Switching power module DC chopping
brief introduction
Switching power supplies can be divided into two categories: AC/DC and DC/DC. DC/DC converters have now achieved modularization, and the design technology and production process have been mature and standardized both domestically and internationally, and have been recognized by users. However, the modularization of AC/DC, due to its own characteristics, encounters more complex technical and manufacturing problems in the process of modularization.
dc chopping
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 ways in which choppers work: one is to keep the pulse width modulation mode Ts unchanged and change T (universal), and the other is to keep the frequency modulation mode T unchanged and change T (prone to interference). The specific circuits are divided into the following categories:
(1) Buck circuit - a buck chopper with an average output voltage Uo less than the input voltage Ui and the same polarity.
(2) Boost circuit - boost chopper, with an average output voltage Uo greater than the input voltage Ui and the same polarity.
(3) Buck Boost circuit - a buck or boost chopper with an average output voltage Uo greater than or less than the input voltage Ui, opposite polarity, and inductive transmission.
(4) Cuk circuit - a buck or boost chopper with an output average voltage Uo greater than or less than the input voltage UI, opposite polarity, and capacitor transmission.
AC/DC
AC/DC conversion is the process of converting AC to DC, and the power flow direction can be bidirectional. The power flow from the power source to the load is called "rectification", and the power flow from the load to the power source is called "active inverter". The AC/DC converter input is 50/60Hz AC power. Due to the need for rectification and filtering, relatively large filter capacitors are essential. At the same time, due to safety standards (such as UL, CCEE, etc.) and limitations of EMC directives (such as IEC, FCC, CSA), EMC filtering and the use of components that meet safety standards must be added to the AC input side, which limits the miniaturization of the AC/DC power supply volume. Additionally, due to internal high-frequency, high-voltage The action of high current switches increases the difficulty of solving EMC electromagnetic compatibility problems, which puts forward high requirements for the design of internal high-density installation circuits. Due to the same reasons, high voltage and high current switches increase power consumption and limit the modularization process of AC/DC converters. Therefore, it is necessary to adopt power system optimization design methods to achieve a certain degree of satisfaction in its 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 multiphase. According to the working quadrant of the circuit, it can be divided into one quadrant, two quadrants, three quadrants, and four quadrants.
advantage
Simple design. You only need one power module with a small number of discrete components to obtain power.
Shorten the development cycle. Modular power supplies are generally available with multiple input and output options. Users can also repeatedly stack or cross stack to form a modular combination power supply, achieving multiple inputs and outputs, greatly reducing prototype development time.
Flexible changes. If the product design needs to be changed, simply convert or connect another suitable power module in parallel.
Low technical requirements. Modular power supplies are generally equipped with standardized front-end, highly integrated power modules, and other components, making power supply design simpler.
The module power supply casing has a structure that integrates heat sink, heat sink, and casing, achieving a conductive cooling method for the module power supply, making the temperature value of the power supply close to the minimum value. At the same time, it also endows the module power supply with the packaging of its watch.
High quality and reliability. Modular power supplies are generally fully automated and equipped with high-tech production technology, resulting in stable and reliable quality.
Widely used: Modular power supplies can be widely used in various fields of social production and life, such as aviation and aerospace, locomotives and ships, military weapons, power generation and distribution, postal and telecommunications communication, metallurgy and mining, automatic control, household appliances, instruments and meters, and scientific research experiments, especially in highly reliable and high-tech fields, playing an irreplaceable important role.
