Direct Effective Power Control (D-EPC) for LLC Resonant Converters Operating in Boost Mode Using Event-Driven-Timer Based Digital Controller

The LLC converter is a topology using resonance and is effective for miniaturization and high efficiency. Generally, LLC converters use a direct frequency control (DFC) method, which has the issue of slow transient response characteristics. Therefore, power factor control (called previously), which directly controls the effective power (D-EPC) of the resonant circuit in LLC, has been proposed previously. However, it has been adopted only in series resonant operation (buck mode) because the magnetizing inductance was not considered. In this paper, a small-signal characteristics considering the effect of magnetizing inductance is derived, showed that D-EPC is effective even in boost mode, and confirm the characteristics by experiments