Protection circuit for power management semiconductor devices and power converter having the protection circuit
First Claim
1. A protection circuit for a power semiconductor device having a collector, a gate, and an emitter, the circuit comprising:
- a first comparator which detects a collector voltage of said power semiconductor device to output a first detection signal when the detected collector voltage exceeds a first reference voltage;
a second comparator which detects a gate voltage of said power semiconductor device to output a second detection signal, when the detected gate voltage exceeds a second reference voltage which is set, relative to the potential at the emitter of said power semiconductor device, to be lower than a line power voltage of a drive circuit for outputting a drive signal that drives said power semiconductor device and to be higher than a terraced voltage of the power semiconductor device, the terraced voltage being a gate voltage allowing a rated collector current to flow at the collector of the power semiconductor device and being higher than a threshold voltage to turn on said power semiconductor device, the rated collector current being higher than an initial current flowing at the collector when the threshold voltage is applied to the gate;
logic means for outputting a protection start signal when both the first and second detection signals are being output; and
gate voltage reduction means for reducing said gate voltage in accordance with the protection start signal from said logic means.
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Accused Products
Abstract
A collector voltage of a power management semiconductor device is detected by a first comparator, and when the detected collector voltage exceeds a first reference voltage, the first comparator outputs a first detection signal. Furthermore, a gate voltage of the power management semiconductor device is detected by a second comparator, and when the detected gate voltage exceeds a second reference voltage, the second comparator outputs a second detection signal. The second reference voltage is a minimum gate voltage for feeding a rated power to the power management semiconductor device or over, and less than a line power voltage of a drive circuit of the power management semiconductor device. When both the first detection signal and second detection signal are being outputted, the gate voltage is reduced by a gate voltage reduction means so as to protect the power management semiconductor device from overcurrent and overvoltage.
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Citations
13 Claims
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1. A protection circuit for a power semiconductor device having a collector, a gate, and an emitter, the circuit comprising:
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a first comparator which detects a collector voltage of said power semiconductor device to output a first detection signal when the detected collector voltage exceeds a first reference voltage; a second comparator which detects a gate voltage of said power semiconductor device to output a second detection signal, when the detected gate voltage exceeds a second reference voltage which is set, relative to the potential at the emitter of said power semiconductor device, to be lower than a line power voltage of a drive circuit for outputting a drive signal that drives said power semiconductor device and to be higher than a terraced voltage of the power semiconductor device, the terraced voltage being a gate voltage allowing a rated collector current to flow at the collector of the power semiconductor device and being higher than a threshold voltage to turn on said power semiconductor device, the rated collector current being higher than an initial current flowing at the collector when the threshold voltage is applied to the gate; logic means for outputting a protection start signal when both the first and second detection signals are being output; and gate voltage reduction means for reducing said gate voltage in accordance with the protection start signal from said logic means. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An inverter for converting DC current to AC current, the inverter comprising:
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a power semiconductor device for converting DC current to AC current; and a control unit which controls a switching operation of said power semiconductor device, said control unit comprising; a first comparator which detects a collector voltage of said power semiconductor device to output a first detection signal when the detected collector voltage exceeds a first reference voltage; a second comparator which detects a gate voltage of said power semiconductor device to output a second detection signal, when the detected gate voltage exceeds a second reference voltage which is set, relative to the potential at the emitter of said power semiconductor device, to be lower than a line power voltage of a drive circuit for outputting a drive signal that drives said power semiconductor device and to be higher than a terraced voltage of the power semiconductor device, the terraced voltage being a gate voltage allowing a rated collector current to flow at a collector of the power semiconductor device and being higher than a threshold voltage to turn on said power semiconductor device, the rated collector current being higher than an initial current flowing at the collector when the threshold voltage is applied to the gate; logic means for outputting a protection start signal when both the first and second detection signals are being output; gate voltage reduction means for reducing said gate voltage in accordance with the protection start signal from said logic means; and computer processor means for controlling the ON/OFF operation of said power semiconductor device. - View Dependent Claims (12, 13)
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Specification