Rohm Co Ltd developed a module that uses silicon carbide (SiC)-based power devices and has an output density as high as 145kW/L.
The output density of the module (including a gate driver circuit, cooling fins and smoothing capacitor) is the highest in the industry, Rohm said. It can drive a 60kW three-phase alternating-current (AC) motor and has a withstand voltage of 600V and an output current of 600A.
Rohm confirmed a 20kHz switching operation with a voltage of 350V and a current of 575A. The module was prototyped for automotive use and operates even at a temperature of 200°C.
The prototype uses six small modules, each of which is a so-called "1-in-1" type and equipped with a high-side (or low-side) transistor for one phase. For the transistor, Rohm employed an SiC MOSFET having a "double trench structure" and used the body diode of the MOSFET.
Each small module is equipped with five chips of the MOSFET. Its withstand voltage and on-resistance are 600V and about 1mΩcm2, respectively.
This time, Rohm used a capacitor that is currently being developed by the company and whose capacity does not lower much even at a high temperature. Even when a temperature rises from a room temperature to 225°C, its capacity lowers only by about 10%. In the case of normal laminated ceramic capacitors, their capacities lower by about 50% under the same condition.
The capacity of the capacitor is 0.1μF, and its dimensions are 39 x 33 x 3mm.