Futuristic electric vehicle charging station with glowing converter.

Revolutionizing Electric Vehicle Charging: The Future is Here!

Soraya Malik in Tech & Innovation August 2025 • 4 min read.

"Unveiling the Five-Switch Bridge Reconfigurable LLC Converter for Deeply Depleted PEV Charging"

Electric vehicles (EVs) are rapidly becoming the go-to choice for eco-conscious consumers. At the heart of every EV is its battery, typically a Li-ion pack, which stores the energy needed to power the vehicle. However, charging these batteries, especially when deeply depleted, presents a significant challenge. Imagine a scenario where your EV battery is almost completely drained. The standard charging process can be slow and inefficient, causing frustration and limiting the usability of the vehicle.

The charging profile of a deeply depleted Li-ion battery cell is unique, requiring a wide voltage range to ensure optimal charging. Traditional charging systems often struggle with this, leading to longer charging times and reduced efficiency. This is where innovative solutions like the five-switch bridge reconfigurable LLC converter come into play, promising to revolutionize how we charge our EVs.

A frequency modulated LLC resonant converter is considered as a suitable candidate, mainly due to its attractive features such as soft switching, galvanic isolation, low EMI, and low components count. However, to achieve such a wide voltage range, an ultra-wide switching frequency (fs) range is required. This might lead to efficiency reduction, soft-switching loss, and degraded voltage regulation.

The Innovation: A Five-Switch Bridge Reconfigurable LLC Converter

Futuristic electric vehicle charging station with glowing converter.

Researchers have developed a groundbreaking solution: a reconfigurable dual LLC converter based on a five-switch bridge. This innovative design allows the converter to operate in four different modes, each with a distinct voltage gain. What does this mean for EV owners? Faster, more efficient charging, especially when the battery is deeply depleted. The beauty of this system lies in its adaptability. By reconfiguring the primary-side switch network, the converter can optimize its performance across an ultra-wide output voltage range, ensuring that your EV battery charges quickly and efficiently, no matter its current state.

The four operation modes of the converter, with their normalized voltage gains scaled to 1:2:3:4, enable a squeezed switching frequency span. This is crucial because it keeps the switching frequency close to the resonant frequency, optimizing efficiency over a broad output voltage range. Think of it like finding the sweet spot for your car's engine – operating at the right frequency ensures peak performance and minimal energy waste. The result is zero-voltage-switching, which can be realized in all power MOSFETS over the entire load range.

Here's a quick breakdown of the key advantages:

Ultra-Wide Voltage Range: Handles the diverse voltage requirements of deeply depleted batteries.
Squeezed Frequency Range: Optimizes efficiency by maintaining frequencies near resonance.
Zero-Voltage Switching (ZVS): Minimizes energy loss during switching.
Reduced Conduction Loss: Halves the resonant current, improving overall performance.

In simpler terms, this converter intelligently adapts to the battery's needs, providing the right amount of power at the right frequency to ensure the fastest and most efficient charge possible. The operating principles and voltage gains have been rigorously analyzed, and a 1.1-kW-rated prototype has been designed and tested. The results? A peak efficiency of 97.64% and consistently good efficiency across the full charging range.

The Future of EV Charging is Here

The five-switch bridge reconfigurable dual LLC converter represents a significant step forward in EV charging technology. By optimizing efficiency and adapting to the unique needs of deeply depleted batteries, this innovation promises to make EV ownership more convenient and practical. As the demand for electric vehicles continues to grow, solutions like this will be essential in paving the way for a sustainable transportation future.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

Everything You Need To Know

Why is the five-switch bridge reconfigurable LLC converter needed for charging electric vehicles?

The five-switch bridge reconfigurable LLC converter addresses the limitations of traditional charging systems when dealing with deeply depleted Li-ion batteries in electric vehicles. Traditional systems often struggle with the wide voltage range required for optimal charging, resulting in longer charging times and reduced efficiency. The converter overcomes this by operating in four different modes, each with a distinct voltage gain, optimizing performance across an ultra-wide output voltage range.

How do the different operation modes of the five-switch bridge reconfigurable LLC converter contribute to its overall efficiency?

The four operation modes of the five-switch bridge reconfigurable LLC converter are designed with normalized voltage gains scaled to 1:2:3:4. This arrangement enables a squeezed switching frequency span, which is crucial for maintaining the switching frequency close to the resonant frequency. By operating near the resonant frequency, the converter optimizes efficiency over a broad output voltage range, similar to finding the sweet spot for an engine to ensure peak performance and minimal energy waste. This facilitates zero-voltage-switching (ZVS) across all power MOSFETs throughout the entire load range.

What are the main benefits of using a five-switch bridge reconfigurable LLC converter for electric vehicle charging, and how do these benefits improve performance?

The key advantages of the five-switch bridge reconfigurable LLC converter include its ability to handle an ultra-wide voltage range, which is necessary for deeply depleted batteries, and its squeezed frequency range, which optimizes efficiency by keeping frequencies near resonance. Furthermore, the converter achieves zero-voltage switching (ZVS), minimizing energy loss during switching, and reduces conduction loss by halving the resonant current, improving overall performance. These features allow the converter to intelligently adapt to the battery's needs, ensuring the fastest and most efficient charge possible.

What were the results of testing the 1.1-kW-rated prototype of the five-switch bridge reconfigurable LLC converter?

The prototype of the five-switch bridge reconfigurable LLC converter, rated at 1.1 kW, achieved a peak efficiency of 97.64% during testing. Furthermore, it demonstrated consistently good efficiency across the entire charging range. This level of efficiency represents a substantial improvement over traditional charging systems, making EV ownership more practical and convenient. While the text does not specify what the efficiency of a standard system is, this represents a large step forward for EV charging.

How does the five-switch bridge reconfigurable LLC converter help to create a more sustainable transportation future?

The five-switch bridge reconfigurable LLC converter contributes to a more sustainable transportation future by optimizing the charging process for electric vehicles, particularly those with deeply depleted batteries. This innovation addresses the limitations of traditional charging systems, offering faster and more efficient charging. As the demand for EVs grows, solutions like this are essential in promoting their widespread adoption and reducing reliance on fossil fuels. While the text does not mention specific comparisons in sustainability, the increase in efficiency will lead to less power used and more sustainable practices.