Tabrez

A dual band circularly polarized coplanar waveguide - fed microstrip patch antenna consisting of four inverted L grounded strips near the corners and a multi-level vertical stack excited by a 50 Ω impedance microstrip feedline is proposed. The complete dimension of the proposed antenna is only 60 x 60 x 0.8 mm3. The Circular Polarization (CP) is achieved by embedding a pair of inverted - L grounded strips into the square slot and by altering the dimensions of vertical stub. The frequency bandwidth of the proposed antenna is achieved for two bands, from 2.79 GHz to 3.99 GHz with resonating frequency at 3.3 GHz and 3.5 GHz for 5G and WiMAX applications respectively and the other one is from 6.94 GHz to 8.28 GHz featuring a resonating frequency of 7.9 GHz, this design is primarily utilized for satellite communication within the lower X-band for fixed satellite service (FSS) uplink. The uplink frequency from Earth to satellite ranges from 7.9 GHz to 8.4 GHz, making it ideal for applications such as fixed satellite services uplink. VSWR ≤ 2dB is achieved for both the bands and axial ratio (AR) ≤ 3dB is from 2.85 GHz to 3.85 GHz and 7.85 GHz to 8.33 GHz respectively. Performance of the fabricated antenna is experimentally validated and its Return Loss, VSWR, Axial Ratio, Radiation Pattern, Gain, Radiation Efficiency, Surface Current are also observed.

Brushless DC motor (BLDCM) drives are highly sensitive to current and torque ripples, which can lead to reduced efficiency, increased acoustic noise, and degraded control performance. A major contributor to these ripples is the presence of undamped AC components in the DC‐link power (DCLP) supply, particularly during rapid switching and commutation events. The DC–DC converters are typically employed to regulate and provide the required input voltage to BLDCM drives; they do not inherently suppress these undamped AC components. To address this limitation, various filter‐based stabilization methods have been proposed, primarily relying on low‐pass filters (LPFs) or band‐pass filters (BPFs). However, such filters often demand complex coordination with active compensation loops, precise current references, and nonlinear interactions. In this context, this paper explores a notch‐filter (NF)–based stabilization approach for the DCLP supply in a super‐lift Luo (SLL) converter‐assisted BLDCM drive. The SLL converter is mainly employed for voltage regulation, while the NF is integrated to suppress the undamped AC signals in the DC‐link. A hardware prototype has been developed to validate the proposed design. Experimental results confirm that the suggested stabilization strategy effectively enhances DC‐link stability and improves the overall performance of the BLDCM drive.

Brushless DC motor (BLDCM) drives often experience significant current and torque ripples, which negatively affect the overall performance. Moreover, the dynamic characteristics of BLDCMs such as low mechanical oscillations and tight speed regulation can introduce undamped AC components that destabilize the DC‐link supply (DCLS). This study presents a novel compensation strategy to address DCLS instability in BLDCM drives. A quasiproportional‐resonant compensator (QPRC) is proposed to enhance DCLS stability. This paper explores a QPRC‐based stabilization approach for the DCLS in an in‐front zeta converter (IFZC)–assisted BLDCM drive. The IFZC is mainly employed for voltage regulation while the QPRC is integrated to suppress the undamped AC signals in the DC link. A hardware prototype has been developed to validate the proposed control strategy. Experimental results confirm that the suggested stabilization strategy effectively enhances DC‐link stability and improves the overall performance of the BLDCM drive.

Although brushless direct current motor (BLDCM) drives are becoming more popular in industrial and commercial applications, there are still significant difficulties and unresolved research issues that must be addressed. In BLDCM drives, commutation current ripple (CCR) and diode freewheeling during non-commutation zone (NCZ) are the major challenges. To overcome these limitations, this paper proposes a novel PWM-Model Antiseptic Control (PWM-MAC) technique to alleviate the freewheeling of the diode. The proposed PWM technique is used to alleviate the diode freewheeling in the NCZ, whereas the DCLV circuit is utilized to obtain variable DC-link voltage to address the CCR in the CZ. The MATLAB/Simulink results are included along with experimental results obtained from a laboratory prototype of 325 W. The proposed module reduces the current ripple by 31.7% and corresponding torque ripples are suppressed by approximately 32.5%. This evidences the performance of the proposed control technique.

Recently, the superiority of multi-phase systems in comparison to three-phase energy systems has been demonstrated with regards to power generation, transmission, distribution, and utilization in particular. Generally, two techniques, specifically semiconductor converter and special transformers (static and passive transformation) have been commonly employed for power generation by utilizing multi-phase systems from the available three-phase power system. The generation of multi-phase power at a fixed frequency by utilizing the static transformation method presents certain advantages compared to semiconductor converters such as reliability, cost-effectiveness, efficiency, and lower total harmonics distortion (THD). Multi-phase transformers are essential to evaluate the parameters of a multi-phase motor, as they require a multi-phase signal that is pure sine wave in nature. However, multi-phase transformers are not suitable for variable frequency applications. Moreover, they have shortcomings with regard to impedance mismatching, the unequal number of turns which lead to inaccurate results in per phase equivalent circuits, which results in an imbalance output in phase voltages and currents. Therefore, this paper aims to investigate multi-phase power transformation from a three-phase system and examine the different static multi-phase transformation techniques. In line with this matter, this study outlines various theories and configurations of transformers, including three-phase to five-, seven-, eleven-, and thirteen-phase transformers. Moreover, the review discusses impedance mismatching, voltage unbalance, and per phase equivalent circuit modeling and fault analysis in multi-phase systems. Moreover, various artificial intelligence-based optimization techniques such as particle swarm optimization (PSO) and the genetic algorithm (GA) are explored to address various existing issues. Finally, the review delivers effective future suggestions that would serve as valuable opportunities, guidelines, and directions for power engineers, industries, and decision-makers to further research on multi-phase transformer improvements towards sustainable operation and management.

In the recent past, multiphase power generation, power transmission, and electrical drive system are the main focus of research due to their several advantages over three phase. Multiphase drives have better performance over three-phase drives. A multiphase transformer is required at the input of a fixed frequency multiphase drive, rectifier circuit for HVDC applications and multiphase generation and transmission systems. This paper investigates a static three to seven phase conversion technique and presents a design of transformer and control strategy to analyze the effect of unbalanced supply on a three phase to seven phase transformer. The transformer so designed takes three phase as input and seven phase output is obtained at the secondary terminals. The paper also discusses input-output unbalancing. A complete design, analysis, simulation of the proposed technique and experimental validation is presented in this paper. Experimental and simulation results prove that the presented design produced a seven-phase from a tree-phase ac power. Input unbalance is reflected to output but is less than the input unbalance. A seven phase output is not produced if one phase of input is open and the transformer has more than three limbs for flux to flow. A balanced seven phase output in steady state is produced even in one phase open condition for a three limb core type transformer. A new definition of sequence components of an unbalanced seven phase system is defined in this paper.