Abstract: A method for detecting an arc fault in a photovoltaic power circuit includes operating a photovoltaic generator at a first working point. A first signal related to a DC-current and/or a DC-voltage in the power circuit is determined. The first signal is analyzed and it is determined whether the signal indicates the presence of an electric arc in the power circuit. If so, the photovoltaic generator is operated at a second working point and a second signal related to the DC-current and/or the DC-voltage is determined. The first and second signals are then compared; and the occurrence of an arc fault in the power circuit is selectively signaled based on the comparison.

Abstract: An AC inductor includes a core, at least one permanent magnet for magnetically biasing the core, an inductor winding on the core, and a circuitry which guides an alternating current which flows through the AC inductor in such a way through the inductor winding that, during each half-wave of the alternating current, the alternating current generates a magnetization of the core which is opposite to the magnetization by the permanent magnet. This circuitry includes a commutator which guides the alternating current flowing between two contacts of the AC inductor through the same part of the inductor winding with a same flow direction during each of the half-wave of the alternating current.

Abstract: A converter for converting a DC input voltage includes two input lines receiving the DC input voltage; at least one normally off semiconductor switch which is not conductive without application of a control voltage to its gate and which is provided in one of the input lines. The converter also includes electric circuitry connected between the input lines and including at least one normally on semiconductor switch which is conductive without application of a control voltage to its gate; and a controller. In operation of the converter, the controller operates the at least one normally on semiconductor switch of the electric circuitry by temporarily applying a first control voltage to its gate; and permanently applies a second control voltage to the gate of the at least one normally off semiconductor switch in the one input line. Any normally on semiconductor switch of the electric circuitry is spatially separated and thus thermally isolated from any normally off semiconductor switch.

Abstract: To operate a semiconductor power switch having a control electrode and a reference electrode in response to first and second switching commands, a control voltage between a first electric pole and a second electric pole is provided. Upon each first switching command, the control electrode is coupled to the first electric pole, and the reference electrode is coupled to the second electric pole; and upon each second switching command, the control electrode is coupled to the second electric pole, and the reference electrode is coupled to the first electric pole. Upon each switching command, continuously transitioning an electric potential of the one of the control and reference electrodes during a first transition period, and continuously transitioning an electric potential of the respective other of the control and reference electrodes during a second transition period occurs, wherein the first transition period beginning before and ending after the second transition period.

Abstract: An inverter has two input lines; an inverter bridge connected between the input lines and including at least one half-bridge having two normally conductive gate-controlled semiconductor switches; a controller which supplies control voltages to the gates of the semiconductor switches in an operative state of the inverter; and a DC voltage source for supplying an auxiliary control voltage to the gates of the semiconductor switches in an inoperative state of the inverter so as to hold the inverter bridge in a non-conductive state between the input lines. The DC voltage source has a charging unit connected between the input lines in series with a further normally conductive gate-controlled semiconductor switch, and charging a storage unit for electric charge, which is connected to the gate of the further semiconductor switch such that this switch becomes non-conductive, when the storage unit has been sufficiently charged for providing the auxiliary control voltage.

Abstract: To operate a semiconductor power switch having a control electrode and a reference electrode in response to first and second switching commands, a control voltage between a first electric pole and a second electric pole is provided. Upon each first switching command, the control electrode is coupled to the first electric pole, and the reference electrode is coupled to the second electric pole; and upon each second switching command, the control electrode is coupled to the second electric pole, and the reference electrode is coupled to the first electric pole. Upon each switching command, continuously transitioning an electric potential of the one of the control and reference electrodes during a first transition period, and continuously transitioning an electric potential of the respective other of the control and reference electrodes during a second transition period occurs, wherein the first transition period beginning before and ending after the second transition period.

Abstract: A converter for converting a DC input voltage includes two input lines receiving the DC input voltage; at least one normally off semiconductor switch which is not conductive without application of a control voltage to its gate and which is provided in one of the input lines. The converter also includes electric circuitry connected between the input lines and including at least one normally on semiconductor switch which is conductive without application of a control voltage to its gate; and a controller. In operation of the converter, the controller operates the at least one normally on semiconductor switch of the electric circuitry by temporarily applying a first control voltage to its gate; and permanently applies a second control voltage to the gate of the at least one normally off semiconductor switch in the one input line. Any normally on semiconductor switch of the electric circuitry is spatially separated and thus thermally isolated from any normally off semiconductor switch.

Abstract: The subject matter of the present invention is a method for monitoring a photovoltaic generator (1) for generating current with a number of solar cells connected between two external connections by repeated feeding of a current with a frequency spectrum into the generator current circuit, detecting thereby a respective frequency response in the frequency spectrum with the supplied current as the input variable and an electric variable of the generator as the output variable, and detecting a change in the frequency response for monitoring the photovoltaic generator (1) in the event of a change during repeated feeding.

Abstract: A power generation system for feeding electrical power from a generation unit into a three-phase grid via three AC terminals is disclosed. The system includes a relay arrangement for disconnecting the system from the grid having at least three relays. Each of the three relays includes a control coil and two switching contacts operated by the corresponding control coil. Each of the AC terminals is connectable to the grid via a first and a second switching contact, each of which is assigned to a different one of the relays. Further disclosed are a relay arrangement and an inverter with a relay arrangement.

Abstract: An inverter comprises two input lines; an inverter bridge connected between the input lines and including at least one half-bridge comprising two normally conductive gate-controlled semiconductor switches; a controller which supplies control voltages to the gates of the semiconductor switches in an operative state of the inverter; and a DC voltage source for supplying an auxiliary control voltage to the gates of the semiconductor switches in an inoperative state of the inverter so as to hold the inverter bridge in a non-conductive state between the input lines. The DC voltage source has a charging unit connected between the input lines in series with a further normally conductive gate-controlled semiconductor switch, o and charging a storage unit for electric charge, which is connected to the gate of the further semiconductor switch such that this switch becomes non-conductive, when the storage unit has been sufficiently charged for providing the auxiliary control voltage.

Abstract: The subject matter of the present invention is a method for monitoring a photovoltaic generator (1) for generating current with a number of solar cells connected between two external connections by repeated feeding of a current with a frequency spectrum into the generator current circuit, detecting thereby a respective frequency response in the frequency spectrum with the supplied current as the input variable and an electric variable of the generator as the output variable, and detecting a change in the frequency response for monitoring the photovoltaic generator (1) in the event of a change during repeated feeding.