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PurposeThe purpose of this paper is to suggest a procedure which makes it possible to reduce the radial vibrations of doubly salient switched reluctance motors (SRMs).Design/methodology/approachAn analytical method for the SRM radial vibration determination is first described. It is then extended to the active vibration reduction. An auxiliary winding equips the stator. The paper explains how the corresponding currents have to be adjusted to achieve a simple and robust control, with a special emphasis about the compatibility of the main and auxiliary supplies and about the reduction control principle. At last, an example of drastic noise reduction is presented.FindingsThe proposed method makes possible to define the theoretical vibration spectrum of SRM and thus it gives the major components to be reduced. The feasibility of automating the principle of active reduction is shown. The process of active reduction shows that a vibration component can be diminished by over 90 percent.Research limitations/implicationsThe active reduction is applied for reducing one component of the vibration spectrum. Future developments will focus on the simultaneous reduction of several components of vibration spectrum.Originality/valueThe method offers an automated process to reduce considerably the component of highest amplitude in the vibration spectrum.

A method has been developed which allows a reduction in magnetic noise of induction machines by injecting current harmonics. Its achievement needs an accurate knowledge of the flux density harmonics in the airgap of the machines. First, the principle of the magnetic noise generation is reviewed. A fictitious slot model allows one to determine the airgap permeance expression and, multiplying this last one by the expression of the magnetomotive force distribution, to define the flux density harmonics. The stator harmonics are described. They induce electromotive forces and currents into the rotor conductors which generate rotor flux density harmonics. The knowledge of those quantities allows to calculate the Maxwell forces which can generate magnetic noise. A method of noise reduction is then explained. Its principle is to inject a small controlled current harmonic into the stator windings in order to create a supplementary force wave which opposes those contributing to noise. A small supplementary current allows a reduction of magnetic noise in a big machine. The method limits, precisions, calculations, control principles and injection ways, are described in order to know if the noise of a motor can be reduced and how to do it. Experimentations illustrate those descriptions.

The effects of the battery current created by a charger operating in power factor correction (PFC) mode is investigated. In this case, the charging current contains a sinusoidal perturbation. This could deteriorate the performance of the charge compared to the classic charging technique, which uses a constant current. A dynamical model of the battery is proposed which facilitates an explaination of the contribution of the sinusoidal perturbation on the performances of a lead-acid battery. This theoretical facilitates the supposition that the DC component of the charging current is at the origin of the charge. This assumption is validated by the experimental results which show that the sinusoidal perturbation has no effect on the electrical performance of a lead-acid battery.

This paper presents several methods which allow characterisation of the order, the rank and the magnitude of three-phase harmonic systems generated by PWM inverter switching. In a second part, the authors describe an active magnetic noise reduction which controls the harmonic currents due to the switching in order to generate forces. These last are controlled to act in opposition with the forces due to the slots.