During the past five years, cogging torque in HDD spindle motors has decreased drastically as designers and manufacturers have developed a better understanding of the cogging phenomenon. This paper examines various methodologies of cogging torque reduction. Timing techniques such as dead zones and tooth notching, smoothing techniques such as sinusoidal magnetization, and geometric techniques su...

In many machines, where permanent magnets are used, the effects due to cogging torque generated by permanent magnets (PMs) aggravate the output characteristics of the machines. This paper presents the method for reducing cogging torque in surface-mounted permanent magnet synchronous motor (SPMSM). A new cogging torque suppression method called axial pole pairing is proposed. Compared to convent...

In wind energy systems employing permanent magnet generator, there is an imperative need to reduce the cogging torque for smooth and reliable cut in operation. In a permanent magnet generator, cogging torque is produced due to interaction of the rotor magnets with slots and teeth of the stator. This paper is a result of an ongoing research work that deals with various methods to reduce cogging ...

As one of the main parasitic parameters in permanent magnet (PM) synchronous machines (PMSMs), cogging torque is the main component of the torque ripple, which has always been the handicap in the high-performance, low-speed drive systems. Over the last two decades, various methods have been proposed to decrease the cogging torque in both radial-flux and axial-flux PMSMs. Among these methods, st...

High performance motor drive applications require permanent–magnet synchronous motors that produce smooth torque with very low components of cogging torque. To fulfil such demands a variety of design techniques can be used to reduce or even eliminate cogging torque components. Rotor design techniques are in comparison to the stator ones much more effective, but their effectiveness depend consid...

This paper focuses on the state-periodic adaptive compensation of cogging and Coulomb friction for permanent magnet linear motors (PMLM) executing a task repeatedly. The cogging force is considered as a position dependent disturbance and the considered Coulomb friction is non-Lipschitz at zero velocity. The key idea of our disturbance compensation method is to use one trajectory-period past inf...

Abstract: A novel modular arc-linear flux-switching permanent-magnet motor (MAL-FSPM) used for scanning system instead of reduction gearboxes and kinematic mechanisms is proposed and researched in this paper by the finite element method (FEM). The MAL-FSPM combines characteristics of flux-switching permanent-magnet motor and linear motor and can realize the direct driving and limited angular mo...

The utility of PM-BLDC machines is extending its tentacles in industrial arena. The key features of BLDC machines include high starting torque density and extending speed range, though the cogging torque is a threat for its performance. Various techniques have been devised to minimize cogging torque, out of which two approaches Bifurcation and Slot Opening methods have been focused in this pape...