Protective circuit for a field-effect transistor
AssigneeGKN Automotive AG
InventorRoman Liebsch
Life of this patent
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Abstract
A protective circuit includes a first field-effect transistor having a first drain terminal, a first source terminal and a first gate terminal, a control device by which an electrical first voltage between the first drain terminal and the first source terminal can be determined, and a first temperature sensor by which a first temperature of the first field-effect transistor can be detected, wherein a first resistance of the first field effect transistor and an electrical first current conducted via the first field-effect transistor can be determined by the control device based on the first temperature.
Claims17
A protective circuit comprising:
- a first field-effect transistor having a first drain terminal, a first source terminal and a first gate terminal, wherein the first source terminal is connected to at least one electrical machine and to an electrical ground via the electrical machine;
- a control device by which an electrical first voltage between the first drain terminal and the first source terminal is determinable,
- a first temperature sensor by which a first temperature of the first field-effect transistor is detectable;
- a third field-effect transistor arranged between the electrical machine and the electrical ground;
- and
- a measuring resistor arranged between the third field-effect transistor and the electrical ground;
- wherein a first resistance of the first field-effect transistor and an electrical first current conducted via the first field-effect transistor are determinable by the control device based on the first temperature;
- an electrical third current conducted via the third field-effect transistor is determinable by the control device via the measuring resistor;
- and
- a limit value for a ratio of the electrical first current and electrical third current is stored in the control device, such that specific measures are initiated and control signals are communicated to the gate terminals of the field-effect transistors upon the limit value being reached.
A motor vehicle comprising an electrical machine and a protective circuit, the protective circuit including:
- a first field-effect transistor having a first drain terminal, a first source terminal and a first gate terminal;
- a control device by which an electrical first voltage between the first drain terminal and the first source terminal is determinable;
- a first temperature sensor by which a first temperature of the first field-effect transistor is detectable;
- a third field-effect transistor arranged between the electrical machine and an electrical ground;
- and
- a measuring resistor arranged between the third field-effect transistor and the electrical ground;
- wherein a first resistance of the first field-effect transistor and an electrical first current conducted via the first field-effect transistor are determinable by the control device based on the first temperature;
- wherein the first drain terminal of the first field-effect transistor is connected to the electrical machine and to the electrical ground via the electrical machine
- wherein an electrical third current conducted via the third field-effect transistor is determinable by the control device via the measuring resistor;
- and
- wherein a limit value for a ratio of the electrical first current and electrical third current is stored in the control device, such that specific measures are initiated and control signals are communicated to the gate terminals of the field-effect transistors upon the limit value being reached.
A method for operating an electrical circuit comprising at least one protective circuit including a first field-effect transistor having a first drain terminal, a first source terminal and a first gate terminal, wherein the first source terminal is connected to at least one electrical machine and to an electrical ground via the electrical machine;
- a control device by which an electrical first voltage between the first drain terminal and the first source terminal is determinable;
- a first temperature sensor by which a first temperature of the first field-effect transistor is detectable;
- a third field-effect transistor arranged between the electrical machine and the electrical ground;
- and a measuring resistor arranged between the third field-effect transistor and the electrical ground;
- the method comprising:
- determining an electrical first voltage between the first drain terminal and the first source terminal;
- detecting a first temperature of the first field-effect transistor, wherein a first resistance of the first field-effect transistor and an electrical first current conducted via the first field-effect transistor are determinable by the control device based on the first temperature;
- calculating an electrical first current conducted via the first field-effect transistor based on the detected first temperature;
- determining, by the control device via the measuring resistor, an electrical third current conducted via the third field-effect transistor;
- and
- initiating specific measures and communicating control signals to the gate terminals of the field-effect transistors upon a limit value being reached, wherein the limit value is for a ratio of the electrical first current and electrical third current and is stored in the control device.
Dependencies are inferred from the claim text.