The safety and stability study on Northeast, North, East, Northwest and Central China power grids had been carried out, which provided technical supports to planning design of regional power grids. By analyzing safety...The safety and stability study on Northeast, North, East, Northwest and Central China power grids had been carried out, which provided technical supports to planning design of regional power grids. By analyzing safety and stability under severe faults in regional power grids, revealed weaknesses on power grid configurations and measures for preventing from loss of stability were presented. In comparison of various schemes of power system safety and stability among parts of power grids, more than two recommended schemes can be chosen as reference in planning design for regional power grids. Considering the safety and stability control measures necessary for each power grids, it is believed the trunk networks of all power grids can fulfill the third criteria of Guideline for Power System Safety and Stability, while the weakness and predominated hydropower may deteriorate safety and stability of power grids. The power grid shall be regulated in line with the variation of boundary conditions.展开更多
A novel silicon carbide(SiC) trench metal–oxide–semiconductor field-effect transistor(MOSFET) with a dual shield gate(DSG) and optimized junction field-effect transistor(JFET) layer(ODSG-TMOS) is proposed. The combi...A novel silicon carbide(SiC) trench metal–oxide–semiconductor field-effect transistor(MOSFET) with a dual shield gate(DSG) and optimized junction field-effect transistor(JFET) layer(ODSG-TMOS) is proposed. The combination of the DSG and optimized JFET layer not only significantly improves the device’s dynamic performance but also greatly enhances the safe operating area(SOA). Numerical analysis is carried out with Silvaco TCAD to study the performance of the proposed structure. Simulation results show that comparing with the conventional asymmetric trench MOSFET(Con-ATMOS), the specific on-resistance(Ron,sp) is significantly reduced at almost the same avalanche breakdown voltage(BVav). Moreover, the DSG structure brings about much smaller reverse transfer capacitance(Crss) and input capacitance(Ciss), which helps to reduce the gate–drain charge(Qgd) and gate charge(Qg). Therefore, the high frequency figure of merit(HFFOM) of Ron,sp·Qgdand Ron,sp· Qgfor the proposed ODSG-TMOS are improved by 83.5% and 76.4%, respectively.The switching power loss of the proposed ODSG-TMOS is 77.0% lower than that of the Con-ATMOS. In addition, the SOA of the proposed device is also enhanced. The saturation drain current(Id,sat) at a gate voltage(Vgs) of 15 V for the ODSGTMOS is reduced by 17.2% owing to the JFET effect provided by the lower shield gate(SG) at a large drain voltage. With the reduced Id,sat, the short-circuit withstand time is improved by 87.5% compared with the Con-ATMOS. The large-current turn-off capability is also improved, which is important for the widely used inductive load applications.展开更多
The high voltage and high power adjustable speed drive (ASD) system is one of the most attractive fields in power electronics, and it is also a very crucial technique for energy saving and emission reduction. This pap...The high voltage and high power adjustable speed drive (ASD) system is one of the most attractive fields in power electronics, and it is also a very crucial technique for energy saving and emission reduction. This paper discussed and analyzed the main cutting-edge knowledge and issues in the process of exploiting the high voltage and high power ASD system.展开更多
文摘The safety and stability study on Northeast, North, East, Northwest and Central China power grids had been carried out, which provided technical supports to planning design of regional power grids. By analyzing safety and stability under severe faults in regional power grids, revealed weaknesses on power grid configurations and measures for preventing from loss of stability were presented. In comparison of various schemes of power system safety and stability among parts of power grids, more than two recommended schemes can be chosen as reference in planning design for regional power grids. Considering the safety and stability control measures necessary for each power grids, it is believed the trunk networks of all power grids can fulfill the third criteria of Guideline for Power System Safety and Stability, while the weakness and predominated hydropower may deteriorate safety and stability of power grids. The power grid shall be regulated in line with the variation of boundary conditions.
基金Project supported by the China Postdoctoral Science Foundation (Grant No. 2020M682607)。
文摘A novel silicon carbide(SiC) trench metal–oxide–semiconductor field-effect transistor(MOSFET) with a dual shield gate(DSG) and optimized junction field-effect transistor(JFET) layer(ODSG-TMOS) is proposed. The combination of the DSG and optimized JFET layer not only significantly improves the device’s dynamic performance but also greatly enhances the safe operating area(SOA). Numerical analysis is carried out with Silvaco TCAD to study the performance of the proposed structure. Simulation results show that comparing with the conventional asymmetric trench MOSFET(Con-ATMOS), the specific on-resistance(Ron,sp) is significantly reduced at almost the same avalanche breakdown voltage(BVav). Moreover, the DSG structure brings about much smaller reverse transfer capacitance(Crss) and input capacitance(Ciss), which helps to reduce the gate–drain charge(Qgd) and gate charge(Qg). Therefore, the high frequency figure of merit(HFFOM) of Ron,sp·Qgdand Ron,sp· Qgfor the proposed ODSG-TMOS are improved by 83.5% and 76.4%, respectively.The switching power loss of the proposed ODSG-TMOS is 77.0% lower than that of the Con-ATMOS. In addition, the SOA of the proposed device is also enhanced. The saturation drain current(Id,sat) at a gate voltage(Vgs) of 15 V for the ODSGTMOS is reduced by 17.2% owing to the JFET effect provided by the lower shield gate(SG) at a large drain voltage. With the reduced Id,sat, the short-circuit withstand time is improved by 87.5% compared with the Con-ATMOS. The large-current turn-off capability is also improved, which is important for the widely used inductive load applications.
基金Supported by ther National Natural Science Foundation of China (Grant Nos.50737002 and 50707015)
文摘The high voltage and high power adjustable speed drive (ASD) system is one of the most attractive fields in power electronics, and it is also a very crucial technique for energy saving and emission reduction. This paper discussed and analyzed the main cutting-edge knowledge and issues in the process of exploiting the high voltage and high power ASD system.
