Abstract: A method of balancing voltages in a group of capacitors of a power electronic device, such as a multilevel power inverter, includes making a balancing determination regarding whether to (i) inject energy into the selected one of the capacitors from an energy storage element, or (ii) extract energy from the selected one of the capacitors into the energy storage element based on the voltage of a selected one of the capacitors, and either injecting energy into the selected one of the capacitors from the energy storage element, or extracting energy from the selected one of the capacitors into the energy storage element based on the balancing determination. Also, a voltage balancing circuit that implements the method. In one particular implementation, a spatial second derivative algorithm is used. In another particular implementation, a comparison to an average capacitor voltage is used.

Abstract: This set of roller bearings, which is a grounding bearing for a rotary machine, comprises a first-angular contact rolling bearing having a first outer race, a first inner race and first rolling elements, a second angular-contact rolling bearing having a second outer race, a second inner race and second rolling elements, a mount in which the first angular-contact rolling bearing and the second angular-contact rolling bearing are mounted. The first outer race and the second outer race are arranged in the mount either directly one beside the other or via the interposition of an intermediate member, the axial stiffness of which is greater than that of the mount and than those of the first and second outer races. Application for example to asynchronous motors.

Abstract: The present invention provides a permanent magnet rotor arrangement for a rotating electrical machine including a rotor body having an outer rim. A circumferential array of magnet carriers is mounted to the rotor body by fixing members and support members and is spaced apart from the rotor body in the radial direction to define a series of axially gaps or spaces which can optionally be used as passages for cooling air. At least one pole piece made of permanent magnet material is located adjacent to a surface of each magnet carrier. The magnet carriers and pole pieces preferably have a laminated or divided construction to virtually eliminate eddy currents that may be particularly problematic in certain types and construction of electrical machine. The flux path between adjacent pole pieces flows in the circumferential direction within the magnet carriers and does not use the rotor body.

Abstract: An electric circuit is described for generating electric power. In this circuit, an asynchronous generator includes a stator and a rotor. On the stator side, the asynchronous generator is coupled to a power grid. The rotor current flowing to the rotor of the asynchronous generator can be measured. A control device is designed such that, in case of a fault in the power grid, the stator current flowing to the stator of the asynchronous generator is calculated from the measured rotor current as a function of parameters of the asynchronous generator.

Abstract: The energy conversion device (10) includes a power module (14), elements (16) for cooling the power module (14), and a sealed enclosure (12) for housing the power module (14) and at least one portion of the cooling elements (16). The cooling elements (16) include a cooling circuit 18, in which a heat transfer fluid circulates, a first heat exchange (20) with the power module (14), through which passes the heat transfer fluid of the cooling circuit (18) and at least one pump (24) for driving the heat transfer fluid circulating in the circuit (18). The enclosure (12) includes an area (26) for receiving heat transfer fluid, filled with heat transfer fluid, and the cooling circuit (18) includes an inlet orifice (28) in the circuit (18) made upstream from the driving pump (24) and opening into the heat transfer fluid of the receiving area (26).

Abstract: Described is a method for operating a converter for a system for generating electrical energy. In an embodiment of the method, the output voltage of the converter is converted to a d, q coordinate system, wherein the d, q coordinate system is assigned to the frequency of the voltage for the energy supply grid. A desired value is furthermore specified in the d, q coordinate system, several momentary or future values are determined from the output voltage in the d, q coordinate system for different switch positions of the converter, deviations between the desired value and the momentary or future values are determined in the d, q coordinate system, and the converter is switched to one of the switch positions in dependence on these deviations.

Abstract: A system for generating electrical power is described. In at least one embodiment, the system includes a turbine that is mechanically connected to a generator, wherein the generator is electrically connected via a first converter to a load. The first converter generates a first output current. A second output current is generated by a second converter and is added to the first output current. The second output current is generated such that an actual current over the load follows a desired current.

Abstract: A method for operating an electrical circuit, in particular of a converter is described. The circuit, in at least one embodiment, includes a line-side converter that is coupled to a capacitor. The line-side converter includes at least two series connections, each including at least two power semiconductor elements, and each of the at least two series connections being connected parallel to the capacitor. The line-side converter is coupled to an energy supply system. The DC voltage that is present at the capacitor is determined. A maximum voltage is predetermined. If the DC voltage present at the capacitor is determined to be greater than the maximum voltage, then at least two of the power semiconductor elements are switched into their conductive state in such a manner that the capacitor is discharged in the direction of the energy supply system.

Abstract: Described is a method for testing a power producer or a power consumer that can be connected to a power grid. The power producer or the power consumer is connected to a terminal point. A converter circuit is provided for influencing a voltage that is present at the terminal point. The converter circuit is connected via a transformer to the terminal point. In at least one embodiment, a series connection is configured with a choking coil and a first switch and connected to the terminal point. In a time coordinated manner, the first switch is initially closed and the converter circuit is influenced such that the voltage has the desired value at the terminal point, whereupon the second switch is then opened.

Abstract: This system for converting a direct input voltage into an alternating output voltage comprises two input terminals, two voltage generators connected in series between the input terminals and connected to one another by a middle point, as well as, for each phase of the alternating voltage, an output terminal, two switching branches each connected between the output terminal and a respective input terminal, each switching branch comprising N first switching cells connected in series and N?1 intermediate points, the first switching cells successively being connected to one another by a corresponding intermediate point, N being an integer greater than or equal to 2, and control means for controlling the first switching cells. The system includes, for each phase of the alternating voltage, N?1 pair(s) of capacitors, each pair of capacitors being connected between intermediate points of one of the two switching branches and the other of the two switching branches.

Abstract: The present invention relates to armature windings for DC electrical machines, and in particular to those that use electronic commutation and have relatively few slots per pole-pair. The armature windings are particularly well suited for use with rotating DC electrical machines that have a large diameter and a large number of poles such as those that might be directly coupled to the turbine blade assembly of a wind turbine. The armature winding is arranged in relation to the magnetic field generated by a field winding or by permanent magnets such that a number of commutation events during the time taken for the relative movement between the armature and the field system of one pole-pair is much larger than the number of coils per pole-pair.

Abstract: The present invention relates to a vacuum switch assembly for interrupting and isolating fault current. The vacuum switch assembly includes first and second dc lines that, in use, are electrically connected to the dc output terminals of a primary dc power source and a dc network. Each dc line includes at least one vacuum switch having contacts that are opened and closed under the control of a vacuum switch controller. A passive dc power supply unit is electrically connected to the first and second dc lines and includes a secondary dc power source that provides a substantially ripple-free sensing voltage. The vacuum switch controller is adapted to open the vacuum switch contacts when a fault condition (e.g. a fault current or other fault) or an operator request has been identified and when the current flowing between the vacuum switch contacts is below a chopping current associated with the vacuum switches.

Abstract: The present invention relates to a retaining band which provides outer reinforcement for the rotor assembly of a high speed electrical machine. The rotor assembly includes a plurality of circumferentially-spaced permanent magnet assemblies. A retaining band is fitted around the rotor assembly and applies a pre-load to the permanent magnet assemblies in the radial direction. The retaining band has a plurality of voids that are sized and shaped to provide the retaining band with a progressive spring stiffness in the radial direction. The voids are open before the retaining band is fitted and during the fitting process the retaining band is deflected in the radial direction so that the voids close up and the retaining band becomes substantially solid.

Abstract: A method of controlling a combined plant to provide frequency support to a power grid operating at a variable grid frequency, wherein the combined plant includes at least one generator and an energy store, and the combined plant is adapted to supply power to the power grid, the method including the steps of charging the energy store at less than its rated power when frequency support is not needed. When frequency support is needed the combined plant is controlled to increase or decrease the overall power that it supplies to the power grid to provide frequency support. The control of the combined plant can be designed to maximize frequency support revenues.

Abstract: This set of roller bearings, which is a grounding bearing for a rotary machine, comprises a first-angular contact rolling bearing having a first outer race, a first inner race and first rolling elements, a second angular-contact rolling bearing having a second outer race, a second inner race and second rolling elements, a mount in which the first angular-contact rolling bearing and the second angular-contact rolling bearing are mounted. The first outer race and the second outer race are arranged in the mount either directly one beside the other or via the interposition of an intermediate member, the axial stiffness of which is greater than that of the mount and than those of the first and second outer races. Application for example to asynchronous motors.

Abstract: A reactive energy compensator that can be electrically connected to an AC electrical network, including at least one input direct voltage bus, at least one voltage inverter including switches and first and second capacitors having first and second voltages at their terminals, control means for the switches, including computation means capable of generating a target control current, means for combining the target control current and the output current from the inverter, means for transmitting a control signal capable of driving the switches, and correction means for the control signals of the switches, the correction means being capable of adding a balancing current to the target control current, the balancing current being able to correct the target control current so as to reduce the difference between the values of the first and second voltages, the target control current being increased for an even harmonic of the network frequency.

Abstract: A direct current (DC) circuit breaker for power transmission or distribution system includes a current sensor for sensing current of a system, a controller, a physical switch, and multiple switch modules. The multiple switch modules are electrically coupled to the current sensor and the physical switch in series. Each switch module includes multiple base elements electrically coupled in parallel. Each base element includes a first silicon carbide (SiC) metal-oxide-semiconductor field-effect transistor (MOSFET) and a second SiC MOSFET electrically coupled in an opposite series connection mode. The first and second SiC MOSFETs are configured in a synchronous rectification mode by channel reverse conduction control. The controller controls the multiple switch modules to connect current in the system, and break current of the multiple switch modules according to sensed current signals from the current sensor.

Abstract: A multi-phase electric circuit including an electric machine and an inverter, wherein machine encompasses a rotor connected to the inverter via at least two brushes for each phase, wherein each of the brushes of each phase is connected to the inverter via a separate brush line.

Abstract: A static energy supply unit has an energy store connected to an ac supply network by a power converter. A unit controller for the static energy supply unit includes an amplitude controller, a phase controller and a frequency controller. These measure and record characteristics of the supply network and provide output signals indicative of the voltage characteristics for an operating condition of the supply network. A signal generator for generating a simulated output voltage signal for each phase of the supply network is provided. A comparator is used to compare the simulated output voltage signal for each phase and a measured voltage for a corresponding phase of the supply network. The controller controls the operation of the power converter to vary the amount of power that is supplied to the supply network from the energy store based on the comparison of the simulated output voltage signal(s) and the measured voltage(s).

Abstract: The present invention provides a method of controlling the position of a spread moored marine vessel (1). In particular, the method of the present invention substantially maintains the position of a spread moored vessel (1) in, or on the boundary of a target area (2) using thruster assistance. This is done by monitoring the position of the vessel and when the vessel (1) is positioned outside of the target area (2) applying a position correcting thrust (7) to the vessel (1) in the direction of an aim position located on the boundary of the target area (2) and when the vessel (1) is positioned within the target area (2) reducing the position correcting thrust (7) applied to the vessel (1) or maintaining the position correcting thrust (7) applied to the vessel (1) at zero. The present invention may also apply a damping thrust (7) to the vessel (1) in order to damp the positional variation of the vessel (1).