Method and circuit for protecting power circuits against short circuit and over current faults
First Claim
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1. A protection circuit for high power switching devices, comprising:
- at least one pair of series-connected power devices including a first and a second power device connected between a high side and a low side of a DC bus, respectively;
a first control circuit for activating said power devices to obtain a pulsed output voltage from said power devices;
a gate drive desaturation protection circuit coupled to said first power device;
a current sensing element connected to said low side of said DC bus for sensing a current flowing through said low side;
a second control circuit coupled to said current sensing element for sensing at least one of an over current and a short circuit current flowing in said low side and being effective to turn off said second power device through a gate drive; and
wherein said gate drive desaturation protection circuit is effective to protect said first power device on a cycle by cycle basis against an over current condition until an input into said first power device is disabled in response to a control signal from said second control circuit.
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Abstract
A fault protection circuit for protecting IGBT'"'"'s and other non-latching semiconductor devices in power circuits, for example, power converting/inverting circuits, against phase to phase, phase to earth and shoot through short circuit faults as well as against over current faults. The circuit provides local protection for devices on the high side of such power circuits, and transfers the fault to the low side where it is detected and appropriate control circuitry is activated to latch the fault, thereby avoiding the need for isolcated sensing or feedback to protect the high side devices as well as the complete power circuit.
65 Citations
6 Claims
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1. A protection circuit for high power switching devices, comprising:
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at least one pair of series-connected power devices including a first and a second power device connected between a high side and a low side of a DC bus, respectively; a first control circuit for activating said power devices to obtain a pulsed output voltage from said power devices; a gate drive desaturation protection circuit coupled to said first power device; a current sensing element connected to said low side of said DC bus for sensing a current flowing through said low side; a second control circuit coupled to said current sensing element for sensing at least one of an over current and a short circuit current flowing in said low side and being effective to turn off said second power device through a gate drive; and wherein said gate drive desaturation protection circuit is effective to protect said first power device on a cycle by cycle basis against an over current condition until an input into said first power device is disabled in response to a control signal from said second control circuit. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification