Design Of Constant Current Control Strategy Based On The Primary-Side Regulation Flyback Converter

The primary-side feedback flyback converter is widely used in chargers,adapters,and LED drivers due to its simple structure,low cost,and input/output isolation.With the continuous upgrading of integrated circuit process technology,the process and cost of the chip are also changing,and the advantages of constant current control technology in power management are becoming more and more obvious.The constant current control technology plays an important role in the stability and anti-interference of the integrated system.Therefore,it is of great research value to study the constant current control technology.First,this paper designs a constant current control strategy based on the primary side feedback flyback converter.The constant current control system samples the change of the primary current in the flyback main circuit topology through the sampling resistor,compares the primary peak threshold set in the control circuit with the primary current sampling value,and makes the primary peak in a single switching cycle.The same current.The inflection point tracking sampling method is used to compare the voltage at the auxiliary winding end with the reference voltage to obtain an infinitely close voltage at the inflection point.At the same time,the PI control module has no steady-state error after the system enters steady state.The PWM control makes the switch control signal constant during each switching cycle,achieving constant current control.Second,in order to make the output current of the system more accurate,this paper designs a primary peak current compensation algorithm.The delay time is obtained by the change of the primary current at the current input voltage,and the primary peak current compensation amount required for the delay time is obtained through calculation,thereby obtaining the primary peak current reference threshold that is more in line with the actual change of the system,and the system is improved.Linear adjustment rate.Finally,using MATLAB simulation software to achieve system simulation,the constant current control system designed in this paper was verified.The test results show that under the condition of AC input voltage of 110-220 V and AC input frequency of 48-65 Hz,the output current of the system is 2A,the maximum working efficiency of the system reaches 84%,and the linear adjustment rate of the system is The error is controlled within 1%.