This paper presents a quasi 3-D nonlinear magnetic equivalent circuit (MEC) model for double-sided axial flux permanent magnet machines (AFPMMs) with fractional slot concentrated windings. The proposed model can take into account not only the local magnetic saturation effect but also the 3-D flux distribution. A coupled variable permeance element is proposed in airgap modeling that captures both axial and circumferential airgap flux densities. With the help of the coupled variable permeance element, the transient magnetic field is considered by the time varying connection of the airgap and the rotor. The proposed model can be used to predict the performance of AFPMMs, including the 3-D distribution of no-load and armature airgap flux densities, no-load back EMF and electromagnetic torque. In order to verify the reliability of the MEC model, two AFPMM prototypes are taken as examples, and the accuracy is verified by comparing the calculated parameters of the MEC model with the finite element analysis and experimental results. Finally, the effect of local saturation on the performances of AFPMMs is investigated.

To research the impact of temperature-dependent characteristics of windings and magnets on the electromagnetic power loss and thermal properties of high-speed (HS) interior permanent magnet synchronous machines (PMSMs), an electromagnetic-thermal bi-directional coupling method (BDCM) is proposed for water-cooled HS PMSMs considering the assembling gaps between the motor components in this paper. The electromagnetic power loss is calculated by 3-D transient finite-element method and loaded into the 3-D temperature field according to the actual loss distribution, and the materials’ properties are in turn updated according to the temperature distributions. The loss and temperature calculation results of a 15kW HS amorphous metal PMSM are calculated by two different coupling methods in the conditions of the rated-load sinusoidal supply and converter supply, and compared with the measured results in the case of converter supply. The results obtained by the BDCM are more consistent with the experiment results, verifying the superiority of the proposed analyzing method in improving the calculation accuracy of motor loss and temperature rise. In addition, the applicable conditions of the proposed method are also summarized in the paper.

Two types of surface-mounted permanent magnet synchronous machines (PMSMs) with the same physical dimensions but different stator core materials are comparatively analyzed, prototyped, and tested in this paper. In order to quantify the magnetization and loss characteristics of the stacked amorphous metal (AM) stator core, an experiment is conducted under different supply frequencies. Based on the data, the no-load iron losses, harmonic losses generated by the inverter-induced non-sinusoidal current harmonics, and the d-axis and q-axis inductances of two types of motors are comparatively analyzed by the finite-element method under different conditions and verified by experiments carried out on the two types of PMSM prototypes. The results illustrate that the AM PMSM has a characteristic of extremely low no-load iron losses, relative to the conventional silicon steel PMSM.

This paper investigates the no-load iron loss, on-load loss, and thermal performance of a high-speed surface-mounted permanent-magnet synchronous machine with an amorphous metal stator core (AMSC) and a titanium alloy retaining sleeve by numerical methods. The electromagnetic properties of the AMSC are tested by an experimental platform. The distributions of no-load iron loss, rated-load loss, and the thermal behavior of the motor are investigated under converter supply conditions. Finally, the loss and thermal performances of the prototype are tested and compared with the corresponding simulation results to verify the accuracy of the calculation results and the superiority of the prototype.

This paper presents a totally enclosed self-circulation (TESC) axial ventilation system (AVS) for large direct-drive permanent magnet synchronous machines (PMSMs). The configuration and the cooling air circulation process of the cooling system are described in detail. Then, the lumped parameter (LP) based airflow analysis and thermal analysis applicable to large PMSMs with the presented TESC AVS are proposed. The airflow network model and thermal network model are set up, respectively, and both of them are programmed. In order to verify the feasibility of the ventilation system and the accuracy of the LP models, a 1.65-MW PMSM prototype with the proposed ventilation system is developed and manufactured, and the temperature rise of the prototype is tested under generator operation mode. The accuracies of the developed airflow network model and thermal network model are verified by comparing the calculation results of the temperature rise with the test results. The LP models can be used to investigate the effects of different geometrical and operational conditions on the distributions of the airflow rate and the temperature of PMSMs with the TESC AVS.