This paper investigates the utilization of the zero-sequence component (ZSC) to increase the voltage and enhance the operation area of five-phase electric drives with permanent magnet synchronous machines (PMSM). Although the ZSC allows reaching higher voltage, its application in multiphase drives is constrained by the usage of x-y planes activated by harmonic components. Since some odd harmonics allow torque enhancement, these planes are typically involved in voltage and current control as part of field-oriented control strategies (FOC) to maximize the torque while minimizing the losses (e.g., Joule losses in the Maximum Torque per Ampere strategy). In five-phase systems, the third harmonic is used for torque enhancement, which affects the maximum value and shape of the resulting voltage waveform across the torque-speed map. Consequently, the space available for ZSC injection is limited and depends on the actual operation point. This paper presents an analysis of how ZSC can be leveraged within these constraints to improve the torque-speed operating map of a five-phase PMSM drive, especially in the field-weakening region. Experimental results obtained on a laboratory five-phase PMSM setup validate the theoretical findings and demonstrate the practical benefits of the proposed approach.

Maximum torque per current (MTPA) and other optimal curves are well-known for three-phase machines. Since multiphase machines dispose by more degrees of freedom than their three-phase counterparts, the solution is much more complicated and a variety of regimes can be found. In this paper, optimal current setpoints for five-phase synchronous machines are analyzed. Besides the first harmonic, the optimization includes also the third harmonic, used for both torque enhancement and waveform shaping. It is shown that the MTPA curves, field weakening (FW) and maximum current (MC) regions have an inner structure with multiple regimes. This variety comes from the phase voltage and phase current limits that yield optimizing waveforms containing multiple peaks (peak shaving). A taxonomy of these regimes is provided, and their mutual relations are demonstrated on a case study machine. The optimal current setpoints in their waveforms are analyzed in selected operating points.

The interturn short-circuit is one of the most often failures of electric motors which can lead to serious consequences with the irreversible damage of the whole drive. The detection of these short-circuits is a challenging task depending also on the parameters of the winding of the analyzed machine. The equivalent circuit parameters are minimally affected if the winding consists of a high number of parallel wires, and only a single turn of one parallel wire is short-circuited. The measurement of additional Joule losses are then expected to be the most proper approach; the special rotor and testing stand for this purpose is designed in this paper to ensure easy manipulation with the measured stators.

This paper deals with an experimental injection of harmonics to a stator winding of a nine-phase machine. Different combinations of the harmonic components are applied with the optimal magnitudes calculated by a linear programming to maximize exploitation of a magnetic circuit. The theoretical analysis provides magnetic flux waveforms including distribution in the air gap. Thanks to the prototype of the nine-phase induction machine with in-built test coils wound on the stator tooth and the magnetic pole, the magnetic flux waveforms calculated in the theoretical analysis are verified by those obtained by the experimental measurements.

Inductance variation with the load can have a significant effect on the operation and control of the machine and it should to be implemented in the analytic design of the machine. In this paper a magnetic equivalent circuit (MEC) method used for the analysis of the permanent magnet flux linkage and both direct- and quadrature-axis inductances of surface-mounted PMSM at different current conditions is presented. The nonlinear characteristic of iron parts is considered and different conditions are analyzed to evaluate the equivalent circuit parameters and the saturation level of stator parts. The MEC results are then implemented to the operation maps calculation.

This paper is focused on the modification and improvement of the passive cooling system of the high speed electrical machines body. In the paper are described, compared, and evaluated variants of cooling rib shapes. For each shape is created the fluid CFD model and used the model boundary condition for steady state and transient thermal model. The contribution of the paper is possibilities for relatively cheap modification of the shape of the machine housing to get better values of the continuously working temperature.