A power device may have at least two capacitors in series with each other and in parallel with a DC power source. The power device may have at least a first converter that has at least a controller configured to balance a voltage of the at least two capacitors. The power device may have at least a second converter connected to the at least two capacitors. The second converter may have at least three input conductors, each connected to a terminal of the at least two capacitors. The second converter may have at least two output conductors. The second converter may have at least a switching circuit between the at least three input conductors and at least two output conductors. The second converter may have at least a controller configured to operate the switching circuit. The second converter may passively preserve the voltage balance between the at least two capacitors.

In an embodiment a method for operating a wireless charger includes providing a set of parameter records, assigning parameter records of the set of parameter records to individual converters and generating and providing, for each converter depending on an assigned parameter record, a control signal vector so that a multi-level converter arrangement including the converters provides a supply power with a desired signal waveform to a power source resonator, wherein the parameter records depend on the desired signal waveform of the multi-level converter arrangement, wherein each parameter record defines a duty-cycle and/or a phase shift angle of the converter output signal, and wherein the duty-cycles and/or the phase shift angles of at least two parameter records are different.

In an embodiment a method for operating a wireless charger includes providing a set of parameter records, assigning parameter records of the set of parameter records to individual converters and generating and providing, for each converter depending on an assigned parameter record, a control signal vector so that a multi-level converter arrangement including the converters provides a supply power with a desired signal waveform to a power source resonator, wherein the parameter records depend on the desired signal waveform of the multi-level converter arrangement, wherein each parameter record defines a duty-cycle and/or a phase shift angle of the converter output signal, and wherein the duty-cycles and/or the phase shift angles of at least two parameter records are different.

A method includes charging a capacitor of a power inverter to a direct current (DC) input voltage from an input terminal of the power inverter. The capacitor has first and second terminals. The method also includes providing a first voltage at an output terminal of the power inverter at a first time by controlling one of either: an output switch that selectively couples the output terminal to either the first terminal or the second terminal; or a set of input switches that selectively couple the first and second terminals to either the input terminal or a ground terminal. The method further includes providing a second voltage at the output terminal at a second time by controlling the other of the output switch or the set of input switches.

A first converter station is part of a high voltage direct current transmission system that includes a DC transmission link connected to the first converter station a second converter station. A DC current and a DC voltage of the DC transmission link are sensed by the first converter station. It is determined that the sensed DC current is equal to or larger than a threshold current value, that the sensed DC current is equal to or larger than the threshold current value, and that at least a partial recovery of the sensed DC voltage has occurred. On the basis that it is determined that the at least a partial recovery of the sensed DC voltage has occurred, it is determined that a phase-to-ground fault has occurred. In response to determining that a phase-to-ground fault has occurred, a power delivered by the first converter station can be reduced.

An inverter with an amplitude pulse width (APW) architecture that generates a single phase AC (Alternating Current) power waveform is disclosed. The inverter generates a multi-level stepped voltage waveform, each step of the multi-level stepped waveform having a modulated width of a selected voltage. The inverter further comprises a soft fuse protection system. This disclosure also relates to a personal power plant system using said inverter and a method to generate an AC power sine wave with reduced harmonic distortion.

An inverter with an amplitude pulse width (APW) architecture that generates a single phase AC (Alternating Current) power waveform is disclosed. The inverter generates a multi-level stepped voltage waveform, each step of the multi-level stepped waveform having a modulated width of a selected voltage. The inverter further comprises a soft fuse protection system. This disclosure also relates to a personal power plant system using said inverter and a method to generate an AC power sine wave with reduced harmonic distortion.

In one embodiment, a power conversion device that converts power between a DC circuit and an AC circuit includes a plurality of leg circuits connected in parallel between first and second DC terminals and electrically connected to the AC circuit. Each of the plurality of leg circuits includes at least one first converter cell and a plurality of second converter cells other than the first converter cell. A first control signal that controls switching of a semiconductor switching element included in at least one first converter cell is higher in frequency than a second control signal that controls switching of a semiconductor switching element included in each of the plurality of second converter cells.

In one embodiment, a power conversion device that converts power between a DC circuit and an AC circuit includes a plurality of leg circuits connected in parallel between first and second DC terminals and electrically connected to the AC circuit. Each of the plurality of leg circuits includes at least one first converter cell and a plurality of second converter cells other than the first converter cell. A first control signal that controls switching of a semiconductor switching element included in at least one first converter cell is higher in frequency than a second control signal that controls switching of a semiconductor switching element included in each of the plurality of second converter cells.

A four-level rectifier may include an output, a first capacitor, a second capacitor, a third capacitor, and three phases. The first, second, and third capacitors may be connected in series. The output may be connected between the first capacitor and the third capacitor. Each of the three phases may include an input, a first diode, a second diode, a first switch, a second switch, and a third switch. The first diode may be connected between the input and the first capacitor. The second diode may be connected between the input and the third capacitor. The first switch may be connected between the input and the second switch and the third switch. The second switch may be connected to the first capacitor and to the second capacitor. The third switch may be connected to the second capacitor and to the third capacitor.