A novel high performance enhanced-planar IGBT with p-type buried layer (PBL-EPIGBT) is proposed in this paper. The p-type buried layer (PBL) is placed outside the n-type carrier stored (N-CS) layer and encompasses it partially. Compatible with the conventional EPIGBT technology, the PBL of the proposed structure can be formed by ion implantation and diffusion before the formation of the N-CS layer. Since additional bulk electric field modulation introduced from the charges in the PBL, the negative impact of the positive charges in the N-CS layer on the breakdown voltage (BV) is addressed effectively. The proposed structure breaks the limitation of the doping concentration of the N-CS layer (N N-CS ) on the BV and hence, a higher N N-CS can be used for the proposed PBL-EPIGBT structure with almost constant BV. As a result, in comparison with the conventional EPIGBT without a PBL, the novel structure offers not only high BV, but also improved E off -V ce(on) trade-off characteristics.
Uniform and stable bed density is the basis of efficient coal separation by a gas−solid dense medium fluidized bed. The traditional air dense medium fluidized bed (ADMFB) is a kind of bubbling bed. By introducing vibration energy, a vibrated dense medium fluidized bed (VDMFB) with uniform and stable bed density can be formed, where the bubble merger is suppressed, the gas−solid contact can is strengthened, and the fluidization quality is also improved. In this paper, the transfer process of vibration energy in a fluidized bed is studied in detail. By calculating the coherence of pressure signals induced by vibration energy and bubbles at different bed heights, the suppression effect of vibration energy on bubble merger is analyzed. The coefficient R imp to quantitatively evaluate the improvement effect of vibration energy on the fluidization quality is proposed. The differences and incentives of density uniformity and stability in different height bed areas have been clarified under different vibration parameters and gas flow parameters. It is proposed that the optimal separation bed height area of VDMFB is about H = 40−150 mm. The separation effect of the ADMFB and the VDMFB on 1−6 mm fine coal was compared. The results show that, compared with the ADMFB, the VDMFB reduces the separation probable error, E, from 0.134 to 0.083 g/cm 3 , and the ash content of the clean coal is reduced from 18.83 to 14.97%. The vibration energy significantly improves the fluidization quality of the ADMFB and the separation effect of fine coal.
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