t2~t3: When the resonant inductor current is
equal to the main inductor current, the main
diode, Cr and Lr began resonant, resonant
capacitor Cr discharges. When the end resonance,
resonant capacitor voltage is zero. t2, the
resonant capacitor voltage is equal to the output
voltage Vo, the time t1 to the time when the two
current time is equal is