In this paper,the switching power supply uses push-pull power converter which is based on KA3525 PWM control chip,realizing the continual adjustable DC output voltage which ranges from 28v~38v.

A switching power is designed,in which the push-pull converter is consider to be the main circuit.

In this paper,voltage loop and peak-value current loop are used to control a high power DC/DC converter,one strategy to eliminate the transformer magnetic bias is proposed,3 kW push-pull converter is designed and MATLAB verifys the strategy of eliminating the transformer magnetic bias.

The Boost converter with transformer-isolated was used in Boost mode,which was cascaded by a Boost converter and a push-pull converter,eliminating the redundancy com-ponents by a control strategy,a novel step-up circuit topology was formed.

There are some intrinsic drawbacks in traditional push-pull converter,such as higher voltagestress and hard-switching of the switches,so the application area of the converter is limited.