A voltage source converter as well as a method and computer program product for controlling the converter. The converter includes at least one phase leg connected between a first DC terminal having a first voltage and a second DC terminal having a second voltage, the phase leg including an upper arm and a lower arm with cells, where a junction between the arms is connected to a corresponding AC terminal. The converter also includes a control unit configured to control the cells to output a train of pulses of trapezoidal shape where the generation of a first control signal for a first cell used to initiate a transition between two levels of a pulse coincides with the decision that a transition is to be made.

A voltage source converter as well as a method and computer program product for controlling the converter. The converter includes at least one phase leg connected between a first DC terminal having a first voltage and a second DC terminal having a second voltage, the phase leg including an upper arm and a lower arm with cells, where a junction between the arms is connected to a corresponding AC terminal. The converter also includes a control unit configured to control the cells to output a train of pulses of trapezoidal shape where the generation of a first control signal for a first cell used to initiate a transition between two levels of a pulse coincides with the decision that a transition is to be made.

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.

[OBJECT] To provide a radio-frequency power source capable of outputting radio-frequency power having a desired waveform changing at high speed.

[SOLUTION] A radio-frequency power source 1 includes two DC-RF converting circuits 4A, 4B and an RF combining circuit 5 for combining the outputs from both DC-RF converting circuits 4A, 4B. The DC-RF converting circuits 4A, 4B amplify radio-frequency voltages v.sub.a, v.sub.b inputted from a radio-frequency signal generating circuit 8, and output radio-frequency voltages v.sub.PA, v.sub.PB. The RF combining circuit 5 outputs radio-frequency voltage v.sub.PX at a ratio corresponding to the phase difference θ between the radio-frequency voltages v.sub.PA and v.sub.PB. A controlling circuit 9 switches the phase difference θ between θ1 and θ2. As a result, the power P.sub.X outputted from the RF combining circuit 5 becomes pulsed radio-frequency power having a high level period and a low level period. Since the switching of the phase difference θ can be performed at high speed, it is possible to output pulsed radio-frequency power with a high switching frequency between the first level and the second level.

A power conversion system includes a first converter effectively connected in series to a second converter. Each converter has a plurality of output levels. A phase-shifted transformer is coupled to the converters. The phase-shifted transformer has a delta-wound winding and an open star winding. The first converter is coupled to the open star winding and the second converter is coupled to the delta winding. The open star winding is configured for direct connection to either of a load or the open star winding of a second phase-shifted transformer, having a delta winding connected to a third converter. One or more DC voltage sources are each connected to the first and second converters by a respective DC link capacitor. Each DC voltage source is connected to a common power grid by an isolated multiphase transformer winding.

A power conversion system includes a first converter effectively connected in series to a second converter. Each converter has a plurality of output levels. A phase-shifted transformer is coupled to the converters. The phase-shifted transformer has a delta-wound winding and an open star winding. The first converter is coupled to the open star winding and the second converter is coupled to the delta winding. The open star winding is configured for direct connection to either of a load or the open star winding of a second phase-shifted transformer, having a delta winding connected to a third converter. One or more DC voltage sources are each connected to the first and second converters by a respective DC link capacitor. Each DC voltage source is connected to a common power grid by an isolated multiphase transformer winding.

A semiconductor device, according to one possible configuration, includes switching circuits, each switching circuit comprising IGBT chips connected in series and clamping diodes. The semiconductor device also includes a first and a second wiring line and auxiliary emitter lines. The first wiring line and a first auxiliary emitter line connect the emitter terminals of IGBT chips of the first and second switching circuits. The second wiring line and another auxiliary emitter line connect the emitter terminals of the third IGBT chips of the first and second switching circuits. The wiring lines have a large current carrying capacity and a lower resistance value than their respectively connected auxiliary emitter line.

A semiconductor device, according to one possible configuration, includes switching circuits, each switching circuit comprising IGBT chips connected in series and clamping diodes. The semiconductor device also includes a first and a second wiring line and auxiliary emitter lines. The first wiring line and a first auxiliary emitter line connect the emitter terminals of IGBT chips of the first and second switching circuits. The second wiring line and another auxiliary emitter line connect the emitter terminals of the third IGBT chips of the first and second switching circuits. The wiring lines have a large current carrying capacity and a lower resistance value than their respectively connected auxiliary emitter line.

A first control unit outputs a closing-operation command signal to a first switch at a timing calculated based on either a first closing time or a second closing time, whichever is later. The first closing time is a time required for the first switch to transition to a closed state after the first control unit detects a first detection signal indicating that a voltage detected by a voltage detection unit exceeds a predetermined threshold value. The second closing time is a time required for a second switch to transition to a closed state after the first detection signal is detected by a second control unit. The second control unit outputs a closing-operation command signal to the second switch at a timing calculated based on a first time. This can suppress variations in an operating time between a plurality of switches.

A new class of DC-AC inverter comprises a buck or two buck converters and two or four low frequency switches, and it achieves ultra-high efficiency, reactive power flow capability, small size and low cost in grid-connected applications.