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About LLC Converter Topology

Power conversion is the process of converting electrical energy from one form to the other. The devices responsible for this conversion can work to convert alternating current (AC) into direct current (DC) & vice versa. They range from simple setups like a transformer to more complex conversion systems like resonant converters. 

What are Resonant Converters?

Used in integrated circuits, resonant converters are those electric power converters that have a combination of capacitors & inductors to work at a set frequency. It offers high savings, both in component size & weight, delivering the highest switching frequency with limited losses. 

Resonant converters are classified based on the use of resonant tanks. One of those topologies is the LLC converter topology.

LLC Converter Topology

Invented in 1988, this structure remained unused practically for a long time because of its complicated control & intricate parameter design. However, the rise in demand for high energy density in power electronics initiated the demand for a structure with voltage adjustment and a decent soft-switching range. 

The LLC converter is a resonant converter with a soft-switching operation. It has a switching bridge, an LLC tank, an output capacitor, a transformer and a rectifier. It can be implemented with a full-bridge or half-bridge circuit on the primary side and tackles switching loss by the process of zero-voltage switching, resulting in low electromagnetic emission (EMI) levels. This type of converter is desirable due to its high efficiency and high power density with low EMI. Let’s dig deeper into its benefits.

 

High Efficiency

The efficiency of resonant converters highly depends on the losses that occur during switching. As the LLC converter realises both zero current switchings & zero voltage switching, it reduces the losses during switching and avoids the reverse recovery effect of diodes. This in turn improves the overall efficiency of the converter.

Electrical Isolation

The LLC resonant converter doesn’t indulge in the entirety of the power supply. Instead, it isolates the load from the power supply because of the use of a high-frequency transformer. This isolation of the load prevents it from affecting or polluting the power grid. 

Wide Output Range

This system can work in various loading conditions as it changes switching frequencies by a process called pulse frequency modulation (PFM). Using this it can adjust the output voltage & current, enhancing adaptability while ensuring operational stability. 

Low EMI Pollution

Sudden current/voltage change results in electromagnetic noise. The smooth working of the LLC converter doesn’t let this become a problem, effectively keeping EMI and harmonic pollution under control.
The choice of a good ferrite core is paramount to making the best use of this complex setup. This is where Cosmo Ferrites come in.

Our range of soft ferrites could be the best fit with benefits like High flux density, Low losses, Excellent shielding, High magnetic path length & cost efficiency. We suggest selecting from the following core types for power conversion:

  • EE Core
  • UU Core
  • RM Core
  • Pot Core
  • PQ Core
  • EFD Core
  • Toroids

For more details Contact us today to get in touch with our experts who will guide you to the perfect ferrite core for your use.