Single-phase power factor correction (PFC) circuits—a kind of front-end AC/DC converters—are ubiquitous in a variety of consumer electronic devices, including laptop adapters, LED driver power supplies, and portable chargers. They enhance the current quality drawn from the source, delivering stable DC voltage with high efficiency.
However, current sensors in traditional boost PFC converters introduce issues such as noise susceptibility, signal delays, increased hardware complexity, and potential sensor failures that can degrade system reliability and lifespan. By eliminating current sensors, the proposed sensorless strategy reduces these risks, improves noise immunity, and decreases hardware failure points, leading to enhanced reliability and potentially longer-lasting power adapters and consumer electronics.
In a remarkable breakthrough achievement, a team of researchers from South Korea and China, led by Sung-Jun Park, a Professor from the Department of Electrical Engineering at Chonnam National University, has successfully demonstrated a new control method that eliminates the need for a current sensor. Their findings were made available online and have been published in the journal IEEE Transactions on Consumer Electronics on 30 September 2025.
In this study, the team proposes a simple and reliable single voltage loop current sensorless PFC control strategy. They derive the expression for the duty cycle—which consists of a feedforward component and a control component—by leveraging the fundamental equation of inductor voltage. Notably, delay compensation helps mitigate the effect of phase delay on input current distortion in the proposed control strategy.
"In this way, we specifically identified and solved a common issue in digital control systems: phase delay caused by signal processing. This delay distorts the input current. Our built-in compensation technique effectively counteracts this, which is a key reason for our method's high-power quality," remarks Prof. Park.
The novel technology foregoes complex observers and mathematical models, directly translating into lower component cost, reduced circuit complexity, and a smaller physical size. This simplification also reduces maintenance demands by minimizing components prone to degradation or recalibration, improving long-term operational efficiency compared to current sensor-based solutions.
Furthermore, the method is not highly sensitive to variations in circuit parameters, making it reliable and suitable for mass production. Because it relies on standard digital signal processors and eliminates the need for extra current sensor hardware, manufacturers can adopt and integrate this control strategy quickly and easily into existing power supply production lines without extensive redesign or increased component inventory.
This technology is designed for the AC/DC power supplies found in a vast array of electronic devices, enabling higher power levels in a smaller, more reliable form factor. The researchers validated its performance on a 1.3 kW prototype, a power level highly relevant for consumer and industrial electronics. The prototype achieved near-unity power factor (up to 0.9998) and low total harmonic distortion (THD) (2.12% at full load), performing comparably or better than traditional sensor-based methods. Additionally, by eliminating current sensors and reducing component count, the design achieves a smaller physical size and simpler circuitry, enabling more compact, efficient, and cost-effective power adapters.
The key products poised to benefit first from this technology include laptop and notebook adapters, smartphone fast chargers, LED televisions and monitor power supplies, server power supplies, and industrial and consumer power tools, due to their widespread use and medium power requirements. Over the next 5 to 10 years, widespread adoption could lead to smaller, lighter everyday electronics, reduced electronic waste, and lower costs, along with a more stable and efficient electrical grid that supports accelerated electrification.
Prof. Park explains, "By simplifying the power circuitry and reducing component count, chargers and power adapters for everything from laptops to kitchen appliances can become more compact and portable. As millions of electronic devices draw cleaner, sinusoidal current—with high power factor and low THD—from the wall socket, it reduces stress on the power grid. Lastly, cheaper and more reliable power supplies could mean lower upfront costs for consumers, furthering electric vehicles and renewable energy systems."
In essence, this research contributes to a future where the power supplies inside our electronics not only are cheaper and smaller but also collectively contribute to a more efficient and sustainable energy ecosystem.
