Abstract: A high-speed rotor for an AC permanent magnet synchronous motor includes a stack of magnetically permeable rotor laminations. Each rotor lamination comprises a plurality of conductive bar slots for holding a starter winding and having openings facing outside for minimizing the flux leakage from the rotation magnetic field produced by primary windings on the stator, and magnet slots for holding permanent magnets to produce an even number of magnetic poles on the periphery of the rotor. The lamination further includes a plurality of flux barrier slots connected to the magnet slots for minimizing the flux leakage from the permanent magnets and forming bridges in a ring configuration between the conductive bar slots and the barrier slots so that the integrality of the lamination is very much enhanced, while the power loss is minimized.

Abstract: A control circuit for a three phase induction motor includes a voltage controller having a silicon controlled rectifier in each of a first, second and third supply line connected to the motor. The control circuit further includes a first, second and third phase control means for controlling the firing angles of the respective silicon controlled rectifiers, a circuit for providing a positive ramp signal, and a circuit for providing a constant level signal. A starter circuit includes a "run" push button and a "brake" push button. The depressing of the "run" push button connects a three phase power supply to the supply lines of the voltage controller and causes the positive ramp signal to be applied to the first, second and third control means to control the firing angles of the silicon controlled rectifiers to provide a soft start for the motor.