A dynamic dead time controller is presented, specifically intended to operate in synchronous boost converters based on GaN field-effect transistor switches. These transistors have a reduced stored charge with respect to silicon metal-oxide-semiconductor field-effect transistors with similar breakdown voltage and series resistance, and can operate at higher frequencies with reduced switching losses. On the other hand, the voltage drop in reverse conduction is typically more than doubled with respect to silicon devices resulting in relevant power losses during the free-wheeling phases. Therefore, dynamic control of dead time can be profitably applied even in converters operating in the tens of volts range. The device presented in this study controls the switching delays taking into account both variations of the fall/rise times and of the turn-off/on delays, in order to keep dead time within a range of a few nanoseconds above its minimum value. A discrete-component prototype was designed, built in a synchronous boost converter and extensively tested at 1-2MHz switching frequency, in a range of operating parameters corresponding to significant variations of the switching times (currents in the 1-6A range, output voltage up to 50V). The prototype demonstrated the capability to match dead time to actual operating conditions with a smooth and fast transient response
The paper provides an investigation of a possible application of wireless power transfer (WPT) technology to recharge the battery of a short-distance electric vehicle. The performance of the WPT system working at 85 kHz is first investigated by simulations. A robust LCC compensation network suitably tuned is then investigated with the goal to analyze the influence of design parameters on the compensation strategy. Particular attention is addressed to evaluate the deterioration of the WPT system performance due to coil misalignment. Finally, the WPT performances are evaluated demonstrating the feasibility of the proposed WPT technology
Power losses in high-efficiency dc-dc step up convert-4 ers based on the synchronous Three Levels Neutral Point Clamped 5 (TLNPC) configuration were investigated. TLNPC converters 6 benefit from the reduced stress on components and from the non-7 insulated stacked-boost output stage to provide reduced power 8 losses and large voltage gains. Several prototypes with increasing 9 efficiency were produced and tested; voltage gains larger than 10 20× were achieved by means of hard-switched prototypes with 11 composite switches consisting of both low-R ds(ON ) and high-12 speed MOSFETs. At lower voltage gains conversion efficiencies 13 exceeding 98% were demonstrated. A thorough loss analysis is 14 reported, extended to subtle power dissipation processes, which 15 in high efficiency converters grow in relevance after weakening of 16 the major loss mechanisms. The related model is proven capable 17 to accurately predict circuit performance in a wide range of 18 operating conditions.19
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