Research And Design Of Single-terminal Flyback Switching Power Supply

Power is an indispensable component,which guarantee electrical equipment will work normally, reliably and steadily.And the switching power supply has become the research hotspot, because of its high efficiency, energy saving and light. With the development of the power electronics technology, the innovation of power components, the integration of chip and the modulation of power source, the switching power supply which is more economical and practical is being widely used.The paper designed a single-terminal low power flyback switching power supply.On the basis of deeply analyzing the relative theories of switching power supply and its key technologies, the design of the single-terminal flyback switching power supply system is completed;the detailed design of the concrete electric circuit module is finished, including the EMI filter circuit,the high-frequency transformer,the former protection and the bridge rectification electric circuit, the passive clamp RCD electric circuit, the SR circuit, the controls ring circuit and the out-port filter circuit;the various circuit value of switching power supply is choiced,designed and assigned reasonably;the electric circuit schematic diagram is designed;the circuit is modeled and simulated by the software of Cadence 16.2, which validated the rationality of the power value;then according to the standard, the PCB is designed and manufactured ,the power model is fixed;finally, the model of the designed switching power supply is tested and validated.The accuracy of the model output voltage is 0.78%(5V), 0.42%(12V), 0.5%( - 12V) respectively and its accuracy is within 1% error range and the stability of its voltage is highe, output load regulation is 2%(5V), 2.17%(12V), 2.25%( - 12V) respectively,load regulation satisfy the requirements of less than or equal - 3%;its ripple is 24mV(5V), 34mV(12V), 36mV( V)and is less than 50mV which meets the requirements of design specifications;the ripple factor is 0.48%(5V), 0.28%(12V), 0.3%( V) and all less than 1%;the high-frequency transformer meet the design requirements of the indicators and is less heat by testing. The overall test results of the model show that the various indicators meet the demands of design and the model is output stability, good performance.