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Safe start-up procedure is critical for reliable operation of power converters. The challenges in start-up schemes of high-frequency (HF) transformer link inverters involve pre-charge of the capacitors without significant inrush currents and over-voltages. The pre-charge is normally followed by enabling of the closed-loop control. The over-voltage or inrush current problems in conventional start-up...
This paper presents a novel approach to compensate the voltage error due to switching dead times in voltage-fed inverters using a field-programmable gate array (FPGA) and current oversampling. The FPGA controls an analog-to-digital (AD) converter which operates at a high conversion rate and processes numerous current samples taken at equidistant time steps within each pulse width modulation (PWM)...
Ultracapacitors (UCs) are the significant component of the energy storage systems (ESS) in the electric traction applications. In the field of electric transportation the UCs need to be modeled dynamically in order to capture real-time characteristics. The model should provide precise estimation of UC responses to various charge/discharge conditions and also predict the behavior of UCs under varied...
This paper proposes a power decoupling method based on single-phase quasi-Z-source inverter (SPQZSI) for DC microgrid applications. Single-phase inverter would cause harmonic issues especially voltage ripple in DC microgrid because of low-frequency (100/120Hz) power ripple. Non-linear load or source would generate other harmonic on the common DC link as well. In order to achieve power decoupling,...
Gallium Nitride (GaN) HFETS are an enabling technology for high-density converter design. This paper proposes a three-level dc-dc converter with dual outputs based on enhancement-mode GaN devices, intended for use as a battery charger in aircraft applications. The charger can output either 28 V or 270 V, selected with a jumper, which meets the two most common dc bus voltages in airplanes. It operates...
Modular multilevel converters (MMCs) are being developed for the grid connection of offshore wind or tidal farms. In order to reduce the construction and maintenance costs, it is desirable to reduce the weight and volume of the MMC systems. In most existing MMC submodule designs, the reservoir capacitor usually accounts for over 50% of the total volume and 80% of the total weight. This paper presents...
In stand-alone brushless doubly fed generator (BDFG) based shaft power generation system, the output voltage of BDFG is strong influenced by the filter of load side converter (LSC) because of the coupling caused by the stator power winding leakage inductance. In order to eliminate the harmonic of the voltage, the LC-L filter based on the leakage inductance is put forward in this paper. The relationship...
This paper presents a quasi Z-source integrated multiport converter (ZIMPC) for switched reluctance motor (SRM) drives to reduce the dc link capacitance. In conventional SRM drives, employing multi-phase asymmetrical H-bridge (ASHB) topology, large capacitors are necessary to absorb the transient energy during phase current commutation. However, electrolytic capacitors would affect the lifetime, cost...
Recently, high efficiency LLC resonant converters have gained popularity to implement battery chargers and employ traditional wire-wound transformers. Due to the height of traditional cores, the form factor of LLC chargers is often plump and bulky. In order to implement slim profile chargers for EVs and portable electronic applications, planar transformers can be used featuring low height, reproducibility,...
Due to the interaction between human and the power supply equipment, more and more Switch-mode power supplies (SMPS) require lower leakage current. In the AC-DC SMPS, the leakage current is mainly caused by the Y-capacitors. It is better to remove the Y-caps in this situation. But connecting Y-caps between the primary return line terminal and the secondary return line terminal is a very common method...
This paper introduces a low-complexity, novel dynamic measurement technique to extract Ciss and Crss of a power MOSFET under high current conduction, providing an accurate description of the transistor dynamic characteristics while hard-switching an inductive load. The results of our dynamic measurements revealed larger capacitance values when compared to those extracted from conventional static measurements.
High frequency is the major catalyst for size reduction in the advancement of power conversion technology. It is essential to understand the EMI characteristic of high frequency converter since the EMI filter typically occupies one third of total system volume. This paper presents an insight view of CM/DM noise transformation in Flyback converter for low power adapter applications. The so-called mixed-mode...
The dual active bridge converter is examined as the DC/DC stage of a battery charger for the plug-in hybrid electric vehicle where both load voltage and load current have very wide operating range. The load current for sinusoidal charging scheme could swing down to zero. To optimize the battery charger under this charging scheme, a DAB loss model over wide load range is needed. Traditional DAB analysis...
Active front end (AFE) converters have been extensively used in industrial motor-drive systems due to their energy regenerative capability and low harmonic distortions. However, the Pulse Width Modulation (PWM) switching operation in AFE converters generates higher common-mode voltage than their non-regenerative diode front-end (DFE) counterparts. Such significant common-mode voltage can be converted...
Multi-resonant converters like the CLLLC topology are known for their outstanding efficiency and high power density. Little information has however been published about the influences of secondary side diode junction capacitances on the output characteristics of the resonant converter. This paper presents a detailed analysis of these influences in the inductive working range and reviews practical...
This paper presents the first monolithically integrated two-phase series capacitor buck converter. This converter achieves over 60 A/cm3 current density. The series capacitor buck converter topology enables high frequency (HF) operation up to 5 MHz per phase without special magnetics or compound semiconductors. An adaptive constant on-time controller provides fast load transient response and fixed...
In power transistor models, it is very important that device capacitances are modelled accurately so that switching losses, EMI filter requirements and gate timing requirements of the converter can be accurately determined. In this paper, a modelling technique utilizing modified sigmoid functions to describe the device capacitances is applied on a GaN HEMT and a silicon MOSFET to develop their corresponding...
This paper presents a new bidirectional multilevel modular switched-capacitor dc-dc converter for high voltage and high conversion ratio application with low capacitor voltage rating. For the high voltage and high conversion ratio application, high voltage capacitor with good performance will not be available either, like the switching devices. For the traditional multilevel modular switched-capacitor...
A highly accurate filter simulation requires a high precision SPICE model for the common mode choke. Conventional SPICE models for chokes consist of parallel RLC circuits and show a substantial difference between the measured and simulated impedance characteristics due to the lack of frequency-dependent complex permeability considerations. Here, we propose a novel SPICE model for a common mode choke...
The trend towards SiC-based high power density converter requires to drive SiC MOSFET with high-speed switching. However, it tends to aggravate dv/dt effect due to the impact of parasitic parameters, resulting in shoot-through and high device stress in the half bridge configuration. In this work, a novel gate assisted circuit is proposed to eliminate shoot-through issue without compromise on switching...
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