Accident detection circuit of a voltage-type self-excited power converter

An accident detection circuit of a voltage-type self-excited power converter having an arm series circuit in which a plurality of arm circuits are connected in series, said each arm circuit comprising a power semiconductor element of self turn off type, a diode connected in anti-parallel to said semiconductor element and an anode reactor for suppressing the current rising rate which is connected in series to the anode included in the semiconductor element, which comprises:

• voltage direction-detecting means which is connected, respectively, in parallel to the anode reactor of said each arm circuit, and detects that a voltage generated in said each anode reactor and applied in a direction exceeds a predetermined value when the current flowing in the direction of from the anode to the cathode of said each semiconductor element increases,
• arm current direction-detecting means which is provided in every said arm circuit and detects that the current flows in the direction of from the anode to the cathode of said each semiconductor element,
• delay means which is provided for every said arm circuit and delays an output signal of said arm current direction-detecting means by a certain period of time, and
• output means which is provided for every said arm circuit, and inputs the output signal of said each voltage-direction-detecting means and the output signal of said each delay means, and designates the output signals as the accident detection signal of said power converter when both output signals are simultaneously present.

An accident detection circuit of a voltage-type self-excited power converter having an arm series circuit in which a plurality of arm circuits are connected in series, said each arm circuit comprising a power semiconductor element of self turn off type and an anode reactor for suppressing the current rising rate which is connected in series to the anode included in the semiconductor element, which comprises:

• voltage direction-detecting means which detects, respectively, that a voltage generated in the anode reactor of said each arm circuit and applied in a direction exceeds a predetermined value when the current flowing in the direction of from the anode to the cathode of every semiconductor element of said each arm circuit increases,
• continuity period-control means which controls, respectively, the continuity period of the semiconductor element of said each arm circuit,
• delay means which delays, respectively, an output signal of said each continuity period-control means by a certain period of time, and
• output means which designates the output signals as the accident detection signal of said power converter when the output signal of said voltage direction-detecting means and the output signal of said delay means are simultaneously present in every said arm circuit.

An accident detection circuit of a voltage-type self-excited power converter having an arm series circuit in which a plurality of arm circuits are connected in series, said each arm circuit comprising a power semiconductor element of self turn off type, a diode connected in anti-parallel to said semiconductor element and an anode reactor for suppressing the current rising rate which is connected in series to the anode included in the semiconductor element, which comprises:

• voltage direction-detecting means which is connected, respectively, in parallel to the anode reactor of said each arm circuit, and detects that a voltage generated in the anode reactor of said each arm circuit and applied in a direction exceeds a predetermined value when the current flowing in the direction of from the anode to the cathode of said each semiconductor element increases,
• continuity period-control means which is provided in said each arm circuit and controls the continuity period of said semiconductor element,
• delay means which delays the output signal of said continuity period-control means by a certain period of time, and
• output means which is provided for every said arm circuit, and designates the output signals as the accident detection signal of said power converter when the output signal of said voltage direction-detecting means and the output signal of said delay means are simultaneously present.

An accident detection circuit of a voltage-type self-excited power converter having an arm series circuit in which a plurality of arm circuits are connected in series, said each arm circuit comprising a power semiconductor element of self turn off type and an anode reactor for suppressing the current rising rate which is connected in series to the anode included in the semiconductor element, which comprises:

• voltage direction-detecting means which detects, respectively, that a voltage generated in the anode reactor of said each arm circuit and applied in a direction exceeds a predetermined value when the current flowing in the direction of from the anode to the cathode of every semiconductor element of said each arm circuit increases,
• voltage detecting means which detects, respectively, the off-gate voltage between the gate and the cathode of every semiconductor element of said each arm circuit,
• delay means which inverts and delays by a certain period of time, respectively, the output signal of said each voltage detecting means, and
• output means which designates the output signals as the accident detection signal of said power converter when the output signal of said voltage direction-detecting means and the output signal of said delay means are simultaneously present in every said arm circuit.

An accident detection circuit of a voltage-type self-excited power converter having an arm series circuit in which a plurality of arm circuits are connected in series, said each arm circuit comprising a power semiconductor element of self turn off type, a diode connected in anti-parallel to said semiconductor element and an anode reactor for suppressing the current rising rate which is connected in series to the anode included in the semiconductor element, which comprises:

• voltage direction-detecting means which is connected, respectively, in parallel to the anode reactor of said each arm circuit, and detects that a voltage generated in the anode reactor of said each arm circuit exceeds a certain value when the current flowing in the direction of from the anode to the cathode of said each semiconductor element increases,
• voltage detecting means which is provided for every said arm circuit and detects, respectively, the off-gate voltage between the gate and the cathode of every semiconductor element of said each arm circuit,
• delay means which is provided for every said arm circuit, and inverts and delays by a certain period of time, respectively, the output signal of said voltage detecting means, and
• output means which designates the output signals as the accident detection signal of said power converter when the output signal of said voltage direction-detecting means and the output signal of said delay means are simultaneously present in every said arm circuit.