Magnetic levitation control and spiral-linear transformation system for spiral motor

Various industrial applications utilize linear actuators which are usually performed by rotational type motors combined with ball gear and by linear motors. Each of their methods has advantages and disadvantages. A spiral motor is expected to be superior to traditional linear actuator. The spiral motor is a tubular type linear actuator which has a spiral type mover and stator with magnetic levitation. It realizes friction free screw motion and few flux leakage. However, it needs a large winding current to activate the mover because the magnetic attraction force between the mover and the stator of the spiral motor is very large. Large current may break the windings of the spiral motor. Also two inverters are required when the spiral motor is driven because the two stator windings have to be independently controlled. However, the experimental apparatus and the cost increase if two inverters are used. Thus, a novel inverter which can independently control two windings is proposed. A novel transformation system from spiral motion to linear motion is introduced to realize effective motion. In this paper, a current value at activation and a novel inverter were verified by simulation. The development of simplified motor and the spiral-linear transformation system are reported