Abstract: A control device (101) for controlling a power converter (109) is configured to form a frequency droop value based on electric power supplied by the power converter to an alternating current system, decrease a frequency control value by the frequency droop value, form a power control value based on a target value of the electric power, increase the frequency control value by the power control value, and supply the frequency control value to the power converter to control alternating voltage frequency of the power converter. The electric power is driven to a value at which a combined effect of the frequency droop value and the power control value makes the alternating voltage frequency of the power converter to be the same as operating frequency of the alternating current system. Thus, the electric power can be controlled by changing the power control value.

Abstract: A positioning device (101) for producing a position signal indicative of a rotational position of a resolver is presented. The positioning device comprises a signal interface (102) for receiving alternating signals (V_cos, V_sin) from the resolver and a processing system (103) for generating the position signal based on position-dependent amplitudes of the alternating signals and on polarity information indicative of a polarity of an excitation signal (V_exc) of the resolver. The processing system is configured to recognize a polarity indicator, such as a change of frequency or phase, on a waveform of one or both of the alternating signals and to determine the polarity information based on the recognized polarity indicator. Thus, the polarity information related to the excitation signal is included in the alternating signals and therefore there is no need for a separate signaling channel for transferring the polarity information to the positioning device.

Abstract: A device-system comprises parallel operating devices (105-107) for driving an operating quantity towards a target value, and a control system for controlling each device at least partly based on a device-specific integral term relating to a time integral of a device-specific error signal that is indicative of a deviation of the operating quantity from the target value. The control system comprises a stabilizing system that computes an arithmetic average of the device-specific integral terms and corrects the device-specific integral terms towards the computed arithmetic average. The correction of the device-specific integral terms makes it possible to avoid unwanted drifts in the device-specific integral terms in a situation where there are differences between the device-specific error signals. The devices can be peers to each other and thus redundancy is achieved because one device can be removed from or added to the device-system without actions from the other devices.

Abstract: An electric machine element comprises electric terminals (101) for connecting to an external AC system and a multiphase winding (102) comprising at least two multiphase winding portions (103, 104). Each multiphase winding portion comprises phase-windings (106a-106c, 107a-107c) each having a first end (109) and a second end (110). The multiphase winding portions are successively connected to constitute chains (113a-113c) of the phase-windings so that the first ends of the phase-windings of a first one (103) of the multiphase winding portions are connected to the electric terminals. Each multiphase winding portion comprises switches (114a, 114b, 115a, 115b) for connecting the second ends of the phase-windings of the multiphase winding portion to each other. Thus, the number of turns of the multiphase winding is changeable by selecting which one of the multiphase winding portions has a star-point at the second ends of its phase-windings.

Abstract: An electric power system includes electric energy sources and control equipment for controlling the electric energy sources in accordance with a target value of electric power produced by the electric power system. The control equipment activates and deactivates the electric energy sources based on a control value and on activation and deactivation limits. The control value can be the target value or the actual value of the electric power. The control equipment controls active electric energy sources according to the target value and according to power sharing defined for the active electric energy sources. The activation and deactivation limits as well as activation and deactivation order of the electric energy sources can be determined based on properties of the electric energy sources and on a prevailing operational situation of the electric power system.

Abstract: A vessel includes electric connectors for receiving one or more direct voltages from a shore-side electric power system. The vessel includes a transmitter for transmitting, to the shore-side electric power system, a control signal enabling the shore-side electric power system to control the one or more direct voltages to be suitable for the vessel. Alternatively, the vessel includes one or more controllable direct voltage converters and a control system for controlling the one or more controllable direct voltage converters to convert the one or more direct voltages into one or more direct voltages suitable for the vessel. The vessel can be for example a ship, a boat, or a ferry.

Abstract: An electric power system comprises recording devices (101-105) located at different elements of the electric power system and configured to record waveform samples of quantities related to operation of the elements of the electric power system. The electric power system comprises a central device (106) configured to receive the recorded waveform samples from the recording devices. The recording devices are synchronized to maintain a common clock time and to associate, to each of the recorded waveform samples, one or more timing values indicative of the clock time during recording the waveform sample. As the timing values are associated to the waveform samples, it is possible to reconstruct a time order of phenomena indicated by the recorded waveform samples. Thus, it is possible to identify which of the phenomena are causes and which are consequences when analyzing for example what happened prior to a fault situation.

Abstract: A linear electric machine comprises a primary part (101) and a secondary part (102) linearly movable with respect to each other. The primary part comprises primary sections (103, 104) each having an airgap surface. The secondary part comprises secondary sections (105, 106) each having an airgap surface facing towards the air-gap surface of the respective primary section. Each primary section comprises force-generating windings (U1, V1, W1, U2, V2, W2) for generating a magnetic thrust force and a transversal magnetic force pulling the primary section towards the respective secondary section. The resultant of the transversal magnetic forces is controllable to levitate the primary part. The primary part further comprises one or more tilt-control windings (T1, T2) for controlling tilting of the primary part with respect to the secondary part.

Abstract: An electric system of an electromechanical power transmission chain is provided that includes a first capacitive circuit, converter equipment between the first capacitive circuit and an electric machine, a second capacitive circuit, and a direct voltage converter between the first and second capacitive circuits. The electromechanical power transmission chain is a parallel transmission chain where the electric machine is mechanically connected to a combustion engine and to one or more actuators. The electric system includes a control system for controlling the direct voltage converter in response to changes in a first direct voltage of the first capacitive circuit and for controlling the converter equipment in response to changes in a second direct voltage of the second capacitive circuit. The first direct voltage is kept on a predetermined voltage range whereas the second direct voltage is allowed to fluctuate in order to respond to peak power needs.

Abstract: A device for estimating a rotation speed and/or a direction of rotation of an induction machine is presented. The device controls stator voltages (uu, uv, uw) of the induction machine so that a voltage space-vector constituted by the stator voltages has a fixed direction and a current space-vector constituted by stator currents (iu, iv, iw) of the induction machine has a pre-determined length or a predetermined d-component. The rotation speed and/or the direction of rotation is/are estimated based on a waveform of a q-component of the current space-vector, where the d-component of the current space-vector is parallel with the voltage space-vector and the q-component of the current space-vector is perpendicular to the voltage space-vector. The device is usable when the induction machine does not have enough magnetic flux for flux-based determination of the rotation speed and/or the direction of rotation.

Abstract: A power system for supplying electric power from shore-side to a vessel is presented. The power system includes one or more shore-side converters (101-112) for receiving electric power from a shore-side alternating voltage network (137) and for producing one or more direct voltages. Each shore-side converter can be a controllable converter for controlling the produced direct voltage to be suitable for the vessel in accordance with a control signal received from the vessel, or the vessel may include a direct voltage converter for converting the direct voltage received from the shore-side to be suitable for the vessel. The vessel can be an electric vessel which includes a chargeable battery (132) for supplying electric power to the propulsion system (135) of the vessel.

Abstract: A power converter comprises an inductor coil whose first pole is connected to an input terminal of the power converter, a controllable switch between the ground and a second pole of the inductor coil, a first unidirectionally conductive component providing a path for electric current from the inductor coil towards an output terminal of the power converter when the controllable switch is non-conductive, and an over-current protector at the output terminal. The power converter comprises a second unidirectionally conductive component for conducting electric current from the input terminal to the over-current protector in a fault situation where voltage at the output terminal is smaller than voltage at the input terminal. Thus, the second unidirectionally conductive component constitutes a low-inductance bypass route for fault current and enables the over-current protector to react fast to a fault situation.

Abstract: The invention relates to a method and to an arrangement for adjusting the magnetization of a permanent magnet machine, i.e. the magnetic flux induced by permanent magnets of a rotor in a stator, i.e. the air gap flux. According to the invention, the air gap flux is adjusted by adjusting the leakage flux of the permanent magnet.