Abstract In order to improve the torque/speed characteristics of the variable flux reluctance machines (VFRMs), an optimal voltage distribution method is proposed to maximize the utilization of the DC‐link voltage. According to the investigation of operating range VFRM driven by single‐leg converter, the optimal armature voltage and the zero‐sequence voltage can be obtained to generate adjustable zero‐sequence current. Thus, the DC‐link voltage utilization and output capacity of VFRM can be significantly improved by optimizing the zero‐sequence current. For verification, the test results on a prototype 6/4 VFRM with single‐leg excitation are presented. The experimental results indicate that, compared with the constant zero‐sequence current control, the DC‐link voltage utilization of the VFRM with proposed method increases by 11.13% together with 36.67% higher output torque at rated speed.

Abstract It is a known cost‐effective method to employ a DSP‐based electric machine emulator (EME) for motor control unit testing, this paper introduces a novel approach to enhance the emulator's accuracy. The inaccuracies caused by terminal voltage sampling errors in the motor control unit and voltage distortions in the inverter are addressed in this paper. An advanced equivalent voltage acquisition technique, which samples the duty cycle‐amplitude of the inverter's terminal voltage, is developed. Leveraging the acquired equivalent voltage data, a novel voltage compensation strategy that providing more accuracy in EME performance is proposed. The mathematical foundation of the EME is established using Kirchhoff's voltage and current laws. These findings are independently validated through simulations and experiments. The results provide robust evidence that the proposed equivalent voltage acquisition and compensation strategies can enhance the accuracy of the EME.

Abstract A hybrid‐three‐level isolated dual‐active‐bridge (HTDAB) DC–DC converter is widely used for grid‐interactive power converters. However, a traditional extended‐phase‐shift (EPS) modulation scheme would cause voltage‐level‐disorder (VLD) problems in HDAB DC–DC converter system because the output voltage of HTDAB would be clamped at a high‐ or low‐level during power transmission when the inductor current changes directions. Thus, the zero voltage sequence of the HTDAB cannot be stably maintained under EPS control, which not only leads to a significant difference between the actual transmission power and the target output power but also seriously affects the stability of the system control. To address this limitation, the reasons leading to VLD are analysed in detail, that is, an inappropriate PWM switching sequence at the output zero voltage level would occur under EPS control. Then, a novel PWM plus phase shift (PPS) modulation strategy is proposed, which can eliminate VLD completely. Finally, an experimental prototype is built to verify the effectiveness of the proposed PPS modulation scheme. The experimental results demonstrate that the PPS modulation method proposed in this article can effectively eliminate level disturbances and improve system stability.

Abstract Recent research shows a growing interest in low‐power avionic deicing systems, in particular, those based on piezoelectric actuators for their energy efficiency. The system generates micrometric vibrations in the structure to delaminate and break the ice with a low power requirement. However, designing the power supply and its control for driving piezoelectric actuators is challenging due to their distinctive capacitive behavior at most frequencies, especially in deicing applications requiring high operational frequency. This contribution addresses the two cross‐dependent parts of the deicing system, that is the piezoelectric actuator designed for breaking any kind of ice on a large area and its power supply made of a 1 kW/200 V/2 MHz auxiliary resonant commutated pole inverter (ARCPI). The choice of this converter is based on the specific constraints of the application, such as varying the operating frequency with the actuator working conditions, the long cables and necessary insulation between the actuator and its supply, the soft‐switching operation and reactive energy balancing for a good efficiency. Based on these criteria, the converter was developed and realized in the laboratory. Deicing tests confirmed effective operation with a power input density of 122 mW/cm2, using nine piezoelectric patches per dm2.

Abstract This paper presents a new structure of a high step‐up DC–DC converter. The proposed converter has one input and two outputs with different voltage levels, suitable for applications that require multiple voltage levels such as photovoltaic systems, electric vehicles and DC microgrids. The proposed converter is expandable to more outputs and has a higher voltage conversion ratio compared to similar converters. The operational modes of the proposed converter are investigated and the conversion ratio of the converter is obtained. Additionally, small‐signal equations of the converter are derived, and using state‐space matrices, transfer functions of the converter are obtained and the controller is designed. Also, the proposed converter is compared with similar converters and power losses equations of the converter are derived. To investigate the converter's performance, simulations are done using MATLAB/Simulink software. Moreover, to validate the theoretical analysis, a laboratory prototype is implemented. The obtained results confirm the operation of the proposed converter.

Abstract Direct torque control with space vector modulation has been increasingly attracting emphasis for permanent‐magnet synchronous machine control, benefiting from a high dynamic response and low torque ripple. However, the rapid tracking performance of torque and stator flux linkage is gradually deteriorating as the machine enters the overmodulation region because of the output‐voltage limitation of the inverter. Therefore, to enhance the system tracking performance in the overmodulation region, an innovative overmodulation method based on torque and flux optimal tracking is proposed. In contrast to the conventional overmodulation method where only one of the torque and stator flux linkage tracking is considered, the proposed strategy first constructs the weightless cost function to achieve a trade‐off control between the torque and stator flux linkage. Then, by using an equivalent geometric path to intuitively express the weightless cost function, the minimum cost function can be easily solved and the optimal output voltage vector can be determined correspondingly, to achieve the fast‐tracking of both the torque and stator flux linkage. Additionally, the voltage utilization of different overmodulation schemes is also analysed. Finally, the experimental results demonstrate the efficiency and practicality of the proposed strategy.

Abstract Marine current power is attracting more attention as a renewable energy option. Similar to wind power, marine current power often requires a maximum power point tracking (MPPT) method to optimize power extraction from the free‐flowing water. Research into MPPT methods for marine current power remains limited. Therefore, this paper presents a comprehensive investigation of MPPT methods for marine current power, building upon similar research in wind power. Three methods, namely the optimal tip speed ratio (OTSR), optimal torque (OT), and two variants of the perturb and observe (P&O) method, are explored. Using a simulation model developed for a specific marine current energy converter, where hydrodynamic calculations are coupled with electrical simulations, the study demonstrates that the OTSR method achieves MPPT with a comparably fast convergence time. After a change in water speed, the OTSR method achieves optimal operation within two turbine rotations. Additionally, the P&O methods are shown to achieve MPPT, albeit with a significantly longer convergence time. However, the P&O methods can be more convenient since no model of the system is required, and no water speed measurements are necessary. The proposed implementation of the OT method underperforms but positions the system close to the optimal operational point.

Abstract This article details the design process for a new three‐phase coil array. All of the coils are made to be mutually decoupled from one another which is achieved by introducing a high reluctance path in the ferrite structure for mutual flux using an airgap in addition to controlling the coil overlap. Simulation and experimental results of a matched three‐phase primary and secondary coupler, designed using the proposed novel decoupling mechanism, are presented to show that the high reluctance path introduced to decouple the coils still allows the main couplings to be maintained within an acceptable range. In contrast, negligible interphase couplings between coils in the primary or secondary were observed. Effective coupling, voltage and uncompensated power measurements are shown to verify the design is able to meet SAE J2954 WPT3 requirements. Finally, the leakage magnetic flux density, simulated under WPT3 conditions, shows that its RMS value remains significantly less than 27 µT at a 800 mm distance from the centre of the secondary coupler.

Abstract For the purpose of enhancing the performance of interior permanent magnet synchronous motors (IPMSMs) sensorless control, a flux observer based on a third‐order generalized integrator with enhanced frequency‐locked loop (TOGI‐EFLL) is introduced in this paper. Compared with the traditional second‐order generalized integrator with frequency‐locked loop (SOGI‐FLL), the proposed TOGI‐EFLL can effectively mitigate the direct current (DC) bias stemming from non‐ideal factors, such as the inverter non‐linearities and detection errors, without introducing additional parameters. Initially, the active flux observer model and the limitations of the conventional SOGI‐FLL are presented. Subsequently, the proposed flux observer based on TOGI‐EFLL has been intensively investigated. Furthermore, the design of the damping factor and the digital implementation of the algorithm are developed to ensure seamless integration into digital systems. Finally, the effectiveness of the proposed sensorless control strategy is validated through the comprehensive experimental results.

Abstract Series connection of Silicon Carbide (SiC) Metal‐Oxide‐Semiconductor Field‐Effect Transistors (MOSFETs) is an interesting solution to design switches for voltages that are not yet commercially available or limited for single‐die devices. However, inherent static and dynamic voltage balancing must be achieved. Voltage imbalance is caused by the device parameters spread, whose impact is pronounced in low‐inductive circuit layouts. This study investigates the optimal design and tuning limits of resistor‐capacitor (RC)‐snubber circuits and non‐adaptive, standard, voltage‐source gate drivers for achieving the best balancing in transient and steady‐state voltage distributions among series‐connected discrete SiC MOSFETs operating at speeds up to . It has been shown that a larger parameter mismatch will lead to uneven switching energy losses and larger voltage imbalances. It was also experimentally shown that increasing the gate resistor to slow down the devices will not always improve balancing when their parameter spread is large. Thus, tuning recommendations for the RC‐snubber circuit and gate driver were developed based on these findings.