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Reijo Kalevi Virtanen

Osmo Pasuri

Simo Pöyhönen

Jouko Niiranen

Jorma Keronen

Slavomir Seman

Tomas Melin

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.

Method and arrangement in connection with electric device system

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.

Control method for doubly-fed electric generator

A method and an arrangement are disclosed for balancing load between parallel connected inverter modules, which inverter modules are arranged to supply a common load. The method can include providing similar switching instructions for parallel connected inverter modules, determining on the basis of phase currents of each parallel inverter module a first time period for each output phase of each inverter module for correcting current imbalance by advancing or delaying turn-on or turn-off time instants of switch components of the inverter modules, and advancing or delaying the turn-on or turn-off time instants of the switching instructions based on the first time period. The method also can include determining temperatures of each output phase of each inverter module, modifying the switching instructions for one or more of the parallel inverter modules for controlling the temperatures of the output phases, and controlling the inverter modules with a switching instruction in which the turn-on or turn-off times have been advanced or delayed in respect of one or more parallel modules and further modified in respect of one or more inverter modules.

Load balancing of parallel connected inverter modules

A method and an arrangement for determining the rotation speed of a motor fed by an inverter, the arrangement comprising means for determining the rotation speed of the motor in at least two alternative manners, whereby the means for determining the rotation speed of the motor comprise one of the at least two alternative manners of performance: means for measuring the frequency of the voltage fed to the motor by the inverter; and means for estimating the rotation speed of the motor on the basis of the measured frequency.

Method and arrangement for determining rotation speed of a motor

A protection configuration for converter means which comprise a plurality of controllable switches, the protection configuration comprising a protection circuit coupled to the alternating voltage side of the converter means, which protection circuit comprises at least one protective switch configured to short-circuit the alternating voltage side of the converter means, wherein the protection configuration, in predetermined failure situations, is configured to close the protective switch and thus to short-circuit the alternating voltage side of the converter means. After the failure situation has cleared up, the protection configuration is configured to short-circuit the alternating voltage side of the converter means by means of the controllable switches to enhance commutation of the protective switch.

Configuration and method for protecting converter means

A method for operating a doubly-fed machine by determining its rotational speed (n), forming a rotational speed reference (n), measuring network voltage and current, and calculating network active power (P) and reactive power (Q). Thereafter, calculating shaft torque (T) based on active power (P) and rotating speed (n), forming a frequency reference (F) for the inverter based on machine rotating speed (n), rotating speed reference (n), shaft torque (T), and the known pole pair number and network frequency, forming a reactive power reference (Q) for the machine. Forming an Ir compensation reference (IR) for the inverter on the basis of the reactive reference (Q) and the reactive power (Q), and controlling the inverter to produce rotor voltage based on frequency reference (F) and the IR compensation reference

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Vantaa, Finland

Reijo Kalevi Virtanen