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This paper is a study of control algorithms used in multiphase bridge converters with an odd number of phases cut into multiphase motor windings. It is found that the phase voltage amplitude for the fundamental harmonic at a converter's unit input voltage does not depend on the number of phases and reaches 0.637. With the implementation of vector pulse-width modulation, the generalized voltage vector amplitude equal to the one of the fundamental phase voltage harmonic and calculated by the vector technique exhibits pulsation relative to 0.637. The amplitude pulsation frequency of the generalized voltage vector increases with the implementation of the above modulation and an increase in the number of motor (converter) phases. [ABSTRACT FROM AUTHOR]

Eccentricity detection is an important topic in motor fault diagnosis and bearingless motor controls. In this study, a novel method is proposed for eccentricity detection of a six‐phase motor based on high‐frequency injection (HFI). Unlike the other planes of the multiphase motors, the 0_ component (the average of the differences between adjacent phases) is seldom adopted for signal injections. The proposed method exploits the 0_ component for signal injection which allows the injected signals to be decoupled from the rotating‐magnetic‐field‐producing planes without occupying any of them (so that they can be assigned to other uses). In this study, the induction motor under HFI is simplified as a model with mutually decoupled winding pairs. The HF impedance of each phase under eccentricity is derived on the basis of this model. The proposed method is drawn from these theories and verified with experiments. It is shown in the experiments that the proposed method has excellent linearity; the estimations on orthogonal directions are decoupled; and the proposed method has satisfactory tracking bandwidth. The influence of saturation on the proposed method is justified by simulations. The capability of the proposed method to discriminate between different types of eccentricities is proved with experimental data. [ABSTRACT FROM AUTHOR]

Radial force control in electrical machines has been widely investigated for a variety of bearingless machines, as well as for the conventional structures featuring mechanical bearings. This paper takes advantage of the spatial distribution of the winding sets within the stator structure in a multisector permanent-magnet (MSPM) machine toward achieving a controllable radial force. An alternative force control technique for MSPM machines is presented. The mathematical model of the machine and the theoretical investigation of the force production principle are provided. A novel force control methodology based on the minimization of the copper losses is described and adopted to calculate the d–q axis current references. The predicted performances of the considered machine are benchmarked against finite-element analysis. The experimental validation of the proposed control strategy is presented, focusing on the suppression of selected vibration frequencies for different rotational speeds. [ABSTRACT FROM PUBLISHER]

The article considers the areas of applying multiphase induction motors. Their advantages against three phase motors have become the main reason for employing them in multiphase drives. The paper deals with the six-phase induction motor having two similar three phase windings in the stator shifted by 30 degrees in space and three phase windings in the rotor. Differential equations for this motor are presented and transformed to dq synchronous reference frame. The transformed equations are expressed in a matrix form and solved by MATLAB software using the Dormand-Prince (ode45) method. The transient characteristics of the torque, speed and current of the six-phase induction motor are calculated and discussed. Santrauka Nagrinėjamos daugiafazių variklių naudojimo sritys, pabrėžiami pagrindiniai jų privalumai lyginant su trifaziais varikliais. Nurodomos daugiafazių variklių teigiamos savybės, lemiančios jų naudojimą šiuolaikinėse elektros pavarose. Nagrinėjamas šešiafazis asinchroninis variklis. Jo statoriuje yra dvi vienodos trifazės apvijos, kurių magnetinės ašys skiriasi 30 erdvinių laipsnių kampu, o rotoriuje yra trifazė apvija. Pateikiamos tokio variklio dinamikos lygtys, transformuotos į dq sinchroniškai besisukančią koordinačių sistemą. Transformuotos lygtys užrašomos matricos pavidalu ir sprendžiamos MATLAB programiniu paketu taikant Dormand-Prince (ode45) metodą. Gautos ir ištirtos šešiafazio asinchroninio variklio greičio, momento ir srovių dinaminės charakteristikos. Reikšminiai žodžiai: daugiafaziai varikliai, modelis, dinaminės charakteristikos.

This paper presents a nine-phase permanent-magnet synchronous motor (PMSM) drive system based on multiple three-phase voltage source inverters. The nine-phase PMSM was developed as a traction motor for an ultrahigh-speed elevator. The mathematical model of the motor was simplified through symmetry of the system. Using the simplified model, the drive system can be controlled by the well-known d-q control theory. The feasibility and validity of the drive system were experimentally demonstrated at the world's tallest elevator test tower. Moreover, an additional experiment was performed to ensure the fault-tolerance capability of the system. [ABSTRACT FROM PUBLISHER]

The article considers the areas of applying multiphase induction motors. Their advantages against three phase motors have become the main reason for employing them in multiphase drives. The paper deals with the six-phase induction motor having two similar three phase windings in the stator shifted by 30 degrees in space and three phase windings in the rotor. Differential equations for this motor are presented and transformed to dq synchronous reference frame. The transformed equations are expressed in a matrix form and solved by MATLAB software using the Dormand-Prince (ode45) method. The transient characteristics of the torque, speed and current of the six-phase induction motor are calculated and discussed. [ABSTRACT FROM AUTHOR]

In order to increase the fault tolerance of a motor drive, multiphase systems are adopted. Since custom solutions are expensive, machines with dual three-phase windings supplied by two parallel converters seem to be more convenient. In the event of a fault, one of the two three-phase windings (the faulty winding) is disconnected, and the motor is operated by means of the healthy winding only. A fractional-slot permanent-magnet (PM) motor with 12 slots and 10 poles is considered with two different rotor topologies: the interior PM (IPM) rotor and the surface-mounted PM rotor. Various winding configurations of dual three-phase windings are taken into account, comparing average torque, torque ripple, mutual coupling among phases, overload capability, and short-circuit behavior. Considerations are given regarding the winding arrangements so as to avoid excessive torque ripple and unbalanced radial forces in faulty operating conditions. An IPM motor prototype has been built, and experimental results are carried out in order to verify the numerical predictions. [ABSTRACT FROM PUBLISHER]

Multiphase motors are usually designed to have the concentrated winding and nonsinusoidal airgap flux density distribution in order to maximize the torque per ampere. This means that the phase voltage of a multiphase motor has the nonsinusoidal waveform. Accordingly, the conventional analysis on a multiphase space vector pulse-width modulation (SVPWM), which is confined to a sinusoidal phase voltage, should be extended to a nonsinusoidal phase voltage. In this paper, based on a multiple d-q spaces concept a novel analysis on a multiphase SVPWM to synthesize an arbitrary nonsinusoidal phase voltage is proposed. Throughout this paper, a five-phase inverter is used as a practical example. The basic concepts can be easily extended to an n-phase inverter. [ABSTRACT FROM AUTHOR]

Multiphase (more than three) power system has gained popularity due to their inherent advantages when compared to three-phase counterpart. Multiphase power supply is extensively used in AC/DC multi-pulse converters, especially supply with multiple of three-phases. AC/DC converter with multi-pulse input is a popular solution to reduce the ripple in the DC output. Single-phase and three-phase transformers and phase transformation from single to multiphase are employed in variable speed drives application to feed the multi-cell H-Bridge converters and multi-pulse AC-DC converters. Six-phase system is extensively discussed in the literature for numerous applications ranging from variable speed drives to multiphase wind energy generation system. This paper shows the systematic phase transformation technique from three-phase to six-phase (both symmetrical and asymmetrical) for both understanding and teaching purposes. Such an approach could help students understand a promising advanced concept in their undergraduate courses. When phase difference between the two consecutive phases of six phases has a phase difference of 60°, it is called a symmetrical six-phase system; while an asymmetrical or quasi, six-phase has two set of three-phase with a phase shift of 30° between the two sets. Simulation and experimental results are also presented. [ABSTRACT FROM AUTHOR]