Improvement of conventional electret motors

Improved Gubkin- and Jefimenko-type electret motors, where the electrets are not shielded and are not required to have mechanical strength, were designed and produced. Their rotors were constructed using Teflon FEP film electrets and metal disks. An intermediate type electret motor was produced to complete the family of electret motors. An experimental torque close to the theoretical value for each type of motor is obtained. In a Jefimenko-type motor the maximum value of the experimental torque is 38 μN-m when the applied DC voltage is 2000 V. Each type of motor has been run synchronously with a square wave voltage. The Jefimenko-type motor had the highest rotation rate. The upper limit was 1260 rpm when the peak voltage of the square wave was 1400 V. None of the motors dealt with in this study can be started, nor can their rotational direction be changed by applied voltage only. However, it is suggested that an electret motor consisting of a stator and a rotor having different number of poles could be controlled by applied voltage only