| The output voltage is detected indirectly through the auxiliary coil of the transformer and some system components are reduced in the primary side regulated flyback converter, which makes the system more efficient, lower cost, and has been widely used. This kind of converter is needed to adapt to a wide range change of the load in electronic equipments, and more attention has been attracted to its dynamic response. Therefore, the dynamic response will be researched, and an optimization scheme will be proposed in this thesis.The background and the status of research of flyback converter is firstly introduced in this thesis. Then the average switching network method has been selected to establish the modeling of the peak current control and the pulse frequency modulation controlof flyback converter in discontinuous current mode, and obtain the corresponding equivalent circuit. Based on the transfer functions of flyback converter system, frequency domain methodto has been used to analyse its dynamic characteristics. According to the time variant characteristics of flyback converter, the self-tuning control strategy has been applied to optimize the loop to improve the dynamic responseof the system, which using fading memory least square tracking algorithm to identify the parameters of the system and using minimum variance control to calculate the PI control parameters. Through detailed analysis of the flyback converter system with the minimum variance control, traditional PI parameter configuration scheme has been put forward to guide the design.Simulation results have been demonstrated that:with self-tuning control, overshoot and droop of the flyback converter can be controlled within 100mV, compared with the fixed proportional integral parameters control. The recovery time of load from heavy to light has been reduced by 20%, and the recovery time of load from light to heavy has been reduced by 60%. It is showed that the dynamic response has been effectively improved. |
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