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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...
A new simple and low cost method for paralleling multiple power stages in high-power high-gain isolated full-bridge boost converters is presented. A small current balancing transformer and serial connection of transformer secondary windings provides ideal current sharing between paralleled power stages. Effective and safe parallel operation of multiple switching stages can thus be performed. By splitting...
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...
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.
A method for estimating and compensating the zero introduced by the capacitor equivalent series resistance (ESR) in the buck converter transfer function is introduced. The method is well-suited for practical implementation with digital controllers. The ESR zero is estimated by online measurement of the output voltage ripple and the power stage corner frequency. Accordingly, the coefficients of the...
Current sensing and sharing are important functionalities for paralleled and multiphase power converters. For reliable and efficient operation, current sensing accuracy and the current sharing performance are required. Therefore, sensing errors and mismatches should be eliminated and calibrated. On the other hand, conventional current sharing controllers are designed to force equal current sharing...
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,...
Nowadays, "black box" behavioral models of power converters are becoming interesting for system level simulation of power electronic based systems. Hence, new modeling and identification procedures become needed. In this paper, an easy modeling method and identification procedure based on a transient response analysis is presented. Using this method, a behavioral model with reduced order...
In order to accommodate increasing energy demand from "more electrified" domestic and vehicular applications, simultaneous use of various renewable sources are encouraged. Multiple converters are commonly adopted to process the renewable power as a distributed power system (DPS). However, due to the loose structure of DPS, reliability and load/source regulation will degrade as compared to...
Design consideration of a three-phase inverter with 1200 V Si-IGBT and SiC-JBS hybrid pairs has been implemented to further reduce the power loss and increase the power density. A low-on-voltage SiC-JBS has been developed to reduce the conduction loss. In order to minimize the switching loss of Si-IGBT, a high-speed gate driving technique is introduced. A 4 kVA class three-phase hybrid pair inverter...
The paper focuses on a new driving strategy for improving the efficiency of power converters even if they are not used at there nominal power. The converters are using an output filtering structure with magnetical coupling. These filtering structures are usually employed to minimize in a significant way the mass of the converters. These filters are normally sized to work with a fixed number of phases...
Joule heating of copper traces and vias in high current PCBs can significantly deteriorate the reliability of power electronics products. Optimization of the PCB layout is therefore fundamental to guarantee the thermal performance of a converter. This paper investigates the temperature distribution of copper traces and through via holes, when number and disposition of parallel vias are changed in...
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...
This paper focuses on the non-inverting buck-boost converter supplying an adjustable DC voltage to a WCDMA RF power amplifier (RFPA) in order to improve the system efficiency under different transmitted RF power levels. It is shown that precise output voltage positioning and low output voltage ripple over a wide output voltage range, including buck, boost and buck/boost transition modes, can be accomplished...
Due to the high rise in luminous efficiency that HB-LEDs have experienced in the last recent years, many new applications have been researched. In this paper, a streetlight LED application will be covered, using the integrated buck-flyback converter developed in previous works, which performs power factor correction (PFC) from a universal AC source, as well as a control loop using the LM3524 IC, which...
High brightness (HB) LED provides higher efficacy and reliability over incandescent light bulb. Different from incandescent light bulb, HB LED needs to be driven by accurate constant current for consistent brightness and color-temperature light emission. With a novel method pulse-level-modulation (PLM) control applied on conventional switched-mode power stage, a more robust, power-efficient and accurate...
A non-isolated soft-switched high power factor offline LED driver is introduced in the paper. The buck-boost converter is chosen for this application due to its simplicity and low cost. The converter operates with constant peak current for constant power control, and in transition mode (boundary mode between CCM and DCM) to achieve soft switching. High power factor is achieved by reshaping the peak...
With the advent of battery-powered portable devices and the mandatory adoptions of power factor correction (PFC), non-inverting buck-boost converter is attracting numerous attentions. Conventional two-switch or four-switch non-inverting buck-boost converters choose their operation modes by measuring input and output voltage magnitudes. This can cause higher output voltage transients when input and...
In the high power direct drive wind energy conversion systems, the power factors of both the generator-side converter and the grid-side converter are controlled to one in order to make full use of the capability of the power converters. In this paper, a novel sensorless unity power factor control method based on the reference coordinate system rotating synchronously with the voltage of the generator-side...
This paper presents a controller with duty-cycle dynamic distribution within parallel-connected PFC converters based on average-current control strategy, which can distribute the control duty-cycle automatically for each parallel-connected PFC converter to realize current balance by the difference from its reference current, and it can decrease and even eliminate the disturbance resulted by current-balancing...
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