Research Of High Power Density Class-E Resonant Converter

Nowadays with the rapid development of the technology, the cell phone becomes smaller and smaller, which brings great challenge to the charger: higher power density. To increase the power density, generally there are two ways: high switching frequency and magnetic integration technology. The traditional topology for the charger is not suitable for high switching frequency, so Class-E resonant converter is brought as the topology of the cell phone charger. Class-E resonant converter can realize ZVS of the main switch, which is suit to work at high switching frequency.Standby loss of the converter is a big problem at high switching frequency. To decrease the standby loss, we use the "burst mode" standby control in Class-E resonant converter. With the burst mode control and low-loss start-up circuit, the standby loss of the converter is reduced to lower than 0.3W, which meets the international standard. And the output voltage ripple is lower than 5% all through 90～265V AC input.To reduce the size of the converter further, the magnetic integration has to been used. There are four magnetic components in Class-E resonant converter: the input inductor, the series resonant inductor, the parallel inductor and the transformer. The parallel inductor can be integrated with the transformer by using transformer magnetizing inductor. The series resonant inductor and the input inductor can be integrated with the transformer by using "common magnetic path" method. According to the different positions of the magnetic components in EE magnetic core, there are three different fully integrated structures. We analyze the power loss of the three different structures by Ansoft simulation. The prototype of the fully integrated structure is built and we analyze the experimental results. Compared to the discrete structure, the size of the total magnetic components is reduced to only 27.4%.