Switching Power Supply Module Introduction Switching Power Supply Module DC Chopper
brief introduction
Switching power supplies can be divided into two categories: AC/DC and DC/DC. DC/DC converters have now been modularized, and the design technology and production process have been mature and standardized both domestically and internationally, and have been recognized by users. However, the modularity of AC/DC, due to its own characteristics, encounters complex technical and process manufacturing problems in the process of modularization.
dc chopper
DC/DC conversion is the process of converting a fixed DC voltage into a variable DC voltage, also known as DC chopping. There are two working modes of a chopper: one is the pulse width modulation mode, where Ts remains unchanged and ton is changed (universal), and the other is the frequency modulation mode, where ton remains unchanged and Ts is changed (prone to interference). The specific circuits are divided into the following categories:
(1) Buck circuit - a step-down chopper whose average output voltage Uo is lower than the input voltage Ui and has the same polarity.
(2) Boost circuit - a boost chopper whose output average voltage Uo is greater than the input voltage Ui and has the same polarity.
(3) Buck Boost circuit - a step-down or step-up chopper, whose output average voltage Uo is greater or less than the input voltage Ui, with opposite polarity and inductive transmission.
(4) Cuk circuit - step-down or step-up chopper, whose output average voltage Uo is greater or less than the input voltage UI, with opposite polarity and capacitive transmission.
AC/DC
AC/DC conversion is the process of converting alternating current into direct current, and its power flow can be bidirectional. The power flow from the power source to the load is called "rectification", and the power flow from the load back to the power source is called "active inverter". The input of an AC/DC converter is 50/60Hz AC power, which must be rectified and filtered. Therefore, a relatively large filtering capacitor is essential. At the same time, due to safety standards (such as UL, CCEE, etc.) and EMC directives (such as IEC, FCC, CSA), EMC filtering must be added to the AC input side and components that meet safety standards must be used, which limits the miniaturization of the AC/DC power supply. In addition, due to the high frequency, high voltage, and high current switching actions inside, it is more difficult to solve EMC electromagnetic compatibility problems, which puts high demands on the design of high-density installation circuits inside. For the same reason, high voltage and high current switches increase the power consumption and limit the process of modular AC/DC converters, Therefore, it is necessary to adopt power system optimization design methods to achieve a certain level of satisfactory work 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 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 quadrant one, quadrant two, quadrant three, and quadrant four.
