Torque availability from small synchronous motors using high coercivity magnets

The torque available from small synchronous machines having high-coercivity rotor magnets is calculated from purely electromagnetic considerations. A general number of stator slots is considered together with circular and trapezoidal slot profiles. A method of optimising the stator lamination is presented for both slot forms. Torque performance and lamination details are given as a function of the airgap flux density produced by the rotor magnets. Experimental data is given in support of the findings.