There are two modes of operation for a constant on-time PFM series resonant converter (SRC), discontinuous conduction mode (DCM), and continuous conduction mode (CCM). In DCM operation, the inductor current remain at zero for some interval, and this mode occurs when the switching frequency 5) is less then half of the resonant frequency f,. In CCM operation, it occurs when 0.5 f, Fig. 5 shows the constant on-time PFM control signals and resonant current wavefomis. Because one-half cycle of the inverter operating frequency exceeds the resonant period (Tr), the discontinuous interval of the resonant current i, flowing through the leakage inductance Lr in Fig. 5(a) occurs, and therefore in this mode of operation. f0cf42, the active power switches turn off naturally at zero current and zero voltage, since the inductor current goes through zero, the active power
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