Disclosed are a grid-connected power conversion system and a control method thereof. The grid-connected power conversion system includes a fuel cell stack generating a DC voltage, a power conversion system (PCS) converting the DC voltage supplied from the stack into an AC voltage, a multi-input transformer including a primary coil having a plurality of voltage input terminals and a secondary coil transforming a magnitude of the voltage applied to the primary coil and outputting the transformed voltage, the plurality of voltage input terminals determining the number of turns of the primary coil differently from each other, one of the plurality of voltage input terminals receiving the AC voltage converted in the PCS, and a controller selecting the one of the plurality of voltage input terminals of the multi-input transformer based on the magnitude of the DC voltage generated from the stack and determining whether to replace the stack.

Techniques for an electronic device to perform power-stealing techniques to harvest energy from a power-control circuit to power components of the electronic device. In some examples, the electronic device may be connected in the power-control circuit between a power supply and a relay that is selectively configured to activate a power load. According to the techniques described herein, the electronic device may include voltage-drop circuitry that is connected in the power-control circuit such that a voltage drop is produced across electrical components of the electronic device while the relay is in the activated, or triggered, state. In this way, the electronic device may perform power-stealing from the power-control circuit while the relay is maintained in the activated state.

A power converter includes an arm in which a plurality of converter cells are connected in series, each of the converter cells including at least two switching elements, a power storage element and a pair of output terminals. A control device controls the power converter. The converter cell includes a switch to have the converter cell bypassed. When the control device senses failure of the converter cell, it has the failed converter cell bypassed, estimates an output voltage lost by bypassing the failed converter cell, and has a normal converter cell supply the estimated output voltage of the failed converter cell.

The power supply apparatus includes a transformer, a switching element, a full-wave rectification circuit, a smoothing circuit having one end connected to a first primary winding of the transformer, and another end connected to a second primary winding of the transformer through the switching element, and a circuit connected to an output end of the full-wave rectification circuit and including an inductor and a rectifying element connected in series with each other, wherein the number of turns of the first primary winding is greater than the number of turns of the second primary winding.

The power supply apparatus includes a transformer, a switching element, a full-wave rectification circuit, a smoothing circuit having one end connected to a first primary winding of the transformer, and another end connected to a second primary winding of the transformer through the switching element, and a circuit connected to an output end of the full-wave rectification circuit and including an inductor and a rectifying element connected in series with each other, wherein the number of turns of the first primary winding is greater than the number of turns of the second primary winding.

A power converter includes an arm in which a plurality of converter cells are connected in series, each of the converter cells including at least two switching elements, a power storage element, and a pair of output terminals. A control device controls the power converter. The converter cell includes a switch to have the converter cell bypassed. When the control device senses failure of the converter cell, it has the failed converter cell within the arm bypassed and controls a normal converter cell within the arm to suppress a ratio of a harmonic component in an arm current that increases due to the failure.

A transformer includes a core with a surface, a primary winding with two or more primary winding turns wrapped about the core, and a secondary winding with one and only one secondary winding turn extending about the core. The one and only one secondary winding turn is interleaved among the two or more primary winding turns on the surface of the core to limit magnetic flux leakage along the primary winding and the secondary winding. Power converters and power conversion methods are also described.

A transformer includes a core with a surface, a primary winding with two or more primary winding turns wrapped about the core, and a secondary winding with one and only one secondary winding turn extending about the core. The one and only one secondary winding turn is interleaved among the two or more primary winding turns on the surface of the core to limit magnetic flux leakage along the primary winding and the secondary winding. Power converters and power conversion methods are also described.

A transformer arrangement includes a first and a second arrangement side and a transformer with first windings coupled to the first arrangement side and with second windings having a first to a fourth tap. The transformer arrangement comprises a converter coupling the first, second and third tap to the second arrangement side, a first filter circuit coupling the first tap to the third tap and a second filter circuit coupling the third tap to the second tap.

A transformer arrangement includes a first and a second arrangement side and a transformer with first windings coupled to the first arrangement side and with second windings having a first to a fourth tap. The transformer arrangement comprises a converter coupling the first, second and third tap to the second arrangement side, a first filter circuit coupling the first tap to the third tap and a second filter circuit coupling the third tap to the second tap.