Hey Georgios
I understand that you are not obtaining the
In an LLC resonant half-bridge converter, the current waveform (Ir) can exhibit multiple peaks near the resonance frequency (fsw = 1/(2π√(LrCr))). This behaviour is a characteristic of resonant converters and is caused by the interplay of the resonant tank components (inductor Lr and capacitor Cr) and the switching frequency (fsw).
Here are a few reasons why the current waveform may have different peaks near resonance:
1. Resonant behaviour: At resonance, the inductor and capacitor in the resonant tank exchange energy efficiently. The current waveform reaches its maximum amplitude during this exchange, resulting in a peak in the current waveform. The resonant behaviour causes the current to oscillate with multiple peaks as the energy is transferred back and forth between the inductor and capacitor.
2. Soft switching: In resonant converters, soft switching techniques are often employed to minimize switching losses. Soft switching allows the switching devices (typically MOSFETs) to turn on or off when the voltage across them is close to zero. This soft switching action can contribute to multiple peaks in the current waveform near resonance.
3. Nonlinear behaviour: Near resonance, the behaviour of the LLC resonant converter can become nonlinear. The nonlinear characteristics of the tank components, such as the inductor and capacitor, can lead to additional harmonics and multiple peaks in the current waveform.
4. Load variations: The presence of different loads can also affect the current waveform near resonance. As the load changes, the resonant tank components may interact differently, resulting in variations in the current waveform and the number of peaks.
It's important to note that the specific characteristics of the current waveform near resonance can vary depending on the design parameters, component values, control strategy, and operating conditions of the LLC resonant converter. Simulation and careful analysis can help in understanding and optimizing the converter's performance near resonance.
