Applied Mechanics and Materials Vols. 568-570

Abstract: This paper studied the relationship of breakdown voltage and charge imbalance of 600V tapered sidewall trench superjunction MOSFETs. Simulation structures including three types of structures: 600V vertical sidewall trench superjunction MOSFET (Type1) and 600V tapered sidewall trench superjunction MOSFET (Type2 and Type3). Under the condition of P-column and N-column uniform doping, Type1 structure has the highest peak breakdown voltage. Type2 structure has the lowest peak breakdown voltage under the condition of P-column doping concentration slightly lower than N-column doping concentration. The peak breakdown voltage of structure Type3 is higher than Type2, but the sensitivity of breakdown voltage in the charge imbalance state is the highest. The Gaussian dopant profile in P-column can make the peak breakdown voltage of the tapered sidewall trench superjunction MOSFET achieved the same level of the peak breakdown voltage of the vertical sidewall trench superjunction MOSFET. It is concluded that the sensitivity of breakdown voltage in the charge imbalance state is related to the structure: Type2 structure under the condition of P-column undercompensation and Type3 structure under the condition of P-column overcompensation are both beneficial to the process control.

Abstract: A 3300V/50A NPT-IGBT was designed by process simulation, which had an internal transparent collector and a planner cell structure. The Static characteristics were studied. The simulation results show that the threshold voltage of the device can be adjusted by changing the injection dose of the p-well. The saturation voltage of the device can be adjusted by changing injection dose of the p-well or the internal transparent collector. This device was fabricated using a self-aligned process, the test results show that the breakdown voltage is more than 4300V, the saturation voltage is between 3.4V and 3.7V and the threshold voltage is between 5.2V and 6.5V, which are similar with the simulation results.

Abstract: Difference equations of multi-conductor transmission lines (MTL) were derived. Finite Difference Time Domain (FDTD) method combined with MTL theory was used to model and simulate the impacts of radius, height from the ground, distance between wires, raise/fall time of excitation source and types of wires on wires crosstalk. This study proposes the corresponding improvement scheme and has a certain reference value on the vehicle wiring harness layout and its EMC design.

Abstract: This paper aims at proving the complex impedance of the inductor and capacitor elements and applying the proved complex impedance concept to directly obtain the transfer function model of the complicated circuit network. Based on Laplace Transformation method, the complex impedances of the inductor and capacitor elements are proved. Using the proved complex impedances and the equivalent complex impedances in series and in parallel, both the transfer functions of the passive and active circuit networks are modeled. This facilitates the transfer function modeling of the complicated circuit network very much.

Abstract: In order to improve the efficiency of the switching power supply in whole load range, the controller with PWM, PFM and BURST operating modes is designed in this paper, which changes the operation mode automatically according to the load. The operating principle and the advantages and disadvantages of the three operating modes are analyzed and compared. PWM mode is used in heavy load; PFM mode is used in light load to reduce switching losses by reducing the switching frequency and BURST mode is used at the standby time to further reduce switching losses. The main control module is designed and simulation results verify the feasibility of the designed circuit.

Abstract: The model of the photovoltaic power generation system is complex, and it requires multiple iterations in calculation, which is not available for simulation analysis and calculation when a large number of PV systems connected to the grid. This paper presents a simplified model for PV system based on functional equivalence. DC part consisting of PV array and MPPT controller is simplified into a maximum output model; and inverter with its control strategy, of which the function is to achieve decoupling control of active and reactive power, are simplified to controlled voltage source with control module. Last, simulation tests are conducted based on Matlab/Simulink platform. The results show that the simplified model can not only ensure accuracy, but also improve the simulation efficiency, which is of a good practical value.

Abstract: IGBT is the important component of electric vehicle. According to the characteristics of IGBT module in electric vehicle, this article introduces the package design of a high power IGBT module. The feature of the scheme is analyzed from the aspects of power chip, substrate, power electrode, control electrode and epoxy resin layer. Experimental results of the sample show the design meets the qualification.

Abstract: The capacitor voltage balance of the sub-module is the necessary condition for normal operation of the STATCOM. In this paper, the topology and mathematical model of the STATCOM are introduced briefly, the instantaneous power characteristic and capacitor voltage balance principle are studied in detailed, and the balance control algorithm for real project is put forward, in this algorithm, the modified reference wave is got by delay the phase modulation wave by 90°, rather than calculate the sine value of the PLL phase. So the algorithm in this paper can realize in sub-module in real project, the simulation result and real project validated its efficient.

Abstract: The DC voltage of the VSC is very high and it is necessary to connect several IGBT in series. Some snubber circuits have to be used to restrain the over-voltage of IGBTs so as to avoid its damage and the snubber circuit will increase the current stress too. The over-voltage of IGBT in the converters is studied in the paper firstly. Then, the common snubber circuits used in series-connected IGBTs are discussed and compared. A simulated model is set up in Saber to study the snubber circuit at last, the results show that the RC snubber circuit is more suitable for series-connected IGBTs.

Abstract: Steady-state magnetic field Superconducting magnets power supply with double inverse star thyristor rectifier technology solutions, is a typical non-linear loads, will bring great reactive power impact and harmonic pollution at runtime. This paper according to the scheme of scientific facility chain type high voltage active power filter (APF), combined with the non-linear characteristics of the active filter system and proposed a current inner-loop decoupling method using fractional order PI controller instead of ordinary PI controller. Based on the improved Oustaloup algorithm, the solution of fractional order calculus is realized. Finally, the working effect of fractional order PI controller and ordinary PI controller are comparative analysis through simulation and experimental results, the results show that: fractional order current inner-loop PI controller used in this paper is correct, and has a certain reference value.