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In this paper, a previously proposed converter to be used for inductive wireless power transmission is modeled and a control strategy is proposed. The converter topology combines into a single stage, two buck converters and a half-bridge converter to feed a resonant stage. This simple and symmetrical topology is straightforward to design; only a buck converter and a parallel resonant tank must be specified. It would be desirable for the converter to feed a wide range of loads and be robust under input voltage variations. These objectives can not be attained with a linear model and control. For this reason, in this paper, a nonlinear converter model is derived step by step and controller strategy is developed without relying on system linearization. The proposed controller does not measure the output but only its peak value. This can be conducted because it takes advantage of the square current pulse fed into a resonant tank; it outputs an approximately sinusoidal signal. The control strategy is completed with a scheme to build the required pulse at the input of the resonant tank. The resulting nonlinear controller has a fast closed-loop performance; furthermore, it is robust under parameter uncertainty, and load and input voltage variations. Despite its features, the controller is fairly simple to implement. [ABSTRACT FROM AUTHOR]

In this paper, the generalized average model of the Class-E$^2$ DC-DC resonant converter has been introduced. The standard average model is not interesting in resonant converters due to their large waveform oscillations. In addition, steady-state approaches restrain the converter to hysteresis control. The resonant tank voltage, reconstructed by the fundamental component, as performed in LLC converters by extended describing function, is not suitable for the Class-E$^2$ topology because the inverter/rectifier interface voltage requires, at least, the third-order harmonic usage. This work relies on the generalized average method to perform the large-signal and small-signal models of the Class-E$^2$ converter. This paper shows how to systematically deal with the following modeling issues: negative index from the convolution summation, complex numbers from the Fourier coefficients and high number of state-space variables. The theoretical approach is confirmed by measurement in an assembled 800 kHz Class-E$^2$ converter based on voltage-controlled oscillator.

In this research work, an independently controlled two output half-bridge resonant LED driver is proposed. Half bridge series converters will be providing power to two LED lamps. The devices in half-bridge converter are switched at zero voltage using LC resonant circuit. Therefore, switching transition power losses are minimized which increases the LED driver efficiency. Each LED lamp's ripple current is decreased by adding an inductor in series with it, eliminating the need for an electrolytic capacitor and extending the life of the resonant LED driver. Both regulating and dimming operations use asymmetrical duty cycle (ADC) control. Numerical simulations are conducted to examine the suggested resonant converter topology's steady state performance as it sources LED applications. Using the OrCAD/PSPICE tool for universal AC mains, 25 W and 29 W LED driver analysis, design, modeling, and simulation are carried out. The proposed driver needs to provide high efficiency even at reduced illumination. [ABSTRACT FROM AUTHOR]

This paper introduces the concept of an active DC. The active DC bus consists of a reduced passive DC bus and an Active Resonant Voltage Balancer (ARVB). The ARVB, operating as a series resonant converter, reduces the DC bus current ripple by injecting balancing current into the DC bus mid-point. This injected current effectively counteracts the fundamental component of the current flowing to the mid-point of the DC bus, resulting in a significant reduction in both the gravimetric and volumetric volume of the DC bus. The proposed concept is thoroughly analyzed through a case study involving a single-phase half-bridge rectifier application. Through theoretical analysis and experimental validation, the usefulness and feasibility of the proposed concept are demonstrated, showing in the presented case study a reduction of the DC bus volume by a factor of 4 at the expense of an increase in losses. The concept represents a viable option in power conversation applications where volume and weight reduction and optimization are required.

Piezoelectric resonators promise to increase dc-dc converter power density by replacing inductive components. However, piezoelectric resonators are not direct circuit level replacements for inductors, requiring new topologies. In this paper, we present a stacked converter using two piezoelectric resonators, providing improved efficiency at low conversion ratios. This converter is realized with a lithium niobate thickness-shear mode resonator with interdigitated electrodes that allow the two resonators required for the topology to be realized as tightly matched sub-resonators on the same substrate. The 180 V to 60 V converter operates between 6.15 MHz and 6.35 MHz and achieves a resonator-level power density of $\text{1.34}\;\text{kW}/\text{cm}^{3}$.