Low fuel consumption: Toyota’s SiC power semiconductors intend to increase fuel efficiency by 10%
At this exhibition, visitors are in a constant stream, and the most interesting thing is the silicon carbide (SiC) power semiconductor exhibited by Toyota. The power semiconductor is the core component of the power control unit (PCU). The function of the PCU is to control the current of the drive motor of the hybrid vehicle (HEV). The use of SiC to make power semiconductors can reduce power loss, greatly reduce the size of the PCU and greatly improve fuel efficiency. Toyota has produced two SiC power semiconductors, a transistor that controls the current switch and a diode that controls the unidirectional current flow (rectification).
The left is a transistor, and the right is a diode. Manufactured on Toyota Motor’s own production line.
SiC power semiconductors are jointly developed by Toyota Motor, Denso, and Toyota Central Research Institute. Toyota Motor has set up a dedicated cleaning workshop for SiC in the company. Except for the wafers that came from the outside world, the rest are basically completed by Toyota.
Using SiC power semiconductors can maintain the same performance and reduce the size of the PCU to about 1/5.
The goal of development is to replace the current Si (silicon) power semiconductors, increase fuel efficiency by 10%, and reduce the size of the PCU to 1/5 of the original. Strive to make PCUs equipped with SiC semiconductors put into practical use around 2020. Regarding the cost issue, Toyota’s commentator said that although the cost of SiC power semiconductors is high, we pay more attention to the advantages of reducing fuel consumption, so we adopt it and hope to reduce costs in other places.
Low fuel consumption: Mitsubishi Electric exhibited the industry’s smallest EV drive system using SiC power semiconductors
Mitsubishi Electric has developed the EV Motor Drive System, a pure electric vehicle (EV) drive system that uses SiC power semiconductors to reduce the size. The inverter’s power module uses SiC power semiconductors. Compared with the existing system using Si power semiconductors, the volume is reduced by half.
In addition to reducing losses, SiC power semiconductors also contribute to the miniaturization of inverters, because compared with Si power semiconductors, the use of SiC power semiconductors can reduce the volume of capacitors and coils in the circuit. The Si transistor cannot be powered off immediately after it is turned off, and will continue to be energized (tail current) for a period of time, but there is no tail current in the SiC transistor. Because there is no tail current, compared with Si, SiC transistors can achieve about 10 times the high-frequency drive (high-speed switching). After high-frequency drive is realized, the amount of electricity stored by the switch in one cycle can be reduced, and the size of the capacitor can also be reduced.
The industry’s smallest EV drive system.
The inverter is embedded in the motor casing to achieve integration. This not only simplifies wiring and wiring, but also combines the motor and inverter cooler into one, thus simplifying the water-cooling piping.
Mitsubishi Electric’s goal is to put this drive system into practical use in 2023. It is hoped that the mass production effect of the popularization of SiC power semiconductors, coupled with miniaturization and integration, will gradually reduce costs.
Small size and light weight: 40% lighter than glass, Toyota Auto Loom realizes resin roofing
Resinizing the entire car roof Toyota Auto Loom exhibited a multifunctional resin roof that evolved from the Toyota Prius’s polycarbonate (PC) two-color molding roof and integrates many devices such as solar cells and cameras. Devices integrated with the roof include cameras (front-view camera and rear-view camera), antennas (shark fin antenna), brake lights (high-position brake lights), and solar cells. When solar cells are embedded, the weight of the new resin roof can be reduced by 40% compared with the use of glass covering. In addition, the resin has a high degree of freedom in shape, and can easily realize shapes that are difficult to make with glass. Because there is no dividing line (joining surface of the parts), resin also has the advantage of good appearance quality.
Small size and light weight: the rear seat back panel is made of bamboo fiber, which is 10% lighter than wood
Compared with wood board, the back board made of bamboo fiberboard has higher strength and lighter weight.
NHK Spring has developed bamboo fiberboard for automotive interior materials. The back seat back panel was made using bamboo fiber produced in Thailand. Compared with the current products using wooden boards, the weight can be reduced by 10%.
The reason why bamboo is considered is that bamboo is a natural resource, and it grows faster than trees, so stable procurement is expected. It takes nearly 60 years for trees to grow from planting to harvesting, while bamboo only takes about 3 years. Moreover, the yield of materials made of bamboo is higher than that of hibiscus. Hibiscus uses only the epidermis, while bamboo can be used except for branches and leaves.
The manufacturing method adopts papermaking, which is the same as the manufacture of washi. The green bamboo is pulverized into a fiber shape with a width of 0.2 mm and a length of about 50-60 mm, and is dried at a temperature of 120° C. for 2 hours to obtain a bamboo fiber material. The material is paper-made, that is, mixed with water and polypropylene (with a particle size of about 200μm) as a binder, and poured on a metal mesh to make a sheet with a thickness of 5-10mm. Then the sheet is heated at a temperature of 130-160°C for about 1 minute, and the sheet is pressed when it becomes soft by heating.
Small and light weight: Dacheng PLAS showcases structural materials that can float on the water, using a three-layer composite structure
A three-layer structure is formed of aluminum, polypropylene (PP), and aluminum.
Dacheng PLAS uses MetalSand, a material with an aluminum plate/polypropylene (PP)/aluminum plate structure, to manufacture the seat frame and place it in the water for display. The frame can float on the water surface, which shows its light weight. In fact, the company exhibited this material in 2013, but this time it has a clear purpose. The company gave a more detailed introduction to the related technology.
MetalSand is a polypropylene with a thickness of 4.0mm enclosed between two aluminum plates with a thickness of 0.25mm. Polypropylene is foamed using the MuCell process in which supercritical nitrogen is blown in. MuCell is a patented process by the Japan Steel Corporation. MetalSand has the same bending strength as 1.6mm thick steel plate (SPCC), but the weight is reduced from 108g to 31g, a reduction of about 70%. This is due to the polypropylene layer that keeps the two aluminum plates at a certain distance, and the stress applied to each aluminum plate is transformed into tensile and compressive axial forces without causing bending. In addition to simple structural materials such as seat frames and floors, it can also be used as a structural material and heat insulating material.
is used in Suzuki HUSTLER. The wall thickness is reduced to 1.5mm, thereby reducing the weight. Use PA66 with 34% glass fiber added.
Small size and light weight: MAHLE, Germany, launched cylinder head covers for light vehicles, reducing weight by reducing the wall thickness to 1.5mm
Mahle, Germany, exhibited the Suzuki light-duty car cylinder head cover, which was reduced in weight by reducing the wall thickness to 1.5mm. The cover adopts the injection molding method, and the resin used is polyamide (PA) 66 with 34% glass fiber added. Suzuki has adopted this cover for the engine R06A of the light car HUSTLER (launched in January 2014). The wall thickness of the cylinder head cover in the past was 2mm, and the weight was reduced by 20% by reducing the thickness. In order to avoid short shots and insufficient strength, ribs are set on the side from the valve to the other side.
Small size and light weight: Toyota Boshoku has developed a new type of separator, which reduces the size to 1/4
The function of the separator is to remove the oil droplets when recovering air leakage (unburned mixed gas leaking to the crankcase). Toyota Boshoku adopts a new method of inertial impact, reducing the size of the separator to about 1/4 of the past. This method is to install a nozzle and a non-woven fabric in the middle of the flow path to accelerate the leakage of the nozzle and the non-woven fabric. touch. After the oil droplets penetrate into the non-woven fabric, they will drip down. In the past, the method used to remove oil droplets was to make the leaked gas pass through a labyrinthine flow path and use the oil droplet’s own weight for separation.
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