Design of the magnetic circuit of DC motors having electronic commutation

摘要

The invention relates to the design of the magnetic circuit of DC motors having electronic commutation, especially of low-power machines, having a polarised, preferably permanent-magnetic rotor and at least three coils or coil groups in the stator. The aim of the invention is to achieve a torque which is as constant as possible over the entire rotation angle of the rotor of 360 DEG , with optimum efficiency and very favourable magnetic utilisation, in the case of motors having electronic commutation with as few stator windings as possible, and at the same time to obtain a very low ripple on the rectified generator half-cycle of the winding source voltage. According to the invention, this is achieved in that the stator laminate comprises three main poles and three auxiliary poles or in each case an even multiple thereof, the main poles and auxiliary poles being in an alternating sequence and each main pole carrying one of the coils of a coil group, while the auxiliary poles have no windings. The ratio of the width of the main poles to the width of the auxiliary poles in the circumferential direction is preferably 3:1.