Abstract:
The motor parameters change when the mover runs from one segment to another of a segmented powered linear motor. The converter output current overshoots or breaks when the motor mover is running at high speed. Furthermore, as the mover passes through two adjacent segments, larger thrust fluctuations occur. Several traditional switching methods are analyzed, and a new switching method for switching current from one segment to another is proposed. First, the neutral points of the stator segment powered alternately by the same converter are connected. When the phase current of the converter reaches zero, the phase switch of the previous stator segment is turned off, and simultaneously the phase switch of the next stator segment is turned on. The switch is made of anti-parallel thyristors. The converter output current intermittence or fluctuation is suppressed, and thrust fluctuation of the motor is reduced during the switching process. The frequency-doubled harmonic current caused by inductance imbalance of the motor is suppressed by using a PIR controller. As an example, a dual three-phase permanent magnet linear synchronous motor (PMLSM) is used, and the effectiveness of the method is demonstrated through simulations and experiments.