SLUAAX1 July   2024 UCC24624

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Background
  5. 2Problems with a Synchronous Rectification Strategy
  6. 3Solution
  7. 4Simulation Verification
  8. 5Conclusion
  9. 6References

3 Solution

Much literature in the analysis of the LLC converter uses the First Harmonic Approximation (FHA) method, which has a certain guiding role in design but cannot accurately analyze the modality. To directly calculate the length of 0 – t1 in Figure 3-1, use the time domain analysis method. The specific analysis process is very complicated, and you can refer to process in the Steady-state analysis of the LLC series resonant converter article(1). The calculation formula for time domain analysis is as follows:

Equation 1. α 1 = γ - ϕ ,   α 3 = γ + ϕ sin ϕ = γ l M cos y + M sin y M = ν 0 ν i n , γ = 2 ω 0 T s 2 = 2 π F , F = f s f 0 , l = L r L m
where:
  • Vo is the output voltage
  • Vin is the input voltage
  • fs is the switching frequency
  • f0 is the resonant frequency
  • Lr is the resonant inductor
  • Lm is the magnetizing inductor.
UCC24624 PMP41042 Detailed Waveforms When fs > fr Figure 3-1 Detailed Waveforms When fs > fr