Search Results (59)

This paper reports on the performance of an optical voltage transducer (MVT) module after undergoing lightning impulse withstand tests. The device was designed to monitor the output voltage of a dedicated capacitive voltage divider (CVD) to facilitate a voltage sensor dedicated for 132-kV high voltage (HV) networks. Hard piezoelectric transducer (PZT) and fiber Bragg grating (FBG) technologies were combined in the module to serve as a voltage-to-strain-to-wavelength converter. The FBG peak wavelength shifts were calibrated against the input voltage to provide precise measurements of the network voltage. The module was subjected to lightning impulse withstand tests as per the requirements of the IEC 60044-7 and IEC 60060-1 standards, and the impact of the lightning impulses on the performance of the MVT module was evaluated based on the accuracy tests performed before and after the lightning impulse tests. The experimental results demonstrated that the MVT module successfully withstood the lightning impulse tests without any disruptive discharges or voltage collapses. The performance of the module was not affected by the lightning impulse tests within the practical constraints of the reference measuring equipment: its amplitude and phase errors remained within the original limits of ±0.1% and ±0.1° at 80–120% of the rated voltage, and below ±4% and ±2° at 2% of the rated voltage, respectively. Full article

Although compression therapy is widely used to improve wound healing, selecting the appropriate pressure remains a challenge in clinical practice. This work proposes an intelligent patch integrated into a bandage that allows for the simultaneous monitoring of the applied pressure and wound condition using Near-Field Communication (NFC). The proposed patch integrates a force-sensitive resistive sensor to measure pressure and a capacitive sensor to detect wound exudate through capacitance variations. Capacitance is obtained by analyzing the delay in the stepwise response of the sensor, while resistance is measured from the voltage drop across a resistive divider, which is read by a microcontroller’s analog-to-digital converter. The system is powered wirelessly through NFC energy harvesting, triggered by a mobile device that acts as a reader. The NFC module can be moved away after measurement to improve patient comfort or remain integrated into the dressing for periodic monitoring. Experimental results demonstrate pressure measurements up to 140 mmHg and exudate detection up to 200 $\mathsf{\mu }$L, confirming the feasibility of battery-free NFC smart bandages for therapeutic monitoring based on wound compression. Full article

To address the malfunction and unreliable operation of traditional open discharge gaps in high-altitude environments (with sandstorms and low pressure), which are prone to interference from factors like electrode corrosion and contamination, this study proposes an intelligent sealed neutral point protection device for transformers. Its core is a sealed discharge gap filled with nitrogen gas, effectively isolating it from external conditions and significantly stabilizing the power frequency discharge voltage. Innovatively, an active breakdown technology is introduced. Overvoltage signals at the transformer neutral point are acquired in real time via a capacitive voltage divider. After processing by a microcontroller unit (MCU), if both the amplitude and duration meet the preset thresholds, the MCU triggers a pulse to actively induce a discharge at the gap’s low-voltage end, enabling controlled breakdown. This allows the transient discharge voltage to be raised to 3–4 times the steady-state value, avoiding overlap with the surge arrester’s residual voltage. Tests confirm that the gap breaks down stably only when both amplitude and duration conditions are met, remaining reliable otherwise. This design successfully resolves the critical issues of failure and maloperation under both steady-state and transient overvoltages in high-altitude settings, significantly improving protection selectivity and reliability, and offering a novel solution for transformer safety in such regions. Full article

As distribution networks become increasingly intelligent, primary–secondary integrated distribution switches are replacing the traditional electromagnetic type. However, the high degree of integration intensifies inherent electromagnetic compatibility (EMC) challenges. This paper presents a field-circuit hybrid full-wave model to investigate switch characteristics during lightning strikes. A 3D full-wave model of the switch and a distributed parameter circuit model of the connecting lines are coupled via a network parameter matrix. This approach comprehensively accounts for the impacts of transmission lines and structural components on electromagnetic disturbances. Simulation and experimental results reveal that lightning strikes induce high-frequency damped oscillatory waves, primarily caused by traveling wave reflections along overhead lines. The characteristic frequency of disturbance is inversely proportional to the transmission line length. Additionally, internal components significantly influence this frequency; specifically, a larger voltage dividing capacitance in the voltage transformer results in a lower frequency. Model validation was performed using a 20 m transmission line setup. A 75 kV standard lightning impulse was injected into Phase B. At a distance of 500 mm from the voltage transformer, the measured radiated electric field amplitude was 14.12 kV/m (deviation < 5%), and the characteristic frequency was 1.11 MHz (deviation < 20%). These findings offer vital guidance for the lightning protection and EMC design of primary–secondary integrated distribution switches. Full article

In this study, the operation features of a transformerless voltage divider, with transistor–diode commutation of switchable capacitors, designed to operate as a part of low-power autonomous electronic systems with reduced output voltage are studied both theoretically and experimentally. The analysis is carried out for a divider operation with a constantly or periodically connected voltage source V₀ with unlimited power. It is found that the divider’s efficiency during operation with a constantly connected primary voltage source V₀ with unlimited power is very low. However, the efficiency can reach 60% during the divider’s operation using a periodically connected voltage source V₀ with unlimited power. It has been shown that the efficiency can only reach 40% in the case of using a voltage source with limited power connected to the divider periodically. It has been established that for circuits with transistor–diode commutation of the capacitors, the stabilization effect is much stronger than for circuits with diode commutation of the capacitors. Therefore, an excess of the maximum load voltage relative to the expected value V₀/N is significantly lower for transistor–diode commutation in comparison with diode commutation (N is the number of divider stages). Based on the ideas developed regarding the divider operation, analytical expressions are obtained, enabling us to calculate the parameters of the studied divider circuits in a wide range. The good agreement between the analytical estimations and experimental data suggests that these calculations adequately describe the operation of the dividers, and that the derived analytical expressions can be successfully used during the preliminary design stage. In general, the analysis carried out herein and the developed approach make it possible to significantly narrow the range of search for the necessary system parameters when designing voltage dividers. Full article

The condition monitoring of machine elements and, more precisely, journal bearings, is beneficial to prevent unnecessary wear and identify critical operating conditions. One method for that is the monitoring of the electric behavior of the bearing by monitoring its capacitance. While the general electric behavior of journal bearings is known, assessments of suitable measurement setups and data analysis methods are usually neglected. This contribution identifies potential measurement setups and analysis methods used in the literature for monitoring rolling-element bearings or journal bearings. These setups and analysis methods are then discussed theoretically and based on measurements of the electric behavior of journal bearings. The findings show that voltage divider setups with AC signals are the most promising solution to monitor the journal bearing electrically. Linear regression algorithms can be used to obtain the amplitude and phase of the measured voltage signal. These values are then used to calculate the impedance and capacitance of the bearing. Lastly, this contribution investigates how existing PCT (percent contact time) analyses need to be altered to improve the precision and robustness of the analysis and allow for the physical interpretation of the measurement results. These findings may be used in the future to predict wear and identify critical operating conditions in journal bearings, such as mixed lubrication. Full article

Parallel-type slew-rate enhancers (PSREs) improve the driving capability of operational transconductance amplifiers (OTAs) for large capacitive loads. While capacitive-boosting (CB) techniques enhance PSRE efficiency in fully-differential designs, their application to single-ended configurations—common in off-chip load driving—remains unexplored. This work identifies a critical limitation of standard CB in single-ended unity-gain buffers: severe slew-rate degradation due to large common-mode input swings. To overcome this, we propose a novel split CB (SCB) technique for single-ended PSREs that strategically divides the boosting capacitance. Simulated in a 0.18-µm CMOS process, the proposed method achieves a ×5.53 reduction in settling time compared to standard CB when driving a 1-nF load. With only 4 µA quiescent current under a 3.3-V supply, it attains a 1% settling time of 2.56 µs for 2.64-V steps, demonstrating robust performance across process-voltage-temperature variations. This technique enables low-power, high-speed interfaces for drivers of off-chip devices. Full article

This paper presents a low-power, fully differential, programmable gain amplifier (PGA) for ultrasound receiver analog front-ends (AFE). It consists of a programmable attenuator implemented by a capacitive voltage divider and a closed-loop amplifier based on a differential difference amplifier (DDA). A suitable sizing strategy provides orthogonal control over gain and bandwidth. The PGA was designed using a standard 180 nm CMOS process. The gain value can be set between −18 dB and +20 dB in 2 dB steps; the bandwidth can be programmed independently of gain, to values from 5 MHz to 20 MHz, in 5 MHz steps; it draws 600 µA from a 1.8 V supply line. It achieves a differential output swing of 0.8 V peak-to-peak differential with no more than 1.7% total harmonic distortion (THD) and an input-referred noise density of 22 nV/√Hz at 10 MHz, measured at the gain of 20 dB. The PGA exhibits high input impedance and low output resistance for easy integration within the AFE signal chain. The digitally controlled gain and bandwidth make this PGA suitable for ultrasound imaging applications requiring precise time gain compensation and adjustable frequency response and/or additional anti-aliasing filtering. Full article

High-purity germanium (HPGe) detectors occupy a prominent position in fields such as radiation detection and aerospace because of their excellent energy resolution and wide detection range. To achieve a broader detection range, conventional HPGe detectors often need to be expanded to cubic-centimeter-scale volumes. However, this increase in volume leads to a large detector area, which in turn increases the detector capacitance, affecting the detector’s noise level and performance. To address this issue, this study proposes a novel high-purity germanium drift detector (HPGeDD). The design features a small-area central collecting cathode surrounded by concentric anode rings, with a resistive chain interposed between the anode rings to achieve self-dividing voltage. This design ensures that the detector’s capacitance is only related to the area of the central collecting cathode, independent of the overall active area, thus achieving a balance between a small capacitance and large active area. Electrical performance simulations of the novel detector were conducted using the semiconductor simulation software Sentaurus TCAD (P-2019.03). The results show a smooth electric potential distribution within the detector, forming a lateral electric field, as well as a lateral hole drift channel precisely directed toward the collecting cathode. Furthermore, simulations of heavy ion incidence were performed to investigate the detector’s carrier collection characteristics. The simulation results demonstrate that the HPGeDD exhibits advantages such as fast signal response and short collection time. The design proposal presented in this study offers a new solution to the problem of excessive capacitance in conventional HPGe detectors, expands their application scope, and provides theoretical guidance for subsequent improvements, optimizations, and practical manufacturing. Full article

The paper proposes an original single-phase transformerless three-level (S-PT) photovoltaic (PV) inverter in the cascade H bridge (CHB) configuration. The DC-link voltage of the inverter is created by two serial voltage sources with a voltage twice as low as the DC-link voltage. An appropriate V_CC DC-link voltage is generated by a two-phase DC-DC boost converter, fed from the string panel output at a level determined by the maximum power point tracking (MPPT) algorithm. Two symmetrical sources with V_CC/2 are formed by a divider of two series-connected capacitors of large and the same capacitance. The common mode (CM) voltage of the proposed inverter is constant, and the voltage stresses across all switches, diodes and gate drive circuits are half of the DC-link voltage. The principles of operation of the S-PT inverter, an implementation of a complete gate control system with galvanic isolation for all IGBTs, are also presented. The proposed inverter topologies have been implemented using high-speed IGBTs and simulated in PSPICE, as well as being experimentally validated. Full article

To address the demand for high-precision insulation testing in modern complex cable networks, this study proposes and implements an intelligent insulation testing system based on FPGA technology. The system integrates decision tree (DT) models to enable efficient anomaly detection and process optimization. Utilizing the voltage-divider principle for insulation testing, the system extracts features such as maximum values, minimum values, and entropy to construct an explainable classification model capable of accurately monitoring different types of currents (leakage, absorption, and capacitive currents) during their decay processes. An adaptive post-processing filtering method is introduced to enhance classification accuracy and optimize testing efficiency by minimizing redundant range switching. Experimental results demonstrate that the proposed system achieves exceptional recognition accuracy and process stability across a wide range of resistances, significantly advancing the intelligence of insulation testing while improving measurement efficiency by 54.71%. This innovative solution provides a robust approach for high-demand electrical performance assessments. Full article

This report evaluates the pulsed breakdown performance of $C_4{F}_{7}N$ under a 6.8 kV/ns voltage excitation. The pulsed dielectric strength of $C_4{F}_{7}N$ is compared to $S{F}_6$ in the same experimental setup, and it is found that $C_4{F}_{7}N$ concentrations of 50% or greater are required to achieve a dielectric strength greater than or equal to $S{F}_6$. Pure $C_4{F}_{7}N$ demonstrated higher electric field hold-off for longer time periods and less statistical variance under pulsed conditions when compared to $S{F}_6$. Mixtures of 50%$C_4{F}_{7}N$ with $N_2$ or $C{O}_2$ as buffer gases showed no appreciable difference in pulsed dielectric strength. Full article

Operating overvoltage occurs when the pantograph or main breaker of an electric locomotive is operated, which is prone to causing insulation failure of high-voltage equipment. The HX_D1 electric locomotive is taken as the research object in this paper to explore the characteristics and influencing factors of operating overvoltage. Under pantograph lifting, main breaker closing, main breaker opening, and pantograph dropping, operating overvoltage waveform in the high-voltage system is recorded by a high-speed oscilloscope and resistance–capacitance voltage divider to analyze the overvoltage characteristics and distribution law. Tested data show that the amplitude of operating overvoltage is in the range of 80 to 330 kV with ultra-high steepness, which is similar to the Very Fast Transient Overvoltage (VFTO) in power systems. The maximum overvoltage during the entire test occurred during the main breaker closing and its amplitude is 328.60 kV with a steepness of 4.21 × 10⁴ kV/μs. The max overvoltage of the other operations (pantograph lifting, main breaker opening, and pantograph dropping) are 280.60 kV, 194.73 kV, and 305.56 kV with ultra-high steepness. High-amplitude overvoltage is predominantly located at the pantograph, while the low-amplitude sort is mainly observed around other high-voltage equipment. The result indicates that operating overvoltage belongs to ultra-fast transient overvoltage and its amplitude and steepness are higher than existing research. Full article

In this study, we analyze metal–insulator–metal (MIM) capacitors with different thicknesses of SixNy film (650 Å, 500 Å, and 400 Å) and varying levels of film quality to improve their capacitance density. SixNy thicknesses of 650 Å, 500 Å, and 400 Å are used with four different conditions, designated as MIM (N content 1.49), NEWMIM (N content 28.1), DAMANIT (N content 1.43), and NIT (N content 0.30). We divide the C–V characteristics into two categories: voltage coefficient of capacitance (VCC) and temperature coefficient of capacitance (TCC). There was an overall increase in the VCC as the thickness of the SixNy film decreased, with some variation depending on the condition. However, the TCC did not vary significantly with thickness, only with condition. At the same thickness, the NIT condition yielded the highest capacitance density, while the MIM condition showed the lowest capacitance density. This difference was due to the actual thickness of the film and the variation in its k-value depending on the condition. The most influential factor for capacitance uniformity was the thickness uniformity of the SixNy film. Full article

A fixed-slope soft-start method applicable to Buck converters for on-chip integration is proposed to address the issue of varying power stresses (device voltage, current stress) during start-up with different output voltages. The main mechanism involves combining feedback coefficient sampling with a fixed-slope reference voltage to achieve a slow rise in the reference voltage by equating the soft-start charging current to a pulse current through the on-chip integration of a small capacitor. This allows for fixed-slope start-ups for different set output voltages. Spike elimination techniques are employed to address charging current spikes caused by pulse periods, enhancing precise control over the soft-start time. By replacing the traditional resistor divider network with a capacitive divider network in the soft-start method, DC power consumption is minimized. Upon completion of the soft start, a smooth transition to a steady-state operation occurs, with the automatic shutdown of the soft-start module reducing static power consumption. A specific circuit design and layout verification based on 0.18 μm high-voltage BCD technology demonstrates that the proposed method maintains a fixed-slope start-up of approximately 5 mV/μs within the chip’s output range of 0.9 V to 4 V, with a slope control accuracy of up to 98%. The soft-start circuit effectively eliminates surge currents generated during start-up under full load conditions of 3 A and no-load conditions of 0 A, reducing the overall surge current by 44% and enabling a stable voltage rise and the smooth transition to a steady-state operation. Full article