商業(yè)MOSFET已經啟動。本文將提供功率轉換碳化硅產品概述，包括設備從克里（cmf10120d，cmf20120d，csd01060），英飛凌科技（idd03sg60c），IXYS（fbs16-06sc）、ROHM（scs120ke2c）和STMicroelectronics（stpsc2006cw）。

　　Tradeoffs are commonplace in power-component design. Properties that are good for energy efficiency – such as low on-resistance – can lead to process and design decisions that result in less desirable characteristics such as reduced breakdown voltage. Although silicon remains the material of choice for most power devices， other options are appearing that will make it possible to reduce the effects of these tradeoffs. Options have opened up thanks to the arrival of two wide band-gap materials now being actively investigated and productized by manufacturers. One is gallium nitride （GaN） and the other is silicon carbide （SiC）。

　　The band-gaps of GaN and SiC are around three times larger than the band-gap of conventional silicon. The critical field rating is approximately ten times higher than that of silicon. This leads not just to higher breakdown voltages， but better performance at high temperatures， which reduces the cost of power-supply products by allowing the use of smaller or even no heatsinks， as well as lower leakage.