Abstract: A flying capacitor converter comprises a converter input comprising a positive pole and a negative pole, an output terminal, and a plurality of cells, each cell comprising two switches and a flying capacitor arranged between each cell. A method for detecting a plurality of faults in the converter includes measuring, by a second current sensor arranged at the positive pole, a second current; measuring by a third current sensor arranged at the negative pole, a third current; and detecting a first fault in the flying capacitor converter when the second current or the third current exceeds a first current threshold, and/or when a gradient of the second current or a gradient of the third current exceeds a first gradient threshold.

Abstract: A temperature measurement arrangement for measuring a temperature in a noise voltage-inducing environment includes a sensing circuit including a Negative Temperature Coefficient Thermistor (NTC) for sensing a temperature and a filter for compensating the induced noise voltage at a filter frequency.

Abstract: A system and method for compensating a faulty switch in a multi-level flying capacitor converter includes a converter capacitor arranged in parallel to an input, a first and second converter switches arranged respectively between first and second ends of the converter capacitor, first and second bypass switches respectively arranged in parallel to the first and second converter switches, wherein operation includes detecting a faulty converter level that includes at least one of the first and second converter switches, discharging all capacitors arranged in parallel to the input of the multi-level converter, wherein all capacitors comprise the converter capacitors and an input capacitor; closing the first and second bypass switches of the faulty converter level; adapting a modulation of the converter switches of the other converter levels; and restarting the multi-level converter.

Abstract: A protection circuit for a power converter with cascaded bipolar and/or unipolar semiconductors is provided. The protection circuit includes at least one comparator circuit which is adapted to monitor a voltage characteristic on a collector-emitter path of at least one semiconductor which is arranged in a polarity selection stage of the power converter and/or to monitor a voltage characteristic on at least one capacitor, which is arranged in the power converter. The at least one comparator circuit is further adapted to output an electrical signal, representing the voltage characteristic of the semiconductor and/or the at least one capacitor to at least one evaluation unit. The at least one evaluation unit is further adapted to evaluate the result from the at least one comparator circuit and to deactivate the semiconductors in case that the voltage characteristic of the semiconductors and/or the capacitors deviate from a predetermined threshold.

Abstract: A flying capacitor switching cell-system includes at least two flying capacitor switching cells, wherein each of the cells comprises an arrangement of at least one semiconductor system, and wherein the cells are in parallel in an electrical circuit.

Abstract: A protection circuit for a power converter with cascaded bipolar and/or unipolar semiconductors is provided. The protection circuit includes at least one comparator circuit which is adapted to monitor a voltage characteristic on a collector-emitter path of at least one semiconductor which is arranged in a polarity selection stage of the power converter and/or to monitor a voltage characteristic on at least one capacitor, which is arranged in the power converter. The at least one comparator circuit is further adapted to output an electrical signal, representing the voltage characteristic of the semiconductor and/or the at least one capacitor to at least one evaluation unit. The at least one evaluation unit is further adapted to evaluate the result from the at least one comparator circuit and to deactivate the semiconductors in case that the voltage characteristic of the semiconductors and/or the capacitors deviate from a predetermined threshold.

Abstract: The present disclosure describes a modulation method for controlling at least two parallel-connected, multi-phase power converters. The method comprises generating synchronized switching sequences for the power converters on the basis of a common modulation reference, wherein each synchronized switching sequence comprises a first half sequence followed by a second half sequence, and wherein, for at least one of the power converters, the first half sequence is a rising-edge half sequence rising-edge half sequence and the second half sequence is a falling-edge half sequence, and, for at least one other of the power converters, the first half sequence is a falling-edge half sequence and the second half sequence is a rising-edge half sequence.

Abstract: A converter circuit with short-circuit protection can include a plurality of phase legs having a series connection of normally-on switches, between voltage rails of a DC voltage link, a DC link capacitor, and AC voltage connection points between the normally-on switches. A phase-to-phase short-circuit protection circuit includes a parallel connection of a resistive component and a controllable switch. The phase-to-phase short-circuit protection circuit including a first terminal connected to an AC voltage connection point and a second terminal forms an input or an output of the converter circuit; and a controllable switch is connected in series with the DC link capacitor. Upon lack of control of the normally-on switches the controllable switch of the at least one phase-to-phase short-circuit protection circuit and the controllable switch of the phase leg short-circuit protection circuit are adapted to be controlled to a non-conductive state.

Abstract: An exemplary method and apparatus for detecting islanding conditions of a distributed grid are disclosed, wherein transfer of power through a power electrical unit is controlled on the basis of a control reference. The apparatus includes a first stage and a second stage performing a respective portion of the method. The first stage injects a reactive component to the control reference, and, for at least one electrical quantity of the grid, determines a change in the quantity induced by the injected component, and determines, on the basis of the change in the electrical quantity, whether to move to the second stage of the method.

Abstract: An exemplary method and an apparatus implementing the method for an arrangement having a three-phase, multi-level inverter, an output LCL-filter connecting the inverter to a grid, and a virtual-ground connection between the LCL-filter and the neutral point of the DC-link. The method includes determining a zero-sequence component of an LCL-filter inverter-side current, calculating a zero-sequence damping and balancing voltage term based on the LCL-filter inverter-side current zero-sequence component and voltages over the two halves of the DC-link, and adding the zero-sequence damping and voltage balancing term to the output voltage reference.

Abstract: A converter circuit with short-circuit protection can include a plurality of phase legs having a series connection of normally-on switches, between voltage rails of a DC voltage link, a DC link capacitor, and AC voltage connection points between the normally-on switches. A phase-to-phase short-circuit protection circuit includes a parallel connection of a resistive component and a controllable switch. The phase-to-phase short-circuit protection circuit including a first terminal connected to an AC voltage connection point and a second terminal forms an input or an output of the converter circuit; and a controllable switch is connected in series with the DC link capacitor. Upon lack of control of the normally-on switches the controllable switch of the at least one phase-to-phase short-circuit protection circuit and the controllable switch of the phase leg short-circuit protection circuit are adapted to be controlled to a non-conductive state.

Abstract: A method and an apparatus for controlling a grid-connected converter which includes a boost converter, a buck converter, and a current source inverter having an output CL filter. An input of the buck converter input is connected to an output of the boost converter, and an input of the current source inverter is connected to an output of the buck converter. The method includes controlling a boost converter input voltage, controlling a boost converter output voltage through control of a buck converter output voltage, and controlling the current source inverter to produce an AC current from the buck converter output voltage. The apparatus implements the method.

Abstract: Exemplary embodiments provide a method and an adaptive RCD snubber circuit for a switching converter having a series-connection of a main inductor and a main switching device. A voltage stress of the main switching device is sensed, and the sensed voltage stress is controlled to a reference level by controlling a snubber capacitor voltage, wherein the snubber capacitor voltage is controlled by adjusting the snubber resistance of the RCD snubber.

Abstract: The present disclosure relates to an LC snubber circuit for a switching converter, wherein the switching converter includes an inductor and a switching device connected in series. The LC snubber circuit can include a first snubber diode, a snubber capacitor, a second snubber diode, and a snubber transformer having a primary winding and a secondary winding. The secondary winding of the snubber transformer is connected to an output of the switching converter.

Abstract: An exemplary method and arrangement for estimating the frequency and the positive sequence of a fundamental component of a measured three-phase voltage are disclosed (???).

Abstract: A phase-locked loop and method for estimating a phase angle of a three-phase reference signal is disclosed, which includes an adaptive quadrature signal generator configured to calculate an estimated first state and an estimated second state of a model of an unbalanced three-phase system at a fundamental frequency of the reference signal on a basis of the reference signal and an estimated fundamental frequency; a reference frame transformation block configured to calculate a direct component and a quadrature component in a rotating reference frame synchronous with an estimated phase angle on a basis of the fundamental positive sequence component and the estimated phase angle, and configured to determine an estimate of an amplitude of the fundamental positive sequence component on the basis of the direct component; and an estimator configured to determine estimates of the estimated fundamental frequency and the estimated phase angle on the basis of the quadrature component.

Abstract: An exemplary method and an apparatus implementing the method for an arrangement having a three-phase, multi-level inverter, an output LCL-filter connecting the inverter to a grid, and a virtual-ground connection between the LCL-filter and the neutral point of the DC-link. The method includes determining a zero-sequence component of an LCL-filter inverter-side current, calculating a zero-sequence damping and balancing voltage term based on the LCL-filter inverter-side current zero-sequence component and voltages over the two halves of the DC-link, and adding the zero-sequence damping and voltage balancing term to the output voltage reference.

Abstract: A method of controlling the grid-side current of a single-phase grid-connected converter having an LCL filter connected between the output of the converter and the grid includes measuring a grid voltage and at least one signal in a group of signals consisting of a grid-side current, a converter-side current and a capacitor voltage, estimating the fundamental component of the grid voltage, forming a grid-side current reference, a converter-side current reference and a capacitor voltage reference for the grid-side current of the LCL filter, forming estimates for the non-measured signals in the group of signals, forming a grid-side current difference term, a converter-side current difference term and a capacitor voltage difference term, and controlling the output voltage of the converter based on the grid voltage, a formed injection term and a formed estimate of the harmonic distortion term to produce a grid side current corresponding to the current reference.

Abstract: A method and an apparatus for controlling a grid-connected converter which includes a boost converter, a buck converter, and a current source inverter having an output CL filter. An input of the buck converter input is connected to an output of the boost converter, and an input of the current source inverter is connected to an output of the buck converter. The method includes controlling a boost converter input voltage, controlling a boost converter output voltage through control of a buck converter output voltage, and controlling the current source inverter to produce an AC current from the buck converter output voltage. The apparatus implements the method.

Abstract: An exemplary method is disclosed for searching a global maximum power point in an arrangement comprising a series connection of photovoltaic power sources. The method can include determining a value of a reference by adding an increment to a previous value of the reference, wherein the value of the increment is determined on the basis of the power produced by the power sources.