Abstract: A method for operating an inverter includes applying, via a switching unit of the inverter, an AC voltage to a phase line in which a filter inductor is arranged, determining a coil current (iL) of the filter inductor and determining a coil voltage (uL) of the filter inductor, determining a first value (L(Ix)) of the filter inductor for a first value of the coil current (Ix), determining an inductance profile of the filter inductor with respect to the coil current, using the determined first value of the filter inductance and optionally using the at least one determined further value of the filter inductance, and controlling the switching unit of the inverter, via a control unit, to generate an alternating current in the phase line. At least one parameter of the control process is continuously adapted to the momentary coil current according to the determined current-dependent inductance profile.

Abstract: To improve voltage balancing at the DC link capacitor voltages of a multi-level inverter with a split DC link a modulation signal with a modulation signal amplitude as even harmonic signal of the output voltage or output current of the inverter is calculated from an actual electric power difference of the actual electric powers at the DC link capacitors and is superimposed onto the setpoint value for setting an output voltage or output current of the inverter.

Abstract: A switching arrangement of an inverter with a filter circuit and a grid relay. For the filter circuit use is made of an equivalent circuit consisting of effective filter inductance, from filter inductance and topology of the filter circuit and effective filter capacitance, from the filter capacitance and topology of the filter circuit. The effective filter inductance and the effective filter capacitance are system parameters. To determine system parameters, a voltage pulse is applied between a first conductor output and a second conductor output when the grid relay is open; the first conductor output and the second conductor output are connected via the switching arrangement to form a closed oscillating circuit a current value of the effective filter inductance and the effective filter capacitance is determined from a current curve and/or voltage curve in the resonant circuit as system parameters for controlling the switching arrangement.

Abstract: A method for operating an inverter includes applying, via a switching unit of the inverter, an AC voltage to a phase line in which a filter inductor is arranged, determining a coil current (iL) of the filter inductor and determining a coil voltage (uL) of the filter inductor, determining a first value (L(IX)) of the filter inductor for a first value determining an inductance profile of the filter inductor with respect to the coil current, using the determined first value of the filter inductance and optionally using the at least one determined further value of the filter inductance, and controlling the switching unit of the inverter, via a control unit, to generate an alternating current in the phase line. At least one parameter of the control process is continuously adapted to the momentary coil current according to the determined current-dependent inductance profile.

Abstract: The invention relates to an inverter system (1) with several inverters (2), each of which having at least one control unit (6), with at least one line (7) each being provided between the inverters (2) for data exchange, as well as to an inverter (2), and to a method of operating several inverters (2) in such an inverter system (1). To achieve a high transmission safety, and a high data-transmission rate, it is provided that each inverter (2) has a communication device (8) which is connected to a control unit (6) of the inverter (2) and to the data lines (7) of two neighboring inverters (2), and which has a switching device (13), the switching device (13) being configured to switch the data lines (7) between a ring system and between a bus system logically based on this ring system.

Abstract: The invention relates to a method for controlling the voltage and power of several HF inverters (2), connected in parallel at the output, of an electrically isolated inverter assembly as well as for distributing the load to these HF inverters (2) each consisting of at least one DC-DC converter (3), one intermediate circuit (4) and one DC-AC converter (5), with a command variable (Ui?) being formed for each HF inverter (2) so as to preset a nominal value for control of an intermediate-circuit voltage (UZKi) at the intermediate circuit (4) of the HF inverter (2). The load of each HF inverter (2) is determined by a control unit (13) by measuring the current or power required, an internal resistance of the HF inverter (2) is simulated via which internal resistance a virtual voltage drop (UVR) is caused which depends on the load determined and is used for controlling the voltage (UZKi) of the intermediate circuit (4) so as to produce a purposive change in the output voltage of each HF inverter (2).

Abstract: The invention relates to an inverter system (1) with several inverters (2), each of which having at least one control unit (6), with at least one line (7) each being provided between the inverters (2) for data exchange, as well as to an inverter (2), and to a method of operating several inverters (2) in such an inverter system (1). To achieve a high transmission safety, and a high data-transmission rate, it is provided that each inverter (2) has a communication device (8) which is connected to a control unit (6) of the inverter (2) and to the data lines (7) of two neighboring inverters (2), and which has a switching device (13), the switching device (13) being configured to switch the data lines (7) between a ring system and between a bus system logically based on this ring system.

Abstract: The invention relates to a method for controlling the voltage and power of several HF inverters (2), connected in parallel at the output, of an electrically isolated inverter assembly as well as for distributing the load to these HF inverters (2) each consisting of at least one DC-DC converter (3), one intermediate circuit (4) and one DC-AC converter (5), with a command variable (Ui?) being formed for each HF inverter (2) so as to preset a nominal value for control of an intermediate-circuit voltage (UZKi) at the intermediate circuit (4) of the HF inverter (2). The load of each HF inverter (2) is determined by a control unit (13) by measuring the current or power required, an internal resistance of the HF inverter (2) is simulated via which internal resistance a virtual voltage drop (UVR) is caused which depends on the load determined and is used for controlling the voltage (UZKi) of the intermediate circuit (4) so as to produce a purposive change in the output voltage of each HF inverter (2).

Abstract: The invention relates to a method for recognizing the operational state of a load (10) connected to the output (6, 7) of an island inverter (1). A load recognition signal (SL) is applied at specific moments in time to the output (6, 7) of the island inverter (1), during which specific electric parameters are measured on the island inverter (1), enabling the operational state of the load (10) to be determined, wherein the island inverter (1), when the load (10) is activated, is switched from a possible standby mode into a permanent operation mode and, when the load is deactivated (10), the island inverter is switched from a possible permanent operation mode to a standby mode. The invention also relates to an island inverter (1). In order to ensure reliable recognition of all possible collected loads (10), a load recognition signal (SL) with parameters (T, d, A, H, f) that are modified at least according to the type of load (10) is applied to the output (6, 7) of the island inverter (1).

Abstract: The invention relates to a method for recognizing the operational state of a load (10) connected to the output (6,7) of an island inverter (1). A load recognition signal (SL) is applied at specific moments in time to the output (6, 7) of the island inverter (1), during which specific electric parameters are measured on the island inverter (1), enabling the operational state of the load (10) to be determined, wherein the island inverter (1), when the load (10) is activated, is switched from a possible standby mode into a permanent operation mode and, when the load is deactivated (10), the island inverter is switched from a possible permanent operation mode to a standby mode. The invention also relates to an island inverter (1). In order to ensure reliable recognition of all possible collected loads (10), a load recognition signal (SL) with parameters (T, d, A, H, f) that are modified at least according to the type of load (10) is applied to the output (6,7) of the island inverter (1).