The invention relates to a primary component for an electrical machine, the primary component being formed from at least one laminated core and having an element on one or both of its respective front faces to reduce the force ripple. Furthermore, the invention relates to a linear motor with a primary component of this kind.
Linear motors have a primary component and a secondary component. The secondary component in particular is located opposite the primary component. The primary component is designed for energizing with electric current. The secondary component has permanent magnets or energizable windings for example. Both the primary component and the secondary component have active magnetic means for generating magnetic fields.
For constructional reasons, permanently excited linear motors have force variations which have an adverse effect on even running and dynamics.
In order to guide the magnetic flux from the excitation field of the secondary component and main field of the primary component, toothed laminations are normally used for the active component, i.e. the active wound component, of the motor (primary component). A magnetic interaction takes place between the excitation poles and the toothed structure of the primary component which leads to parasitic cogging forces, also referred to as passive force ripple. This results in vibrations, uneven running and tracking errors in machining processes. Furthermore, the induced voltages, i.e. the electromotive forces (EMF), in the first and last coil on the front faces of the primary component are usually smaller than in the middle coils due to the absence of a magnetic return path. This results in the induced voltages of the motor not forming a symmetrical system and, as well as force losses, an additional current-dependent force ripple, also referred to as active force ripple, is produced.