views: 1831 time: 2022-06-09
IGBT is an isolatedgatebipolar thyristor. It is a new composite power electronic device that was born in the early 1980s and developed rapidly in the 1990s. IGBT combines the advantages of MOSFET and GTR. It not only has high input impedance, fast speed, good thermal stability, voltage driven, but also has the advantages of reduced on state voltage, high voltage and large current. Applications with power ranging from 5000 watts to hundreds of kilowatts. IGBT devices will continue to open up new application fields, providing new business opportunities for energy efficiency, new energy and industrial automation (high-frequency electric welding machine, high-frequency ultrasonic, inverter, chopper, ups/eps, induction heating). The following are the basic instructions.
(1) Select modules with appropriate specifications according to the working voltage, rated current and use frequency of the load.
Before using the module, please read the module parameter data sheet in detail to understand the technical indicators of the module; Determine the use scheme according to the technical parameters of the module, calculate the on state loss and switching loss, and select the matching radiator and drive circuit.
(2) Use of IGBT module
1. anti static IGBT is an electrostatic sensitive device. In order to prevent the device from being damaged by static electricity, the following two points should be paid attention to:
① The black sponge on the drive terminal of IGBT module is anti-static material. When the user uses the connector lead, remove the anti-static material and insert the lead immediately; Do not touch the drive terminal by hand without anti-static measures.
② When the drive terminal needs to be welded, the equipment or electric soldering iron must be grounded.
2. selection and use
① Please use it within the maximum rated value (voltage, current, temperature, etc.) of the product. Once the maximum rated value is exceeded, the product may be damaged. In particular, avalanche breakdown may occur when the IGBT is applied with a voltage exceeding the Vces, resulting in component damage. Please use it within the rated value of the Vces! The higher the operating frequency, the smaller the operating current; For reasons of reliability, the safety factor must be considered.
② Drive circuit: due to the compromise between igbtvce (SAT) and short-circuit tolerance, it is recommended to select the grid voltage as +vge=14 ~ 15V and -vge=5 ~ 10V to ensure that the drive voltage and waveform on the drive terminal of the module meet the drive requirements; The grid resistance Rg is closely related to the turn-on and turn off characteristics of IGBT. When the value of RG is reduced, the switching loss is reduced, the fall time is reduced, and the turn off pulse voltage is increased; On the contrary, when the grid resistance Rg increases, the switching loss will increase and the switching frequency will be affected; The appropriate RG value shall be selected according to the best compromise between surge voltage and switching loss (related to frequency), generally between 5 Ω and 100 Ω. To prevent open circuit of grid, it is recommended to connect 10K ~ 20K Ω resistor in parallel between grid and emitter. Drive wiring shall be as short as possible and twisted pair shall be used; When the power supply is input, please input the power supply of the driving control part first to make the driving circuit work, and then input the power supply of the main circuit.
③ Protection circuit: when the IGBT module is used at high frequency, the wiring inductance is easy to generate peak voltage. Attention must be paid to reducing the configuration of wiring inductance and components. Attention should be paid to the following protection items: overcurrent protection, overvoltage protection, grid overvoltage and undervoltage protection, safe working area, over-temperature protection.
④ Absorption circuit: because IGBT switches fast, it is easy to generate surge voltage, so surge clamp circuit must be set.
⑤ Parallel operation: grid circuit, line wiring, current imbalance and temperature imbalance between devices shall be considered, positive temperature coefficient shall be selected, and saturation voltage drop shall be at the same level (the same batch).
⑥ Please avoid the place where corrosive gas and serious dust are generated.
(3) IGBT installation
① The radiator shall be matched and selected according to the use environment and module parameters to ensure the requirements for the radiator when the module works.
② The surface finish of the radiator shall be less than 10mm, and the plane distortion between each screw shall be less than 10mm. If there is a depression on the surface of the radiator, it will increase the contact thermal resistance. In order to reduce the contact thermal resistance, it is recommended to apply a thin layer of heat transfer paste between the radiator and the module. After the module is uniformly stressed, it is best to see that a little heat transfer paste is extruded from the edge of the module. (it is better to use screen printing technology to print thermal conductive paste on the surface of radiator)
③ When the module is installed on the radiator, the screws shall be tightened with the torque given in the manual. Insufficient torque leads to increased thermal resistance or screw looseness during movement. Excessive torque may damage module shell or module insulation;
④ When only one module is installed, it shall be installed in the center of the radiator to achieve the best thermal resistance effect.
⑤ When installing several modules, corresponding space shall be reserved according to the heating condition of each module, and more space shall be reserved for modules with large heating.
⑥ When installing fastening screws at two points, first tighten 1/3 of the rated torque in turn, and then reach the rated torque in reverse order.
⑦ The four point installation is similar to the two-point installation. The long direction of IGBT follows the pattern of radiator. When tightening the screws, tighten 1/3 of the rated torque diagonally, and then reach the rated torque in reverse order.
⑧ When using a heat sink with a grain, the IGBT length follows the grain of the heat sink to reduce the deformation of the heat sink. When the two modules are installed on one radiator, they shall be placed side by side in a short direction with sufficient distance between them. The main reason is that the fan reduces the heat superposition during heat dissipation, which is easy to dissipate heat and maximize the efficiency of the radiator.
Second, the module terminals are easy to connect, which is conducive to reducing stray inductance, especially in high-frequency use.
⑨ When connecting devices, the bus bar connecting the module shall not cause excessive mechanical and thermal stress to the main terminal electrode of the module, so as to avoid internal welding fracture of the module electrode or overheating of the electrode terminal due to heating.