Interface circuit, power conversion device, and vehicle-mounted electric machinery system

An interface circuit comprising:

• a signal transmission circuit;
• and
• an automatic potential selection circuit for automatically selecting a potential of an operating power supply voltage for said signal transmission circuit,
• wherein a plurality of different potentials are applied to said automatic potential selection circuit, which selects one therefrom,
• wherein a first potential, a second potential, and said selected potential are applied to said signal transmission circuit, said signal transmission circuit having a first voltage inverter circuit being operated on the basis of a potential difference between said selected potential and said first potential and a second voltage inverter circuit being operated on the basis of a potential difference between said selected potential and said second potential and for inputting the output signal from said first voltage inverter circuit, and
• wherein via said first and second voltage inverter circuits, a signal having said first potential as reference is converted into a signal having said second potential as reference to be transmitted.

An interface circuit comprising:

• a signal transmission circuit;
• and
• a potential selection circuit for selecting a potential for the operating power supply voltage for said signal transmission circuit,
• wherein a plurality of different potentials are applied to said potential selection circuit, which selects one of said plurality of potentials in response to a switch instruction signal,
• wherein a first potential, a second potential, and said selected potential are applied to said signal transmission circuit, said signal transmission circuit having a first inverter circuit being operated on the basis of a potential difference between said selected potential and said first potential and a second inverter circuit being operated on the basis of a potential difference between said selected potential and said second potential and for inputting the output signal from said first voltage inverter circuit,
• wherein via said first and second voltage inverter circuits, a signal having said first potential as reference potential is converted into a signal having said second potential as reference to be transmitted.

A semiconductor integrated circuit device comprising a signal transmission circuit between circuits having different signal reference potentials, said device having a plurality of terminals, said plurality of terminals comprising:

• a first terminal having a low-potential point of a first power supply as a first potential;
• a second terminal having a high-potential point of said first power supply as a second potential;
• a third terminal having a low-potential point of a second power supply as a third potential;
• a fourth terminal having a high-potential point of said second power supply as a fourth potential;
• a fifth terminal via which a voltage signal having said first potential as reference potential is inputted;
• a first voltage inverter circuit being operated on the basis of a potential difference between said first potential and said second potential and for inverting said voltage signal;
• a second voltage inverter circuit being operated on the basis of a potential difference between said third potential and said fourth potential and for inverting said voltage signal outputted from said first voltage inverter circuit;
• and
• a sixth terminal via which a voltage signal from said second voltage inverter circuit as reference potential is outputted.

A power conversion device for converting power fed from a power supply source into a predetermined power that is outputted, comprising:

• a conversion unit having a switching semiconductor device;
• a control unit for outputting a control signal for controlling the operation of said switching semiconductor device;
• and
• a drive unit for outputting a drive signal for operating said switching semiconductor device to said conversion unit, in response to said control signal,
• wherein said drive unit comprises:
• a driving interface circuit responsive to said control signal;
• and
• a drive circuit for outputting said drive signal,
• wherein a plurality of different potentials are applied to said driving interface circuit, which selects one of said plurality of potentials and said driving interface circuit having a first voltage inverter circuit being operated on the basis of a potential difference between said selected potential and the reference potential of said control signal, and a second voltage inverter circuit being operated on the basis of a potential difference between said selected potential and a potential different from the reference potential of said control signal and for inputting the output signal from said first voltage inverter circuit, said driving interface circuit being adapted to output, in response to said control signal, a signal from said second voltage inverter circuit to said drive circuit,
• wherein said drive circuit, in response to said signal outputted from said driving interface circuit, outputs said drive signal for operating said semiconductor switching device, and
• wherein said conversion unit, as a result of the operation of said switching semiconductor device based on said drive signal, converts power fed from the power supply source into a predetermined power.

A vehicle-mounted electrical machinery system for converting power fed from a vehicle-mounted power supply into an electric driving force, comprising:

• an electric motor for generating electric driving force;
• and
• a power conversion device for controlling the power fed from said vehicle-mounted power supply and feeding it to said electric motor,
• wherein said power conversion device converts power fed from said vehicle-mounted power supply into a predetermined power and feeds it to said electric motor, said power conversion device comprising:
• a conversion unit having a switching semiconductor device;
• a control unit for outputting a control signal for controlling the operation of said switching semiconductor device;
• and
• a drive unit for outputting, in response to said control signal, a drive signal for operating said switching semiconductor device to said conversion unit,
• wherein said drive unit comprises:
• a driving interface circuit responsive to said control signal;
• and
• a drive circuit for outputting said drive signal,
• wherein a plurality of different potentials are applied to said driving interface circuit, which selects one of said plurality of potentials and said driving interface circuit having a first voltage inverter circuit being operated on the basis of a potential difference between said selected potential and a reference potential of said control signal, and a second voltage inverter circuit being operated on the basis of a potential difference between said selected potential and a potential different from the reference potential of said control signal and for inputting the output signal from said first voltage inverter circuit, said driving interface circuit being adapted to output, in response to said control signal, a signal from said second voltage inverter circuit to said drive circuit,
• wherein said driving circuit, in response to said signal from said driving interface circuit, outputs said drive signal for operating said semiconductor switching device,
• wherein said conversion unit converts the power fed from the vehicle-mounted power supply into a predetermined power as said switching semiconductor device is operated by said drive signal,
• and wherein said electric motor generates a driving force using the power fed from said conversion unit.