Study On High Frequency Soft-Switching Power Supply

With the development of electronic technology, switching supply has been widely used for industry, transportation, electricity etc. But the conventional converter operates in hard switching, low switching frequency and low efficiency. So the soft switching PWM technology is proposed. And it makes converter that operates in high efficiency and high frequency as possible.In order to restrain the parasitic oscillation and the voltage ringing of the rectifier diodes, auxiliary resonant commutating network including a resonant inductor and two clamping diodes auxiliary branches can be introduced to the Primary side. The converter can be improved that the auxiliary branch is connected with the leading leg of the transformer. So, the improved converter not only restrains the voltage ringing of the rectifier diodes, but also reduces secondary duty cycle loss and the Primary current in zero state. Because of a resistance in the clamping diodes auxiliary branch, the effect of the clamping diodes auxiliary branch is weakened. In order to restrain the parasitic oscillation and the voltage ringing of the rectifier diodes better, a simple RLCD clamping circuit is placed in the secondary side of the full bridge converter. It not only restrains the voltage ringing of the rectifier diodes, but also avoids the defect of the general RCD buffer absorption network.Based on the analyzing of the theory, a switch power supply of 220V/10A for electrically operated power supply is designed. The scheme verified by PSPICE simulation shows the circuit topology is right.