Yongxiang Xu

A New End Windings Transposition to Reduce Windings Eddy Loss for 2 MW Direct Drive Multi-Unit PMSM

The additional eddy loss in the solid strand of the formed coil is an important part of windings copper loss in the superpower direct drive permanent magnetic synchronous motor (PMSM). This eddy loss produces due to the uneven leakage magnetic field in the stator slot region. The traditional windings transposition technology is difficultly applied to the multi-turn and less-strand formed coil, because of the limited slot fill factor. Therefore, aiming to reduce the additional eddy loss, this paper proposes a new end windings transposition technology and it was used in a 2 MW low-speed and high-torque multi-unit PMSM prototype. The additional eddy loss inhibitory excellent effect is verified by finite element analysis. It should be emphasized that this technology can be directly used in the permanent magnetic direct drive wind generator.

Optimization of split ratio to design the PM brushless DC motor

The split ratio of the permanent magnet motor is one of the most important design parameters. It can not only influence the motor electrical torque and efficiency, but also can influence the motor thermal behavior. According to the high torque, short duty permanent magnet brushless motor, the thermal behavior should be investigated carefully. In this paper, the influence of the split ratio on the motor characteristics is investigated by field and circuit coupling finite elements analysis firstly. Then the influence of the split ratio on the motor thermal behavior of is analyzed, emphasis on the high torque short duty operation. The optimal design results are verified experimentally.

Rotor eddy-current loss of permanent magnet machine in brushless AC and DC modes, used for deep-sea HUV's propeller

Permanent magnet brushless motor used for deep-sea Human Occupied Vehicles (HUVs) propeller was studied in this paper. Based on analyzing the influences of waveform of phase current on flux density in air gap, rotor eddy-current losses were determined in BLAC and BLDC modes. This paper proposed that rotor loss is the minimum in BLAC mode. In BLDC mode, with optimal commutation advance angle (20°), rotor loss is the lowest. Finally the temperature distribution of the motor was gained considering the rotor eddy-current loss.

Influence of periodic carrier frequency modulation on low frequency electromagnetic interference of permanent magnet synchronous motor drive system

This paper introduces periodic carrier frequency modulation (PCFM) to permanent magnet synchronous motor (PMSM) drive system to improve the electromagnetic compatibility. PCFM is introduced to reduce low frequency CM conducted EMI of PMSM drive system. Simulations and experimental results verify that sinusoidal and sawtooth PCFM can reduce CM conducted EMI of PMSM drive system effectively. Furthermore, sawtooth PCFM is more effective than sinusoidal PCFM in suppressing CM conducted EMI of PMSM drive system. Moreover, the reduction about CM conducted EMI of PMSM drive system by sinusoidal and sawtooth PCFM improves with the increase of spreading frequency widths.

Analysis and design of FSCW SPM machines for a given constant power region

This paper focuses on the design and analysis of fractional-slot concentrated windings synchronous permanent magnet machines for a given constant-power speed ratio using FEM. The constant power ability is concerned with magnet flux linkage, synchronous inductance, and phase voltage. The main dimensions and turn number of the machine are obtained on the basis of electric loading, magnetic loading, winding factor, and torque. Experimental measurements are also performed to validate the results obtained by FEM.

Optimization of cogging torque and back-EMF for a 16-pole/24-slot IPM machine

This paper analyzes the winding configuration and gap flux density of a 16-pole/24-slot IPM machine, and reduces the EMF harmonics and cogging torque with the methods of optimizing the surface of the rotor core and corner cut associatively by FEA. It will be seen that the method used by this paper is better than the rotor optimization method used alone. A prototype machine is manufactured and validates effectiveness of the optimization.

The effect of magnet depth on magnet eddy current loss in 16-pole/24-slot IPM machines

PMSMs with concentrated windings gain more and more interests due to the very short end winding and advantages in the production process, for which they are desirable for wind power generations, electric vehicles and torque propulsion and so on. However, concentrated windings produce a rich spectrum of flux density harmonics, which rotate asynchronously with respect to the rotor, inducing eddy current loss in the rare-earth PMs.

Investigation of electromagnetic torque in permanent magnet synchronous machines with fractional slot concentrated winding

Electric Machine is an energy conversion device, which realizes the electrical energy and mechanical energy convert to each other through electromagnetic power or electromagnetic torque. Electromagnetic torque is an important medium for this conversion progress. Thus accurate estimation or model of electromagnetic torque is desired for designing and analyzing the electric machines. Furthermore electromagnetic torque estimation for servo control and torque ripple depress, where the model of torque is utilized directly or indirectly, is urgent.

Reduction of the acoustic noise in PMSM drives by the periodic frequency modulation

In the PMSM (Permanent-Magnet Synchronism Motor) driven by fixed switching frequency inverter, the acoustic noise spectrum has highly concentrated harmonic energy near switching frequency and its multiples. In this paper, triangular and sawtooth periodic switching frequency modulation patterns are proposed to transfer these discrete power spectrum to more wider frequency ranges, so as to limit the acoustic noise at low cost. Both simulated and experimental results showed that periodic frequency modulation can reduce the acoustic noise effectively with more continuous spectrum compared with fixed switching frequency.

Design of a novel flywheel reaction torque measurement system based on disturbance observer

A novel flywheel reaction torque measurement system is proposed to measure the output torque of flywheels. The system structure and principle of the measurement system are presented. Finite-element method is applied to compute the magnetic field and characteristics of the measurement system. An improved disturbance observer is applied in the position closed loop control system. Simulation and experiment show that the system dynamic characteristics can be improved by the disturbance observer.