Push-Pull Bi-Directional Current Mode High-Frequency Link Inverter And Its Soft Snubber Technique

Based on an overview of traditional push-pull bi-directional current mode high-frequency link inverter, the operation principles, feature and exist problems of this inverter are described. Also, some current improved methods are introduced. In low power application, without the complex configurations and laborious control methods, with the aid of a LC nondissipative snubber composed of inductor, capacitor and diode, a research on reducing the voltage spike caused by the energy stored in the transformer leakage inductance is conducted.First, the "Injected-Absorbed Current" method is utilized to model a Flyback converter operating in discontinue current mode (DCM) and after that the control to output characteristic is derived.Second, the LC snubber is applied to the Flyback converter operating in DCM and constant duty ratio. Its fundamental operation principles, operation modes are analyzed in detail and each operation mode is approximately calculated. Base on the derived expressions, a group of appropriate parameters are determined.Finally, the LC snubber is applied to the traditional push-pull inverter which duty ratio is varied. With the help of Pspice simulation analysis, the final parameters are derived. A prototype is constructed and experimental results show its possibility and validity.Utilizing the technology called soft snubber properly can improve the performance of the high-frequency link inverter to some extent and reduce the voltage stress on the switching devices and decrease the turn-off power losses.Even though the performance of this LC snubber is not as good as that of active clamp circuit and the current waveforms of switching devices are not good enough, in low power application, this soft snubber technology is still valuable for application. So, it is possible for the inverter to operate at higher frequency and helps to improve the development of current mode inverter with high-frequency link.