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The paper aims to present the comparison between the performances of the exterior‐rotor permanent magnet synchronous motors with distributed windings and the performances of the exterior‐rotor permanent magnet synchronous motors with concentrated windings.

Finite element method is used for motors performance determination. The BLDC operation mode for the motors with different slot and pole number combination and concentrated windings was accounted for in the comparison.

In the BLDC operation mode motor structures with concentrated windings with similar slot and pole numbers exhibit at the same current density similar or even higher torque capability and lower electromagnetic torque ripple in comparison to the motor structure with distributed windings. Motor structures with 9‐slot/8‐pole, 9‐slot/10‐pole, 12‐slot/10‐pole slot and pole number combinations are the most appropriate for the BLDC operation.

The paper shows which motor structures with distributed or concentrated windings in the BLDC operation mode produce lower torque ripple and higher average torque per ampere.

The finite element (FE) method calculations are used to improve dynamic behavior of the two‐axis linear synchronous reluctance motor (LSRM) model, which is appropriate for the control design, the real time applications and the low speed servo applications. By the FE method, calculated current and position dependent flux linkages, their partial derivatives and motor thrust are approximated by the continuous functions and incorporated into the dynamic LSRM model as a nonlinear iron core model. The agreement between the calculated and the measured flux linkages, their partial derivatives and the motor thrust is very good. The agreement between all trajectories calculated by the improved dynamic LSRM model and measured during the experiment in the case of kinematic control is very good as well.

Many authors reported the decrease of performances when electric machines and electromagnetic devices were supplied by pulse width modulated (PWM) voltages. However, these statements are rarely supported by measurements performed under fair conditions. The aim of this paper is to compare the performances of a single‐phase transformer and a three‐phase permanent magnet synchronous motor (PMSM) supplied by sinusoidal and PWM voltages and to find a way to evaluate the decrease of performances when PWM voltages are applied.

In order to perform a fair comparison between performances of the tested objects supplied by sinusoidal and PWM voltages, an experimental system was built. It contains a single‐phase and a three‐phase linear rectifier for supply with sinusoidal voltages and an H‐bridge inverter and a three‐phase inverter for supply with PWM voltages. The tests and measurements were performed on a single‐phase transformer and three‐phase PMSM, where different constant loads and different modulation frequencies were used. The test conditions were identical for the supply by sinusoidal and PWM voltages. The measured data, used for the evaluation of performances, were the input and output power and the time behaviours of currents and voltages together with their THDs.

The results presented in the paper clearly show that the efficiency of the singe‐phase transformer and three‐phase PMSM decreases with the increasing level of voltage THD. To properly determine the THD of PWM voltage, the sampling frequencies above 1 MHz and special equipment are normally required. However, if the modulation frequency is not too high, also the current THD, which can be easily determined, can be used to evaluate the decrease of efficiency in the case of supply by PWM voltages.

The results presented in the paper clearly show that the efficiency of the singe‐phase transformer and three‐phase PMSM decreases with the increasing level of voltage THD.