Processing power of ten technology focus

Nineteen sixties, switching power supply, which is gradually replacing the linear regulated power supply and SCR phase controlled power supply. For over 40 years, switching power supply technology with fly fast development and change, experienced a power semiconductor devices, high frequency switching power supply and soft switch technology, system integration technology in three stages of development.
Power semiconductor devices from the bipolar devices ( BPT, SCR, GTO ) for the development of type MOS devices ( MOSFET, IGBT, IGCT, power ), the power electronic system has the potential to achieve high frequency, and greatly reduce the conduction loss, the circuit is more simple.
Since the nineteen eighties began, and high frequency soft switch technology research and development, so that the power converter with better performance, lighter weight, smaller size. High frequency and soft switch technology is international power electronics industry over the past 20 years, one of the hot research topics.
Nineteen ninties metaphase, integrated power electronics system and integrated power electronic module ( IPEM ) technology began to develop, it is current international power electronics sector one of the problem that solves urgently.
Focus one: power semiconductor device properties
In 1998, Infineon launched the MOS pipe cold, it uses a" super node" ( Super-Junction ) structure, so it is also called the super node power MOSFET. Working voltage 600V ~ 800V, resistance is reduced almost an order of magnitude, still maintain a high switching speed characteristics, is a promising high power semiconductor device.
IGBT first appeared, voltage, current rating of only 600V, 25A. For a long time, voltage level is limited to 1200V ~ 1700V, after a long time of exploration and improvement, now the IGBT voltage, current rating has reached 3300V / 1200A and 4500V / 1800A, voltage IGBT monolithic voltage has reached 6500V, the general IGBT working frequency limit of 20kHz ~ 40kHz, based on penetrating ( PT ) structure the application of new technology of manufacturing IGBT, which can work in the 150kHz (hard switch ) and 300kHz ( soft switch ).
IGBT technology progress is actually the on-state voltage drop, fast switching and high pressure resistance three compromise. With the technology and structure of different forms of IGBT, in the 20 year history of the development process, has the following several types: perforating ( PT ) type, non perforating ( NPT ) type, soft perforating ( SPT ) type, groove type and electric field stop ( FS ) type.
Silicon carbide power semiconductor wafer SiC is an ideal material, its advantages are: the forbidden bandwidth, high operating temperature ( up to 600 degrees C), good thermal stability, resistance is small, good thermal conductivity, low leakage current of PN junction voltage, higher, is beneficial for producing high temperature high frequency large power semiconductor device.
Can foreknow, silicon carbide in twenty-first Century will be most likely to succeed application of novel semiconductor materials.
Two focus: switching power supply power density
Improve the switching power supply power density, so that miniaturization, lightweight, people are constantly in pursuit of goals. Power supply high frequency is the international power electronics industry one of the hotspots in the research. Power supply miniaturization, reduce the weight of the portable electronic device ( such as mobile phones, digital cameras and other ) is particularly important. The switching power supply miniaturization of the specific measures are as follows:
One is the high frequency. In order to realize the power of high power density, must improve PWM converter working frequency, thereby reducing circuit energy storage element volume weight.
Two is the application of piezoelectric transformer. Application piezoelectric transformer can make the high frequency power converter of light, small, thin and high power density. Piezoelectric transformer using piezoelectric ceramic materials specific to" voltage" vibration" transform and vibration - voltage" transform the nature of energy transmission, its equivalent circuit as a series parallel resonant circuit, the power converter is one of the hot areas of research.
Three is a new type of capacitor. In order to reduce the volume and weight of power electronic equipment, the need to improve the properties of capacitors, improve the energy density, and suitable for the development of power electronics and power supply system using a novel capacitor, electric capacity, the equivalent series resistance of small, small volume and ESR.
Focus three: high frequency magnetic and synchronous rectification technology
Power supply system in the application of a magnetic component, high-frequency magnetic components of the material, structure and properties are different from power frequency magnetic components, many problems need to be studied. On the high frequency magnetic material for magnetic element has the following requirements: loss of small, good heat radiating performance, superior magnetic properties. Applicable to MHz frequency magnetic material is concerned, nanocrystalline soft magnetic materials have also been developed application. High frequency, in order to improve the efficiency of switching power supplies, must the development and application of soft switch technology. It was in the past a few years in international power is a hot point in the field of.
For low voltage, high current output of the soft switch converter, further enhances the efficiency of the measures is to try to reduce the switch conduction losses. For example, synchronous rectification technology of SR, i.e. to power MOS tube reverse as the rectifying switching diodes, instead of Shaw Teji diode (SBD ), can reduce the pressure drop, thereby improving the efficiency of the circuit.
Focus four: distribution of power structure
Distributed power supply system suitable for high speed integrated circuit consisting of a large workstation ( such as image processing station ), large scale digital electronic switching systems such as power supply, its advantages are: can realize DC / DC converter module; easy to realize N+1 power redundancy, improve system reliability easy amplification; load capacity; can reduce the 48V bus on the current and voltage drop; easy to achieve uniform heat distribution, to facilitate heat dissipation design; transient response; online replaceable failure module.
Now the distributed power supply system has two kinds of structure types, one is the two level structure, the other is a three class structure.
Focus five: PFC converter
As a result of AC / DC transform circuit and the input end of a rectifier and filter capacitor, in sinusoidal voltage input, single phase rectifier power electronic devices, power side (AC input power factor ) is only 0.6 ~ 0.65. Using PFC (PFC ) converter, the power factor can be increased to 0.95 ~ 0.99, THD less than 10% of the input current. Both control the harmonic pollution of power system, but also improve the efficiency of the whole power supply. This technology is called the active power factor correction single-phase APFC APFC domestic and foreign development is earlier, technology has been more mature; three-phase APFC topology and control strategy has many kinds, but also to continue research and development.
High power factor AC / DC switching power supply, consisting of two stages of topology, for small power AC / DC switching power supply, using two topological structure overall efficiency is low, cost is high.
If the input power factor requirements are not very high, the PFC converter and the level of DC / DC converter are combined into a topology, constitute a single stage high power factor AC / DC switching power supply, only a master switch tube, the power factor correction to above 0.8, and the DC output voltage adjustable, this topology called the single single-stage S4PFC converter.
Six focus: a voltage regulator module VRM
Voltage regulator module is a kind of low voltage, high current output DC-DC converter module, to supply power to the microprocessor. Now the data processing system for speed and efficiency increasing, in order to reduce the electric field intensity and the power consumption of a microprocessor IC, must reduce the logic voltage, a new generation of microprocessor logic voltage is reduced to 1V, while the current is high up to 50A ~ 100A, so the VRM requirements are: output voltage is very low, large output current, current high rate of change, such as rapid response.
Focus seven: full digital control
Power control has been simulated by control, hybrid control, access to the full digital control phase. Full digital control is a new development trend, already in a lot of power conversion devices.
But in the past the digital control in DC / DC converter with less. In recent years, the power of the high performance digital control chip has been developed, costs have been reduced to a more reasonable level, and a number of companies have to develop and produce switching converter digital control chip and software. Full digital control has the advantages that: the digital signal is mixed with the analog signal can be compared to the calibration of smaller volume, chip at a lower price; the detection error can be accurate digital correction, the voltage detection is more accurate; can realize fast, flexible control design.
Focus eight: electromagnetic compatibility
High frequency switching power supply of electromagnetic compatibility EMC problem has its particularity. Power semiconductor switch in the switch process from di / dt and DV / DT, causing strong conduction electromagnetic interference and harmonic interference. In some cases would cause a strong electromagnetic field (usually near field radiation ). Not only the serious pollution to the surrounding electromagnetic environment, in the vicinity of the electrical equipment caused by electromagnetic interference, it may endanger the safety of the operating personnel near. At the same time, the power electronic circuit ( such as switching converter ) internal control circuit also must be generated by the action of the switch EMI and application field of electromagnetic noise interference. The particularity, coupled with the EMI on the measurement of specific difficulties, in power electronics EMC field, there are many cross the frontiers of science research topics to be people. Many domestic and foreign university began the power electronic circuit of electromagnetic interference and electromagnetic compatibility issues, and gained many delectable achievement. In recent years the research results show that, in switching converters electromagnetic noise source, mainly to independent switching device to switch the effects produced by the voltage, current change. Changes faster, larger electromagnetic noise.
Focus nine: design and testing technology
Modeling, simulation and CAD is a new design tool. For the simulation of power system, the first to establish the simulation model, including power electronic devices, converters, digital and analog control circuit and magnetic component and magnetic field distribution model, but also consider the switch tube thermal model, the reliability model and EMC model. Various models vary greatly, modelling is the development direction of digital - analog mixed: modeling, hybrid hierarchical modeling as well as various model consisting of a unified multi level model.
Power system CAD, including the main circuit and the control circuit design, component selection, parameter optimization, magnet design, thermal design, EMI design and printed circuit board design, reliability prediction, computer aided synthesis and optimization design. Based on the simulation expert system for power system CAD, the design of the optimization of system performance, reduce design and manufacturing costs, and can make the manufacturability analysis, simulation and CAD technology was twenty-first Century one of the development directions. In addition, the power system thermal test, EMI test, reliability test technology development, research and application and developing.
Focus ten: system integration technology
Power equipment manufacturing features are: non-standard pieces, large labor intensity, long period, high cost, low reliability, and user requirements factory in the production of power products more practical, more reliable, more light weight, lower cost. These circumstances make power supply manufacturers under great pressure, there is an urgent need for integrated power module research and development, so that the power source product standardization, modularization, manufacturability, the scale of production, reducing the cost to realize the aim of.
In fact, in power integrated technology in the development process, has experienced a power semiconductor device module, power and control circuit integration, integrated passive components ( including magnetic integration technology ) development stage. In recent years, will be the direction of the small power system integrated on a chip, can make the product more compact, smaller volume, reduced the length of wire, thus reducing the parasitic parameters. On this basis, can realize the integration of all components, together with the control and protection are integrated into a module.
The last century 90's, along with the large scale distribution of power system development, the integration of design concept was extended to the larger capacity, higher voltage power system integration, improve the integration degree, appeared for integrated power electronics module ( IPEM ). IPEM will power devices and circuits, control and detection, such as the implementation of components integrated package, standard, manufacture module, which can be used for standard design, also can be used for special, special design. The utility model has the advantages of fast and efficient to provide users with products, reduce cost, improve the reliability of.