Performance, design and pulse width control of a CLL resonant DC/DC converter operating at constant frequency in the lagging power factor mode

One of the different available topologies of the CLL resonant power converter has been re-investigated in this paper in the lagging power factor mode. It has been shown that the converter has a load-independent feature and may be designed to operate (ideally) at constant frequency. However, because of the nonidealities of the power converter components and to compensate for the variation in input DC voltage, frequency and/or PWM control is required. Optimization issues of the transformer-coupled topologies have also been discussed. A design procedure has been chalked out considering a voltage regulator-type application. Experimental results from a prototype power converter confirm the analysis. Pulse width control of the inverter output voltage shows very smooth control in converter output voltage to operate at constant frequency, despite changes in input voltage and/or output load.