Abstract: A method and arrangement in connection with an electric drive system are provided. The electric drive system includes an intermediate circuit with two or more supply units and two or more inverter units connected thereto, and an electric machine having two or more three-phase windings galvanically separated from each other. Two or more inverter units are connected to the three-phase windings. The arrangement also includes first main circuit switches to galvanically separate each supply unit from a supply, second main circuit switches to galvanically separate each supply unit from the intermediate circuit, first intermediate circuit switches to galvanically separate each inverter unit from the intermediate circuit, and second intermediate circuit switches to galvanically separate each inverter unit from the electric machine.

Abstract: Exemplary embodiments are directed to a method for controlling a switching branch of a three-level converter to enter a stop state. The switching branch including a first semiconductor switch and a second semiconductor switch, a first diode and a second diode, a third semiconductor switch and a fourth semiconductor switch, a third diode, and a fourth diode, a fifth semiconductor switch and a sixth semiconductor switch, a fifth diode, and a sixth diode, and a manner of controlling the semiconductor switches. When the switching branch is set to enter a stop state, current flowing in a main circuit of the switching branch is transferred in a controlled manner to diodes that conduct the current, when all the semiconductor switches of the main circuit of the converter are turned OFF.

Abstract: Exemplary embodiments are directed to a system, method, apparatus, and arrangement for operating a photovoltaic system. The photovoltaic system including a boost converter having a controllable duty ratio, at least two strings of photovoltaic panels supplying an input of the boost converter, wherein the strings are connected in parallel with each other. The system having detector configured to detect a reverse current in any of the strings, and a controller configured to increase, in response to the detection of a reverse current in at least one of the strings, the duty ratio of the boost converter at least until the reverse current stops.

Abstract: A system and method for cooling a solar power plant are disclosed. The system includes a foundation, a protective housing built on the foundation, and one or more heat sources inside the protective housing. An air inlet can provide a cooling air flow from outside the protective housing to inside the protective housing, and an air outlet can allow an air flow heated by the at least portion of the heat sources to exit the protective housing. An air duct system within the foundation can direct at least part of an incoming air flow to another part in the protective housing.

Abstract: A control system for semiconductor switches, the control system (CTRL) being configured to calculate an estimate of the instantaneous dissipation power of at least one semiconductor component unit (SU1) during an analysis period, whereby the at least one semiconductor component unit (SU1) includes at least one semiconductor switch (S1), and the instantaneous dissipation power includes the conduction losses and switching losses of the at least one semiconductor component unit (SU1).

Abstract: A cooled base plate is provided for electric components. A first side of the cooled base plate is provided for attaching exothermal electric components thereto. On a second side of the base plate, opposite to the first side, there is embedded a cooling channel system having a cooling fluid inlet at a first end of the base plate and a cooling fluid outlet at a second end of the base plate. In order to minimize differences in temperature between the electric components, the thickness of the base plate increases in the direction from the inlet of the cooling channel system towards the outlet of the cooling channel system, e.g., in the flow direction of the cooling fluid, for at least a portion of the length of the base plate.

Abstract: A cooling assembly includes a device chamber, a cooling chamber separated from the device chamber, a heat exchanger, a device chamber fan arrangement and a control unit. The heat exchanger includes a first portion located in the device chamber and a second portion located in the cooling chamber for transferring heat from the device chamber to the cooling chamber. The device chamber fan arrangement is configured to generate a device chamber cooling medium flow including a first partial flow interacting with the first portion of the heat exchanger. The cooling assembly also includes a first throttle arrangement for regulating the first partial flow. The control unit is configured to reduce a cooling power of the heat exchanger as a response to predetermined operating conditions by decreasing the first partial flow with the first throttle arrangement.

Abstract: A cooling assembly includes a device chamber containing a device chamber cooling medium, a heat exchanger including at least one cooling surface in contact with the device chamber cooling medium, a control unit configured to control the heat exchanger, a humidity sensor configured to detect a humidity level in the device chamber, and a receptacle. The control unit is configured to perform a dehumidification operation as a response to the humidity level exceeding a predetermined threshold value in the device chamber. The dehumidification operation includes lowering a temperature of the at least one cooling surface in order to condensate water from the device chamber cooling medium on the at least one cooling surface. The receptacle is configured to receive water dripping from the at least one cooling surface.

Abstract: A frequency converter assembly including an input for supplying electric power having an input frequency into the frequency converter assembly from a supply network, a direct voltage intermediate circuit having capacitor component, and at least one controllable switch. The switch being electrically positioned between the input and the direct voltage intermediate circuit. The assembly also includes an output for supplying electric power having an output frequency from the frequency converter assembly, and control component arranged to control the at least one controllable switch. The control component provides a recovery function to recover the capacitor component by supplying restricted recovery current from the supply network to the capacitor component through the at least one controllable switch, the control means also prevents supply of electric power from the direct voltage intermediate circuit towards the output during the recovery function.

Abstract: An exemplary propulsion arrangement is disclosed which includes two propulsion units situated side by side at the stern of a ship at opposite sides of a center line of the hull of the ship. Each propulsion unit can include a hollow support structure attached to the hull, a chamber attached to the support structure, an electric motor within the chamber, a propeller connected through a shaft to the electric motor, and a pivotably supported rudder at the rear end of the chamber. Each propulsion unit can be mounted in a toe-out position forming a horizontal tilt angle (?) of 0.5 to 6 degrees to the center line (CL) of the hull.

Abstract: A method and arrangement are provided in connection with a continuous material web, which runs from an unwinder to a winder, at least one of which being a center winder. The method includes providing an initial value for density of a material on the center winder, calculating a moment of inertia for a roll of material on the center winder, determining tightness of the material web, producing a correction term for torque calculation based on a material web tightness reference, the material web tightness and the moment of inertia of the roll of material, calculating a torque reference based on the produced correction term and the calculated moment of inertia of the roll of material, and controlling the torque of the center winder based on the torque reference. The method also includes correcting the density value of the material on the center winder based on the produced correction term.

Abstract: An exemplary propulsion arrangement includes at least one propulsion unit situated at the stern of a ship having a hull with a horizontal water line (WL) and a center line (CL). The propulsion unit can include a hollow support structure attached to the hull, a chamber attached to the support structure, an electric motor within the chamber, a propeller at the front end of the chamber, and a pivotably supported rudder at the rear end of the chamber. The propulsion unit can be mounted so that the shaft line (SL) forms a vertical tilt angle (?) in a range of 1 to 8 degrees in relation to the water line (WL) so that the front end of the chamber is lower than the rear end of the chamber in relation to the water line (WL).

Abstract: A method for controlling a frequency converter unit, the frequency converter unit containing an input connection for supplying electric power at an input frequency to the frequency converter unit, and an output connection for supplying electric power at an output frequency from the frequency converter unit, the method comprising a control step, in which the frequency converter unit is controlled by means of control signals. In the control step the control signals are supplied through an inductive connection to at least one wire connected to the input connection or the output connection of the frequency converter unit for transmitting electric power, the control signals being supplied to the frequency converter unit over the at least one wire.

Abstract: A method and arrangement are disclosed for a vehicle inverter drive having a voltage distribution block and two or more inverters, intermediate circuits of which are connected in parallel to the voltage distribution block for supplying voltage to the intermediate circuits, in which the intermediate circuits of the inverters are interconnected with a coaxial cable to minimize inductance in the parallel connection.

Abstract: Exemplary embodiments provide a method of controlling a doubly-fed electric generator using a frequency converter having a torque and flux controller. The frequency converter is connected to a rotor of the generator. The frequency converter calculates a stator flux positive sequence component from a stator flux. A rotor flux amplitude reference and an estimated torque is then calculated by using the stator flux positive sequence component. The frequency converter selects a voltage vector to steer the rotor flux by using the rotor flux amplitude reference and the estimated torque.

Abstract: A method in connection with a pump drive connected to a container or the like, wherein a frequency converter is arranged to supply power to a pump in such a manner that a pump flow (Qp) is responsive to an estimated mean incoming flow (Qest) to the container. The method includes draining the container, allowing the container to fill during a predefined filling time (tfill) while the pump is inactive, draining the container again at a known pump flow (Qp,nom), defining the drainage time (tdrain), defining an estimated mean incoming flow (Qest) on the basis of the filling time (tfill), drainage time (tdrain) and known pump flow (Qp,nom), and setting the power supplied by the frequency converter to the pump to be such that the pump flow (Qp) corresponds to the produced estimated mean incoming flow (Qest).

Abstract: A method for operating an inverter, and an inverter for coupling with a photovoltaic array having at least one photovoltaic panel are disclosed. The inverter can be configured: to connect output poles of the photovoltaic array in short circuit with each other; to measure a current supplied by the photovoltaic array through the output poles after they have been connected in short circuit with each other; and to start a DC-to-AC conversion of power supplied by the photovoltaic array if the measured current exceeds a predetermined threshold.