Abstract: A converter and a method of operating a converter. The converter comprising a DC link capacitor, an upper arm (S1) and a lower arm (S4) with switching cells in series, an upper switch (S2) and a lower switch (S3). The upper switch (S2) and the lower switch (S3) are connected together and the connection point forming an output voltage terminal (a). The converter comprising further an upper valve component and a lower valve component, which are arranged such that the upper valve component allows current from the center point of the DC link capacitor towards the upper arm and the lower valve component allows current from the lower arm towards center point of the DC link capacitor. A current path through the upper valve component or the lower valve component comprises inductance to form a resonance circuit.

Abstract: A method of monitoring an electrical machine, wherein the method includes: a) obtaining temperature measurement values of the temperature at a plurality of locations of the electrical machine, b) obtaining estimated temperatures at the plurality of locations given by a thermal model of the electrical machine, the thermal model including initial weight parameter values, c) minimizing a difference between the temperature measurement values and the estimated temperatures by finding optimal weight parameter values, d) storing the initial weight parameter values to thereby obtain a storage of used weight parameter values, and updating the optimal weight parameter values as new initial weight parameter values, and repeating steps a)-d) over and over during operation of the electrical machine.

Abstract: A voltage source converter is configured to generate a pulse train using two voltage levels. The voltage source converter includes a first converter arm coupled between a junction and a first DC terminal having a first voltage level and a second converter arm coupled between the junction and a second DC terminal having a second voltage level. At least one of the first and second converter arms comprises cells. A string of capacitors is coupled between the first and second DC terminals. A control unit is configured to control a group of cells used in a transition between the first and second voltage levels for commutating a current running through a corresponding one of the first and second converter arms involved in the transition.

Abstract: A converter and a method of operating a converter. The converter comprising a DC link capacitor, an upper arm (S1) and a lower arm (S4) with switching cells in series, an upper switch (S2) and a lower switch (S3). The upper switch (S2) and the lower switch (S3) are connected together and the connection point forming an output voltage terminal (a). The converter comprising further an upper valve component and a lower valve component, which are arranged such that the upper valve component allows current from the center point of the DC link capacitor towards the upper arm and the lower valve component allows current from the lower arm towards center point of the DC link capacitor. A current path through the upper valve component or the lower valve component comprises inductance to form a resonance circuit.

Abstract: A voltage source converter is configured to generate a pulse train using two voltage levels. The voltage source converter includes a first converter arm coupled between a junction and a first DC terminal having a first voltage level and a second converter arm coupled between the junction and a second DC terminal having a second voltage level. At least one of the first and second converter arms comprises cells. A string of capacitors is coupled between the first and second DC terminals. A control unit is configured to control a group of cells used in a transition between the first and second voltage levels for commutating a current running through a corresponding one of the first and second converter arms involved in the transition.