Abstract: Method for evaluating electromagnetic performance of a permanent-magnet machine, wherein the method is implemented in a computer processer or in a controller of a permanent-magnet machine, calculating the magnetic field distribution by a sub-domain method; using current density of the equivalent current sheet to represent the boundary condition, iterating by the sub-do-main method and by the magnetic circuit method until a convergent result is obtained, calculating the electro-magnetic performance parameters on basis of the convergent result, so as to evaluate the electromagnetic performance.

Abstract: A rotor assembly for an electromechanical transducer is provided. The rotor assembly comprises a mechanical support structure and a magnet arrangement having a first magnetic component part and a second magnetic component part. The first magnetic component part and the second magnetic component part are attached to the mechanical support structure and are arranged along an axial direction (Z) of the rotor assembly. With respect to the axial direction a first cross section of the first magnetic component part has a first shape and a second cross section of the second magnetic component part has a second shape being different from the first shape. It is further described an electromechanical transducer and a wind turbine, which are both equipped with such a rotor assembly.

Abstract: A tubular body for an electrical machine is provided. The tubular body comprises a curved surface area, a first tooth and a second tooth. The tubular body is arrangable with respect to a further tubular body such that one of the tubular body or the further tubular body is rotatable with respect to the other one around a rotary axis. The first tooth and the second tooth extend from the curved surface area along a radial direction with respect to the rotary axis. The first tooth comprises a first side wall facing a second side wall of the second tooth, wherein the first side wall comprises a first section which is parallel to the second side wall such that a circumferential distance between the first section and the second side wall is constant along the radial direction.

Abstract: A method of inspecting an air-gap of an electrical machine, which method including the steps of directing at least one laser beam (L) into the air-gap; detecting the laser beam (L) after reflection; determining the distance (dOK, dF) travelled by the laser beam (L); and analysing the travelled distance (dOK, dF) to detect an irregularity (Fpole, Foval, Fobject) in the air-gap is provided. The invention further describes an air-gap inspection apparatus for detecting an irregularity in the air-gap of an electrical machine, which apparatus including a laser module realised to direct at least one laser beam (L) into the air-gap and to detect the laser beam (L) after reflection; a computation unit realised to determine the distance (dOK, dF) travelled by the laser beam (L); and an analysis unit realised to analyse the travelled distance (dOK, dF) to detect an irregularity in the air-gap.

Abstract: A converter system for converting alternating current of variable frequency into alternating current of constant frequency is provided, having: a first converter electrically connected to a first set of turns of a generator; and at least a second converter electrically connected to a second set of turns of the generator, wherein the first converter in a first operating mode determines a first estimated rotor position of the generator, and performs driving operations of first power transistors, contained in the first converter, for converting the alternating current based on the first estimated rotor position, wherein the second converter in a first operating mode receives the first estimated rotor position of the generator from the first converter, and performs driving operations of second power transistors, contained in the second converter, for converting the alternating current based on the first estimated rotor position.

Abstract: A rotor assembly for an electromechanical transducer is provided. The rotor assembly comprises a mechanical support structure and a magnet arrangement having a first magnetic component part and a second magnetic component part. The first magnetic component part and the second magnetic component part are attached to the mechanical support structure and are arranged along an axial direction (Z) of the rotor assembly. With respect to the axial direction a first cross section of the first magnetic component part has a first shape and a second cross section of the second magnetic component part has a second shape being different from the first shape. It is further described an electromechanical transducer and a wind turbine, which are both equipped with such a rotor assembly.

Abstract: A tubular body for an electrical machine is provided. The tubular body comprises a curved surface area, a first tooth and a second tooth. The tubular body is arrangable with respect to a further tubular body such that one of the tubular body or the further tubular body is rotatable with respect to the other one around a rotary axis. The first tooth and the second tooth extend from the curved surface area along a radial direction with respect to the rotary axis, wherein the first tooth and the second tooth are spaced apart from each other along a circumferential direction around the rotary axis. The first tooth comprises a first side wall facing a second side wall of the second tooth, wherein the first side wall comprises a first section which is parallel to the second side wall such that a circumferential distance between the first section and the second side wall is constant along the radial direction.

Abstract: A controller of a brushless DC electric machine having a rotor and at least a stator winding powered by a driving voltage is provided. The controller includes a position sensor, an advance angle control circuit, and a driving circuit. The position sensor is moved along a reverse rotating direction of the rotor by a prepositioned angle for outputting a position signal. The advance angle control circuit receives the position signal and a driving voltage reproduction signal reproduced from the driving voltage and outputs a commutation control signal lagging the position signal by a first delay time. The driving circuit receives the commutation control signal for outputting a driving signal for controlling a commutation of the brushless DC electric machine.

Abstract: A permanent magnet motor is provided. The permanent magnet motor includes a stator having a stator shaft having an outer surface, K salient teeth formed upon the outer surface, and K winding slots formed among the K salient teeth, and a rotor having a first inner surface facing the outer surface, and P pairs of permanent magnets formed on the first inner surface, each of which has a second inner surface facing the outer surface and at least a groove formed on the second inner surface to reduce a cogging torque.

Abstract: A controller of a brushless DC electric machine having a rotor and at least a stator winding powered by a driving voltage is provided. The controller includes a position sensor, an advance angle control circuit, and a driving circuit. The position sensor is moved along a reverse rotating direction of the rotor by a prepositioned angle for outputting a position signal. The advance angle control circuit receives the position signal and a driving voltage reproduction signal reproduced from the driving voltage and outputs a commutation control signal lagging the position signal by a first delay time. The driving circuit receives the commutation control signal for outputting a driving signal for controlling a commutation of the brushless DC electric machine.

Abstract: A permanent magnet motor is provided. The permanent magnet motor includes a stator having a stator shaft having an outer surface, K salient teeth formed upon the outer surface, and K winding slots formed among the K salient teeth, and a rotor having a first inner surface facing the outer surface, and P pairs of permanent magnets formed on the first inner surface, each of which has a second inner surface facing the outer surface and at least a groove formed on the second inner surface to reduce a cogging torque.

Abstract: The methods for starting a Hall-less single-phase BLDCM having an asymmetrical air gap are proposed. The provided methods are employed to input a specific amount of current impulse and stop the current impulse at a specific time such that the rotor of the single-phase BLDCM having an asymmetrical air gap can be realized to rotate in the pre-determined direction through one of the cogging torque and the rotor inertia after that specific time so as to accomplish the normal starting of a motor without the Hall-effect sensor.

Abstract: The methods for starting a Hall-less single-phase BLDCM having an asymmetrical air gap are proposed. The provided methods are employed to input a specific amount of current impulse and stop the current impulse at a specific time such that the rotor of the single-phase BLDCM having an asymmetrical air gap can be realized to rotate in the pre-determined direction through one of the cogging torque and the rotor inertia after that specific time so as to accomplish the normal starting of a motor without the Hall-effect sensor.