J.O. Fiedler

Noise Reduction Control Strategies for Switched Reluctance Drives

The usage of switched reluctance machines (SRMs) in acoustically critical applications like vehicles requires low noise emissions. This paper gives a brief introduction to noise development in SRMs with a special focus on the influence of the radial force. Based on this analysis in the time and the frequency domain, several noise reduction control strategies are presented and investigated for their effectiveness using simulation techniques and measurements. One of them is a new approach for partial load operation applying a single current pulse close to the unaligned position

Acoustic noise in switched reluctance drives: an aerodynamic problem?

In this paper, it is shown that under certain conditions aerodynamic sources dominate the acoustic noise emission of switched reluctance drives. It is indicated how the noise sources can be easily identified experimentally. Additionally, simple measures to reduce aerodynamic noise are presented

On the design of a single-phase switched reluctance motor

The principle and design of a single-phase 2/2 switched reluctance motor are presented. The motor uses saturation effects for starting. Design optimization, especially of the shape of the saturable iron part, is carried out using FEM analysis. Starting capability in every rotor position is achieved. A single-phase design offers the opportunity to design the motor for low acoustic noise and low cost.

Electromagnetic Modeling of Switched Reluctance Motor Using Finite Element Method

In this paper, a parametric simulation electromagnetic model for switched reluctance motor (SRM) has been developed using finite element method (FEM), which can be applied properly in optimal design of this motor. In the developed simulation model, the major characteristics of SRM, such as static torque and instantaneous phase current, have been predicted. In addition, an algorithm of core loss calculation for SRM was introduced in this simulation model, which includes more aspects of SRM in comparison with other available core loss models. Some experimental results are presented for evaluation of the developed simulation model

New methodology in sizing and predesign of switched reluctance machines using normalized flux-linkage diagram

This paper presents a new method in sizing and determining a preliminary design solution of switched reluctance machines (SRM). This proposed method is developed based on normalized flux-linkage curves of a generalized SRM model. Derived from the normalized flux-linkage curves, relationships between torque output curves, design parameters and machine configurations are represented in different intuitive graphical diagrams. Using the proposed method, designers can achieve better insights and comprehensive guides for SRM design in comparison to the existing methods. Hence, an appropriate initial preliminary design, minimizing time-expense in further optimization stages, can be systematically determined with ease.

Psychoacoustic quantities and their relevance for sound-quality optimization of switched reluctance machines

This paper gives a brief introduction to noise development in switched reluctance machines (SRMs) and presents psychoacoustic quantities that allow an objective evaluation of their sound quality by taking into account the characteristics of the human hearing system. The relevance of these quantities is determined by listening tests and statistical analyses. The goal of this work is to demonstrate that a successful acoustic optimization of a SRM should be performed based on both technical and psychoacoustic know-how

Extended analytic approach to acoustic noise in switched reluctance drives

Frequency domain analysis of the phase voltage waveform of switched reluctance machines operating in single-pulse operation is performed with the aim to reduce acoustic noise. A method to influence the harmonic content of this waveform is derived. As a result pulse patterns optimized for minimal excitation of natural frequencies can be calculated a priori. These pulse patterns are composed of fixed dwell angles and free wheeling angles rather than turn-on or turnoff angles and freewheeling times, as presented in recent other publications. The derived theory is validated by experiments.

Analysis of Torque Dynamics for Switched Reluctance Drives with Instantaneous Torque Control

This paper presents an analysis of torque dynamics of switched reluctance drive systems with instantaneous torque control. Torque dynamics is useful information in designing drive components, i.e. machine, converter and controller. When developing a switched reluctance drive, torque dynamics has to be taken into account in many design aspects, e.g. switching frequency of converters, sampling time of digital controllers, torque step rise and resulting torque ripples. This paper derives mathematical methods for calculating torque slope for both small signal and step response considerations. Finally, the application of the calculated torque dynamics in design procedures of switched reluctance drives is presented

Effectiveness of Noise Reducing Measures in Switched Reluctance Drives

Acoustic noise reduction in electrical drives can be achieved by either machine design or control measures. The corresponding strategies affect different parts of the acoustic noise transfer path and they can therefore be divided into different categories such as: reduction of the excitation, increase of transfer path impedance, decrease of radiation efficiency or reduction of the annoyance of the sound. In contrast to the first three strategies, the last does not necessarily result in a reduction of the resulting sound pressure level. Annoyance is a subjective impression but may be characterized well by psycho-acoustic quantities such as loudness, sharpness and tonality (Kasper et al., 2005). This paper begins with a detailed study of the acoustic noise transfer path. The derived theory is validated by numerical simulation and experiments. Finally, the effectiveness of the different noise reducing strategies as well as trade-offs are discussed