Refine
Year of publication
Document Type
- Conference Proceeding (16)
- Article (8)
- Other (7)
Keywords
- finite element analysis (2)
- Electrical Coil Arrangement Comprising Litz Wire Conductor Segments (1)
- FEA (1)
- Finite-Elemente-Simulation (1)
- GetDP (1)
- Gmsh (1)
- Helical Winding with Increased Field Use (1)
- Maximum Torque per Ampere (1)
- Method and Device for Operating an Externally Excited Electric Machine (1)
- Monte Carlo Simulation (1)
Institute
The invention relates to an asynchronous machine (1) as can be used particularly in electric vehicles or hybrid vehicles. The asynchronous machine (1) has a rotor (5) and a stator (3). The asynchronous machine is designed and controlled in such a manner that it has a pole pair number p of p=3. Because of the reduced yoke saturation that can consequently be achieved, the stator yoke (9) can be designed with a lesser height hy1, such that a ratio of the outer rotor diameter D2a to the outer stator diameter D1a can assume values between 0.7 and 0.8. As a result, enlarged rotor teeth (19) and correspondingly enlarged rotor grooves (21) can be formed in the rotor (5), such that electrical losses in the material in the rotor grooves (21) acting as the rotor coil element (23) are smaller in comparison to conventional asynchronous machines. The electrical losses occurring to a greater extent in the stator (3) compensating for this lead to a lesser warming of the stator (3) than would be the case with the rotor (5) as the stator (3) can be cooled by simple means. Overall, a higher continuous torque can thus be achieved with the asynchronous machine (1) according to the invention.
The invention describes an electrical coil arrangement (21) comprising at least one conductor turn (wi; wl, w2) with two conductor branches (23a, 23b), the first conductor branch (23a) of which is designed as a forward conductor with respect to the prespecified current flow direction and the second conductor branch (23b) of which is designed as a return conductor with respect to this current flow direction. In this case, the individual conductor branches (23a, 23b) are in the form of pressed litz wire conductors which are made stable by a cured filling material (40) and have a large number of electrically conductive individual wires (38), wherein each individual conductor branch (23a, 23b) is formed as a separate, prefabricated conductor segment (27) which is subsequently electrically conductively connected to one another, associated conductor branch (23b, 23a) in at least one end region (17). The invention further describes an electrical machine (1) comprising a coil arrangement (21) of this kind, and a method for producing a coil arrangement (21) of this kind.
The invention relates to a rotor for an electric machine and to a method for manufacturing such a rotor. The rotor (15) comprises a rotor body (9) having a plurality of holes (5) and a plurality of magnets (7) that are accommodated in the holes (5) of the rotor body (9). The magnets (7) are enclosed at least partially by a thermoplastic material and secured by the latter in the holes (5). In comparison to conventional duroplastic adhesives, the thermoplastic materials enable a simpler positive locking securing of the magnets (7) in the rotor body (9). Magnetic or magnetizable particles can be embedded in the thermoplastic material (13), such that a gap (11) between the magnets (7) and the walls of the holes (5), which gap is filled with the thermoplastic material (13), can contribute to the total magnetic field generated by the rotor.
The invention relates to a stator (3) for an electric alternating current machine (1) with a number p of magnetic poles, wherein - the stator (3) has a central axis A, - the stator (3) has a stator winding (4) with a plurality of conductor windings (13j), - the individual conductor windings (13j) are grouped into a total of n electric phases (u, v, w), - the conductor windings (13j) of a phase each have at least a first conductor branch (23a) and a second conductor branch (23b), - said conductor branches (23a, 23b), over most (1) of the length thereof, are arranged in a helical manner around the central axis (A), and - said helically arranged conductor branches (23a, 23b) each have a pitch h greater than the product of the axial length l of the helical conductor branches (13j) and the pole number p. The invention also relates to an electric machine (1) having a stator (3) of this kind.
The invention relates to a stator (3) for an electric alternating-current machine (1) with a number of magnetic poles p, wherein the stator (3) comprises a central axis A, said stator (3) comprises a stator winding (4) with a plurality of conductor windings (13j), a portion (l) of each winding running helically in relation to the central axis (A), and wherein the individual conductor windings (13j) are grouped together to collectively form n phase windings (u1, u2 to w3, w4), characterised in that the number n of the phase windings is higher than three, particularly an integral multiple of three. The invention further relates to an electric machine (1) comprising such a stator (3).
The invention relates to a method and a device for operating an externally excited electric machine (1), in particular synchronous machine. In this context, a variable which characterizes a rotor temeperature (Temp_Rotor) and/or a stator temperature is determined using a sensor system, and an exciter current (l_E) and stator currents (l_U, l_V, l_W) for the electric machine (1) are defined by a control unit (3) at least in predefinable operating ranges as a function of the variable which characterizes the rotor temperature (Temp_Rotor) and/or the stator temperature.
Electric Machine (Patent)
(2015)
The invention relates to an electric asynchronous machine (1), in particular an induction machine, comprising: - a cylindrical stator (2) with stator teeth (22) on a stator yoke (21), wherein a ratio between a yoke height (hy1) of the stator yoke (21) in the radial direction and a groove height (hn1) of the stator grooves (23) in the radial direction ranges from 1.75 to 2.5; - a cylindrical rotor (4) with poles (42) on a rotor yoke which are defined by short-circuit windings in a rotor body (41), wherein a ratio between the yoke height of the rotor body (41) in the radial direction and the groove height of the rotor grooves in the radial direction ranges from 2 to 2.75.
The estimation and calculation of the acoustic sound of electric machinery is of high interest. Various approaches have been presented relying either on analytical or on numerical models. In general, the analytical models are based on the electromagnetic-field theory and the results are compared to measurements. Numerical models allow for the separation of different exciting forces stemming from various effects. In the studied case of an induction motor with squirrel-cage rotor three effects are taken into account in the analytical model: the fundamental field, saturation, and eccentricity. The numerical analysis is applied for the analysis of acoustic sound of an electric machine. Nevertheless, the numerical results have to be verified. Hence, they are compared to the physically based analytical results. The radiated noise depends directly on the surface's deformation of the machine. Therefore, the analysis is focused on the structure-dynamic vibrations. The combined analysis presented here, allows for the reduction of vibrations and noise optimizing the coupling of stator and housing. Here, an induction machine (IM) with squirrel-cage rotor is studied. Its housing is mounted with six spiral-steel springs to the stator. With the presented method the impact of different numbers of springs is analyzed.
In this paper a phenomenogical energy-based harmonic ferromagnetic material model is presented which considers time-dependent hysteresis losses as a part of the material characteristic. The model is based on the effective reluctivity concept and can be applied to simulate hysteresis losses of electromechanic devices. The hysteresis losses of a C-Core are simulated and compared to the results of an iron loss estimation by loss curves.
The evaluation of the electromagnetic, structural and acoustic behavior of an induction machine is computationaly expensive. Optimization algorithms are therefore not applicable.
This papers demonstrates that the methodology of design of experiments (Taguchi method) has been successfully applied for the multi-objective optimization of such multiphysics devices. A significant improvement of the machine performances can be achieved with this approach after only a few evaluations of the coupled FE model
Non grain-oriented electrical steel has an inherent anisotropy, which is normally neglected in the calculation of electrical machines. Moreover, the magnetic anisotropy is usually measured in small material samples. Due to the cutting effect, the magnetic anisotropy in the machine is not the same as in the sample. In this paper, the magnetic anisotropy is considered as a global problem. A method to measure it is presented and its influence on the electromagnetic and acoustic behavior is considered through the example of an induction motor.
Numerical Calculation of Iron Losses in Electrical Machines with a modified Post-Processing Formula
(2007)
Design of a Medium Voltage Generator with DC-Cascade for High Power Wind Energy Conversion Systems
(2021)
This paper shows a new concept to generate medium voltage (MV) in wind power application to avoid an additional transformer. Therefore, the generator must be redesigned with additional constraints and a new topology for the power rectifier system by using multiple low voltage (LV) power rectifiers connected in series and parallel to increase the DC output voltage. The combination of parallel and series connection of rectifiers is further introduced as DC-cascade. With the resulting DC-cascade, medium output voltage is achieved with low voltage rectifiers and without a bulky transformer. This approach to form a DC-cascade reduces the effort required to achieve medium DC voltage with a simple rectifier system. In this context, a suitable DC-cascade control was presented and verified with a laboratory test setup. A gearless synchronous generator, which is highly segmented so that each segment can be connected to its own power rectifier, is investigated. Due to the mixed AC and DC voltage given by the DC-cascade structure, it becomes more demanding to the design of the generator insulation, which influences the copper fill factor and the design of the cooling system. A design strategy for the overall generator design is carried out considering the new boundary conditions.
The motivation of this analysis is the need of high efficiency and high power density permanent magnet synchronous motor (PMSM) drives for use in electrical vehicle power trains. It is clear that the chosen electrical steel for the lamination stack plays an important role, but proper quantification is missing. The purpose of this paper is to formalize the problem of selecting the optimal steel grade for the construction of PMSM’s. This question is important to steel producers, not only for helping customers selecting the most appropriate existing grade for their application, but also for defining the strategic orientation of the further R&D of enhanced electrical steel grades. The notion of steel efficiency is defined and, after describing the FE implementation of iron loss models, a methodology for material optimisation is proposed.
The estimation and the calculation of the acoustic sound of electric machinery are of particular interest nowadays. Various approaches have been presented, relying either on analytical or on numerical models. The analytical models presented here are based on the electromagnetic-field theory. Numerical models are applied to derive the exciting forces stemming from various sources and effects. The numerical results have to be verified. Hence, they are compared with the physically based analytical results. The radiated noise depends directly on the surface deformation of the machine. Therefore, the analysis is focused on the structure-dynamic vibration. The combined analysis presented here allows for the reduction of vibration and noise, optimizing the coupling of the machine's stator and housing. The studied induction machine's housing is mounted with six spiral-steel springs to the stator. With the presented method, the impact of different numbers of springs is analyzed exemplarily.
Purpose - The purpose of this paper is to describe how a minimisation of cogging torque is performed with respect to the non-ideal manufacturing process, aiming at a robust design of the studied machine, focusing on magnetisation faults and the use of different qualities of the permanent magnet material. Design/methodology/approach - The applied methodology is a combination of design of experiments and finite element analysis to minimise the cogging torque of the estimated machine. Different qualities of the permanent magnet material are investigated by a stochastic analysis. Findings - A robust design of the machine is achieved, which is verified by a stochastic analysis. Furthermore, this analysis shows the strong influence of the magnet quality on the cogging torque. Practical implications - This paper provides a method for a machine design which is robust against non-ideal manufacturing and an approach to prove the use of a bad quality for a possible reduction of the fabrication costs. Originality/value - This paper gives a close insight on how to investigate non-ideal manufacturing and in particular its influence on the cogging torque.