An Input Voltage Compensation Method Of Switching Power Controller Based On PSR

PSR flyback power supply with wide application in LED driver does not need opticalcoupler and the structure is simple, it has advantages of constant current/constant voltage, and low cost With the trend of switching power supply test standard strictly, the demand of PSR flyback power supply will be higher and higher to the stability of the output current and the precision of output current of the whole voltage range will be affected by the input voltage change, In order to effectively compensate the input line voltage drop, at the same time in order to reduce the cost of compensation circuit and the difficulty to design circult,an input line voltage compensation method has to be researched.First,the principle of PSR technology and the difference between PSR technology and traditional feedback technique in main points of design has been analyzed in this thesis. The inherent time delay of switching power supply affects output current unstable has been studied and has made the quantitative analysis to this kind of interference, the concept of Correction factors has been puts forward, and the interference factor of circuit has been used to compensate. And then a new kind of input line voltage compensation circuit has been put forward according to the interference factor expression formula of the defects in the traditional input line voltage compensation circuit, the circuit has been simulated and verificated. Finally based on digital switching power supply structure, a digital input compensation strategy has been proposed in this thesis, and the corresponding Verilog code has been write, has carried on the simulation.Through the simulation and validation, this thesis designed the input line voltage compensation strategy based on PSR implements the whole input voltage range of 85-265V, linear adjustment rate< 2%, load rate< 2%, the circuit meets the design requirements and is simple to implement, strong practicability.