Traditional Class-E circuit features fewer components, high reliability, and soft switching. However, due to the unidirectional excitation, the application of such a topology circuit is limited, i.e., usually used in low-power applications. To relieve this issue, this article proposes a switched-capacitor-based Class-E circuit, to extend the operating power range of the Class-E circuit. With the proposed new circuit, both constant current (CC) and constant voltage (CV) output modes can be achieved by switching the branch once without changing the switching frequency or compensation network. Compared with the existing CC and CV charging strategies, the proposed circuit has the advantages of fewer components, simpler implementation, and higher reliability. Moreover, the studied compensation network can also be extended to other inverter topologies. The working principle of the proposed circuit is described in detail, and the variable zero-voltage switching (ZVS) margin is introduced to make an accurate design of parameters. Subsequently, the influence of high-order harmonic components on the circuit and the sensitivity of parameters are analyzed. Finally, the proposed circuit is simulated and experimented on a 180–450-W prototype with CC and CV characteristics to verify the feasibility of the circuit and the accuracy of theoretical analysis.

The topology morphing (TPM) strategy, which involves switching between full-bridge and half-bridge modes, offers a promising solution to broaden the voltage gain range of LLC converters without adding an extra device. However, due to the distinct voltage gain curves of these two modes, the existence of a stable operating point after TPM is not promised, resulting in system instability. To address this issue, this article proposes a design procedure based on peak gain trajectory, incorporating geometrically simplified steady-state state plane analysis. In this way, the predicted result shows a great agreement with the exact peak gain trajectory. In addition, a state plane–based topology morphing control (SPTMC) is introduced to mitigate significant output voltage transients caused by the abrupt TPM. With such a strategy, the desired switching frequency after TPM is forecasted and feedforward to the conventional linear control to ensure tight regulation of the output voltage during TPM. It is noted that neither a lookup table nor control scheme switching is required for the proposed control strategy. A prototype has been constructed to validate the feasibility of the proposed design procedure and the proposed SPTMC.

Traditional synchronous rectification (SR) strategies in LLC converters are insufficient to meet the stringent demands imposed by the onboard chargers for plug-in hybrid electric vehicles (PHEVs), which require exceptional cost-efficiency, high performance, safety compliance, bidirectional operation, and the ability to handle high output voltage. In contrast, model-based SR strategies for LLC converters, driven solely by sensed DC signals, offer numerous advantages, including cost-effectiveness and robust immunity to electromagnetic interference. Nevertheless, the precision of the model significantly impacts the model-based SR strategy’s performance. Furthermore, under light load conditions, LLC converters may enter a discontinuous current mode (DCM), leading to extended SR conduction time and additional reactive current for model-based SR strategies. To solve such issues, a novel state-plane-analysis-based SR strategy for LLC converters is proposed, enhanced with an online DCM identification algorithm. Leveraging geometric principles and tailored simplifications, analytical expressions are derived for both the SR conduction time and the DCM boundary. The proposed SR strategy exhibits remarkable versatility, spanning the entire frequency range of LLC converters, and offers an exceptional dynamic response. The proposed approach is validated with a 6.6 kW prototype, achieving a rated efficiency of 97.5% and demonstrating a weighted SR timing accuracy of 97.8 %.

Second harmonic output voltage ripple in a single-phase grid-connected rectifier can degrade the system's performance. In this letter, a voltage-oriented state plane feedforward control is proposed to suppress the second harmonic output voltage ripple for the LLC converter, which serves as the backstage of the dual-stage single-phase rectifier. Herein, the desired switching frequency of the LLC converter is predicted online through geometrically simplified state plane analysis, and thus the voltage control loop gain at the second harmonic frequency can be increased. The proposed control strategy features a fast dynamic response and is immune to grid frequency deviation. Both simulation and experimental results fully confirm the theoretical analysis.

This paper proposes a state plane feedforward (SPF) control to improve the dynamic response performance of LLC converters. In contrast to the traditional state-plane-based control, the proposed SPF control aims at the steady state analysis of state plane. The proposed SPF control predicts the switching period under specific operating conditions through state plane analysis with geometric simplification, and feedforward it to the conventional linear controller. The switching period predicted by SPF shows good agreement with the actual switching period. Moreover, because the state plane analysis is geometrically simplified, no complex high-order equations need to be solved, and online computation is available. Meanwhile, the SPF control guarantees greater stability compared with other state plane based nonlinear controls, as a result of no transient control structure switching is required during transient states. Finally, both simulation and experiments are carried out to validate the feasibility of the SPF control, the result demonstrates SPF control features a rapid dynamic response to all types of transient.

We propose a see-through near-eye display featuring an exit pupil expander (EPE), which is composed of two multiplexed slanted gratings. Via a two-dimensional expansion, the exit pupil (EP) is able to be enlarged up to 10 × 8 mm². Besides, the prescription for correcting the refractive errors can be integrated as well. The design rules are set forth in detail, followed by the results and discussion regarding the efficiency, field of view (FOV), exit pupil, angular resolution (AR), modulation transfer function (MTF), contrast ratio (CR), distortion, and simulated imaging.