C. Pompermaier

Magnet flux optimization method for Line-Start Permanent Magnet motors

The use of induction motors is the right choice for a great number of household appliances which look for cost-competitive solutions. Therefore, in the past few years, the energy consumption became also an important issue which drives the design of electrical motors, although, permanent magnet motors came to stay. Most of the solutions which are significantly efficient to worth using have also a high cost due to electronics, and among the few options that can be used on this kind of application is the Line-Start Permanent Magnet (LSPM) motor. This paper shows a simple design procedure to increase the net flux generated by the magnets maximizing the magnet short-circuit reluctance and reducing the flux loss in the rotor slot bridges. This method can be used to reduce the magnet volume, also reducing the total cost of the motor, which can contribute to make the LSPM motor a real option to substitute the induction motors in the future. The LSPM motor is analyzed using a 2D finite element method and the rotor movement is modeled by means of the moving band. This approach allows to investigate the influence of design variations on the dynamic behaviour of the LSPM motor.

Braking torque analysis of the single phase line-start permanent magnet synchronous motor

One of the most difficult procedures when designing a single phase line-start permanent magnet synchronous motor is to predict the braking torque, mainly because it has multiple sources, which take place both in the stator and in the rotor. This paper presents a way to explain the braking torque sources and compares the torques obtained by simulation with experimental results.

Analytical and 3D FEM modeling of a tubular linear motor taking into account radial forces due to eccentricity

Electrical linear motors are electromechanical devices that produce short unidirectional or bidirectional strokes. The purpose of this work is to model a tubular linear motor (TLM) using 2D and 3D finite element (FE) method and analytical equations. The 2D and 3D FE magnetodynamic analyses are performed using a magnetic vector potential formulation. The linear displacement is modeled by means of a layer of finite elements placed in the air gap. The analytical model is obtained from a magnetic circuit formed by reluctances and magnetomotive forces. The topologies of these circuits change for each position of the mover. In this paper, the modeling of TLM is carried out focusing the optimization of analytical model and the calculation of radial forces in the presence of eccentricity. In addition, a comparison between simulated and measured performance on a motor prototype is reported.

Study and optimization of a small tubular linear motor with permanent magnet

This paper presents the optimization of a small tubular linear motor in order to obtain the best relationship of power, efficiency and volume. A genetic algorithm method with a mathematical model consisting in a Finite Element program and analytical expressions is employed. The obtained results are compared to experimental ones.

Robust electromagnetic design of Transverse Flux Machines for high volume production

Transverse Flux Machines are attractive for a number of applications where a high torque is required at a relatively low rotational speed. A typical drawback of motors of this type is a high cogging torque in relation to the overall torque output of the motor, this leads to a high torque ripple which can cause unwanted noise and vibration. A number of techniques have been developed that reduce this cogging torque, however for high volume production these techniques need to have a low sensitivity to tolerances and variations in production. This paper focuses on how even small misalignments between phases can influence the cogging torque produced by a motor and how taking this into account in the design procedure can create a robust motor design with low cogging for a wide range of alignments.

Reduction of cogging torque in transverse flux machines by stator and rotor pole shaping

This paper presents a method of reducing the cogging torque of transverse flux machines by shaping the poles of the rotor. A number of different techniques are presented and simulated. These simulations are verified by the construction of a number of rotors from which measured results have been obtained. Further to this, the rotors are applied to machines with different cogging torque reduction techniques applied to the stator. Measurements of cogging torque have been taken in order to assess the overall effectiveness of each technique.

Optimisation of the torque quality of a combined phase transverse flux machine for traction applications

Transverse flux machines can be a torque dense solution for applications requiring a relatively low speed such as electrically assisted bicycles or scooters. Common drawbacks include a high torque ripple caused by a high cogging torque and high back electromotive force harmonics. Cogging torque is of particular importance as it can be felt even when the system is disengaged and the bicycle is being pushed. This paper uses an optimisation procedure to reduce the cogging torque and overall torque ripple of a recently introduced type of transverse flux machine. This machine topology has been shown to have a 10% increase in torque compared to more conventional TFM designs but at the cost of an increased cogging torque and therefore torque ripple. During the optimisation there is a trade-off between reductions in cogging torque and the overall torque production of the machine, this will be analysed and compared to a more conventional TFM design to ensure the benefits of the newer design continue.