We describe a photovoltaic (PV) panel system comprising a PV panel with multiple sub-strings of connected solar cells in combination with a power conditioning unit (microinverter). The power conditioning unit comprises a set of input power converters, one connected to each sub-string, and a common output power conversion stage, to provide power to an ac mains power supply output. Integration of the micro-inverter into the solar PV module in this way provides many advantages, including greater efficiency and reliability. Additionally, embodiments of the invention avoid the need for bypass diodes, a component with a high failure rate in PV panels, providing lower power loss and higher reliability.

When an electrical primary frequency of power fluctuation of a motor is smaller than a determination threshold value fth1 that is a lower limit frequency of a frequency band where resonance occurs in a circuit including a reactor and a capacitor of a boosting converter or greater than a determination threshold value that is an upper limit frequency of the frequency band where resonance occurs, a value G2 is set as a gain G and when the electrical primary frequency is equal to or greater than the determination threshold value fth1 and equal to or smaller than the determination threshold value, a value G3 at which the upper limit frequency of the resonant frequency band has a low frequency than the determination threshold value fth1 is set as the gain G and a current control in the boosting converter is executed using the gain G set in this way. The resonance of the circuit including the reactor and the capacitor of the boosting converter can be prevented.

A SiC Schottky-barrier diode and a SiPiN diode are connected in parallel. Due to a difference in their thermal properties, a relatively large current flows in the SiPiN diode at a high temperature in which electro migration progresses easily in a solder layer, and the progression of the electro migration is suppressed. At a low temperature in which the electro migration does not progress so much, only a relatively small current flows in the SiPiN diode, and a loss suppression by the SiC Schottky-barrier diode is achieved.

A SiC Schottky-barrier diode and a SiPiN diode are connected in parallel. Due to a difference in their thermal properties, a relatively large current flows in the SiPiN diode at a high temperature in which electro migration progresses easily in a solder layer, and the progression of the electro migration is suppressed. At a low temperature in which the electro migration does not progress so much, only a relatively small current flows in the SiPiN diode, and a loss suppression by the SiC Schottky-barrier diode is achieved.

The present specification relates to an electric power converter, comprising at least a set of four controllable power switches, arranged in an H-bridge or a functionally equivalent circuit comprising two switching legs of two series switches connected to a voltage source, each power switch comprising an antiparallel diode, a controller configured for controlling the switches with a blanking time, a feedback loop for the load current, characterised by a first bias current injection circuit, coupled to the central point of the first leg of the H-bridge and a second bias current injection circuit, coupled to the central point of the second leg of the H-bridge. The specification further relates to a MRI scanner, provided with an electric power converter according to any of the preceding claims, for driving the gradient coils.

The present specification relates to an electric power converter, comprising at least a set of four controllable power switches, arranged in an H-bridge or a functionally equivalent circuit comprising two switching legs of two series switches connected to a voltage source, each power switch comprising an antiparallel diode, a controller configured for controlling the switches with a blanking time, a feedback loop for the load current, characterised by a first bias current injection circuit, coupled to the central point of the first leg of the H-bridge and a second bias current injection circuit, coupled to the central point of the second leg of the H-bridge. The specification further relates to a MRI scanner, provided with an electric power converter according to any of the preceding claims, for driving the gradient coils.

A wireless charger for an electric vehicle and a resonant inverter comprising a resonant portion that serially connects to a phase shifting portion and serially connects with a load component and a method for controlling a resonant inverter having multiple phase shifts, comprising operating the frequency of the resonant inverter close to the resonant frequency of the inverter through the full operation range of the resonant inverter; and adjusting phase shifts to control the output power of the resonant inverter.

A wireless charger for an electric vehicle and a resonant inverter comprising a resonant portion that serially connects to a phase shifting portion and serially connects with a load component and a method for controlling a resonant inverter having multiple phase shifts, comprising operating the frequency of the resonant inverter close to the resonant frequency of the inverter through the full operation range of the resonant inverter; and adjusting phase shifts to control the output power of the resonant inverter.

A five-level converting device includes an AC terminal, a bus capacitor module having a positive terminal, a negative terminal and a neutral terminal, a first switch module and a second switch module. The first switch module includes a bidirectional switching circuit, and the bidirectional switching circuit includes two first switching units reversely connected in series. The second switch module includes two second switching units, two third switching units, two fourth switching units, and two fifth switching units. The two second switching units are cascaded and connected to the two fourth switching units in parallel. The third, the fourth and the fifth switching units are cascaded and are connected to the bus capacitor module in parallel. Two different connection points of the first switch module are connected to the third switching units and fifth switching units through two flying capacitor modules respectively.

A five-level converting device includes an AC terminal, a bus capacitor module having a positive terminal, a negative terminal and a neutral terminal, a first switch module and a second switch module. The first switch module includes a bidirectional switching circuit, and the bidirectional switching circuit includes two first switching units reversely connected in series. The second switch module includes two second switching units, two third switching units, two fourth switching units, and two fifth switching units. The two second switching units are cascaded and connected to the two fourth switching units in parallel. The third, the fourth and the fifth switching units are cascaded and are connected to the bus capacitor module in parallel. Two different connection points of the first switch module are connected to the third switching units and fifth switching units through two flying capacitor modules respectively.