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Unlocking the Magic of Resonant LLC Converter Design


Delve into the fascinating world of resonant LLC converter power stage design where inductors, capacitors, and phasor analysis come together to create efficient power conversion.

Deciphering the Resonant LLC Converter Power Stage

The resonant LLC converter power stage comprises a series resonant network with essential components like inductors and capacitors. By employing phasor analysis, the nonlinear nature of the circuit is simplified, streamlining the design process.

Mastering Waveforms in Full and Half Bridges

Replacing the square wave with its first harmonic in full bridges results in a sinusoidal waveform with a ratio of 4/pi. Conversely, half bridges divide this ratio by 2, showcasing the nuanced differences in waveform manipulation.

Balancing Power Dissipation in the Circuit

Equating power dissipation between the nonlinear and linear representations of the circuit unravels a crucial relationship: RAC = 8/pi^2 * RL. This equilibrium is vital for efficient power conversion and heat management within the system.

Harnessing Transformer Reflection for Efficiency

The interplay between power conversion and transformer reflection in the AC equivalent linear circuit optimizes efficiency and performance. By tweaking the circuit through reflection, the resonant LLC converter achieves enhanced operational capabilities.

Optimizing Resonant LLC Converter Ratios

Achieving an optimal ratio of around 6:1 between the inductors in the resonant LLC converter yields high gain and efficiency. Deviations from this ratio impact component size and system efficiency, highlighting the importance of precise design considerations.

Unlocking the Significance of Q in Resonant Circuit Design

Q, defined as Omega R for series resonance in AC circuits, plays a pivotal role in determining design parameters based on input voltage, power requirements, and circuit topology. This value sets crucial boundaries for gain management and circuit optimization.

Translating Ratios into Frequency Performance

Mapping normalized frequency to actual frequency using resonant frequency and ratio values helps in defining the AC minimum for power stage design. Calculating and fine-tuning resonant network values with precision tools like LM and LR enhances performance and efficiency.


Venture into the world of resonant LLC converter design armed with insights on waveforms, power dissipation, transformer reflection, ratio optimization, Q values, and frequency translation. Master the art of balancing components and efficiency for superior power stage performance.

For a simpler understanding, check out a video demonstration below.

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