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DC-excited Vernier reluctance machine (DC-VRM), exhibits the merits of small torque ripple and robustness structure, which has good potential to be applied as an aerospace starter generator. To achieve a sensorless startup with reliable position estimation for a non-salient DC-VRM, a novel saturated inductance differential-based saliency extraction position estimation method is proposed. By exploring the armature winding saturated differential inductance characteristics during field excitation, the inductance saliency is extracted from the different saturation degrees in the two sub-phase coils. Moreover, through reduced order inductance modeling, a linear inductance characteristic can be guaranteed for reliable position estimation. Consequently, the inductance modeling effort and the required memory size for data storage can be effectively reduced. The proposed method can effectively guarantee system reliability. The feasibility of the proposed method is verified by theoretical analysis and experiments.

The brushless dual-electrical-port dual-mech- anical-port machine (BLDDM) is increasingly developed as an effective power split device for continuously variable transmission due to its compactness and high control flexibility. However, the torque performance of BLDDM is relatively disadvantageous. In this article, a novel BLDDM using a high-order harmonic modulation is proposed to improve the torque density of BLDDMs. The key is that the compound outer rotor is artificially designed to enhance the third harmonic component of airgap flux density in the inner airgap while remaining the fundamental component unchanged in the outer airgap. The presented BLDDM is optimized and compared with the conventional design with the same structural dimensions, which shows that the proposed design has 50% higher back EMF in modulation winding and 45.7% larger torque density in the rated conditions. The machine prototype is made and tested, and the experimental results verify the feasibility and advantages of the proposed design.

Metal object detection (MOD) is indispensable for wireless electric vehicle charging (WEVC) systems for safety concerns. Most recently, interests are growing in MOD by electromagnetic (EM) sensing. However, current works based on EM sensing rarely target the systems with DD coils, a promising coil type for commercialization. Additionally, EM sensing schemes are mostly derived from a mindset, viz., cooperation between two sensing coils to obtain the voltage difference as a MOD criterion. Hence, undesired out-of-phase incident becomes an inherent problem jeopardizing the success rates of detection. In this article, noncooperative MOD, which solely relies on the voltages of individual sensing coils rather than cooperative ones, is proposed with absolute confidence in detection results. A unique sensing coil array is devised to suit the field characteristics of DD coils perfectly. Size-modulated patch coils are created to eliminate the undetectable zones with proper polarity configuration. Moreover, virtual double-layer sensing coils are constructed to enhance MOD's reliability. Tested by 13 different positions and three types of MOs using a 3.0-kW WEVC prototype, the induced voltages reach at least four times the threshold value. Moreover, the stability of the proposed method is verified successfully no matter the system operates in light-load or heavy-load conditions.

Portability and efficiency are crucial parameters in wireless power transfer (WPT) systems for extended-distance wireless applications. However, these systems often face challenges of low efficiency and mutual inductance. Generalized solutions employ ferrite, intermediate coils, metamaterials, or increasing operating frequency to address these issues. However, those solutions always lead to poor portability with extra weight and volume, except for increasing the operating frequency. To tackle these challenges, this article proposes a transmitter-embedded metasurface (TEMS) for the WPT system. The design aims to increase efficiency and the coupling coefficient under high operating frequency while maintaining a lightweight and occupying no extra volume, based on the negative permeability property. The L/C-based mathematical model and parametric investigations are conducted to explore the negative permeability property of TEMS. A prototype of the TEMS-based WPT system is implemented to validate the effect of TEMS on efficiency and coupling coefficient enhancement. The experimental results demonstrate that the proposed design can increase efficiency by at least 14.5% over transfer distances longer than 125 mm.