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In this paper, a new critical-conduction-mode (CRM)-based modulation is proposed for three-phase inverters. With this modulation, soft switching is achieved and the efficiency of the inverter is improved, especially for high frequency operation with SiC MOSFET. In three-phase string PV inverter applications, by operating at switching frequency above 300 kHz, power density of the inverter is estimated...
Distributed energy generation systems with energy storage and microgrids have attracted increasing research interest in recent years. Therefore, multi-ports dc-dc converters have gained more interest. However, when integrating into multiple port converters, the power flow control and ports regulation increase in complexity. In this paper, an isolated multi-port bidirectional converter based on an...
This paper presents a universal active power filter (UAPF) based on single-phase ac/dc/ac converters with five legs. The proposed topology has multilevel voltage, reduced total harmonic distortion (THD) in current, and low weighted total harmonic distortion (WTHD) in voltage, when compared to conventional four-leg structure. The proposed UAPF is feasible to compensate reactive power, swells in grid...
DC-DC converters with high dynamic performance and low current ripple, able to drive highly fluctuating loads are nowadays required in a range of applications (e.g. accelerators, plasma research, fusion reactors). In order to fulfill the requirements of these applications, advanced current control concepts have to be employed to harness the full potential of the designed topology. In this paper, an...
A high-performance DC-DC converter is presented to improve the efficiency and modularity of the vehicular power system. The converter is capable of bidirectional power transfer between the isolated voltage sources. GaN semiconductor switches in the converter turn on and off softly by utilizing the energy stored in the leakage inductance of a transformer. A quasi-resonant operation is also explained...
Boost type converters are commonly used as pre-regulators in applications such as photovoltaics, battery storage, and power factor correction. Normally, non-isolated step-up conversion is done using traditional hard-switching boost topologies, but these suffer from low efficiency due to hard switching transitions. Soft-switching boost topologies present an opportunity to increase switching frequency...
In the field of high-speed electrical drives, the use of SiC MOSFET inverters represents a viable solution since this kind of devices allows an improvement of the converter efficiency. Notwithstanding issues related to the high frequency operation of the SiC MOSFET's, like the failure of the motor winding insulation due to the increased electrical stress and hence a reduced system reliability, are...
High-precision applications typically demand very-low ripple, fast response, and high efficiency. The newly proposed concept of Basic Crossover Correction Cell (B3C) aims to achieve exactly that by processing the current ripple independently from the main bulk current. As a consequence, correction cells can be constructed from lower-power switching devices with reduced stress, as compared to conventional...
Applying RF circuit design techniques to dc-dc power conversion has pushed the switching frequency of power converters using discrete components beyond 100 MHz. This paper proposes a simple solution to implement synchronous rectification for resonant dc-dc power converters operating in the Very-High-Frequency (VHF) range, by using a symmetric bandpass matching network between the inverter and rectifier...
The pump back test is widely adopted in the industry for characterizing and qualifying the high-power converters. One popular pump back test mode is to tie the DC link of two converters together and circulate the current through the inductor connected between the AC terminals. In this mode, one of converter operates in voltage mode to generate the virtual grid and another converter regulates the circulating...
Industrial applications, e.g. semiconductor manufacturing equipment, require power amplifiers providing high power with high precision and bandwidth. Due to limitations in system infrastructure, increasing voltage is favorable to increasing current to generate more output power. This research presents a 5-level Flying Capacitor Resonant Pole Inverter (FC RPI) configuration that delivers high output...
This paper proposes an improved phase-shifted pulse-width modulation (PS-PWM) method for a three-phase cascaded H-bridge (CBH) multi-level inverter. In the proposed PS-PWM method, the switches at one leg of H-bridge cell (HBC) only operate and the switches at other leg are clamped. Therefore, the number of the multi-carrier signals depending on the voltage level can be reduced in half compared to...
Resonant filters can be beneficial for significant reduction of the filter size in buck converters. Compared to the conventional low-pass filter, the resonant filters can be designed to provide high attenuation to the ripple components near the pulse width modulation (PWM) switching frequency resulting in much smaller filter components. In traditional resonant filter, the high attenuation at a specific...
48V voltage regulator modules (VRMs) are critical for telecom power supplies, and is becoming popular for future data centers. By using a novel sigma converter topology, an outstanding performance in terms of efficiency (94%) and power density (420 W/in3) have been demonstrated in [11]. Both the efficiency and power density are much higher than state-of-art solutions. The sigma converter is a quasi-parallel...
This paper focuses on the design and implementation of a digital closed-loop control scheme to maintain the 180° phase shift of an interleaved Boundary-Conduction-Mode (BCM) boost converter. The closed-loop control scheme operates by differentially modulating the on-time of each phase to adjust the phase-shift. Zero-Current-Detection (ZCD) circuits control the turn-on instant for the MOSFET of each...
The Class E dc-dc converter, operating with the switching frequency up to multi-megahertz, is usually regulated by the basic ON-OFF control. In this paper, it is found that in the basic ON-OFF control, the resonant inductor current of the Class E dc-dc converter will be increase with the rise of the input voltage, which will enhance the output capacity of the converter and also increase the ON-OFF...
The difficulty of modeling a resonant converter is the fact that, unlike a pulse-width-modulation (PWM) converter, an average concept doesn't work. The only successful equivalent circuit model, proposed by E. Yang, is based on fundamental approximation and harmonic balance theory. However, it is conceptually hard to understand because of an unidentified “equilibrium state.” A resonant converter was...
The second-harmonic circulating current in the phase legs of modular multilevel converter (MMC) leads to additional power losses. Existing circulating current suppressing strategies are realized by injecting the second-harmonic component in arm voltage reference. This paper presents a modified circulating current suppressing strategy including two controllers with a fixed-band submodule (SM) state...
This paper proposes a scheme to improve the system overall efficiency while still meeting a given THD requirement by implementing variable instantaneous switching frequency scheme in a full bridge inverter. Previous work has analyzed variable frequency scheme for unipolar PWM. This paper aims at minimizing the switching loss for inverters using bipolar PWM scheme by including characteristics of the...
Pulse Width Modulation (PWM) control method has been widely studied and applied in the industrial area. For majority of the conditions, the PWM frequency is fixed to guarantee easier control implementation. However, the time constant of the IGBT thermal system is much lower than that of the inverter fundamental frequency at low speed. The lifetime of the inverter are severely reduced under low speed...
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