What knowledge do you need to become a switching power supply engineer?

 　 The author majored in power electronics and electric transmission for his master's degree. After graduating with a master's degree, he went to work for a period of time at the Shanghai Space Power Supply Institute (internally known as "811") under the Shanghai Academy of Spaceflight Technology. His specific job was to design power supplies for spacecraft. Below I will talk about the question raised by the author based on my previous study and work experience.

　　(1) What knowledge do switching power supply engineers need?

　　The following is an example of a simple Buck converter design.

　　[Image from: Erickson RW, Maksimovic D. Fundamentals of power electronics[M]. Springer, 2001]

　　To design a Buck converter as shown in the figure, the following knowledge is required:

　　① Principles and design of circuit topology

　　The first step in power supply design is topology selection and solution design

　　Understand the functions that different converters can achieve and select the appropriate topology according to design requirements;

　　Be familiar with the working state of the converter and be able to perform steady-state analysis and AC small signal analysis on the converter;

　　Be familiar with the mathematical model of the converter and be able to obtain the converter's steady-state input-output relationship and transfer function;

　　According to the transfer function of the converter, the loop design of the converter can be performed;

　　Based on the loop design, analyze the stability of the system (Bode plot, etc.);

　　Be familiar with converter loss calculation (conduction loss, switching loss).

　　②Simulation analysis

　　After the power supply design scheme is determined, it can be simulated and analyzed to verify the accuracy and feasibility of the design scheme.

　　When designing switching power supplies, commonly used simulation software includes

　　PSIM/Pspice (power electronics modeling);

　　Saber (digital-analog hybrid modeling);

　　Matlab/Simulink。

　　Because the above-mentioned simulation software have their own characteristics, my usage habit is to choose to use according to the simulation needs.

　　③ Component knowledge

　　After completing the scheme design and simulation analysis, it is time to proceed to hardware design, and the first issue to be considered is the selection of components.

　　Familiar with the characteristics and usage of power components (IGBT, MOSFET, etc.);

　　Familiar with the use of general components such as RLC;

　　Familiar with the design methods of transformers or inductors;

　　Familiar with filter design methods.

　　④PCB drawing and plate making

　　After the components are selected, the next step is to make the plate, which requires the use of Protel or Altium designer.

　　Draw the schematic diagram of the power supply according to the design plan

　　According to the selected components, make their package library (some need to be made by yourself);

　　PCB board wiring (grounding, EMC and other issues need to be considered);

　　Submit the PCB diagram to the manufacturer for production.

　　⑤Use of digital controller

　　The switching signal of the switching device can be generated by an analog circuit or a digital controller. When using a digital controller, you need to be familiar with its principles and usage methods. Commonly used ones include DSP, FPGA, etc.

　　Familiar with the principles of digital controllers

　　Familiar with the design of peripheral circuits of digital controllers

　　Familiar with the programming language of digital controllers

　　A switching signal of a switching device can be generated according to a corresponding modulation method.

　　⑥EMC design

　　EMC design runs through the entire power supply design, involving shielding, filtering, grounding, PCB design and other aspects, and is very important for the design of switching power supplies .

　　(2) On “How to Study”

　　①Learning of basic theories

　　A journey of a thousand miles begins with a single step. Without a solid theoretical foundation, it is impossible to design a switching power supply well.

　　Recommend a few professional books that I have used:

　　Erickson R W, Maksimovic D. Fundamentals of power electronics[M]. Springer, 2001

　　★★★★★Rich content, detailed explanation, well-organized system and clear logic

　　Xu Dehong. Modeling and control of power electronic systems[M]. Machinery Industry Press, 2006.

　　★★★★ Similar to the first book, but with less content

　　Maniktala S, Wang Zhiqiang. Mastering Switching Power Supply Design[M]. Posts and Telecommunications Press, 2008.

　　★★★★Combined with engineering practice, it is very instructive

　　②Learn by doing

　　Test what you have learned in practice and learn in depth through practice.

　　When you tune a circuit and the output meets the designed target, the joy you feel is something that others cannot understand.

　　We are not afraid of problems, but we are afraid of no problems. In the process of circuit design, simulation and hardware production, every problem that arises is an object of learning, and the application and accumulation of knowledge is also based on such problems.

　　Learning through practice is the best way to improve a power supply designer's level.