Each cell of a cell assembly for a converter may include: first and second terminals, switching elements, and a capacitor. The cells are connected in series such that, for each pair of neighbouring cells, the first terminal of a first cell is connected to the second terminal of a second cell. Each cell includes a bypass connected to the first and second terminals that bypasses switching elements in a short circuit configuration and does not bypass the switching elements in an open circuit configuration. Each cell has a cell controller providing control signals to the sw itching elements to connect the capacitor to the first and second terminals or to bypass the capacitor. The cell controller provides a control signal to the bypass unit of neighbouring cells to change its configuration between the short circuit and open circuit configurations.

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.

The application relates to an electric converter for converting AC or DC input into an electric AC or DC output. A swap circuit with controllable electric switches serves to selectively swap connection of a plurality of DC power banks (DCBs) between an input terminal and an output terminal, thus selectively connecting the DCBs to an electric source or an electric load. The DCBs are formed as series of interconnected submodules (SMs) each having electric energy storage elements (ESEs) and a switching circuit for selectively by-passing or connecting the ESEs. By properly controlling the swap circuit and the switching of the SMs, the converter can be used for DC-AC, DC-DC, AC-DC, or AC-AC conversion, allowing multilevel output.

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 power conversion device and a motor system according to the present disclosure comprises an inverter circuit which is connected to a motor, a switch circuit, and a control circuit. The power conversion device and the motor system are characterized in that the inverter circuit and the switch circuit are capable of two-level operation and three-level operation, and the control circuit switches between the two-level operation and the three-level operation on the basis of the motor torque command and the rotational speed command. As a result, it is possible to reduce the total loss in the power conversion device and the motor.

A power conversion device and a motor system according to the present disclosure comprises an inverter circuit which is connected to a motor, a switch circuit, and a control circuit. The power conversion device and the motor system are characterized in that the inverter circuit and the switch circuit are capable of two-level operation and three-level operation, and the control circuit switches between the two-level operation and the three-level operation on the basis of the motor torque command and the rotational speed command. As a result, it is possible to reduce the total loss in the power conversion device and the motor.

Multilevel conversion circuit having a flying capacitor and method for precharging the same are provided. The multilevel conversion circuit includes: a first bridge arm including a plurality of switches connected in series; a second bridge arm including a plurality of switches connected in series and a flying capacitor group, midpoints of the two bridge arms connected to a power supply and an inductor to form a series branch; a DC bus capacitor to which the two bridge arms are connected in parallel; a first voltage clamping module connected between a first end of the flying capacitor group and a first end of the DC bus capacitor; and a second voltage clamping module connected between a second end of the flying capacitor group and a second end of the DC bus capacitor.

A multilevel conversion circuit having a flying capacitor is provided, including: a first bridge arm; a second bridge arm including a flying capacitor, the midpoints of the second and first bridge arms connected to a series branch defined by a first current limiting circuit, a power supply and an inductor; a DC bus capacitor connected in parallel to the first and second bridge arms; a rectifier circuit having an input end coupled to the power supply and an output end connected to a first auxiliary power supply; and a controller coupled to the first auxiliary power supply and the plurality of switches of the second bridge arm to control corresponding switches of the second bridge arm, the power supply charges the flying capacitor through the corresponding switches of the first and second bridge arms and the first current limiting circuit.

A power converter including a three-input direct current converter capable of performing maximum power point tracking on three power inputs, a step down converter capable of voltage step down of the three power inputs, a bus capacitor and a balance circuit utilizing switches and transformers utilized to balance voltages of the bus capacitor, a three-level inverter capable of creating alternating current voltages for the alternating current grid, an output filter electrically coupled to the three-level inverter, a contactor capable of disconnecting the bus capacitor and the balance circuit from the alternating current grid, and a parameter sensor and a field programmable gate array controller electrically coupled to the power converter, capable of controlling a plurality of power switches based on at least one sensed parameters.

A power converter including a three-input direct current converter capable of performing maximum power point tracking on three power inputs, a step down converter capable of voltage step down of the three power inputs, a bus capacitor and a balance circuit utilizing switches and transformers utilized to balance voltages of the bus capacitor, a three-level inverter capable of creating alternating current voltages for the alternating current grid, an output filter electrically coupled to the three-level inverter, a contactor capable of disconnecting the bus capacitor and the balance circuit from the alternating current grid, and a parameter sensor and a field programmable gate array controller electrically coupled to the power converter, capable of controlling a plurality of power switches based on at least one sensed parameters.