This paper introduces a new fault-tolerant operation method for a symmetrical six-phase induction machine (6PIM) when one or several phases are lost. A general decoupled model of the induction machine with up to three open phases is given. This model illustrates the existence of a pulsating torque when phases are opened. Then, a new control method reducing the pulsating torque and the motor losses is proposed in order to improve the drive performances. The proposed method is compared to two other existing techniques. The simulation and experimental results obtained on a dedicated test-rig confirm the validity and the efficiency of the proposed method for a fault-tolerant symmetrical 6PIM drive.

This paper presents a new space vector pulsewidth modulation (SVPWM) technique for the control of a six-phase voltage source inverter (VSI)-fed dual stator induction machines (DSIM). A DSIM is an induction machine which has two sets of three-phase stator windings spatially shifted by 30 electrical degrees and fed by two three-phase VSIs. Despite their advantage of power segmentation, these machines are characterized by large zero sequence harmonic currents, and in particular those of order 6 k plusmn 1, which are due to the mutual cancellation between the two stator windings. The proposed SVPWM scheme, while easy to implement digitally, reduces significantly these extra stator harmonic currents. Experimental results, collected from a 15 kW prototype machine controlled by a digital signal processor, are presented and discussed.

The paper deals with the possibility of replacing a mechanical planetary gear system by a magnetic planetary gearbox. The magnetic planetary gearbox has many advantages such as contact-free, no gear lubrication, high-speed-reduction ratio and high durability. Firstly, the principle of operation, design equations and Willis relation for the magnetic and the mechanical planetary gears are given. A comparative study between the two systems in terms of torque transmission capabilities is presented.

The major drawback of dual three-phase ac machines (6phiM), when supplied by a voltage-source inverter (VSI), is the occurrence of extra harmonic currents. These extra currents circulate only in the stator windings and cause additional losses. One solution to reduce their amplitude is to act on the supply side using dedicated pulsewidth modulation (PWM) control strategies. The aim of this paper is to investigate new space-vector PWM (SVPWM) techniques suitable for 6phiM and to perform a detailed analysis and a performance evaluation. The proposed performance criteria, specific to VSI-fed 6phiM, lead to analytical formulas and graphics, which aid the design of high-performance PWM techniques and demonstrate the superiority of the proposed SVPWM techniques. Experimental results carried out on a 15-kW prototype machine and using a low-cost fixed-point TMS320F240 digital signal processor are given and discussed

To point out the effects of eccentricity within a dual-stator winding induction machine, one needs to detect the high frequency corresponding to the interaction of both eccentricity and slotting effects. In this paper, a model of this kind of machine, whose rotor is mixed-eccentric, has been suggested. One considers slotting effects. This induction machine has two sets of stator three-phase windings electrically shifted by an angle alpha. This model will be used to analyze the impact of the defect on the machine. It will be seen that the analytical expression of inductances can be directly exploited to predict the eccentricity-related frequencies. First, the impact of the defect will be investigated under an open-loop condition, i.e., the motor will be supplied by the volt-per-hertz control mode. Second, the motors will be supplied by using the indirect rotor field-oriented control. One will see the fault propagation on the control variables, which can be used as a tool for diagnosis under closed-loop conditions. Comparisons between simulation and experimental results will be performed to evaluate the effectiveness of this experiment.