Practical Analysis And Design Technology Of PWM Switching Power Supply

The trends on miniaturization, low power, and high efficiency have grasped the low-voltage electrical devices together with the switching power supply.There are two objectives of this thesis: (1) One is based on their advantages and disadvantages to analyze the structure of power supply control IC, from testing one simple low dropout regulator (LDO) to focusing one PWM IC on key parameter of power-limiting; (2) Another is to propose an effective and useful design method on flyback switching power supply in LD7575 IC, with PSIM simulation versus Tektronix Oscilloscope based testing, and with showing some optimization advices on power supply system design.Four parts of my works include: (1) The known structures of the power IC were compared and analyzed. Aiming at one kind of simple LDO power IC, I primarily understood the architectures and principles of power ICs through analysis and measurements; (2) Three kinds of most popularly applied power PWM ICs were analyzed on emphasis of the power-limiting feature through building its value function; (3) The switching power supply system prototype was successfully constructed with the LD7575 IC for comparing our design accuracy between our PSIM model and tested data; (4) Through re-checking and comparing simulated/tested results in detail, some shortcomings were pointed out and some useful suggestions were presented for future design optimization on power supply system.The typical research result shows the standby power of the designed system is less than 0.26W under 90V~264V/no load and the statistic data such as the average efficiency is more than 88.90% under 90V~264V with different loads.The experiments'conclusions are: Based on summing-up the power-limiting and system design of the power supply in the past, this thesis discussed one novel practical design method of flyback switching power supply, and the designed system in this method was comparable to the reported high performance one. In the end more useful suggestions for the design and optimization of switching power supply were also provided for the future.