SNUBBER CIRCUIT AND POWER SEMICONDUCTOR DEVICE HAVING SNUBBER CIRCUIT

摘要

A conventional snubber circuit as the protective circuit of an inverter has an anode reactor, an Si diode and a resistor; since the junction temperature of the Si diode must be held at 125°C or below during an operation, a large heat sink is required, requiring a large number of components and making a reduction in size thereof difficult. In the snubber circuit for circulating electromagnetic energy of the anode reactor, a wide gap semiconductor (SiC) diode not requiring a heat sink or requiring only a small heat sink is employed. When the current density of the SiC diode is increased by a factor of 20-30 as compared with that during a normal temperature operation, on resistance is increased and it can substitute for the resistance of the snubber circuit. Temperature of the SiC diode is elevated by an increase in current density. Since the SiC diode can operate with no trouble even at temperatures of 300°C or thereabout, a large heat sink is not required.