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May 28th, 2012
Denso reveals details of 60kW/L SiC inverter
The volume of the inverter is 0.5L. The output density of 60kW/L was recorded when the output was 30kWh. At that time, the temperature of the power device rose to about 180°C.
Denso Corp exhibited an inverter with an output power density of 60kW/L and disclosed its details at the 2012 Automotive Engineering Exposition, which took place from May 23 to 25, 2012, in Yokohama, Japan.
The prototyped inverter (left) and a case containing the inverter (right).
Denso also reduced power loss. Compared with an inverter using a silicon (Si)-based IGBT, it is possible to reduce power loss by 68% (30Arms). The inverter consists of (1) a module equipped with silicon carbide (SiC)-based power devices, (2) control circuit that drives the devices, (3) cooling fin, (4) cooling fan, (5) capacitor, etc.
For the inverter module, Denso employed a SiC-based trench MOSFET as a transistor, and it uses the body diode in the MOSFET as a diode to reduce module size. The withstand voltage and on-resistance of the SiC-based MOSFET are 1,200V and 30mΩ, respectively. Its chip size is approximately 5 x 5mm.
SiC-based MOSFETs are mounted on the lower side of the film capacitor.
The inverter module is equipped with SiC-based MOSFETs for the high and low sides (for three phases). For each of the high and low sides for one phase, three SiC-based MOSFET chips connected in parallel are used. Therefore, the entire inverter module has 18 chips.
The MOSFET approximately measures 5 x 5mm. It is possible to flow a current of 100A, but, this time, Denso designed the chip so that a current of 70A flows with three chips. In other words, a current of 23A flows in each chip. Also, the company reduced inductance components of the inverter module's package.
Denso developed the new inverter in a joint research and development project with Toyota Motor Corp and Toyota Central R&D Labs Inc.
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