This article presents the analysis of a vernier machine with spoke-V (SV) array permanent magnet (PM), termed SV-PMV. By combining the spoke- and V-array PMs, the topology of SV-PMV is obtained. Based on the general air-gap flux modulation theory, the operating principle of the SV-PMV is investigated. It is found that the main working harmonics can be effectively enhanced by the SV array PM. To provide general design guidelines, the parametric analysis of the SV-PMV is conducted. The electromagnetic performances of three vernier machines are compared by using finite element method (FEM). It is found that the SV-PMV exhibits the highest torque density, the highest power factor, the best overloading capability, and the highest efficiency among three vernier machines.

This paper presents a new vernier permanent magnet machine (VPMM) with stator-V-shaped permanent-magnet arrangement, termed as (SV-VPMM). The key is to adopt unevenly distributed V-shaped PMs in the stator, which exhibits flux concentration effect and generates abundant working harmonics, thus improving the torque density and PM utilization ratio. Based on the air-gap field modulation theory, the working mechanism of the proposed SV-VPMM is investigated from two perspectives including stator-PM and rotor-PM fields. Then, the electromagnetic performance comparison between the proposed SV-VPMM and an existing VPMM is conducted by using finite element analysis (FEA).

This paper proposes a novel flux switching memory machine (FSMM) in which low coercive force (LCF) magnets are alternatively arranged between adjacent U-shape stator cores. The proposed machine exhibits superiority in flexible online flux regulation capability, large flux regulation range, robust structure and inherent advantage for avoiding uncontrolled generator fault (UGF). Meanwhile, the excitation losses can be almost eliminated since the LCF magnets can be remagnetized or demagnetized by a current pulse of a few milliseconds. The demagnetization risk is avoided due to the parallel pattern between PM flux and armature reaction flux. In addition, the FSMM benefits from a simple and robust salient rotor and easy thermal management as a result. Subsequently, the machine structure and operation principle are illustrated. The stator slot-rotor pole combinations are analyzed. The comprehensive electromagnetic performances are evaluated.

The increase in voltage and power levels of more electric aircraft (MEA) necessitates fast and intelligent protection circuits. Due to the advantage of faster response time, no arc during turn-off and higher reliability, solid-state power controllers (SSPCs) are preferred over electro-mechanical switches. This paper reports a SiC based SSPC connected between the DC bus and downstream capacitive loads. An RC assisted gate voltage control method is presented to pre-charge the capacitive load without any inrush current. Experimental results demonstrating charging of 500 μF within 15 ms without hitting the device SOA limit is presented. Also, a thorough design of over-voltage protection circuit of SSPC is included in this paper to protect SSPC against lightening transients and against voltage spike while breaking short-circuit fault current. Series, parallel combinations of Transient Voltage Suppressor (TVS) diodes are connected across SSPC to keep the peak device voltage below its breakdown voltage. Simulation results are reported for validating the design.

The increase in electrical power requirement in the more electric aircraft (MEA) leads to the deployment of a high energy density battery energy storage system (BESS). In the presented work, a high energy density Lithium Ion (Li-ion) “Li-ion phosphate” battery is selected and is designed as per the requirements of MEA. The proposed Li- ion BESS comprises of 5 Li-ion batteries, which are connected in series and integrated with MEA power distribution bus with a bidirectional isolated DC-DC converter as a charger. A Li-ion battery model based on a modified Shepherd curve-fitting with the addition of the voltage polarization term is also investigated in the paper. The modeled Li-ion battery is integrated to the 270 V DC MEA power distribution bus using the optimal harmonic number based harmonic model of DC-DC converter. The values of duty cycle and coupling inductor used in the modeling is selected in order to achieve maximum power transfer and wide range zero voltage switching (ZVS) operation. The harmonic model representation results for different harmonic number are obtained and are compared with the detailed switch model simulation done in MATLAB®/Simulink simulation environment.

A novel control method using H∞tracking and integral reinforcement learning is applied to a flux-switching permanent magnet (FSPM) machine in a hostile environment. The proposed controller can maintain high performance in the presence of motor parameter uncertainties and load disturbances. The conventional design procedure for an H∞controller is to solve the Hamilton-Jacobi-Isaacs (HJI) equation which requires full information of the system model. The novel control method, the integral reinforcement learning (IRL) makes use of neural networks to parametrically represent the control policy and the performance of system, and learns the solution of HJI equations online. Therefore, the FSPM machine can work optimally under parameter uncertainties due to different operating conditions. The simulation in Matlab/Simulink vividly illustrates the control performance for a 45kW, rotor speed 9000 rpm, 12/5 poles flux-switching permanent magnet machine.

Insulated gate bipolar transistor (IGBT) devices have gained leading position in traction and aerospace applications. The failure of these switches (IGBT) can reduce the efficiency of the system. Two most dominated failure mechanisms of IGBTs are solder fatigue and bond wire lift off. One of the major effects which influence these failure mechanisms is thermal impedance characteristics, which depends on the heat dissipation in the junction. In traction or aerospace application, the operational loads are not always constant. It results in the temperature cyclic in power converter, meaning that change in the device junction temperature. This change in temperature degrades the transient thermal resistance, and induces a mechanical stress especially at contacting surfaces of materials with different coefficient of thermal expansion. This may lead to degradation or complete failure of these components. The aim of this paper is to identify thermal impedance variation due to power cycling and thermal cycling. More importantly which temperature cyclic nature causes degradation in the thermal impedance, and its relation to semiconductor module failure mechanism.

It can be seen presently widespread electrification of high power vehicular systems such as more electric aircrafts and electric ships. To further improve the efficiency, flexibility and reliability of such systems, zonal DC electric distribution technology is proposed. In most cases, the zonal DC bus is fed by front-end AC/DC voltage source rectifiers and is responsible for supporting many onboard loads with complex dynamic characteristics. Due to the small-signal constant power nature of tightly regulated power electronic loads and the large-signal load variations, stability of the zonal DC bus becomes a major concern. It is clear that conventional PI controllers stabilize the system in a small-signal sense. However, they are ineffective under some large-signal disturbances and load changes. Passivity based control method is known to provides global stability under passive loads, such as resistive loads. Nonetheless, the global stability of voltage regulation with nonlinear loads has not been discussed. This paper proposes a cascaded sliding mode control method with global stability and online observation of load power. Moreover, system stability limit constrained by catastrophic bifurcation is also discussed. Simulation results are provided to verify the proposed method.