Papers by Keyword: Rectifier

Abstract: A new rectifier, called SPND or SNPD (Schottky-PN or -NP junction diode) and inherently showing low on-resistance and unipolar operation, was experimentally demonstrated for the first time on 4H-SiC. It is structured with an n^– or a p^– region of very low doping that is sandwiched and completely depleted between a Schottky junction and a one-sided PN junction. Either electrons or holes, but not both, contribute to the current conduction process. Clear and sharp rectifying properties are observed over the entire range of applied voltage.

Abstract: We compare the static electronic performance of the state-of-the-art Junction-Barrier-Schottky (JBS) rectifier (manufactured by ion-implantation) against the Trench-MOS Barrier Schottky (TMBS) rectifier (manufactured by trench-etching and subsequent oxidation). In our 2D numerical simulations, we have chosen identical specifications for the epitaxial drift-layer (3.3 kV application voltage, e.g. traction) and back-side device-design, while investigating the impact of the top-cell active area design on both rectifier IV-characteristics. To enable a meaningful comparison, we designed the depth d of the shields for the electric field E equally deep (p⁺ peak-plateau d_JBS equals trench-depth d_t), such that the peak E-field (close to avalanche breakdown) inside the drift-layer of the device is located at a comparable depth near the anode-side of the rectifier (see Fig. 2). By studying systematically the ratio between shield-to Schottky contact-length (w/s ratio), we found that the unipolar conduction state of the TMBS design is basically unaffected by enlarging the Schottky-contact length s, which is enterly different for the JBS-case.

Abstract: The paper provides the results of experimental study of how the technological characteristics (amount of spatter, stability of the welding process) of manual metal arc welding (MMA) depend upon power supplies providing various kinds of energetic impact upon the electrode metal (inverter power supply, diode rectifier). It was established that inverter power supplies (as they reduce peak loading) provide better quality of welds (more stable process, lower amount of spatter) and this reduces the fabrication cost due to the reduction of deseaming operations, lower welding material consumption as well as improving the service reliability of the welding constructions.

Abstract: The methods of piezoelectric energy harvest and detection based on forced vibration are introduced in this paper. Firstly, the mechanical energy of the forced vibration is converted into alternating current energy by using the piezoelectric harvester, and then the AC currents are rectified through the full bridge rectifier circuits, and finally the capacitor filter circuits are adopted to obtain the stable DC output. It also implements the voltage waveform detection during above energy harvesting process. The experimental results show that piezoelectric oscillator has the characteristics of simple structure and support stability, and its forced vibration frequency is independent of the structural natural frequency. The piezoelectric harvester forced with the vibration source can obtain an effective energy-harvested electric output.

Abstract: Aiming at the problem of low efficiency of recycling energy in the process of regenerative braking for electric vehicle, SVPWM algorithm is applied to the process of energy transformation of regenerative braking in this paper. It is derived and verified that, through using SVPWM, DC voltage fluctuation can be reduced in the process of rectification. The simulation model is built basing on the Volkswagen LAVIDA EV. The simulation experiment was carried out combining with the actual working status of electric vehicle regenerative braking. The simulation experimental results prove that DC voltage fluctuations can be decreased and the efficiency of regenerative braking rectifier can be increased through SVPWM. The following feature of rectifier in the braking condition is good.

Abstract: In view of the problems that traditional direct current control calculation is complex, that sensor precision requirements are high. This paper proposes a new control method of unit power factor power converter, which is easy to realize with simple control structure dispense with current sensor. Through the simulation and experimental verification, the control strategy can achieve unity power factor control, and the harmonic content is small and the operation is stable.

Abstract: The diode uncontrolled rectifier or the phase controlled rectifier is widely used in conventional rectifier link, thus the conventional rectifier link on the grid inject a large number of harmonics and reactive power, and they cause a severe grid “pollution”. This paper starts from the basic principles of the PWM rectifier, then the paper discusses the topological classification of three-phase PWM rectifier in detail. Based on topological structure, the paper builds the mathematical model of three-phase stationary coordinate system and two-phase rotating coordinate system. Based on space voltage vector, the paper studies PWM control method in-depth and simulates in Matlab/Simulink. The correctness of the theoretical study of three-phase voltage source PWM rectifier system is verified by the simulation results.

Abstract: Small gasoline-powered generator is more widely used in an emergency, camping, disaster relief and other occasions. This paper describes a digital generator based on TMS320F28027 solutions. The program uses 2000 series Piccolo A as the master chip to control the work of the entire generator. It has the stable output waveform and better dynamic response at different loads, and it can provide reliable over voltage, over current protection.

Abstract: Traditional rectifier circuit can convert AC to DC, but some disadvantages cant be avoided, such as small output current, high power consumption, low conversion efficiency. This paper designs a new type of rectifier voltage-multiplier circuit named MR_MOS circuit. It uses a low let-through resistance MOS tube to replace the conventional rectifier diode, and adds the voltage-multiplying factor to the synchronous input port. Therefore, it can improve the rectifier effect and increase the output voltage. By the simulation result of Synopsys Saber Platform, it shows that the new type circuit can implement the rectification and voltage-multiplying by the simulating output pulse voltage of nanofiber made in Deakin University as the source of excitation. It can provide the basic theoretical of the piezoelectric energy harvester (PEH) development, and has certain reference significance to the development of piezoelectricity technology.

Abstract: In this paper, we study a modified predictive direct power control scheme (P-DPC).This scheme which based on model predictive control (MPC) uses a discrete rectifier model to infer the predictive direct power control theme again, and selects the operating time of voltage vector and voltage vector to realize fixed switching frequency through setting the minimum power errors of each sampling period. This control scheme has a lower switching frequency compared to MP-DPC; and it is still simple and clear implemented in the stationary reference frame directly, meanwhile, it does not need PI controllers or voltage-oriented controllers compared to other developed control schemes. We make simulations using MATLAB. The result show the excellence of this novel predictive direct power control scheme through improving the switching frequency, current THD and active power and reactive power quality compared to MP-DPC and LUT-DPC.