A SiC epitaxial wafer includes a SiC substrate and a SiC epitaxial layer disposed on the SiC substrate. The SiC epitaxial layer includes a high carrier concentration layer and two low carrier concentration layers having lower carrier concentration than the high carrier concentration layer, and being in contact with a top surface and a bottom surface of the high carrier concentration layer to sandwich the high carrier concentration layer. A difference in carrier concentration between the high carrier concentration layer and the low carrier concentration layers is 5×10.sup.14/cm.sup.3 or more and 2×10.sup.16/cm.sup.3 or less.

A SiC epitaxial wafer includes a SiC substrate and a SiC epitaxial layer disposed on the SiC substrate. The SiC epitaxial layer includes a high carrier concentration layer and two low carrier concentration layers having lower carrier concentration than the high carrier concentration layer, and being in contact with a top surface and a bottom surface of the high carrier concentration layer to sandwich the high carrier concentration layer. A difference in carrier concentration between the high carrier concentration layer and the low carrier concentration layers is 5×10.sup.14/cm.sup.3 or more and 2×10.sup.16/cm.sup.3 or less.

A circuit device includes: a first terminal; a second terminal; a first thyristor circuit whose one end is coupled to the first terminal; a second thyristor circuit whose one end is coupled to the second terminal; and a voltage setting circuit that is shared by the first thyristor circuit and the second thyristor circuit and through which a current from the first thyristor circuit when the first thyristor circuit is turned on and a current from the second thyristor circuit when the second thyristor circuit is turned on flow. The voltage setting circuit sets a voltage at other end of the first thyristor circuit to a first voltage when the first thyristor circuit is turned on, and sets a voltage at other end of the second thyristor circuit to a second voltage when the second thyristor circuit is turned on.

A circuit device includes: a first terminal; a second terminal; a first thyristor circuit whose one end is coupled to the first terminal; a second thyristor circuit whose one end is coupled to the second terminal; and a voltage setting circuit that is shared by the first thyristor circuit and the second thyristor circuit and through which a current from the first thyristor circuit when the first thyristor circuit is turned on and a current from the second thyristor circuit when the second thyristor circuit is turned on flow. The voltage setting circuit sets a voltage at other end of the first thyristor circuit to a first voltage when the first thyristor circuit is turned on, and sets a voltage at other end of the second thyristor circuit to a second voltage when the second thyristor circuit is turned on.

A power inverter includes a bridge circuit including a first half-bridge and a second half-bridge, each half-bridge including a high-side device and a low-side device, and a gate driver circuit connected with each gate of the high-side device and low-side power device of the first and second half-bridges and operable to provide each gate with a respective voltage to control operation of the respective power device. The gate driver is operable to provide a first voltage which is higher than a first threshold voltage of the respective power device, and a second voltage which is higher than a surge threshold of the respective power device. The surge threshold is higher than the first threshold and defines the onset of a surge current operation area of the respective power device at which the power device becomes conducts a surge current that is larger than the rated current of the device.

A power inverter includes a bridge circuit including a first half-bridge and a second half-bridge, each half-bridge including a high-side device and a low-side device, and a gate driver circuit connected with each gate of the high-side device and low-side power device of the first and second half-bridges and operable to provide each gate with a respective voltage to control operation of the respective power device. The gate driver is operable to provide a first voltage which is higher than a first threshold voltage of the respective power device, and a second voltage which is higher than a surge threshold of the respective power device. The surge threshold is higher than the first threshold and defines the onset of a surge current operation area of the respective power device at which the power device becomes conducts a surge current that is larger than the rated current of the device.

A static transfer switch is provided for supplying power to a load alternately from two different power sources. Preferably, switching between the two power sources occurs within one electrical cycle. In order to control inrush currents and reduce disruption during power transfers between the two power sources, switches are provided to configure which input phases are connected to the output phases.

A static transfer switch is provided for supplying power to a load alternately from two different power sources. Preferably, switching between the two power sources occurs within one electrical cycle. In order to control inrush currents and reduce disruption during power transfers between the two power sources, switches are provided to configure which input phases are connected to the output phases.

Provided is multi-phase interleaving control in a power supply device. In power control by the power supply device where the dead beat control is applied to the multi-phase interleaving, combined current of the multi-phase current values is used as control current in the multi-phase control based on the multi-phase interleaving, thereby achieving control independent of the number of the detectors and the control system independent of the number of phases, and further, this control current is used to perform constant current control, so as to prevent overshooting and undershooting. The power supply device has multi-phase interleaving control that performs multi-phase control using a plurality of phase current values, provided with an LC chopper circuit constituting a step-down chopper circuit that operates according to the multi-phase control of multi-phase interleaving, and a controller for performing step response control according to the multi-phase control of the LC chopper circuit.

Inductors that generate a reduced spurious electric-field. One example can provide an inductor where the terminals of the inductor are located at positions that reduce the spurious electric field by determining the types of signals conveyed at the terminals of the inductor and then selecting locations for the terminals based on that determination. For example, where a dynamic differential signal is applied to the inductor, the terminals of the inductor can be positioned near a physical center of the inductor.