Introduction to switching power supply module DC chopper of switching power supply module
Introduction
Switching power supplies can be divided into two categories: AC/DC and DC/DC. DC/DC converters are now modular, and the design technology and production process have been mature and standardized at home and abroad, and have been recognized by users. However, The modularization of AC/DC, due to its own characteristics, encounters relatively complex technical and process manufacturing problems in the process of modularization.
DC chopper
DC/DC conversion converts a fixed DC voltage into a variable DC voltage, also known as DC chopping. There are two working modes of the chopper, one is the pulse width modulation mode, Ts remains unchanged and ton is changed (universal); the other is the frequency modulation mode, ton remains unchanged and Ts is changed (easy to cause interference). Its specific circuits fall into the following categories:
(1) Buck circuit - step-down chopper, its output average voltage Uo is smaller than the input voltage Ui and has the same polarity.
(2) Boost circuit - boost chopper, its output average voltage Uo is greater than the input voltage Ui, and the polarity is the same.
(3) Buck-Boost circuit - a buck or boost chopper whose output average voltage Uo is greater than or less than the input voltage Ui, with opposite polarity and inductive transmission.
(4) Cuk circuit - a buck or boost chopper whose output average voltage Uo is greater than or less than the input voltage UI, with opposite polarity and capacitive transmission.
AC/DC
AC/DC conversion converts AC into DC. The power flow direction can be bidirectional. The power flow from the power supply to the load is called "rectification", and the power flow from the load back to the power supply is called "active inversion". The input of the AC/DC converter is 50/60Hz alternating current, which must be rectified and filtered, so a relatively large filter capacitor is essential. At the same time, due to safety standards (such as UL, CCEE, etc.) and EMC directives restrictions (such as IEC, FCC, CSA), the AC input side must be EMC filtered and use components that comply with safety standards, which limits the miniaturization of the AC/DC power supply. In addition, due to the internal high frequency, high voltage, and large current Switching action makes it more difficult to solve EMC electromagnetic compatibility problems, which also puts forward high requirements for the design of internal high-density installation circuits. For the same reason, high-voltage and high-current switches increase power supply consumption and limit AC /DC converter modularization process, so the power system optimization design method must be adopted to achieve a certain degree of satisfaction in its working efficiency.
AC/DC conversion can be divided into half-wave circuit and full-wave circuit according to the wiring method of the circuit. According to the number of power supply phases, it can be divided into single-phase, three-phase and multi-phase. According to the working quadrant of the circuit, it can be divided into one quadrant, two quadrant, three quadrant and four quadrant.
