Current sensing of emitter sense insulated-gate bipolar transistor (IGBT)
AssigneeAvago Technologies General IP (Singapore) Pte. Ltd.
InventorsBin Zhang, Hock Tiong Kwa
Life of this patent
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Abstract
A control circuit and method are disclosed for controlling a current sense Insulated-Gate Bipolar Transistor (IGBT). In particular, the current sense IGBT creates voltage spikes in a sense voltage as a result of normal switching operations. The control circuit creates a blank period so that the voltage spikes are ignored and false detections of short-circuit events are avoided.
Claims20
A circuit adapted to sense one or more currents output by an Insulated-Gate Bipolar Transistor (IGBT), wherein the one or more currents output by the IGBT include a sense current and an emitter current, wherein the sense current corresponds to a fractional value of the emitter current, wherein the sense current flows through a sense resistor, thereby creating a sense voltage, the circuit comprising:
- a blank circuit that creates a blank period for a voltage being monitored in connection with the sense voltage, wherein the voltage being monitored is at a node connected to the sense resistor, wherein the blank period is created by the blank circuit pulling the voltage being monitored low, and wherein the blank period blanks out noise spikes created in the sense voltage by transients created in the IGBT during normal switching of the IGBT;
- and
- a filter circuit that enables the voltage being monitored in connection with the sense voltage to at least track the sense voltage after the blank period has ended.
A current sensing system, comprising:
- an Insulated-Gate Bipolar Transistor (IGBT) comprising a collector, emitter, gate, and sense, wherein emitter current flows out of the emitter of the IGBT, wherein sense current flows out of the sense of the IGBT, wherein the sense current is a fractional value of the emitter current, and wherein the sense current flows through a sense resistor, thereby creating a sense voltage;
- and
- a control circuit comprising a filter circuit and a blank circuit, the control circuit being configured to monitor the sense voltage with a sense filter voltage, wherein the blank circuit creates a blank period for the sense filter voltage, wherein the sense filter voltage is at a node connected to the sense resistor, wherein the blank period is created by the blank circuit pulling the sense filter voltage low, and wherein the blank period blanks out noise spikes created in the sense voltage by transients created in the IGBT during normal switching of the IGBT, and wherein the filter circuit enables the sense filter voltage to at least track the sense voltage after the blank period has ended.
A control circuit for controlling a current sense Insulated-Gate Bipolar Transistor (IGBT), the control circuit comprising:
- a blank circuit having a transistor, a resistor, and a capacitor that are configured to create a blank period during which a voltage being monitored in connection with a sense voltage of the IGBT blanks out transients created in the IGBT as a result of the IGBT switching, wherein the voltage being monitored in connection with the sense voltage is at a node connected to the resistor, and wherein the blank period is created by the blank circuit pulling the voltage being monitored low;
- and
- a filter circuit having a filter resistor and a filter capacitor that are configured to enable the voltage being monitored in connection with the sense voltage to at least follow the sense voltage after the blank period has ended, but not before the blank period has ended.
Dependencies are inferred from the claim text.