Design and performance of an acceleration drive with permanent magnets

Aspects of the design of an acceleration drive are discussed. To prevent a decrease of torque at high speeds, special reference waveforms of the phase current are proposed. The motor is fed by an inverter with high pulse frequencies. The drives have the ability to accelerate a given moment of inertia up to a high speed within a short transition time. The length, diameter, and inner construction of the rotor are discussed. Because a hollow cylinder is favorable, motors with permanent magnets are superior to induction motors. A simple method of analyzing the magnetic circuit, including saturation effects, is given. Additional losses caused by the inverter-fed operation in combination with the low-inductive armature winding were reduced to one-seventh of the original amount by modifications in the current control loop. Two examples of current reference waveforms that lead to higher torques in the high-speed region than the conventional block form are given. Experimental verification was obtained from the magnetic, electric, and thermal points of view by testing an experimental drive during more than half a million duty cycles