To address global warming, the transportation sector, a significant contributor to carbon emissions, is transitioning toward electric vehicles (EVs), which are rapidly gaining market share. Despite their growth, EVs still face many technical challenges, particularly those related to battery, charging, and motor drive technologies. Among these, charging technology is the primary concern for users. Studying experimental technologies related to EV charging can enrich the knowledge of students within the power electronics discipline.

Currently, onboard chargers mostly utilize a two-stage structure comprising AC–DC and DC–DC conversion stages. The DC–DC conversion stage often employs topological structures such as phase-shifted full-bridge, dual active bridge, and LLC resonant converters. Among these, the LLC resonant converter is particularly notable due to its wide soft-switching range, low electromagnetic interference, high efficiency, and wide output gain. Its output voltage is regulated by adjusting the switching frequency, allowing for analysis in time and frequency domains. The inductive and capacitive components in this converter exhibit frequency-selective characteristics, and the converter operates by transferring energy through the fundamental harmonic of the current. Thus, the fundamental harmonic analysis method can be used to derive the gain expression of the LLC resonant converter and plot its gain curve, facilitating parameter design.

Based on theoretical analysis, an experimental prototype platform with an output power of 3.3 kW was designed. During the design phase, parameters of the resonant tank, transformer, and resonant inductor were calculated, and the prototype was constructed accordingly. We also designed the main, driver, and sampling circuits to ensure stable and efficient converter operation. Steady-state experimental results indicated that the primary-side switching transistors achieved zero voltage switching under varying output voltages and currents. Operating in the below-resonance region allowed the secondary-side synchronous rectifier switches to achieve zero-current switching, ensuring that all switches achieved soft-switching operation. The converter showed high overall efficiency, with the peak efficiency exceeding 96%, and a wide soft-switching range. Dynamic characteristic experiments revealed that the converter quickly stabilized the output voltage following sudden changes in settings or loads, showcasing the reliability of the PI closed-loop control.

The experimental results confirmed that the converter met the design requirements, with steady-state and dynamic performances fulfilling expectations. This experimental platform, which pertains to EV charging applications, serves as a tool for conducting various experiments related to LLC resonant converters, enhancing students' intuitive understanding of resonant converters in power electronics. DC–DC resonant converters are crucial components of power electronics technology. The experimental platform improves students' hardware debugging and software programming skills, enhancing their comprehensive skills in the power electronics discipline.

To accommodate the global shift in electric energy consumption, the total volume of new energy generation, primarily from photovoltaic and fuel cells, is steadily on the rise. However, the input voltage level for these new energy power generation systems typically ranges from 20 to 50 V, while the DC bus voltage of the traditional three-phase grid-connected system requires 380 V. As a result, high step-up, high-efficiency, and high power-density DC–DC converters have become a pivotal research topic.

Current methods of boosting technology include cascade, multilevel, switched-inductor, switched-capacitor, coupled-inductor, and voltage multiplier cells. Among these, switched-capacitor boost technology stands out owing to its scalability and ease of integration, given the absence of magnetic components in the converter. Coupled inductors, with their high power density and excellent voltage regulation characteristics, are also frequently employed in high step-up DC–DC converter topologies. There are a wide variety of high step-up boost converters based on coupled inductors and switched capacitors. Herein, we use a class of units consisting of diodes, capacitors, and magnetic elements. Characterized by their high efficiency and low cost, these units serve as voltage multiplier cells. To help students cultivate a deeper understanding of these converters and master their topology laws, this study adopts the idea of “voltage multiplier cell–converter topology–evolution law.” We aim to provide a comprehensive summary of the evolution laws of nonisolated high step-up DC–DC converters.

A series of coupled-inductor, switched-capacitor, and center-tap coupled-inductor switched-capacitor voltage multiplier cell structures are also presented for derivation. The general structure of the high step-up converter is derived and summarized in relation to the converter topology and the derivation law. Taking the coupled-inductor high step-up boost converter with a Y-source structure as an example, we conduct a modal analysis and voltage gain derivation. To verify the steady-state and dynamic characteristics of the proposed high step-up DC–DC converter, we have designed an experimental prototype with an output power P₀ = 200 W. At the same time, we considered the design of the main circuit, the driver circuit, and the sampling circuit to ensure that the converter works stably and efficiently. Steady-state experimental results show that the efficiency of the rated power (P₀ = 200 W) is 95.81% at a voltage gain B of 10.55. At a voltage gain B of 13.57, the efficiency of the rated power (P₀ = 200 W) is 94.76%. The highest efficiency is achieved at half of the rated power (P₀ = 100 W), with efficiencies of 98.06% and 97.35%, respectively. These results demonstrate the high efficiency of the proposed converter.

Dynamic experimental results indicate that the proposed converter can stabilize the output voltage in response to sudden changes in the input voltage and load resistance. This proves the reliability of the PID closed-loop control. This paper helps students gain a more intuitive understanding of the high step-up DC–DC converter in power electronics and increases their ability to summarize information. The DC–DC converter is a crucial part of power electronics technology, offering an excellent opportunity for students to hone their theoretical analysis and hands-on experimental skills.