Multiphase induction machines (IMs) are gaining increasing interest in industry due to their numerous advantages over the conventional three-phase ones. A lot of different parameter estimation methods have been developed for three-phase IMs, but the existing literature regarding specific identification techniques for multiphase IMs is almost nonexistent at this point. This paper proposes simple offline methods to estimate the stator resistance and stator leakage inductance of multiphase IMs with distributed windings, under different conditions, utilizing the machine's degrees of freedom associated with the nonflux/torque producing current components. Once these parameters are identified, the rotor ones can be easily calculated by combination with the total values obtained from locked-rotor tests. The procedure enables segregation of the stator and rotor parameters in a simple manner, something that is very difficult to achieve in three-phase IMs where, usually, equality of leakage inductances and a constant stator resistance are assumed. In this manner, the magnetizing inductance can be then also more accurately assessed from no-load tests, because the error in its estimation that would be caused by assuming both leakage inductances to be equal is avoided. The proposed methods are experimentally tested on two different five-phase IMs.

Multiphase electric drives have been recently proposed for applications where the highest overall system reliability and a reduction in the total power per phase are required. Strategies derived from the conventional field-oriented control have been traditionally used in high-performance speed-control applications of multiphase drives. The well-known direct torque control (DTC) technique has been also applied in the multiphase case, but the achieved performance with a hysteresis-control-based approach is far from that obtainable with the three-phase drive, although the control structure is actually more complex. In this paper, a predictive-torque-control method is introduced as an alternative to the DTC technique for the high-performance variable-speed operation of multiphase drives. Simulation and experimental results are provided to illustrate the properties of the developed method.

Multiphase drives are advantageous when high overall system reliability and the reduction in the total power per phase are required. The control strategies for these applications require a good knowledge of the machine parameters to ensure a high quality of the dynamic and steady-state drive performance. Multiphase machines are still not common in industry and it appears that very little work has been done so far in relation to parameter identification techniques. This paper presents and implements a procedure to estimate the parameters of a five-phase induction machine, which can be also extended to other multiphase machines with higher phase numbers. The method is based on standstill time-domain tests and recursive least-squares algorithms. Experimental results are provided to illustrate the developed identification method using tests on two different five-phase induction machines. Correlation with corresponding parameters obtained in Part 1 of this paper is established, where electrical parameters of the same two five-phase inverter-fed induction motor drives were identified using various procedures, based on sinusoidal excitation of the machine.

The growing interest in multiphase electrical drives has required the extension of control schemes and modulation techniques already well known for three-phase drives. Specifically, different and more complex space-vector pulse width modulation (SVPWM) methods have been developed for multiphase machines taking into account the increased number of switching possibilities and the new components resulting from generalized Clarke's transformation. In spite of the intensive work undertaken in the last decade, no SVPWM techniques with common-mode voltage (CMV) reduction have been developed for five-phase drives. This work proposes two SVPWM methods that are capable of reducing the peak-to-peak CMV by 40% and 80% compared to standard five-phase modulation strategies. Reduction of the CMV is done at the expense of higher phase voltage and current distortion. Simulation and experimental results confirm the CMV reduction and quantify the performance penalties of the proposed methods.

The common-mode voltage (CMV) is known to be a source of electromagnetic interference, and it is potentially dangerous for the machine windings' insulation and bearings. CMV has been analyzed for three-phase machines supplied by voltage-source inverters, showing that modified pulsewidth modulation and model predictive control (MPC) techniques can significantly reduce the CMV at the expense of increased current distortion. This paper analyzes the CMV for five-phase drives and proposes a modified MPC strategy that accounts for the CMV reduction. The MPC can adjust the weights of the cost function to find a good balance between CMV reduction and low current distortion. The MPC strategy is experimentally tested showing how the CMV can be effectively reduced, thus improving the multiphase drive performance.

Matrix converters are a well‐known class of direct AC–AC power converter topologies that can be used in applications, where compact volume and low weight are necessary. For good performance, special attention should be paid to the control scheme used for these converters. The model predictive control strategy is a promising, straightforward and flexible choice for controlling various different matrix converter topologies. This work provides a comprehensive study and detailed classification of several predictive control methods and techniques, discussing special capabilities they each add to the operation and control scheme for different matrix converter topologies. This study also considers the issues regarding the implementation of model predictive control strategies for matrix converters. This survey and comparison are intended to be a useful guide for solving the related drawbacks of each topology and to enable the application of this control scheme for matrix converters in practical applications.