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The switched reluctance machine (SRM) has seen a lot of interest due to its simplicity and ruggedness. Much attention have been paid in academia to improve on some of the disadvantages of the technology such as torque ripple, acoustic noise and low torque density. In this paper a topology, namely the double U-core SRM, is reviewed. This topology improves on some of the disadvantages of the regular SRM. Torque ripple is reduced and the torque density is increased for the same amount of material, by reconfiguring the topology of the regular SRM and increasing the number of poles. The result is a segmented stator structure where each segment can be wound individually and assembled afterwards. Several similar technologies have been demonstrated, and the claimed advantages have been proven in comparison with regular SRMs with a lower pole count. In this paper, the technology will be compared to a regular SRM with a similar pole count, to assess the advantages of the technology, when disregarding the increased number of poles. This paper therefore serves the purpose of proving and assessing the technology through a straightforward theoretical comparison of a regular and a double U-core SRM. From this comparison the claims of the technology can be proven and the gain from utilising the technology can be assessed objectively.

The present invention relates to an electrical machine stator comprising a plurality of stator segments (131,132,133), each segment comprises a first U-core and a second U-core wound with a winding, where the winding being arranged with at least one coil turn, each coil turn comprises a first axial coil segment and a second axial coil segment and one or more end segments, wherein the first and second axial coil segments are arranged in opposite directions to each other, and where the first U-core receives the first axial coil segment(s) and the second U-core receives the second axial coil segment(s), wherein the first U-core and the second U-core are located adjacent to each other, whereby the winding spans the first and second U-cores. The invention also relates to a SRM machine with a stator mentioned above and a rotor.

This paper presents the novel design of a Magnetic Lead Screw (MLS) with magnetic thread of Halbach Arrays. The MLS where designed and build, tests indicated a stall force which where 12 % lower than calculated in 3D FE. This is explained by demagnetization of the magnet during stall, the behavior of the demagnetization has been studied and the results from these studies are presented in this paper.

The present invention relates to an actuator system with a magnetic lead screw (50), comprises a magnetic rotor (5) and a translator cylinder (2), the translator cylinder (2) comprises a magnetic stator (16), the translator cylinder (2) has a closed first end (14) and a second end confined by a lid (8), the lid having a shaft opening (17) for a shaft (6) coupled to the magnetic rotor (5), wherein the magnetic rotor (5), when inserted in the translator cylinder (2), is arranged to translate a linear movement of the translator cylinder (2) into a rotational movement of the magnetic rotor by using magnetic flux (82) interacting between the magnetic stator and the magnetic rotor, said rotational movements is being transferred through a shaft (6), the lid (8) with a shaft opening (17) arranged for receiving the shaft (6), wherein the shaft is arranged to make both the linear and the rotational movement in the shaft opening (17), the lid (8) being arranged for confining the second end (15) of the translator cylinder (2), the translator cylinder confined by the lid (8) forms,when divided by the magnetic rotor (5), a first chamber (TC) with a first volume and a second chamber(BC) with a second volume, wherein the first volume and the second volume changes as a function of the linear movement. The invention also relates to a method of operating an actuator system with a magnetic lead screw.

The invention relates to a magnetic gear for converting linear motion into rotational motion and vice versa. The present invention converts slow linear irregular oscillating motion of wave energy devices into torque on a high speed shaft for powering a generator while making the wave energy device resonate with the waves. The invention relates to the field of energy-harvesting from energy sources, where the energy-harvesting requires the extraction of energy from slow and often irregular reciprocating motion of bodies. The present invention relates to a wave power apparatus for converting power of sea or ocean waves into useful energy, such as electricity. The invention relates to the control and operation of a magnetic gear based motor/generator system. The invention provides a high force density electric powered linear actuator.

Electrical machines for traction in electric vehicles are an essential component which attract attention with respect to machine design and control as a part of the emerging renewable industry. For the hybrid electric machine to replace the familiar behaviour of the combustion engine torque, control seems necessary to implement. For hybrid permanent magnet (PM) machines torque control in an indirect fashion using dq-current control is frequently done. This approach requires knowledge about the machine shaft position which may be obtained sensorless. In this article a method based on accurate knowledge of machine flux linkages is proposed for analysing the suitability for sensorless control at zero and low speed. Electrical machines for traction in electric vehicles are an essential component which attract attention with respect to machine design and control as a part of the emerging renewable industry. For the hybrid electric machine to replace the familiar behaviour of the combustion engine torque, control seems necessary to implement. For hybrid permanent magnet (PM) machines torque control in an indirect fashion using dq-current control is frequently done. This approach requires knowledge about the machine shaft position which may be obtained sensorless. In this article a method based on accurate knowledge of machine flux linkages is proposed for analysing the suitability for sensorless control at zero and low speed.

Udgivelsesdato: November

This paper present a new motor integrated permanent magnet gear with a wide torque-speed range. In the paper a 35 kW permanent magnet motor with a base speed of 4000 rpm and a top speed of 14000 rpm is integrated into a permanent magnetic gear with a gearing ratio of 8.67. The design process of the combined unit is described together with a description of the construction of the part for a test model. The unit is unique in the sense that it has superior traction characteristics and a torque density of 130 Nm/l which is more 1.5 times of other reported motor integrated permanent magnet gears. The unit may be useful as a direct drive wheel motor for EV's and no liquid cooling system is required.

Accurate knowledge of the high frequency inductance profile plays an important role in many designs of sensorless controllers for Surface inductance. A special algorithm is used to decouple the cross-coupling effects between the d-axis and the q-axis, which allows Mounted Permanent Magnet (SMPM) synchronous motors. This paper presents an AC+DC measurement method for determination of the d-axis and q-axis high frequency inductance profiles of SMPM synchronous motors. This method uses DC currents to set a desired magnetic working point on the motor laminations, and then superimpose balanced small AC signals to measure the incremental a separate determination of the d, q inductance profiles as functions of the d, q currents. Experimental results on a commercial SMPM motor using the proposed method are presented in this paper. Accurate knowledge of the high frequency inductance profile plays an important role in many designs of sensorless controllers for Surface inductance. A special algorithm is used to decouple the cross-coupling effects between the d-axis and the q-axis, which allows Mounted Permanent Magnet (SMPM) synchronous motors. This paper presents an AC+DC measurement method for determination of the d-axis and q-axis high frequency inductance profiles of SMPM synchronous motors. This method uses DC currents to set a desired magnetic working point on the motor laminations, and then superimpose balanced small AC signals to measure the incremental a separate determination of the d, q inductance profiles as functions of the d, q currents. Experimental results on a commercial SMPM motor using the proposed method are presented in this paper.

This paper presents calculation and measurement results of a high-performance permanent-magnetic gear. The analyzed permanent-magnetic gear has a gear ratio of 5.5 and is able to deliver 27 N/spl middot/m. The analysis has shown that special attention needs to be paid to the system where the gear is to be installed because of a low natural torsion spring constant. The analyzed gear was also constructed in practice in order to validate the analysis and predict the efficiency. The measured torque from the magnetic gear was only 16 N/spl middot/m reduced by the large end-effects. A systematic analysis of the loss components in the magnetic gear is also performed in order to figure out why the efficiency for the actual construction was only 81%. A large magnetic loss component originated in the bearings, where an unplanned extra bearing was necessary due to mechanical problems. Without the losses of magnetic origin in the bearings and less end-effects caused by relatively short stack, an impressive efficiency estimated at 96% can be obtained. Comparison with classical mechanical gears has shown that the magnetic gear has a better efficiency and a comparable torque per volume density. Finally, it is concluded that the results in this paper may help to initiate a shift from mechanical gears to magnetic gears.

Udgivelsesdato: MAR-APR