Chun Qiu

Design and Analysis of a New Magnetic Gear With Multiple Gear Ratios

This paper proposes a new magnetic variable gear which offers different speed ratios. In order to provide the gear-ratio-changing ability, a high-remanence low-coercivity permanent magnet (PM), namely the aluminum-nickel-cobalt (Alnico), is utilized. By incorporating the concept of the magnetic gear and the concept of memory machine, a new double-deck structure of the stationary ring is developed to locate the magnetizing winding which can dynamically magnetize or demagnetize the Alnico PM. By using finite element analysis, the electromagnetic performance of the proposed magnetic gear at different gear ratios is analyzed. Hence, the corresponding validity can be verified.

An efficient wireless power transfer system with security considerations for electric vehicle applications

This paper presents a secure inductive wireless power transfer (WPT) system for electric vehicle (EV) applications, such as charging the electric devices inside EVs and performing energy exchange between EVs. The key is to employ chaos theory to encrypt the wirelessly transferred energy which can then be decrypted by specific receptors in the multi-objective system. In this paper, the principle of encrypted WPT is first revealed. Then, computer simulation is conducted to validate the feasibility of the proposed system. Moreover, by comparing the WPT systems with and without encryption, the proposed energy encryption scheme does not involve noticeable power consumption.

Overview of wireless power transfer for electric vehicle charging

This paper presents an overview of current wireless power transfer (WPT) technologies for the application of electric vehicles (EV) wireless charging. The basic principles of each technology are introduced. Followed by classification, the advantages and limitations of each technology for EV charging are discussed. Promising technologies such as coupled magnetic resonance and magnetic gear technologies are systematically reviewed. The latest development, key technical issues, challenges and state-of-art researches are introduced. The research trends are also been given.

Energy Encryption for Wireless Power Transfer

This paper presents a novel energy encryption strategy for wireless power transfer (WPT) systems, which can effectively improve the security performance of wirelessly transferred energy. In a WPT system, energy is expected to transfer to specific receptors as well as to switch off other unauthorized energy transmission channels, so the security of energy transmission is an important issue. In the proposed secure WPT system, the energy is encrypted by chaotically regulating the frequency of the power source. Then, the authorized receptor can receive the energy by simultaneously adjusting the circuit to decrypt the encrypted energy based on the security key obtained from the power supply, while the unauthorized receptor cannot receive the energy without knowledge of the security key. Hence, a secure energy transmission channel is established to effectively prevent unauthorized receptors from stealing the energy. In this paper, both simulation and experimental results are provided to verify the validity of the proposed encrypted WPT system.

Design and Analysis of a Flux-Controllable Linear Variable Reluctance Machine

This paper proposes a linear variable machine equipped with a set of field winding which is capable for adjusting the air-gap flux. As conventional variable reluctance machines, the proposed machine has a doubly salient structure and no permanent magnets or windings on the mover. The distinct feature of the proposed machine is that there are both the ac armature winding and the dc field winding in the stator. By inviting the dc field winding, the proposed machine not only has the flux control capability, but also realizes the bipolar operation. In this paper, the proposed machine design and its operating principle are presented and discussed. Then, a two-phase machine in modular design is dimensioned. By using the three-dimensional finite element analysis, both the steady and transient performances are quantitatively analyzed and evaluated.

Investigation of energy harvesting for magnetic sensor arrays on Mars by wireless power transmission

This paper proposes the energy harvesting for magnetic sensor arrays on Mars, which can receive the power from Mars Rover by wireless power transmission (WPT). The schematic idea is presented with the energy receiver as the magnetic sensor and the energy transmitter as the transducer on Mars Rover. The key is to adopt the resonant inductive power transmission (IPT) topology between the magnetic sensor and Mars Rover. The basic topology and its operating principle are discussed. By using the magnetic frequency analysis with the finite element method, the output power and efficiency of the WPT system are calculated. The results show that Mars Rover could flexibly transmit its power to different types of small-size magnetic sensors based on their energy on demand using different resonant frequencies and distances.

Design and Analysis of a New Magnetic-Geared Memory Machine

In this paper, a new hybrid-structure machine, namely magnetic-geared memory (MGM) machine, is proposed. It artfully integrates the magnetic-gearing effect and flux-mnemonic capability together. The design is to adopt the hybrid-structure which incorporates the flux-modulation ring, dual-magnets and magnetizing winding. In this way, the flux-modulation ring is able to modulate the high-speed armature rotating field to the low-speed permanent magnet (PM) rotor. Meanwhile, the electromagnetic field which is generated by the dual-magnets of NdFeB and AlNiCo can be online tuned by the magnetizing winding. Thus, the proposed machine achieves the merits of both high-torque production and wide-speed operation. Finite element analysis is employed to verify the validity of the proposed MGM machine. Also, a parallelogram hysteresis model is built for the AlNiCo PM.

Quantitative Comparison of Dynamic Flux Distribution of Magnetic Couplers for Roadway Electric Vehicle Wireless Charging System

This paper gives a quantitative comparison of magnetic couplers for electric vehicle (EV) wireless charging applications. Circular pad with ferrite spokes and coreless rectangular coils are specially selected for analysis. The dynamic flux density between couplers under high misalignment is studied by calculating the uncompensated power of the pick-up coupler. By using finite element analysis, the performance of each type of coupler is evaluated, and its adaptation to on-road EV charging are compared according to the flux distribution and effective charging area.

Design and Analysis of a New Multitoothed Magnetless Doubly Salient Machine

In this paper, the high temperature superconductor (HTS) winding and multitoothed structure are newly incorporated into the doubly salient (DS) and flux-switching (FS) machines, leading to create two new magnetless machines, namely the HTS-based multitoothed switched reluctance (HTS-MSR) and HTS-based multitoothed flux-switching (HTS-MFS) machines. Consequently, the design equations of the three machines, namely the MSR, HTS-MSR, and HTS-MFS, are formulated. The corresponding performances are analyzed by using the time-stepping finite element method (TS-FEM). By utilizing both torque-producing zones, the two HTS-based machines can achieve better performances than the MSR one. Moreover, the HTS-MFS can offer higher torque density than the HTS-MSR, but associated with larger torque ripple.

New Approach for Pole-Changing With Dual-Memory Machine

Memory machines possess the ability of memorizing magnetization level on their permanent magnets (PMs) and hence provide flexible flux-tuning without using the dc field winding for continual excitation. In this paper, two kinds of memory machines, namely the dual-memory and single-memory, are investigated for pole-changing operation with emphasis on the new pole-changing approach for the dual-memory machine. In essence, the dual-memory machine realizes the pole-changing by dropping some poles whereas the single-memory one achieves the pole-changing by reversing some poles. The finite element analysis validates the proposed pole-changing approaches.