Switching power supply design should mainly meet the technical performance indicators: output/input voltage ratio (UO/UI), output power Po, converter efficiency η, output voltage ripple △UO, the input voltage source voltage UI electromagnetic interference (EMI) amplitude limit, etc.. In optimization design, inequality constraints are generally used to represent each performance index (if a certain inequality constraint is satisfied, it means that the design result satisfies a corresponding performance index).
In the design of the main circuit of switching power supply, the main content should be calculated and selected: select the main circuit structure form, select the switch tube (transistor, power MOSFET or IGBT) and rectifier diode model and its voltage and current specifications, determine the input, output filter form and parameters; Select and calculate magnetic components (inductors, transformers, current transformers, etc.) core specifications, size, winding turns and wire specifications, as well as the selection of capacitors, etc.
The design of control circuit compensation network of switching power supply should meet the transient performance index of power supply, so it belongs to transient design. Transient performance indicators of switching power supply are: the stability of the power supply system, rapidity (indicated by the recovery time), the transient response of the up and down rush, the anti-disturbance of the power supply (the disturbance includes the transient disturbance of the input voltage, the transient disturbance of the load of a sudden add or reduce the load) and so on. Since the main circuit parameters have a great relationship with the transient response performance of switching power supply, the transient design should be carried out after the main circuit design is completed.
The main contents of the transient optimal design of switching power supply include: the selection of feedback control mode (voltage feedback or voltage and current feedback, respectively called single loop control and double loop control), the circuit form of compensation network (proportional integral differential or PID amplifier), the optimal design of PID parameters and so on.
