At present, the IGBT package form mainly has a module form in which the plastic single tube and the bottom plate are insulated from each main circuit, and the high power IGBT module also has a flat plate crimping form. Since the closed form of the module is extremely convenient for designing the heat sink, it is widely used by major device companies. On the other hand, the IGBT module production process is complicated. In the manufacturing process, more than ten fine lithography engravings are performed, and the corresponding number of high-temperature processing is performed. Therefore, it is necessary to manufacture a large-area, that is, a large-current IGBT single piece, and the yield rate thereof will be Greatly reduced. However, the MOS characteristics of the IGBT make it easier to connect in parallel, so the module package form is more suitable for manufacturing high current IGBTs. At first, due to the use of high-resistance epitaxial wafer technology for IGBTs, it is difficult to break the voltage. Because such high-voltage IGBTs are required to be fabricated, the epitaxial thickness exceeds micrometers, which is technically difficult and practically impossible. In 1996, many companies in Japan used IGBT devices with high-resistance silicon single crystals of <110> crystal planes. The thickness of silicon wafers exceeded 300 micrometers, and the withstand voltage of single-chip IGBTs exceeded 2.5KV. Therefore, Toshiba introduced 1000A/2500V flat panels in the same year. The crimp IGBT device consists of 24 80A/2500V cores in parallel. In 1998, ABB adopted a transparent P+ emitter layer and an N-layer buffer layer structure on the anode side to make the IGBT module withstand voltage as high as 4.5KV. The 1200A/3300V IGBT module developed by the company in the same year is composed of 20 The IGBT chip and 12 FWD chips are made in parallel. Since then, the trial production of non-punch-through (NPT) and soft-through (SPT) structure IGBTs has succeeded in making IGBT devices have a positive temperature coefficient of resistance, which is easier to connect in parallel. This is a high-voltage, high-current IGBT module that requires only parallel connection without the need for series connection. technical foundation. At present, IGBT standard modules of one unit, two units, four units, six units and seven units have been mass-produced, and the highest level has reached 1800A/4500V. Figure 2 is a circuit diagram of a 300A/1700V IGBT module consisting of four 160A/1700V IGBT chips and eight 100A/1700V fast recovery diodes. However, as the module frequency increases and the power increases, the general IGBT module structure with large internal parasitic inductance can not meet the needs of the application. In order to reduce the parasitic inductance inside the module and minimize the overvoltage generated during switching, the ABB company developed a planar low inductance module (ELIP) as shown in Figure 3. The new structure, the main difference between this structure and the general structure is: (1) It uses a lot of wide and booked copper sheets to overlap to form the emitter terminal and the collector terminal, which is parallel to the module copper base plate and is of equal length. The parallel wires are connected directly from the emitter of the IGBT to the emitter terminal, and the collector terminals are connected to the spatial position of the DBC board, thereby eliminating the mutual inductance, limiting the proximity effect and reducing the internal parasitic inductance; (2) many parallel connections Both the IGBT and the FWD chip are soldered on the DBC board without pattern, and the emitter of the IGBT and the anode of the FWD are soldered with a molybdenum buffer sheet, and the gate of the IGBT is connected with the gate current sharing resistor aluminum wire, so that the chip is inter-chip The current distribution and the rectified voltage conditions are the same, which is beneficial to the module chip to work at the same temperature, which greatly improves the module output and reliability; (3) the module adopts a stacked design. Lay the upper and lower insulation layers, the upper and lower electrode terminals, and the printed circuit board on each other, and bond them together with adhesive glue (bubble prevention during bonding), which can circulate well with temperature, without considering the so-called weld stress, ie The so-called electrode "S" shape design. Since the MOS structure IGBT is voltage-driven, the driving power is small, and the IC can be used for driving and control, and then the IGBT chip, the fast diode chip, the control and driving circuit, the overvoltage, the overcurrent, the overheating and the undervoltage are developed. Intelligent IGBT module (IPM) encapsulated in the same insulating case, such as protection circuit, clamp circuit and self-diagnostic circuit, which creates a device for high frequency, miniaturization, high reliability and high performance of power electronic inverter The foundation also makes the design of the whole machine simpler, the design, development and manufacturing cost of the whole machine is reduced, and the time to market of the whole machine is shortened. Since the IPM uses a standardized gate-level interface with logic levels, the IPM can be easily connected to the control board. The self-protection capability of IPM under fault conditions reduces the damage of the device during development and use, and greatly improves the reliability of the whole machine. Previous page
Butterfly valves are commonly used in piping systems to control and regulate flow and speed.
The use of butterfly valve is also relatively simple, easy to operate. And butterfly valve is widely used in all walks of life, is an important control fluid system equipment.
, for air conditioning system: A butterfly valve can control the flow of air conditioning pump and piping system to adjust the temperature of the air conditioning system, so that the air conditioning system can work more efficiently.
2, for water treatment: butterfly valve can be used for water treatment process, can effectively control and adjust the flow of water pipe, carefully adjust the appropriate quality of water.
3, used for power system: butterfly valve can also be used for power system, can effectively control and adjust the flow of water and pressure in the power system, to ensure the normal operation of the power system.
4, used for heating system: butterfly valve can also be used for heating system, can control the flow of hot water piping system and adjust the temperature of the heating system, in order to meet the temperature requirements of the house.
In general, the use of butterfly valves is very wide, from air conditioning systems to water treatment, from power systems to heating systems, a variety of industries can benefit from the use of butterfly valves. Moreover, butterfly valve structure is simple, easy to maintain, for enterprises is also an affordable choice.
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