A miniature size electrostatic induction motor

A miniature electrostatic induction type motor has been fabricated, and parameters influencing the motor speed, such as voltage and frequency of the three-phase AC power supply, the resistivity and relative dielectric constant of the rotor surface materials, the relaxation time constants, and the resistivity of the rotor liner materials have been studied. The no load motor speed was proportional to the applied three-phase AC voltage. The motor speed increased linearly with increase of the applied frequency of the three-phase AC power supply, having a critical frequency at the higher frequency where partial discharges take place in the air gap between the rotor and the stator. This characteristic makes it possible to control the speed linearly by changing the applied frequency. The maximum no-load rotor speed of the motor tested was about 5500 RPM at an applied voltage of 4.5 kV and a frequency of 220 Hz for a rotor surface material of BaTiO ₃ 80% in the resin binder layered on the copper-foil rotor liner material