RESUMEN

A boost Power Factor Correction (PFC) circuit is connected between the AC grid and converters to meet Electromagnetic Interference (EMI) and Total Harmonic Distortion (THD) standards. An EMI filter should be utilized at the input of the PFC to attenuate high-frequency noise injected into the grid. This article discusses the low-conducted EM emission boost PFC with Sliding Frequency Modulation (SFM) proposed by Power Integrations. The proposed boost PFC is compared with a conventional boost PFC operated using Constant Frequency Modulation (CFM) at 120 kHz. Both PFCs are rated for the same nominal power (i.e., 300 W) and output voltage (i.e., 383 V). An analytical loss model is also developed to compare the performance of the SFM and CFM PFCs. The analytical findings are verified by means of simulations and experiments.

RESUMEN

PURPOSE: To enable power wheelchair users with limited mobility to safely and independently charge their wheelchairs. METHODS: Stakeholders of multiple roles - including potential users, their caregivers, and clinicians with specifically relevant expertise - were engaged in a user-centred design process. Initial informal interviews, focus groups, online surveys, prototype demonstrations, semi-structured interviews, and expert reviews were utilized to guide development and iteratively evaluate prototypes. RESULTS: The resulting wireless charging system enables independent charging while also significantly increasing capacity and charging speed. Autonomous positioning and remote control features further address the particular use cases of the target population, and vital features of existing power wheelchairs are retained according to stakeholder input. Pertinent topics emerging from stakeholder input are discussed. CONCLUSIONS: Careful application of user-centred design principles is essential to the successful development of usable assistive technology devices, particularly for target populations with complex disabilities. The diverse perspectives of all relevant stakeholders must be considered and synthesized to produce a practical and usable solution.Implications for rehabilitationBattery charge is a constant and critical concern for power wheelchair users.Many power wheelchair users cannot independently use and monitor existing chargers.A wireless wheelchair charging system was developed to alleviate this issue.Sustained user engagement is crucial in the effective development of such assistive technology.

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RESUMEN

A two-stage charger (PFC+LLC) is developed for Power Mobility Device (PMD) charging applications (i.e., power wheelchairs). The LLC topology is selected due to its ability to maintain ZVS operation over a wide range of load variations. This paper discusses the challenges of designing a dual-loop controller for an LLC-based charger with a wide operation region. It proposes modifying the inner current loop to maintain stable operation over a wide input and output range-the proposed internal loop control switches intelligently between two current controllers based on the output voltage level. A 300-W prototype is designed and tested with a resistive load. Moreover, simulation and experimental results are compared to validate the robustness and stability of the proposed controller.