Development and classification of the switching power supply modules, DC / DC, AC / DC converter topology and characteristics elaborated combination of domestic and inteational switching the two categories MTD2002 converter new technology trends are discussed, described the switching power supply module choice.
1 Introduction
With the rapid development of power electronics technology, the increasingly close relations of power electronic devices work, life, power electronic devices without reliable MTD2002 power . 8O’s the begiing of the 20th century, the computer power the full realization of the switching power supply modular, the first to complete the updating of the computer’s power; the 9O’s of the 20th century, the switching power supply module have entered into a variety of electronic and electrical equipment in the field or program-controlled switchboards, communications, power testing equipment power control devices have been widely used switching power supply, but also to promote the rapid development of the switching power supply technology. The switching power supply is the use of mode electronic technology control switch transistor tu on and off the time ratio, to maintain a stable output voltage of a power supply, the switching power is generally controlled by a pulse width modulation (PWM) IC and MOSFET constituting.
Switching power supply module and linear power both off with the output rate, but higher than the switching power supply module, which is known as a cost reversal point. MTD2002 power electronics technology development and iovation, so that the switching power supply technology is constantly iovating the cost reversal point moves increasingly to low-John out of the power end, switching power supply provides a broad space for development. The high frequency of switching power supply is the direction of its development, so that high-frequency switching power supply small plow and worship the switching power supply into a wide range of application areas. Especially in high-tech fields, and promote the miniaturization of high-tech products, lightweight. In addition, the development and application of the switching power supply, energy conservation, resource conservation and environmental protection are of great significance.
2. Classification of switching power supply
People in the field of switching power supply module technology side related to the development of power electronic devices, while the development of the switching frequency technology. Both promote each other pushing. Switch AC / DC and DC / DC power supply can be divided into two broad categories. DC / DC converter is now modular design technology and production processes in the country and outside have already matured and standardized and user acceptance; modular AC / DC, because of its own characteristics, such modular encountered in the process of the more complex issues of technology and manufacturing process.
2.1 DC / DC conversion
The DC / DC converter is a fixed DC voltage is converted into a variable DC voltage, also known as DC-Out wave. The temporary filter work in two ways, First, the pulse width modulation Ts constant change ton (Universal); second is the frequency modulation, ton unchanged. Change Ts (easy to produce interference), specific circuit the following categories:
(1) BUCK circuit buck Out wave, the average output voltage Vo is less than the input voltage Vt, the same polarity.
(2) BUCK circuit a pressure temporarily wave, outputs the average voltage V0 is greater than or less than the input voltage, the same polarity.
(3) BUCK circuit a pressure or boost Out wave, the average output voltage Vo is greater than or less than the input voltage v0, of opposite polarity, the inductor transmission.
(4) the BUCK circuit is a buck or boost transformer, the output average voltage V0 is greater than or less than the input voltage U opposite polarity, capacitive transmission.
Today’s soft-switching technology makes DC / DC occurred a qualitative leap, the American V ~ COR design and manufacture of a variety of EC ~ soft switching DO / DO converter, its biggest MTD2002 output power of 300W, 6OOW, 800W power density 6,2,10,17 watts per cubic centimeter efficiency 200300kHz, power density of 27 watts per cubic centimeter, using the same rectifier the (M0SFET instead of Schottky diodes ), so that the whole circuit power is increased by 90%.
2.2 AC / DC conversion
AC / DC converting the AC is converted to DC power flow is bidirectional, the power flow from the power supply flows, the load is referred to as the “rectifying”. The power retued by the load of power known as “active inverter. AC / DC converter input AC 50/60Hz, must be approved by the rectifier filter, so the relatively large size of the filter capacitor is essential encountered safety standards (such as UI, CCE) and EMC Directive restrictions (such as IEC, FCC, CSA), the AC input side plus EMC rate the components of the wave and used in accordance with safety standards, thus limiting the miniaturization of the AC / DC power module volume. In addition, due to the inteal high-frequency, high-voltage, large current switching action to solve EMC problems more difficult, and also high demands on the inteal high-density mounting circuit design. Many power loss due to the same reason, the high voltage , high current switches increases, limiting the high demands. A lot of power work loss due to the same reason, the high-voltage, high-current switch increases, limiting the process of modular AC / DC converter, power system optimization method, in order to make it work efficiency reaches a certain level of satisfaction.
AC / DC conversion circuit wiring can be divided into a half-wave circuit and full-wave circuit, can be divided into single-phase, three-phase and multiphase power number of phases, the circuit T quadrant is divided into a quadrant, two-quadrant, three quadrant and four quadrant.
3. Switching power supply optional
Switching power supply module input the anti-jamming performance, due to the characteristics of its own circuit (multi-pole series ), the general input disturbances such as surge voltage is difficult to pass, compared with the linear power supply output voltage stability indicators have greater advantages, the stability of the output voltage of up to 0.5 to 1%.
3.1 Output current selection
Due to the high efficiency of the switching power supply module, generally more than 80%, Therefore, on its output MTD2002 current selection, should be accurately measured or calculated the absorption maximum current of the electrical equipment, so that the selection of the switching power supply having a high performance price ratio.
Usually the output is calculated as follows:
3.2 Ground
Switching power supply than linear power supplies will produce more interference, of the total membrane dry around sensitive electrical equipment, the grounding and shielding measures should be taken. ICEIO00, FCC, EMC limits, switching power supplies are used EMC EMC measures, switching power supply with EMC EMC filter generally. Lihua HA series switching power supply to FG terminal earthed or coected users chassis, be able to meet the requirements of the EMC.
3.3 Protection circuit
Switching power supply module is required to have in the design flow thermal short-circuit protection function, it should be designed first to protect full-featured power module, and its technical parameters to protect MTD2002 circuit should match the operating characteristics of the electrical equipment to avoid damage to the electrical equipment or switching power supply.
4. Switching power supply technology developments
The development direction of the switching power supply is a high-frequency, high reliability, low power consumption, low noise, interference and modular. Light, small switching power supply, the key technology of the book is a high-frequency, therefore, the foreign major switching power supply manufacturers are committed to the simultaneous development of a new type of intelligent components, especially the loss becomes secondary rectifiers and power increase scientific and technological iovation ferrite (Mn.Zn) material to obtain high magnetic properties in the high-frequency and a larger magnetic flux density (Bs), capacitance miniaturization is a key technology.
SMT technology application makes switching power supply has made considerable progress, both sides of the cloth star MTD2002 circuit boards, components to ensure that the switch light, small, book. High frequency switching power supply is bound to traditional PWM switching technology iovation. Achieve ZVS, ZCS switching technology has become the mainstream of the switching power supply technology. And greatly improve the efficiency of the switching power supply. For reliability indicators, the U.S. switching power supply manufacturer by lower operating current and temperature and other measures to reduce the stress of the devices, making the switch to greatly improve the reliability.
Modular overall trend type switching power supply module development, module power group distributed $ source system can be used, and can be designed to NI Kang I power systems, and to achieve the capacity expansion of the Contact. While the use of part MTD2002 harmonic board conversion circuit technology, not only in theory but also reduce the high frequency noise, but some resonant converter circuit technology, not only in theory but also reduce the high frequency noise, but some resonant converter technology practical applications there is still the issue of technology applications, it is needed in theory both MTD2002 but also reduce the high frequency noise, but the practical application of some resonant converter technology there are still technical problems, it is needed in this area a lot of work, so that the technology can be applied.













