IGBT accounts for about half of the cost of the motor drive system, while the motor drive system accounts for 15-20% of the total vehicle cost, which means that the IGBT accounts for 7-10% of the total vehicle cost, which is the second highest component except the battery. It also determines the energy efficiency of the vehicle.
Not only the motor drive uses IGBTs, but also the new energy generators and air conditioners. It is precisely because IGBT is too important, Toyota has determined that the IGBT tube should be completely controlled in the development of the hybrid vehicle. Toyota is also the only auto manufacturer that can produce its own IGBT tube. The Prius also gains strong vitality and is currently the only one in the world. Strong hybrid car.
Not only the core of new energy vehicles, DC charging piles and locomotives (high-speed rail) are IGBT tubes, and the raw material cost of 30% of DC charging piles is IGBT. Electric locomotives generally require 500 IGBT modules, EMUs require more than 100 IGBT modules, and one metro requires 50-80 IGBT modules.
Mitsubishi Electric's HVIGBT has become the industry's default standard. China's high-speed locomotive IGBTs are completely monopolized by Mitsubishi. At the same time, Alstom, Siemens and Bombardier in Europe are more than half of Mitsubishi Electric's IGBTs.
In addition to Japanese manufacturers, Infineon has swept all the IGBTs of electric vehicles, and Mitsubishi Electric is intoxicated by the high profits of China's high-speed rail. It has almost nothing in the market below 2500V.
In an electric vehicle, the motor can be regarded as a compressor. The two principles are almost identical.
For hybrid power, in addition to the drive motor, there is also a generator that can be powered by the engine of the car and then charged to the battery after AC/DC conversion by the IGBT module. In DM models, the generator can also act as a drive motor.
The most common form of IGBT is actually a module, not a single tube. The three basic features of the module: multiple chips are assembled to the metal substrate in an insulating manner; the hollow plastic case is encapsulated, and the insulating material with air is high-pressure grease or silicone grease, and other possible soft insulating materials; the same manufacturer For the same technology series, the technical characteristics of the IGBT module are basically the same as those of the IGBT single tube of the same specification.
The main advantages of the module are as follows: multiple IGBT chips are connected in parallel, and the current specifications of the IGBT are larger. Multiple IGBT chips are combined in a specific circuit form, such as a half bridge, a full bridge, etc., to reduce the complexity of external circuit connections. Multiple IGBT chips are on the same metal substrate, which is equivalent to adding a soaking plate between the independent heat sink and the IGBT chip, which is more reliable. Multiple IGBT chips in a module are screened by the module manufacturer and have better parameter consistency than commercially available discrete components. The connection between the multiple IGBT chips in the module is better than the external connection of a plurality of discrete single tubes, and the lead inductance is smaller. The module's external lead terminals are more suitable for high voltage and high current connections. For the same series of products from the same manufacturer, the highest voltage level of the module is generally 1-2 higher than that of the IGBT single tube. If the maximum voltage specification of the single tube product is 1700V, the module has 2500V, 3300V or even higher voltage specifications.
Industrial grade IGBT vs. car IGBT
The first point to solve the heat dissipation is to improve the thermal conductivity and the ability of the IGBT module to withstand the power cycle. The internal lead technology of the IGBT module has undergone the process of thick aluminum wire bonding, aluminum tape bonding and copper wire bonding. Increased current carrying density.
Second, the new soldering process, the traditional solder is tin-lead alloy, low cost, simple process, but there are environmental pollution problems, and the chip temperature of the vehicle power module is close to the melting point of tin-lead solder (220 ° C).
The third point is to improve the DBC and the module backplane, reduce the thermal resistance of the heat dissipation, improve the thermal reliability, reduce the volume, and reduce the cost. Conventional ceramics such as Al2O3 and Si3N4 in DBC are replaced by materials such as AlN and AlSiC, which have higher thermal conductivity and better matching with the thermal expansion coefficient of Si material.
In addition, new heat dissipation structures, such as Pin Fin and Shower Power, significantly reduce the overall thermal resistance of the module and improve heat dissipation. The seventh generation of Mitsubishi uses a thick copper ceramic substrate to greatly improve the thermal conductivity.
The fourth point is to expand the connection area between the module and the heat sink, such as terminal crimping technology.
The key to heat dissipation is materials, and material science is a manifestation of a country's basic science. China is very backward in this respect, and Japan is far ahead, not only in Germany but also in the United States.