Abstract: A method for re-powering a star-connected stator having a plurality of parallel stator slots, wherein a plurality of stator winding bars having external winding connections are disposed in stator slots includes bridging the external winding connections so as to connect the stator winding bars in series and to form a polygonal stator capable of producing a polyphase alternating current.

Abstract: A method for operating a matrix converter to convert n phases of a generator into alternating voltage with nr (nr<n) phases of a load connected to a network includes the steps of alternatingly connecting the nr phases of the load using a plurality of controllable bi-directional switches disposed in an (n×nr) matrix, wherein nr phases of the generator are always connected with the load and (n?nr) phases of the generator are not connected with the load, and controlling the switching of a phase k of the generator at a time t to a phase c of the grid, using a periodical, continuous, segmented function k(t). The function k(t) defines a broken line having a plurality of segments, wherein each segment i is defined by a starting time ti and a pulsation ?i, and the value of the function k(t) is rounded to the closest integer value.

Abstract: A method for re-powering a star-connected stator having a plurality of parallel stator slots, wherein a plurality of stator winding bars having external winding connections are disposed in stator slots includes bridging the external winding connections so as to connect the stator winding bars in series and to form a polygonal stator capable of producing a polyphase alternating current.

Abstract: An apparatus for producing electrical power from mechanical power, includes a generator with a rotor and a stator for conversion of mechanical power to a polyphase alternating current having more than three phases. The stator has a stator core with a cylindrical stator bore and a plurality of parallel stator slots disposed at a distance from one another, extending axially along a length of the stator core and being open towards the stator bore. A plurality of stator winding bars are disposed in the stator slots so as to form delta-connected windings for producing the polyphase alternating current. A static frequency converter in the form of a matrix converter converts the polyphase alternating current to a desired output alternating current, wherein the stator is a polygonal stator having external winding connections that are bridged, wherein inputs to the matrix converter are connected to end connections of the winding bars.

Abstract: A matrix converter for the conversion of a polyphase alternating current into a desired alternating output current in which m phases of the polyphase alternating current are converted into alternating output current with n (n<m) phases of a load by a multiple number of controllable bidirectional switches. The converter includes at least one stage, and in that at least one stage of the converter each phase of the polyphase alternating current is controlled by a controllable bidirectional switch. The at least one stage of the converter is formed by a two-dimensional array of stage stacks of switching elements which stage stacks are arranged substantially parallel to each other along a stack direction perpendicular to the plane of the matrix converter, and wherein the input of the stage stacks is provided by bus bars located on one side of the stage stacks.

Abstract: A rotor for an exciter to be used to energize the field winding of a generator-rotor of a generator, the rotor defining an axis and including at least two conductor bars aligned substantially parallel to the axis. The bars are connected on their first axial end to one of a plurality of collecting ring and on their second axial end individually to one of two rings. By means of at least one diode the flow of current in each bar is allowed in only one direction such that an alternating current induced in the conductor bars due to a static field is converted into a direct current in the two rings.

Abstract: A method for operating a matrix converter in which m phases of a generator generating alternating voltage with n phases of a load are alternatingly connected via a multiple number of controllable bi-directional switches arranged in an (m×n) matrix. An improvement of the spectrum of the generated alternating voltage, i.e. of the alternating voltage with n phases is achieved by means of voltages which are added on-line to the converter output or input.

Abstract: A matrix converter for converting a polyphase alternating current into a desired alternating output current includes at least two stages; a plurality of controllable bidirectional switches, converts m phases of the polyphase alternating current into alternating output current with n (n<m) phases of a load; and a controllable bidirectional switch controlling each phase of the polyphase alternating current in at least one stage of the converter.

Abstract: A method for operating a matrix converter to convert n phases of a generator into alternating voltage with nr (nr<n) phases of a load connected to a network includes the steps of alternatingly connecting the nr phases of the load using a plurality of controllable bi-directional switches disposed in an (n×nr) matrix, wherein nr phases of the generator are always connected with the load and (n?nr) phases of the generator are not connected with the load, and controlling the switching of a phase k of the generator at a time t to a phase c of the grid, using a periodical, continuous, segmented function k(t). The function k(t) defines a broken line having a plurality of segments, wherein each segment i is defined by a starting time ti and a pulsation ?i, and the value of the function k(t) is rounded to the closest integer value.

Abstract: A matrix converter (3) for the conversion of a polyphase alternating current (6) into a desired alternating output current (7) in which m phases of the polyphase alternating current (6) are converted into alternating output current with n (n<m) phases of a load by a multiple number of controllable bidirectional switches (4). The converter includes at least one stage (8,9), and in that at least one stage (8,9) of the converter each phase (6) of the polyphase alternating current (6) is controlled by a controllable bidirectional switch (4).

Abstract: An apparatus for producing electrical power from mechanical power, includes a generator with a rotor and a stator for conversion of mechanical power to a polyphase alternating current having more than three phases. The stator has a stator core with a cylindrical stator bore and a plurality of parallel stator slots disposed at a distance from one another, extending axially along a length of the stator core and being open towards the stator bore. A plurality of stator winding bars are disposed in the stator slots so as to form delta-connected windings for producing the polyphase alternating current. A static frequency converter in the form of a matrix converter converts the polyphase alternating current to a desired output alternating current, wherein the stator is a polygonal stator having external winding connections that are bridged, wherein inputs to the matrix converter are connected to end connections of the winding bars.

Abstract: A rotor for electrical rotating machines includes a rotor core with axial grooves for receiving axial conductors. A first element on the axial grooves and a corresponding second element on the axial conductors interact with one another to fix the axial conductors in the axial grooves in particular with respect to centrifugal and torsional forces. The provision of structural features on the rotor in the grooves and corresponding features on the conductors allows a simple and direct assembly of the conductors to the rotor core without additional fixing means. A method of assembling such a rotor is also provided.

Abstract: A matrix converter for converting a polyphase alternating current into a desired alternating output current includes at least two stages; a plurality of controllable bidirectional switches, converts m phases of the polyphase alternating current into alternating output current with n (n<m) phases of a load; and a controllable bidirectional switch controlling each phase of the polyphase alternating current in at least one stage of the converter.

Abstract: A method for operating a matrix converter in which m phases of a generator generating alternating voltage with n (n<m) phases of a load are alternatingly connected via a multiple number of controllable bi-directional switches arranged in an (m×n) matrix, wherein switching over from a selected connected phase of the generator to a selected non-connected phase of the generator takes place in a controlled sequence of commutation instants of the individual switches.

Abstract: A method for the calculation of an output spectrum of a matrix converter in which m phases of a generator as an input are alternatingly connected via a multiple number of controllable bi-directional switches arranged in an (m×n) matrix with n (n<m) phases of a load as an output. An assessment of the spectrum to be used, for example, for compensation of harmonic distortions of the output spectrum can be obtained by calculating the electromotive force spectrum based on at least one of the connectivity of the phases, on the phase relationship between input and output, and on the instants when commutations of the switches are initiated and on the instants when commutations of the switches are completed.

Abstract: A rotor for an exciter to be used to energise the field winding of a generator-rotor of a generator, the rotor defining an axis and including at least two conductor bars aligned substantially parallel to the axis. The bars are connected on their first axial end to one of a plurality of collecting ring and on their second axial end individually to one of two rings. By means of at least one diode the flow of current in each bar is allowed in only one direction such that an alternating current induced in the conductor bars due to a static field is converted into a direct current in the two rings.

Abstract: A very simple and reliable process for cancelling the reaction field (10) induced by a rotor (4) is proposed, wherein the rotor (4) is rotating in a static magnetic field (7) in a static outer core (3), and wherein the rotor (4) comprises at least two conductors (6) aligned substantially parallel to the axis (8) of the rotor (4). The armature reaction (10) is cancelled by means of a set of auxiliary windings (11) located on the static outer core (3) wherein said auxiliary windings (11) are fed with a direct current (DC) cancelling the reaction field (10). Preferentially, the process is applied to a brushless exciter and the auxiliary windings (11) have the same geometry as the conductors (6) of the rotor (4) and are all equally fed with a direct current corresponding to the current induced in the conductors (6) of the rotor (4) when the rotor is rotating in the static magnetic field (7).

Abstract: A method for operating a matrix converter that includes converting m phases of a generator into alternating voltage with n phases of a load connected to a network, wherein n<m. The n phases of the load are alternatingly connected via a multiple number of controllable bi-directional switches arranged in an (m×n) matrix, whereby n phases of the generator are always connected with the load while (m?n) phases of the generator are not connected with the load. The matrix converter may be used for at least part of the start-up process, in particular for the initial part of the start-up process of the generator reversely operating the matrix converter in cycloconverter mode using power available from the network, wherein the group of m phases of the generator are grouped in corresponding subgroups.

Abstract: A method for operating a matrix converter in which m phases of a generator generating alternating voltage with n phases of a load are alternatingly connected via a multiple number of controllable bi-directional switches arranged in an (m×n) matrix. An improvement of the spectrum of the generated alternating voltage, i.e. of the alternating voltage with n phases is achieved by means of voltages which are added on-line to the converter output or input.

Abstract: A method for operating a matrix converter that includes converting m phases of a generator into alternating voltage with n phases of a load connected to a network, wherein n<m. The n phases of the load are alternatingly connected via a multiple number of controllable bi-directional switches arranged in an (m×n) matrix, whereby n phases of the generator are always connected with the load while (m?n) phases of the generator are not connected with the load. The matrix converter may be used for at least part of the start-up process, in particular for the initial part of the start-up process of the generator reversely operating the matrix converter in cycloconverter mode using power available from the network, wherein the group of m phases of the generator are grouped in corresponding subgroups.