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This paper shows the influence of the shift phase angle ψ between phase currents and back-electromotive forces on magnetic radial forces and torque ripple for a specific low power permanent magnet synchronous machine. This influence is firstly demonstrated through analytical development considering only the first harmonic values. Then, magnetic pressure harmonics versus space and frequency as well as torque ripple are evaluated on the studied motor for different angles using finite element approach. The aim is to establish a good compromise between consumed current, torque and radial force harmonics at the origin of the electromagnetic noise. Experimental measurements with a sensorless field-oriented control are detailed.

Purpose This paper deals with the study of the influence of the phase shift between currents and back-electromotive forces (back-EMF) on torque ripple and radial magnetic forces for a low power synchronous machine supplied with 120 degrees square-wave currents. This paper aims to establish a good compromise between efficiency, harmonics of torque and harmonics of radial forces at the origin of the electromagnetic noise. Design/methodology/approach Based on a finite element approach, torque and magnetic pressure harmonics versus space and frequency are evaluated for different angle values. The evolutions of the different harmonics against the load angle are analyzed and compared to those of experimental measurements. Findings Depending on the load torque, field-weakening or field-boosting can be used to reduce current harmonics contributing the most to the radial magnetic forces responsible for the noise. Besides, a compromise can be found to avoid deteriorating too much the performances of the machine, thus being suitable with an industrial application. Research limitations/implications This study concerns low power permanent magnet synchronous machines with concentrated windings and driven with a trapezoidal control, while having sinusoidal back-EMF. Originality/value The use of a simple mean and suitable with a large-scale manufacturing industry to reduce the identified electromagnetic-borne noise of a specific electric drive makes the originality.

This paper deals with the study of the influence of the phase shift between currents and back-electromotive forces on torque ripple and radial magnetic forces for a low power synchronous machine supplied with 120 degrees square-wave currents. Based on a finite element approach, torque and magnetic pressure harmonics versus space and frequency are evaluated for different angle values. The aim is to establish a good compromise between efficiency, harmonics of torque and harmonics of radial forces at the origin of the electromagnetic noise. The evolutions of the different harmonics against the load angle are analyzed and compared to those of experimental measurements.

This paper shows the impact of the shift phase angle ψ between phase currents and back-electromotive forces (back-EMFs) on torque and radial forces for a low power synchronous machine (20 W). Pressure harmonics versus space and frequency on our motor and torque are evaluated with different angles with finite element approach. The aim is to establish a good compromise between consumed current, harmonics of torque and harmonics of radial forces linked to the electromagnetic noise for two strategies: maximum torque per ampere (MTPA) control and field weakening (FW) control. The evolution of each harmonic versus ψ are compared for both strategies. Experimental measurements in sinusoidal case are detailed.