2. Conventional PWM soft-switching high-frequency
inverter
2.1. Conventional ballast topology
Fig. 1 shows the conventional LCrCdc series–parallel highfrequency
half-bridge inverter. This inverter is used as a
high-frequency power supply for electronic ballast applications
[9–11]. The switching circuit consists of two MOSFETs.
Zero voltage/current turn-on switching is enabled by turning
on the MOSFETs while the diode is in turn-on period. The
resonant circuit comprises of resonant inductance (Lr) and resonant
capacitance (Cr). The DC blocking capacitor Cdc is large
enough, resulting in a negligible impedance at the switching frequency.
The resonant frequency (fr) of the LCrCdc inverter can
be expressed as