New SiC Power Module with Dramatically Reduced Surge Noise

ROHM Co., Ltd. has announced the development of a power module that integrates SiC MOSFETs and Schottky barrier diodes for significantly lower switching loss compared to conventional silicon-based power modules. SiC offers faster switching speeds and lower switching loss than silicon. However there are drawbacks, including higher surge voltage, which results in greater EMI noise and reduced reliability.

ROHM’s proprietary circuit structure dramatically reduces surge voltage – by 35% compared to previous products, from 250V to 150V (600V/100A operation at 125ºC). The result is 77% less switching loss vs. silicon-based products at the same surge voltage. These improvements make ROHM SiC power modules ideal for solar power generation equipment and power conversion devices, such as general-purpose inverters, requiring minimal heat generation during high frequency operation, low temperature dependence, and high resistance to thermal runaway at high temperatures.

In addition to SiC Schottky barrier diodes and MOSFETs, ROHM has begun sample shipments of this new power module now. A controller will soon be offered that integrates protection circuits and gate drivers. Other SiC-based products are also had being developed in collaboration with Honda Co., Ltd.

■Key Features

1. Reduced switching loss (77% less compared to conventional Si modules)
2. Lower heat generation during high-frequency operation (64% less than conventional Si modules)
3. Low temperature dependence and high resistance to thermal runaway

■Terminology

1. Switching Loss
   The power loss that occurs primarily during ON/OFF operation, typically in a transistor or thyristor.
   
2. Surge Voltage
   The voltage generated in excess of the steady state in an electrical circuit or the like. The primary culprit is a parasitic coil capacitor (inductance component) in the circuit.
3. MOSFET (Metal Oxide Semiconductor Field Effect Transistor)
   A metal-oxide-semiconductor field effect transistor – the structure most commonly utilized for FETs. Mainly used as a switching element.
4. Schottky Barrier Diode
   A diode with rectifying properties (diode characteristics) due to the formation of a Schottky junction, in which a metal and a semiconductor are placed in contact with one another (in contrast to doped P and N junctions). The absence of the minority carrier storage effect gives the diode excellent high-speed performance.
   
5. Bridge Circuit
   A circuit equipped with switching devices on both the high and low sides, which are alternately turned ON and OFF. Types of circuits include half-bridge, single-phase bridge, and three-phase bridge circuits.
   
6. SiC (Silicon Carbide)
   A compound semiconductor featuring superior solid state characteristics: approx. 3 times the band gap, 10 times the dielectric breakdown field, and 3 times the thermal coefficient of silicon. These advantages make it a promising material for power devices.