High-performance propulsion motors for more electric aircrafts (MEAs) are highly appreciated in transportation electrification. For the widely adopted permanent magnet synchronous machines (PMSMs) for MEA propulsion, the segmented Halbach magnetization has distinct merit that it contributes to sinusoidal air-gap magnetic fields for smooth operation. However, it is hard to fast predict the field distribution and machine performance due to the model complexity. Based on the subdomain method, this paper first proposes an exact analytical model for slotless PMSM with segmented Halbach PMs. Then, the model is applied in the fast computation of magnetic field and performance prediction. Subsequently, the analytical results are compared with the finite element method (FEM), including the flux density, flux linkage, induced voltage, and steady-state torque at different loads. Also, the computation burden and prediction error are included to validate the model rapidity and accuracy. Finally, by prototype fabrication and unique field measurement methods, the flux density distribution is originally validated.

The wide use of inverters in microgrids motivates the development of digital controllers with sampling systems. This paper proposes a multi-rate sampling frequency and voltage regulation method for inverters-based distributed generators (DGs). The fast-sampling signals are adopted to achieve the primary control, which is composed of the VSG-based frequency control and the voltage droop control with a low-pass filter (LPF). Based on the unified primary control model, the low-sampling distributed model predictive control (DMPC) is proposed as secondary frequency and voltage control. Considering the microgrid network, the inverter-based DGs supply power for both the local load and loads on other buses. The proposed DMPC method can overcome the disproportionate impedances of interconnecting lines among buses. Then the frequency and voltage of islanded microgrid can be restored to rated values with accurate power sharing. The DMPC-based secondary control and the primary control have different sampling rates. The stability and dynamic performance of the proposed multi-rate sampling control system are investigated for the first time. Finally, both simulation and experiment tests are carried out to validate the effectiveness of the proposed control strategy.

As microgrids develop rapidly, more inverters are adopted to achieve DC/AC or AC/DC/AC conversion of distributed generators (DGs). The virtual synchronous generator (VSG) control has started to replace the traditional droop control for inverters. In order to restore the frequency to its nominal value, most existing secondary frequency control (SFC) methods are based on frequency measurements. However, while reducing the rate of change of frequency (ROCOF), virtual inertia also slows down the convergence of frequency-based SFC. Therefore, this paper proposes a new distributed hierarchical control for fast frequency restoration. Based on the real-time VSG control at the bottom level, a novel frequency restoration control is designed. The power reference values generated by the proposed control can accelerate the frequency restoration with accurate power sharing. Meanwhile, by designing event-triggering conditions, parallel inverter controllers only need to communicate with neighbors at the event-triggered moments. Simulations have been performed in MATLAB/Simulink environment. Furthermore, the proposed control has also been tested on the experiment platform, which contains practical physical circuits and real-time controllers. Both simulation and experiment results verify the effectiveness of the proposed control strategy.

To suppress the zero-sequence current and enhance the steady-state performance of the three-phase series-end winding permanent magnet synchronous motor (TPSW-PMSM) drives, a multi-vector-based model predictive current control scheme with zero-sequence current suppression is developed in this paper. The concept of the desired voltage is utilized to preselect the candidate voltage vectors and offer the guidance of the geometric division of the sector. In one sampling period, multi-voltage vectors are employed, and the combinations include one active voltage vector and one null voltage vector, and two active voltage vectors, which improves the steady-state performance. Meanwhile, the duty cycle of each voltage vector is derived based on an intuitive geometric expression of the cost function. Further, the relationship between the zero-sequence voltage injection and the switching sequence is revealed, and it is employed to suppress the zero-sequence current actively. In addition, overmodulation operation is also taken into consideration in the proposed scheme. Finally, the experimental study validates the effectiveness of the proposed scheme.

Series-end winding motor drives double the dc-link voltage utilization compared with the conventional star-connected winding counterparts, which indicates that series-end winding motor drives are suitable for high-speed applications with limited dc-link voltage. To further improve the dc-link voltage utilization and extend the speed range of the dual three-phase series-end winding permanent magnet synchronous motor (DTSW-PMSM) drive system, this paper proposes a novel winding connection sequence (WCS) for DTSW-PMSM drive, and the dc-link voltage utilization is further improved by 36.6% compared with the normal WCS. The dc-link voltage utilizations of different WCSs are analyzed through the phasor relationship between the phase and leg voltages. Besides, the corresponding carrier-based pulse-width modulation to drive the DTSW-PMSM with the proposed WCS is also developed. In the experimental tests, the speed range of the DTSW-PMSM drive with the proposed WCS is extended significantly. Therefore, adopting the proposed WCS can be an effective means for further speed range extension of DTSW-PMSM drives without additional hardware.

The widespread use of electric vehicles (EVs) has introduced many mobile energy storage devices to the power grid. Originally, this paper firstly proposes a novel concept of an EV-based virtual energy router (VER). Through utilizing the energy storage and mobility capabilities of EVs, EV-based VERs can dynamically share power supply within microgrids by adaptive frequency and voltage regulation. Based on the grid-forming role of EV-based VERs, an adaptive distributed model predictive control (DMPC) is proposed for frequency and voltage regulation. Firstly, a discrete predictive model is built based on the primary control with virtual inertia. Adaptable parameters are adopted to accommodate the variable capacity of EV-based VERs. Secondly, a centralized MPC scheme is designed to achieve accurate dynamic power sharing, frequency restoration, and voltage restoration. Thirdly, the DMPC framework is proposed to decompose the centralized MPC by the designed correction multipliers, which can relax dynamic power-sharing constraints. Finally, we analyze the convergence of the distributed algorithm and the stability of the dual-rate sampling system, formed by the adaptive primary control and DMPC-based secondary control. The simulations and experiments verify the effectiveness of the proposed control.