Abstract: A method for operating an inverter and an inverter configured to convert DC power supplied from a DC power source into AC power supplied to an AC network by applying maximum power point tracking, MPPT, such that a harmonic content of an AC current supplied from the inverter to the AC network is kept within a predetermined maximum level, wherein during the converting the inverter is configured to detect a need to increase the harmonic content of the AC current supplied from the inverter to the AC network beyond the predetermined maximum level, perform a check whether an increase of the harmonic content of the AC current beyond the predetermined maximum level is allowed, and, if an increase of the harmonic content of the AC current beyond the predetermined maximum level is allowed, raise the predetermined maximum level used in the converting.

Abstract: A method for operating an inverter and an inverter configured to convert DC power supplied from a DC power source into AC power supplied to an AC network by applying maximum power point tracking, MPPT, such that a harmonic content of an AC current supplied from the inverter to the AC network is kept within a predetermined maximum level, wherein during the converting the inverter is configured to detect a need to increase the harmonic content of the AC current supplied from the inverter to the AC network beyond the predetermined maximum level, perform a check whether an increase of the harmonic content of the AC current beyond the predetermined maximum level is allowed, and, if an increase of the harmonic content of the AC current beyond the predetermined maximum level is allowed, raise the predetermined maximum level used in the converting.

Abstract: A switching branch for a three-level inverter, comprising a first and second switch (S1, S2) in series between a positive DC pole (P) and an AC pole (AC), a first and second diode (D1, D2) parallel to the first and second switches, a third and fourth switch (S3, S4) in series between a negative DC pole (N) and the AC pole, a third and fourth diode (D3, D4) parallel to the third and fourth switches, a fifth diode (D5) between a neutral DC pole (M) and a point between the first and second switches, a sixth diode (D6) between the neutral DC pole and a point between the third and fourth switches, a fifth switch (S5) and a seventh diode (D7) in series between the neutral DC and AC poles, and a sixth switch (S6) and an eighth diode (D8) in series between the neutral DC and AC poles.

Abstract: A switching branch for a three-level inverter, comprising a first and second switch (S1, S2) in series between a positive DC pole (P) and an AC pole (AC), a first and second diode (D1, D2) parallel to the first and second switches, a third and fourth switch (S3, S4) in series between a negative DC pole (N) and the AC pole, a third and fourth diode (D3, D4) parallel to the third and fourth switches, a fifth diode (D5) between a neutral DC pole (M) and a point between the first and second switches, a sixth diode (D6) between the neutral DC pole and a point between the third and fourth switches, a fifth switch (S5) and a seventh diode (D7) in series between the neutral DC and AC poles, and a sixth switch (S6) and an eighth diode (D8) in series between the neutral DC and AC poles.

Abstract: Exemplary embodiments are directed to a method and switching arrangement for an inverter. The inverter including a positive direct current pole, a negative direct current pole, and a neutral direct current pole. The arrangement having a first controllable switch connected between the neutral direct current pole of the inverter and a virtual neutral point of an alternating current network supplied by the inverter; and/or a second controllable switch connected between the neutral direct current pole of the inverter and an earth potential of an alternating current network supplied by the inverter.

Abstract: Exemplary embodiments are directed to a method and switching arrangement for an inverter. The inverter including a positive direct current pole, a negative direct current pole, and a neutral direct current pole. The arrangement having a first controllable switch connected between the neutral direct current pole of the inverter and a virtual neutral point of an alternating current network supplied by the inverter; and/or a second controllable switch connected between the neutral direct current pole of the inverter and an earth potential of an alternating current network supplied by the inverter.

Abstract: A system for the detection of welded contacts in a circuit of a line converter system has a plurality of inverter switches, a plurality of utility switches in which a pair of utility switches is connected in series through a line to a utility, a voltage detector, an electronic controller, and a DC input source. The line converter system converts incoming DC power into AC output power that is delivered to the utility grid. The voltage detector measures the voltage across a first node and a second node of the circuit and provides an output that is interpreted by an electronic controller for each step performed during a method of detection of welded contacts. The detection method has a sequence of test steps in which at least one switch is opened and/or closed, a DC bus of the inverter or the utility grid is used as a stimulus voltage, and the voltage is measured.

Abstract: Exemplary embodiments are directed to an inverter and a method for controlling an inverter. The inverter includes a DC link having two capacitor units in series and a neutral point between the capacitor units, and a first and a second inverter leg. Both inverter legs are connected between the poles of the DC link and include four switching devices connected in series. Both inverter legs include an upper connection point between the two topmost switching devices, a lower connection point between the two bottommost switching devices, and an output between the two middle switching devices. Both inverter legs further include a first rectifier device connected between the DC link neutral point and the leg upper connection point, and a second rectifier device connected between the DC link neutral point and the leg lower connection point.

Abstract: A full-bridge, NPC inverter uses pulse width modulation (PWM) to convert the DC voltage from a solar panel array to an AC voltage at the output of the inverter that is acceptable for connection to a utility. The PWM control unit has a predetermined carrier frequency. The carrier unit uses for each carrier period either positive or negative values of a reference voltage to generate a predetermined number of signals to control the switching on and off of each of the eight inverter switching elements in a predetermined pattern for a predetermined period of the carrier frequency period to thereby produce the acceptable alternating current voltage at the inverter output and not produce between the inverter input and earth ground a carrier frequency component.

Abstract: A system for the detection of welded contacts in a circuit of a line converter system has a plurality of inverter switches, a plurality of utility switches in which a pair of utility switches is connected in series through a line to a utility, a voltage detector, an electronic controller, and a DC input source. The line converter system converts incoming DC power into AC output power that is delivered to the utility grid. The voltage detector measures the voltage across a first node and a second node of the circuit and provides an output that is interpreted by an electronic controller for each step performed during a method of detection of welded contacts. The detection method has a sequence of test steps in which at least one switch is opened and/or closed, a DC bus of the inverter or the utility grid is used as a stimulus voltage, and the voltage is measured.