Dhenuvakonda Koteswara Raju

The research on contactless current sensors is enriched with Rogowski coil-based devices and magnetoresistive material-based electronic current transformers. The coil-based devices have a unique feature of linearity and adequate time drift for measuring high amplitude current waveforms. Conventional coil-based devices are limited in achieving improved sensitivity and time drift due to a limited number of turns and inter-winding capacitances. In this research work, novel coil models are designed using different winding arrangements for achieving improved sensitivity and second-order parameters by maintaining linearity. An interference error compensation scheme is also designed using an Op-amp-based electronic circuit and an extra conducting layer outside the coil models. The mathematical analysis of these coil models exhibits 4.01 times more sensitivity and 77.5% less nonlinearity error as compared to existing coil models. Similarly, these coil models exhibit up to 72.25% less in peak time and 70.92% less in rise time than their conventional models. Experimental results reveal that the proposed interference compensation scheme is able to achieve 78.79% compensation of interference error while measuring a current of 120A in a multiconductor system.

Voltammetric sensor models are widely used in electrolytic applications in industry and the laboratory. Research in these domains is enriched with data analytics tools and electrode design, which need to be revised to improve the sensitivity near the Nernst limit. Therefore, an intense demand exists for enhancing the sensitivity of conventional voltammetric sensor models with minimum alteration of design parameters. This research article focuses on the possible impact of a magnetic field in a conventional voltammetric sensor for electrolytic concentration measurement. The experimental results show a 45% increase in sensitivity with a 3%–43% increment in signal attenuation due to the magnetic field. Apart from analysing the impact of a magnetic field, this research also investigates sensors with different electrode materials and input excitation. Among different electrode materials, a sensor with Iron-Niobium is found to have maximum electrolytic sensitivity of 15.78 V mol⁻¹ l⁻¹ while measuring the electrolytic concentration of oxalic acid in the range of 0.001–0.01 mol l⁻¹. Similarly, the proposed voltammetric sensor with Iron-Niobium electrodes is implemented to measure the concentration of other electrolytes with 10–130 V mol⁻¹ l⁻¹ sensitivity to enhance applicability. A modified electrical equivalent model with an additional inductive component is also proposed in this research work that explains the waveform dip followed by a peak overshoot due to the influence of the magnetic field. The proposed electrical equivalent model of electrode–electrolyte interface is compatible with a conventional model, which is confirmed based on the experimental observations and mathematical analysis.

The linear and nonlinear temperature responses restrict the application of Hall current sensors operating in thermal power plants and industries. The rise in temperature of electron device-based measurement causes a significant error, leading to undesirable consequences for plant operation and relay coordination. This paper investigates four Hall current sensor types with linear and nonlinear temperature responses. The Hall current sensor, which receives the magnetic excitation from the permanent magnet, exhibits a linear temperature response, and the wire-wound design exhibits a nonlinear temperature response in the temperature range of 306–376 K. The solution scheme with amplitude modulation and thermal sensor integration with interdigitated electrode design having graphene and ZnO–KMnO₄ compounds as the dielectric is also proposed. The use of amplitude modulation achieves input frequency immunity with a 0.03% K⁻¹ improvement in the temperature response of the capacitive thermal sensor. Experimental observations confirm the validity of the thermal drift compensation scheme with a 20%–99% reduction of thermal drift error with a suitable choice of a thermal sensor.

The emerging requirements of tunable resistors or pseudoresistors for electrical and electronic circuits demand the rigorous attention of engineers in recent times. The frequency-dependent behavior of conventional pseudoresistors operating with gate-controlled metal oxide field effect transistors (FET) creates a subtle challenge to operate in high-frequency applications. Therefore, this letter investigates a tunable resistor with a planar Hall plate to eliminate the frequency-dependent limitations of FETs. The proposed design of a tunable resistor with an optimized Hall effect sensor is able to achieve resistance tuning in the range of 1.8 Ω–247 KΩ. Apart from that, this letter investigates different geometries of planar Hall plate devices and their impact on biasing and magnetic fields that produce a compelling choice for tunable resistors. The proposed scheme exhibits a THD value of 1.4e-8% for a 10-MHz input signal, which is superior to its counterparts based on gate-controlled field effect devices.

Calibration is the backbone of any sensor and measurement philosophy. The conventional calibration techniques for electrical parameter measurement using nonlinear sensors are affected by the repeating analogue signals and lead to errors in measurement. This research paper investigates different regression‐based mathematical models to calibrate the Hall sensor for measuring RMS and the fundamental frequency. The novelty of this research work lies in the feature‐based input modelling to measure RMS current and frequency with an error of 3.37e‐12% and 7.61e‐9%, respectively. The conventional Fourier transform method is compared with six different bio‐inspired metaheuristic algorithms to estimate the frequency components of the analogue signal received from the measurement setup. Apart from the conventional sine waveforms, this paper investigates sawtooth and square waveforms as the periodic signals for determining the frequency components. The results from the comparison study show that the Whale Optimization Algorithm exhibits 1.25% lesser error whilst predicting the features in measured frequency components. Apart from this, the paper identifies a unique combination of features that effectively measures the instantaneous electrical parameter with RMSE, NRMSE, and value of 158.8, 0.51, and 0.44, respectively. Experimentally it is found that the decision tree and random forest regression models calibrate the Hall sensor with 93% less error than their linear and polynomial counterparts.

The increasing requirement for reliable power demands robust protection with excellent waveform sensors. The presence of nonlinear elements in the modern-day loads brings challenges in sensing the current waveform, which is different from the conventional sinusoids. This research article proposes a novel current waveform sensing philosophy with the help of five numbers of series-connected wire-wound Hall current sensors. Signal conditioning circuits and their mathematical expressions are also discussed here to estimate the current waveform with 9.6 ± 2.4 % linearity and 2.1 ± 1.3 %/A sensitivity. The sensing technology senses the current waveform with a Root Mean Square Error (RMSE) value of 0.2. Apart from sensing the typical sinusoidal current waveform, the proposed sensing philosophy also senses the impulse and switching current waveforms with RMSE values 2.7 and 0.65, respectively. These results have a broad scope of improvement by implementing more wire-wound Hall current sensors in series. Digital output features and the optical link between the sensor and receiver offer necessary isolation to the microcontroller against harmful transients and other waveform distortions. The experimental verification and required data analytics confirm the applicability of the sensor with substantial accuracy, sensitivity, and linearity.

The conventional approach of contactless current sensing using Rogowski’s coil is associated with unavoidable design constraints that limit the sensitivity, rise time, settling time, and bandwidth of operation. This paper discusses some novel coil designs for contactless current measurement along with an electron device that works based on a brace-shaped Hall plate for dynamic precision adjustment. Experimentally, these proposed coil models achieve a sensitivity of 5.76 mV/A and nonlinearity of 0.09 %, which are better than their conventional counterparts. Apart from this, mathematical analysis related to this work with different core materials and geometrical parameters confirms that these coils are also superior based on rise time, peak time, settling time, and sensitivity compared to their conventional counterparts. The dynamic precision adjustment device, made up of a brace-shaped Hall plate, utilizes novel materials like TiO ₂ and NiO to make the device impedance more sensitive to control frequency and voltage. Experimentally, the impedance across the electron device varies between 0.0153 MΩ, and 0.387 MΩ for every change in voltage and frequency in MHz of the switched mode control signal. This impedance-sensitive characteristic makes the output of proposed sensor more efficient in achieving dynamic precision control even at a small range of operating conditions.