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This article is focused on the design of a high-voltage (800 V) bidirectional boost converter with high efficiency at medium-low power levels. Triangular current mode (TCM) enhances the efficiency of the converter at low power, thanks to soft-switching operation, but it requires variable switching frequency and large current ripple through the inductor. The former can be implemented by using silicon carbide (SiC) mosfets and the latter can be minimized by using interleaved modules. At low power, TCM requires high switching frequency, a minimum negative inductor current, and a minimum deadtime to obtain zero voltage switching. These values vary for different input/output voltage ratios and must be properly selected to reduce deadtime losses, normally neglected in the literature since it is assumed that they have low impact. However, it can be relevant at high frequencies (especially for devices with high reverse conduction voltage drop, such as SiC mosfets). In this article, deadtime losses are included in the proposed losses models and the selection of optimum values of deadtime and minimum inductor current to minimize these deadtime losses are analytically evaluated and experimentally validated. [ABSTRACT FROM AUTHOR]

A converter intended to be used for the interconnection of battery-based energy storage systems with the cells of a multilevel converter is addressed in this paper. High efficiency at light and medium loads is important in these applications and it can be achieved using soft switching techniques. Two control techniques with fixed and variable switching frequency are proposed and compared. The use of silicon carbide (SiC) mosfets provides a higher attainable switching frequency, which is especially interesting in variable frequency control techniques, allowing the operation at high voltages and high switching frequencies, with high efficiencies over a wide power range. A synchronous boost DC/DC converter rated for 400 to 800 V and 10 kW is designed and developed with SiC mosfets obtaining efficiencies higher than 97% from 100% to 3.5% of full load using a variable switching frequency (up to 200 kHz) control. Significant efficiency improvement is achieved at medium and light loads. [ABSTRACT FROM PUBLISHER]

Quasi-square wave mode with zero voltage switching (QSW-ZVS) is an operation mode in which the switching losses can be minimized. However, a large inductance current ripple is needed in this mode, which limits the maximum attainable power of the topology. A possible way to increase the power managed by a QSW-ZVS mode converter is to use a modular converter. An input parallel output parallel (IPOP) arrangement, in which the current can be shared among the modules, can increase the total power proportionally to the number of modules. This paper addresses two main proposals. The first one is a master–slave technique to extend the QSW-ZVS mode to an IPOP modular converter, achieving an interleaved solution which minimizes the total input current ripple and assures the current balance among the modules. The second one is a comparison of four different control techniques applied to the IPOP modular converter to improve the overall efficiency at light to medium load: balanced master–slave technique, master–slave with phase-shedding, asymmetrical master–slave, and burst mode (or hysteretic control). These four strategies are theoretically analyzed, experimentally validated and compared using a 150–400 V 2 kW modular IPOP prototype made up of four synchronous boost converter operating in QSW-ZVS mode. [ABSTRACT FROM PUBLISHER]

This paper is focused on a high-voltage (400 to 800 V) bidirectional converter, which is intended to be used for the interconnection of battery-based energy-storage systems with the cells of a modular multilevel converter, providing distributed energy-storage capability to a solid-state transformer. This converter must have a high efficiency at medium and light load and also a low current ripple due to the charging and discharging processes. This work takes advantage of the use of SiC MOSFETs into a synchronous boost converter to accomplish the previous requirements. First, the adoption of a variable-switching frequency control to keep the efficiency high is analyzed, and second, the use of a modular converter with different control techniques to provide a current ripple reduction is also addressed in this study. An input-parallel–output-parallel synchronous boost converter, made up with three modules (3 kW per module), is used to validate experimentally the advantages of the use of SiC MOSFETs and to compare different control techniques. [ABSTRACT FROM PUBLISHER]

Envelope tracking (ET) is a technique designed to enhance the efficiency of radio frequency power amplifiers (RF PA). It is based on providing the voltage to the RF PA with variations that mimic the shape of the envelope of the communication signal that the RF PA is processing. As the bandwidth of these signals can be around several megahertz, the switching frequency of the switching mode power supply designed for ET applications has to be very high. The good switching characteristics of Gallium Nitride devices makes them suitable for this application. This paper presents two multiphase converters to be used as envelope modulators in envelope tracking applications. [ABSTRACT FROM AUTHOR]

The efficiency of linear power amplifiers can be improved by modulating its supply voltage according to the peak value of the signal that is being amplified in a technique usually known as envelope tracking. High bandwidth dc/dc converters called envelope amplifiers (EAs) are used to carry out the supply modulation in an efficient manner. In the case of linear RF power amplifiers, the bandwidth requirements over the EA strongly depend on the signal being amplified: in modern telecommunication applications it can range from several hundred kilohhertzs to a few tens of megahertz. The path to achieve such bandwidths usually goes through increased switching frequencies and/or reduced ratio of switching frequency to converter bandwidth. However, these may lead to lower converter efficiency and increased distortion, making the design of EAs a challenging task. This paper addresses the analysis and design of the output filter for Buck converters operating as EA. The output filter must provide enough attenuation at the switching frequency and harmonics to guarantee a desired level of distortion while enabling tracking of wide-bandwidth envelope signals with high converter efficiency. This paper focuses on the use of high-order filters (up to sixth-order Bessel-Thomson, Butterworth, and Legendre-Papoulis filters) in a buck dc/dc converter working as an EA. The filters are analytically described and characterized, and a design procedure that takes into account the major design constraints is proposed, allowing the selection of the appropriate filter for a given application. The proposed analysis and design method are supported by simulation results, as well as by experiments obtained using a 1 MHz buck converter operating as an EA. [ABSTRACT FROM AUTHOR]