Motor drive

A motor drive with three arms each including a first IGBT and a second IGBT, both connected in series between major terminals, the motor drive being adapted to drive a three-phase AC motor which is a load, the motor drive further comprising:

• three level-shifting circuits each for transmitting a gate signal of the first IGBT connected to a high-voltage side of any one of the arms, from a low-voltage circuit to a high-voltage circuit;
• wherein each arm has an upper arm section and a lower arm section, wherein the first IGBT is located in the upper arm section and the second IGBT is located in the lower arm section, and the motor drive has a circuit composition in which a difference between a grounding voltage of the lower arm section and a grounding voltage of the upper arm section is equal to ΔV1+ΔV2 generated by a change of current and a wiring inductance at the transitional period ON/OFF of the first IGBT which exceeds an operating voltage HVcc of a control power supply for controlling the first IGBT of the upper arm section;
• wherein ΔV1 is a voltage change caused by a time change dI1/dt from a maximum value of a current in the lower arm second electric power semiconductor-switching element to a steady current and by a wiring inductance in the lower arm section;
• wherein ΔV2 is a voltage change caused by a decrement dI2/dt in a recovery current of the upper arm first IGBT and by a wiring inductance in the upper arm section;
• and
• wherein:
• a signal-transmitting high-withstand-voltage element of each of the three level-shifting circuits is an IGBT;
• and wherein:
• the signal-transmitting high-withstand-voltage IGBT includes a first p-type semiconductor layer;
• an n− layer which is a second semiconductor layer formed on the first p-type semiconductor layer;
• a third p-type semiconductor layer formed in the n− layer which is the second semiconductor layer;
• and
• a fourth n-type semiconductor layer formed in the third semiconductor layer;
• and further wherein:
• a gate electrode is disposed via an oxide film formed on an exposed section of the semiconductor substrate surface on which are formed the second semiconductor layer, the third semiconductor layer, and the third semiconductor layer;
• a collector electrode is disposed abutting on the first semiconductor layer;
• a source electrode is disposed abutting on both the third semiconductor layer and the fourth semiconductor layer;
• and
• the n− layer which is the second semiconductor layer is thicker than a depletion layer which spreads when a rated voltage is applied.

A motor drive with three arms each including a first IGBT and a second IGBT, both connected in series between major terminals, the motor drive being adapted to drive a three-phase AC motor which is a load, the motor drive further comprising:

• three level-shifting circuits each for transmitting a gate signal of the first IGBT connected to a high-voltage side of any one of the arms, from a low-voltage circuit to a high-voltage circuit;
• wherein each arm has an upper arm section and a lower arm section, wherein the first IGBT is located in the upper arm section and the second IGBT is located in the lower arm section, and the motor drive has a circuit composition in which a difference between a grounding voltage of the lower arm section and a grounding voltage of the upper section arm is equal to ΔV1+ΔV2 generated by a change of current and a wiring inductance at the transitional period ON/OFF of the first IGBT which exceeds an operating voltage HVcc of a control power supply for controlling the first IGBT of the upper arm section;
• wherein ΔV1 is a voltage caused by a time change dI1/dt from a maximum value of a current in the lower arm second electric power semiconductor-switching element to a steady current and by a wiring inductance in the lower arm section;
• wherein ΔV2 is a voltage change caused by a decrement dI2/dt in a recovery current of the upper arm first IGBT and by a wiring inductance in the upper arm section;
• and
• wherein:
• a signal-transmitting high-withstand-voltage element of each of the three level-shifting circuits is an IGBT;
• and wherein:
• a semiconductor chip with the signal-transmitting high-withstand-voltage IGBT formed therein, and another semiconductor chip in which an arm-driving circuit and a logical circuit are formed constitute a semiconductor device mounted in a resin-molded condition in one package.