A rectifier has at least three outputs at which the rectifier provides a high potential, a low potential and at least one medium potential. Phase voltages of a supply grid can be supplied to the rectifier via feed lines. Inductors are arranged in the feed lines. A clamping circuit has two diode circuits that are connected in series. One of the end points of the series circuit is connected to an output at which the rectifier provides one of the medium potentials. The other end point is connected to another output. The node is connected to a reference potential via an overall capacitor circuit.

An inverter is provided for driving a motor. A first capacitor, and a second capacitor including capacitors connected in series, are connected in parallel to a DC power supply. A switch circuit having switching elements is connected between the inverter and the second capacitor. A control circuit is provided for controlling the inverter and the switch circuit. The control circuit performs control to switch the switch circuit so as to supply current from the second capacitor to the inverter during 3-level operation, and supply current from both of the first capacitor and the second capacitor to the inverter during 2-level operation.

Described herein is a multi-level power convertor and a method for a multi-level power convertor. The multi-level power convertor includes a DC port; an AC port; a first power converting unit, a second power converting unit, a coupling inductor, and an inductive filtering unit. The first power converting unit is coupled to the DC port and includes a first AC terminal adapted to provide a first plurality of voltage levels. The second power converting unit is coupled to the DC port and includes a second AC terminal adapted to provide a second plurality of voltage levels, where the second plurality of voltage levels are phase-shifted by 90 degrees with respect to the first plurality of voltage levels. The coupling inductor includes first and second windings with a same number of turns. The inductive filtering unit is arranged between the AC port and ends of the first and second windings.

A power converter can include a first line, a second line, a capacitor line disposed between the first line and the second line, a first capacitor and a second capacitor connected to the capacitor line in series between the first line and the second line, a midpoint line connected to a midpoint between the first capacitor and the second capacitor, and a protection circuit disposed between the first capacitor and the second capacitor and configured to provide protection to one or more portions of the power converter.

A method includes detecting a voltage signal of a three-level power converter, the voltage signal indicative of a capacitor voltage balancing in the three-level power converter, and dynamically adjusting an operating variable to adjust the voltage signal until the capacitor voltage balancing in the three-level power converter satisfies a criteria.

An output terminal of one phase switched capacitor converter is connected to a first output terminal, and an output terminal of the other phase switched capacitor converter is connected to the first output terminal via a second switch, such that the power conversion structure can operate in a mode of two phase switched-capacitor converters in parallel, and a current formed by the operating of only one phase switched capacitor converter flows through the second switch, thus greatly reducing a value of current flowing through the second switch, greatly reducing the on-state loss of the second switch, and improving the efficiency of the power conversion structure, and because the second switch has lower on-state loss and less heat, there is a larger selectivity of the second switch and a reduction of the cost of power conversion structure.

An output terminal of one phase switched capacitor converter is connected to a first output terminal, and an output terminal of the other phase switched capacitor converter is connected to the first output terminal via a second switch, such that the power conversion structure can operate in a mode of two phase switched-capacitor converters in parallel, and a current formed by the operating of only one phase switched capacitor converter flows through the second switch, thus greatly reducing a value of current flowing through the second switch, greatly reducing the on-state loss of the second switch, and improving the efficiency of the power conversion structure, and because the second switch has lower on-state loss and less heat, there is a larger selectivity of the second switch and a reduction of the cost of power conversion structure.

A circuit arrangement for balancing a split DC link arranged between a first DC-voltage terminal and a second DC-voltage terminal is disclosed. The first DC-voltage terminal is connected via a first semiconductor switch to a first intermediate point that is connected via a second semiconductor switch to a bridge center point that is connected via a third semiconductor switch to a second intermediate point that is connected via a fourth semiconductor switch to the second DC-voltage terminal. A first terminal of a resonant capacitor is connected to the first intermediate point, and a second terminal of the resonant capacitor is connected to a DC-link center point via a connecting path, in which a resonant inductor is arranged in a series circuit with the third semiconductor switch, and which runs via the second intermediate point. An additional winding is magnetically coupled to the resonant inductor and a first terminal thereof is connected via a first diode to a first terminal of a countervoltage source, and a second terminal thereof is connected to a second terminal of the countervoltage source so that an energy coupled into the additional winding from the resonant inductor is discharged into the countervoltage source.

A method relating to control of a system including a single-phase three-level quasi-Z type source inverter connected to an LC filter which is in turn connected to a load, the inverter including first and second bridge arms, each including a plurality of switches, the method including the steps of (a) for each of a plurality of consecutive sampling periods (i) determining the duration of a shoot-through period for the next sampling period during which the inverter is in shoot-through mode; (ii) choosing a configuration of the switches for the next sampling period (iii) at the end of the sampling period setting the switches in the chosen configuration for the next sampling period; and (b) at a time during the next sampling period and for the duration of the shoot-through period setting the switches such that the inverter is in shoot-through mode.

Systems and methods relating to an electrical system comprising at least two modules, each module comprising at least one switching element. A first module comprises a first switching element made of a first semiconductor material and the second module comprises a second switching element made of a second semiconductor material.