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THIS paper explores opportunities and challenges in power conversion in the VHF frequency range of 30-300 MHz. The scaling of magnetic component size with frequency is investigated, and it is shown that substantial miniaturization is possible with increased frequencies even considering material and heat transfer limitations. Likewise, dramatic frequency increases are possible with existing and emerging...
In the last decade there has been a tremendous growth in the number of data centers due to the increasing demand for Internet services. At the same time, the cost for energy and materials have increased because of reducing resources and increased demand. That has caused a change in the driving forces for new power supply development, with more consideration on power density and efficiency. The commonly...
A new interleaved active-clamp forward converter with parallel input and series-parallel output is proposed in this paper. With the proposed topology the secondary windings of the transformers work in series when the input voltage is low but in parallel when the input voltage is high. Therefore, the duty cycle is not limited within 0.5 and the steady state conversion gain of the converter can be improved...
A novel high efficiency polymorphic topology converter whose input range extends to 200~800 Vdc, while the high line input efficiency is still maintained is presented in this paper. By integrated a novel three-level HB L2C converter and a conventional PSFB converter together, the proposed converter intelligently estimate the input voltage condition and automatically change its internal topology forms...
This paper describes a current sharing technique for digitally controlled two-phase buck DC-DC converters where pulse width and resistance mismatches are digitally compensated to achieve approximately equal current sharing without sensing currents. Effects of various non-idealities on the current sharing performance are discussed and corresponding mitigation techniques are presented. An extension...
This paper describes a new approach to the analysis of switched mode power converters utilizing coupled inductors and presents a novel canonical circuit model for N-winding coupled inductors. Waveform and ripple of the winding current in a coupled inductor converter can be easily determined using the developed model similar to those obtained in an uncoupled inductor converter. Influence of coupling...
The constant-on current-mode DC-DC converter is widely used for powering microprocessors because of its fast loading transient response. But the DC regulation accuracy performance of this kind of converter is still unknown. In this paper, the accuracy of constant-on current-mode DC-DC converters for power microprocessors is thoroughly analyzed. The inaccuracy issue is pointed out and the root cause...
To improve efficiency over a wide load range, it is important to dynamically adjust the operational phase number in multiphase voltage regulators. This paper analyzes in detail the power loss profile of a synchronous multi-phase buck converter and defines the optimal phase number under different load conditions. Experimental results are provided to verify the theoretical results.
Cascaded filters offer a possibility to minimize the size of the filter components due to their increased attenuation at high frequencies. A cost optimized design of a cascaded filter of a multi-phase converter for an automotive energy backup system will be shown, that results in small values of the inductances. However, the decreasing inductance values results in increasing current ripples in the...
A sensorless multi-phase average current-program mode controller with an accurate self-tuning current estimator is introduced. Based on the values of the duty ratio, and the input and output voltages, the estimator calculates the average inductor current of each phase in a multi-phase dc-dc converter. The averaged values are calculated over one switching cycle. The estimator employs a phase-by-phase...
Recently, the V2 type of constant on-time control has been widely used to improve light-load efficiency. In V2 implementation, the nonlinear PWM modulator is much more complicated than usual, since not only is the inductor current information fed back to the modulator, but the capacitor voltage ripple information is also fed back to the modulator. Generally speaking, there is no sub-harmonic oscillation...
Constant on-time current-mode control has been widely used to improve light-load efficiency, because it can reduce the switching frequency to save switching-related loss. Therefore, an accurate model for constant on-time control is indispensable to system design. However, available models for constant on-time control are unable to provide accurate physical insight and predict the system response,...
EMI filters are mainly made up of passive components including capacitors and inductors. These passive components can be a significant portion of the total converter system volume. Integration techniques can be used to improve space utilization and reduce the total system volume. This paper gave a comparison on existing passive integration technologies, and then developed an integrated EMI for 2 kW...
With the shortage of the energy and ever increasing of the oil price, research on the renewable and green energy sources, especially the solar arrays and the fuel cells, becomes more and more important. How to achieve high step-up and high efficiency DC/DC converters is the major consideration in the renewable grid-connected power applications due to the low voltage of PV arrays and fuel cells. The...
The ZVS-SVM controlled three-phase boost rectifier can realize ZVS operation for all switching devices. In this paper, the operation principal and design guideline are described in detail. The soft switching restriction is analyzed in particular. The experimental results of a 40 kW hardware prototype are presented to show the superiority of the topology and the reduction on loss.
Two techniques are presented to balance the filter capacitor voltages of a multi-pulse rectifier with active injection operating on a variable frequency supply. The active injector consists of a low-rated, bidirectional switch that modifies the behaviour of a 12-pulse rectifier at either low or high-frequency, resulting in 24-pulse or multi-level PWM operation respectively. The operation of the rectifier...
This paper proposes a three-phase, two-switch, buck converter that can operate with input power factor correction. The key features of the proposed converter are that a switch in it can operate with almost half the voltage stress of that in the standard three-phase, single-switch buck converter and with less current stress. In the paper, the operation of the converter is discussed and a detailed mathematical...
A novel soft switching inverter using two small coupled magnetics in one resonant pole is proposed to guarantee the main switches operating at zero-voltage-switching (ZVS) from zero load to full load and the auxiliary switches at zero-current-switching (ZCS) with load adaptability and small current stress. Since independent magnetics structure avoids the unwanted magnetizing current freewheeling loop,...
This paper presents a variable timing controlled soft-switching inverter. The proposed timing control is based on a simple voltage sensing circuit that detects zero voltage crossing condition to determine the main switch turn-on time. The proposed technique can be applied to different types of zero-voltage switching type inverters. In this paper, the coupled-magnetic type soft-switching inverter is...
In an RF system power amplifiers (PAs) typically consume the most power. This paper presents a buck converter design optimised for a wideband code division multiple access (WCDMA) PA. The design approach taken focuses on the optimization of switch sizing based on the overall power losses of the system including the output inductor losses. The converter is optimised for 20 MHz switching and output...
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