With the increasing share of renewable energy and power electronics, the power system is gradually showing the characteristics of low inertia and spatial distribution. This transition deteriorates system's frequency response and poses a major threat to system stability. The majority of research in this area investigates the methods of providing inertia from the supply side. However, the load response also plays a crucial role in determining the frequency response. Hence, in depth knowledge about the amount of inertia provided by load is extremely important for a future application of units supplying synthetic inertia. In order to accurately grasp the load inertia level, a datadriven equivalent inertia aggregation estimation method is proposed. To achieve the loadside inertia aggregation estimation under different fault scenarios, a dynamic aggregating method is proposed, which uses the Kmeans algorithm to aggregation the grid based on loadside spectral features. Then, according to voltage dependency and rotating characteristic under disturbances, an area inertia estimation model is constructed to estimate the inertia of the aggregated area. By applying the proposed method, the accuracy of inertia estimation under multiple operating conditions is increased by considering the dynamic behaviour of inertia distribution. Finally, using the IEEE 29 buses system, the proposed method is illustrated.

This paper presents a permanent magnet assisted synchronous reluctance motor driven light electric vehicle integrated with solar photovoltaic (SPV) panels and battery storage. The proposed system leverages regenerative braking and energy harvesting from rooftop mounted SPV to extend the driving range, contributing significantly to green mobility. A bidirectional DCDC converter (BDDC) is employed to facilitate energy flow between the battery and the motor drive in either direction. During regenerative braking, the kinetic energy of the PMaSyRM drivebased vehicle is converted into electrical energy. This recovered energy is injected into the battery, effectively charging the battery. This process not only extends the driving range of the vehicle but also minimizes energy loss, thereby enhancing overall efficiency. The conditional integratorbased antiwindup technique is employed for the speed control of LEV, which eliminates the problem of ringing and overshooting during the speed transitions. For better torque control of the PMaSyRM, maximum torque per ampere (MTPA) technique is used. Based on the torque command, MTPA technique produces set of current commands to minimize the magnitude of current vector. Constant voltage, current and torque curve study of the PMaSyRM assures that current and voltage of the drive remains in the safe limit.

In the wireless power transfer (WPT) system of electric vehicles, conventional magnetic shielding techniques usually rely on a large number of magnetic cores and aluminum plates, posing a cost challenge. To address this issue, this paper proposes a composite structure of Tianfont magnetic shielding and antiseries active coils to minimize material use while maintaining safe magnetic leakage levels. First, a calculation method of the magnetic field is introduced to analyze magnetic leakage in the target region of the system, providing a theoretical basis for optimization. Secondly, a composite shielding structure is introduced, its working principle is analyzed in detail and its circuit model is derived. Subsequently, a method for optimizing coil parameters is presented, and the optimal coil and shielding material parameters are determined. Finally, a WPT system based on this structure is built and verified through simulation and experiment. Results show that under a transmission power of 4 kW, the maximum magnetic leakage in the target region before and after offset is lower than 27 µT and the transmission efficiency is more than 93%. Compared to the same size, nongouged magnetic shield structure, it saves 36.78% of the magnetic core and 32.52% of the aluminum plate.

This paper proposes a stationery reference frame proportionalresonant (PR) controller for current control of gridtied converters in an EV charger application. Since it is a viable alternative to rotational reference frame PI compensators in AC applications, the PR controller has been adopted for achieving zero steady state error without using any computationally intensive reference frame transformations. In this paper, a method to design the structure of PR controller and its coefficients according to the desired transient behaviour of AC signal amplitude in PFC converter current loop has been proposed. The importance of suggested PR controller design method is that the grid current magnitude is varying constantly based on the available PV power and battery charger levels which necessitates the controller to act in desired transient behaviour. So, by this way the impact of variation in system parameters have been completely overcome by operating the converter controllers appropriately in a solar powered EV charger system. To verify the effectiveness of the proposed controller design, extensive simulations and experimental studies are performed in a 1.5 kW EV charger system under various PV irradiances and charger power levels. The experimental results obtained from the laboratory prototype confirms the simulation findings.

The sneak circuits caused by internal parasitic parameters can lead to unexpected phenomena and affect the efficiency and reliability of CLLC resonant converter. Therefore, the characteristic analysis, trigger mechanism and suppression method of CLLC converter sneak circuit based on graph theory are proposed in this paper. The complete current based sneak circuit model and accurate CLLC time domain model are established. Then, the possible sneak circuit phenomena are described in detail to explain their negative effects on the converter operating characteristics, the trigger mechanism of sneak operating modes is put forward, and the suppression conditions are derived. By optimizing the parameter design and modulation parameters of CLLC converter, the unexpected sneak circuits can be avoided. Finally, the correctness of theoretical analysis is verified by experiment results, and the proposed suppression method avoids unnecessary power loss and suppresses the waveform oscillations.

The hybrid active neutralpointclamped (HANPC) threelevel inverter (TLI) has the advantage of high efficiency and low cost due to the partial use of SiC devices. However, the magnitude of AC output voltage cannot exceed that of DC input voltage, which limits its application field. This paper puts forward a novel topology and modulation method of the highgain HANPC TLI. The proposed topology combines the advantages of reduced count of SiC MOSFETs and singlestage boosting ability. To further improve system efficiency, a novel modulation method is designed, in which the SiC MOSFETs and Si IGBTs are operated in high frequency and fundamental frequency, respectively. To realize the function of voltage boosting without affecting the normal ac output voltage, the uppershootthrough (UST) and lowershootthrough (LST) states are inserted within the dwell times of small vectors. Moreover, the neutral point (NP) voltage balance is actively controlled by introducing a distribution factor to regulate duty cycle of redundant small vectors, which improve system reliability. Experimental tests verify the performance of the proposed topology and strategy.

In order to facilitate the selection of an optimal topological structure for rational pulsed capacitor charging power supplies (CCPS), this paper presents a comparative analysis of CCPS based on permanent magnet excited (PME) and electrically excited (EE) homopolar inductor alternators (HIA). The findings indicate that the daxis transient inductance of the PME HIA is marginally greater than that of the EE HIA, a result that contradicts initial expectations. Notably, the PME HIA does not require consideration of transient flux variations, whereas the EE HIA does. The study establishes relationships among the enhancement of charge performance, efficiency, capacitance, frequency, and field winding (FW) resistance. It is observed that as capacitance, frequency, and FW resistance increase, there is a corresponding improvement in charge performance. The equipotential line representing the enhancement of charge performance approximates an inverse proportional function, suggesting that if the product of FW resistance and capacitance, or the product of FW resistance and frequency, remains constant, the improvement in charge performance will also be constant. Furthermore, it is noted that as capacitance and frequency increase, the improvement in efficiency diminishes, which is contrary to the trend observed in charge performance. To comprehensively evaluate the enhancement of charge performance and efficiency, a weighted function is proposed. This function aids in the selection of a rational topological structure for CCPS, distinguishing between those based on PME HIA and those based on EE HIA. Based on the results derived from the weighted improvement analysis, appropriate topological structures for CCPS can be identified according to varying capacitance, frequency, and FW resistance. Specifically, when the product of capacitance and FW resistance, or the product of frequency and FW resistance, is substantial, the PME HIA is recommended; conversely, the EE HIA is preferred in other scenarios.

Unintentional islanding in gridconnected photovoltaic inverters (GCPVI) poses a significant challenge to power system reliability and safety. This article introduces a novel islanding detection method that leverages the magnetic characteristics of the GCPVI system. The BH curve, which defines the relationship between the magnetic flux density (B) and the magnetic field strength (H), is derived from the voltage across the inverterside and gridside inductors, and the current flowing through them. These BH curves are obtained for each cycle of the measured signals and analysed over successive cycles to calculate the alienation coefficient and cumulative index. The computed coefficients and indices form a time series vector, referred to as the islanding index. This index is compared against a threshold to detect unintentional islanding, even in the nondetection zone (NDZ). The proposed algorithm is experimentally validated on a singlephase hardwarebased gridconnected inverter driven by bipolar pulsewidth modulation. The measured voltage and current samples of the both side inductors are transmitted to a micro controller for realtime analysis. Using these samples, the method effectively distinguishes islanding from nonislanding events, such as load switching and distributed generation (DG) tripping, within a shorter time frame, adhering to international standards.

Isolated power converters are widely used for its safety and flexible adjustment between input and output voltage range. EMI occurs due to the presence of switching process. The existence of parasitic parameters in transformers causes the work of EMI prediction in isolated DCDC power converters more complicated. Parasitic parameters in transformer are the crucial propagation paths for CM noise conduction. For improving the accuracy of EMI prediction, this paper developed a wideband frequency transformer model based on the twocapacitance model, further considering both the effect capacitive and inductive coupling on conductive common mode noise. Furthermore, the influence of permeability versus frequency of MnZn ferrite on CM transmission, is investigated in detail. Twoport measurement is used for the validation of the proposed high frequency model. The experiment results demonstrate that the proposed windband frequency transformer model can well predict the CM noise behavior in the frequency range of 100 kHz to 100 MHz.

The common ground multilevel inverter (MLI) is highly appreciated in transformerless photovoltaic (PV) systems, which have improved leakage current performance and reduced filter size. The faulttolerant (FT) capability is essential in a common ground inverter to enhance the reliability of the system. This paper highlights a FT strategy for singlephase common ground MLI under different open switch fault conditions. The proposed circuit can selfbalance the voltage across the switched capacitor (SC) in normal and switch open circuit (OC) fault conditions. Moreover, the employed modulation scheme enables the SCs to be connected in series or parallel to obtain a wide range of output voltages with reduced input voltage. Further, the circuit can be extended for higher voltage levels by adding SC cells. A detailed Markov reliability and cost function assessment highlights the merits of the proposed inverter over counter topologies. Finally, the inverter's operational feasibility and effectiveness are validated through 500 W prototype experimentally.