Inductive Load Research Articles

PI Controller Based Automatic Power Factor Correction (APFC) Using Capacitor Bank

Abstract Power factor plays an important role in electrical industries. Low power factor results in loss of power and poor handling capacity. This factor can be overcome by using capacitors in parallel to the load. Since capacitor draws a leading while inductor draws a lagging current, hence by adjusting capacitor banks parallel to the load, it will level the power factor in the line. Earlier, the process of power factor improvement was done through manual connection of capacitor bank. Later a power factor corrector named the automated power factor corrector (APFC) was proposed. It uses a switched capacitor circuit to improve power factor. In this research, the power factor value from the load is measured and it also includes the installation of APFC unit using a PI controller. The design of this auto-adjustable power factor correction scheme is to ensure that the grid power system always operates under the specified power factor. Actual work of APFC is that it selects the capacitor bank for power factor improvement. The capacitor bank block will choose automatically to further improve the power factor. This process goes on until the required power factor is obtained. Later on, this will automatically turn off the connection between the capacitor bank and the circuit. Furthermore, power saving with power factor after improvement is also discussed in the paper. Here APFC plays a key role in order to decrease the time taken to correct the power factor, which is ultimately beneficial to increase the efficiency of the motors and all inductive loads.

유도전동기에서 부하 변동시 역률 보상 장치 적용 여부에 따른 특성 해석

Induction motors are most widely used for driving rotating loads in the industrial applications. This induction motor may be operated at the rated output load in some cases, but it is often operated at lower load than the rated load. Induction motor has a low power factor due to its inductive load. A device such as a capacitor is used to compensate for a low power factor, but it is difficult to maintain a constant power factor in response to load fluctuations. Therefore, reactive power compensators such as Statcom are also used to keep constant the power factor that varies depending on load fluctuations.BRIn this study, when the load of the induction motor changes, the changes in active power, reactive power, and apparent power were confirmed for cases where no capacitor was installed, only capacitors installed, and only Statcom installed. In addition, based on this, the efficiency and power factor fluctuations at the power source side were also analyzed.

Paralleled multi-GaN MIS–HEMTs integrated cascode switch for power electronic applications

A cascode gallium nitride (GaN) switch integrating four paralleled GaN depletion-mode metal–insulator–semiconductor–high-electron-mobility transistors (MIS–HEMT) and a silicon MOSFET (Si-MOSFET) is presented. Each GaN chip is wire-bonded into a multi-chip power module to scale up the power rating. An optimized symmetric configuration and wire bonding of an integral package are used in the cascode switch. By utilizing an optimized packaging approach, the performance of the multi-GaN-chip cascode switch was evaluated through both static and dynamic characterizations. The constructed cascode switch provides a low-static on-state resistance of 72 mΩ and an off-state blocking capability of 400 V with a positive threshold voltage of 2 V. Analysis of dynamic switching characteristics are discussed and demonstrates stable dynamic on-state resistance (R DS-ON) in inductive load circuits with switching dependencies of voltage, frequency, time, and temperature. The extended defects from buffer caused a minimal decrease in dynamic and static R DS-ON with respect to hard switching conditions. However, there was no noticeable degradation in R DS-ON under harsh switching conditions. This study provides a complete analysis of the multi-GaN-chip cascode switch, including MIS–HEMT manufacturing, cascode packaging and static and dynamic characterizations.

A Single DC Source Five-Level Switched Capacitor Inverter for Grid-Integrated Solar Photovoltaic System: Modeling and Performance Investigation

Boost converters and multilevel inverters (MLI) are frequently included in low-voltage solar photovoltaic (PV) systems for grid integration. However, the use of an inductor-based boost converter makes the system bulky and increases control complexity. Therefore, the switched-capacitor-based MLI emerges as an efficient DC/AC voltage convertor with boosting capability. To make classical topologies more efficient and cost-effective for sustainable power generation, newer topologies and control techniques are continually evolving. This paper proposes a reduced-component-count five-level inverter design for generating stable AC voltages for sustainable grid-integrated solar photovoltaic applications. The proposed topology uses seven switching devices of lower total standing voltage (TSV), three diodes, and two DC-link capacitors to generate five-level outputs. By charging and discharging cycles, the DC capacitor voltages are automatically balanced. Thus, no additional sensors or control circuitry is required. It has inherent voltage-boosting capability without any input boost converter. A low-frequency-based half-height (HH) modulation technique is employed in the standalone system for better voltage quality. Extensive simulations are performed in a MATLAB/Simulink environment to estimate the performance of the proposed topology, and 17.58% THDs are obtained in the phase voltages. Using a small inductor in series or an inductive load, the current THD reduces to 8.23%. Better dynamic performance is also observed with different loading conditions. A miniature five-level single-phase laboratory prototype is developed to verify the accuracy of the simulation results and the viability of the proposed topology.

Microactuation of Magnetic Nanofluid Enabled by a Pulsatory Rotating Magnetic Field

A microactuation process was developed with the help of four coils that generate a pulsatory rotating magnetic field. A small actuator stator, which contains a 46 mm acrylonitrile butadiene styrene (ABS) opened box and four coils with E-type ferrite cores, was constructed. Simulations were made for different Duty Cycles, 0.2, 0.5, 0.72 and 0.9, and distances above the E cores, between 0.01 and 6 mm. These simulations determined the magnetic bubble inflating distance, the saturation regions and the average forces that are responsible for nanofluid flow inside the ABS box. An electrical driving scheme was designed, and a drive was constructed to activate four inductive loads that generate a pulsatory rotating magnetic field. The electronic drive can change the actuation frequency (rotation speed) between 1 Hz and 25 Hz and can adjust the Duty Cycle between 5% and 95% (driving force). From simulations and experiments, it was observed that the Duty Cycle must be limited to 0.7 to avoid the magnetic nanofluid saturation at 45 mT. It was found that three applications use a pulsatory rotating magnetic field: a small motor, a small flat pump and a manipulating sheet matrix for displays or chemical droplets mixing.

PPSW-SHAP: Towards Interpretable Cell Classification Using Tree-Based SHAP Image Decomposition and Restoration for High-Throughput Bright-Field Imaging.

Advancements in high-throughput microscopy imaging have transformed cell analytics, enabling functionally relevant, rapid, and in-depth bioanalytics with Artificial Intelligence (AI) as a powerful driving force in cell therapy (CT) manufacturing. High-content microscopy screening often suffers from systematic noise, such as uneven illumination or vignetting artifacts, which can result in false-negative findings in AI models. Traditionally, AI models have been expected to learn to deal with these artifacts, but success in an inductive framework depends on sufficient training examples. To address this challenge, we propose a two-fold approach: (1) reducing noise through an image decomposition and restoration technique called the Periodic Plus Smooth Wavelet transform (PPSW) and (2) developing an interpretable machine learning (ML) platform using tree-based Shapley Additive exPlanations (SHAP) to enhance end-user understanding. By correcting artifacts during pre-processing, we lower the inductive learning load on the AI and improve end-user acceptance through a more interpretable heuristic approach to problem solving. Using a dataset of human Mesenchymal Stem Cells (MSCs) cultured under diverse density and media environment conditions, we demonstrate supervised clustering with mean SHAP values, derived from the 'DFT Modulus' applied to the decomposition of bright-field images, in the trained tree-based ML model. Our innovative ML framework offers end-to-end interpretability, leading to improved precision in cell characterization during CT manufacturing.

Active Current Balancing for Paralleled SiC Semiconductors in Time-Staggered Switching Mode

The steep voltage slopes of today's wide-bandgap, fast-switching power semiconductors — like SiC and GaN — lead, among other challenges, to reflection on long cables and thereby overvoltage at inductive loads. To apply this technology to motor drives without specially reinforced insulation the voltage slopes need to be reduced. This article presents a new low-loss countermeasure, which involves the parallel connection of two half-bridges via an interphase transformer. Undesired components in the cross-current of the interphase transformer occur due to non-idealities in the voltage symmetry. The resulting additional magnetization can cause the core to saturate. Influences on the converter voltage due to various parasitic influences are described. Especially aspects relevant for dimensioning the magnetic core of the interphase transformer are emphasized. Also, this article describes an approach to deal with the undesired cross-current components using two different closed-loop control concepts. The control uses a special differential-mode shunt for a dedicated measurement of the cross-current mean value. Both control concepts are verified and compared on a 500-kVA SiC inverter test bench, using measurements of the controlled current.

Single-phase energy-fed AC electronic load based on DQ current decoupling

The single-phase pulse width modulation (PWM) converter is the main research object to realize single-phase AC electronic load. To achieve high-quality energy feedback, this paper studies the topology of the PWM rectifier, the mathematical model of DQ current decoupling control, SOGI-PLL phase-locked model analysis, and the energy feedback unit with bipolar SPWM inversion to 50 Hz sinusoidal AC. The scheme is simulated and validated by Matlab/Simulink. The simulated characteristic unit can simulate resistive, inductance, and capacitive loads. The energy feedback unit can verify the stability, high efficiency, and practicability of the scheme with 50 Hz sinusoidal AC feedback.

Active Power Filter Integrated with Transformer

In recent years, the use of non-linear load is increasing day by day. Non-linear loads such as traditional diode/ thyristor rectifiers with inductive load generate harmonic and reactive current, which leads to poor power factor, low energy efficiency, and harmful disturbance to other appliances. Also, in recent years, the large-scale use of the power electronic equipment has led to an increase of harmonics in the power system. Harmonics also affects on the performance of distribution transformer. It increases power loss due to skin effect and proximity effect. Current harmonics are one of the most common causes of these problems and are usually resolved by using shunt active filter (SHAF). By the implementation of a shunt active power filter on the secondary side of the transformer, the harmonics can be compensated which is produced by non-linear load. Finally, by the implementation of this concept the efficiency of the transformer, losses of the transformer, overheating of the conductor due to skin effect, power quality, etc. can be improved. Results of simulation and hardware fabrication are presented in this paper.

A Time-Domain Analysis Model for Modular-Multilevel-Based Grid-Forming Converters in Isolated Power Supply

The modular multilevel based grid-forming converter (MMGC) is considered to be a viable solution in isolated island power supply. However, the existing analysis model cannot meet the requirement of its performance evaluation and circuit parameters design. This paper proposes a high-accurate time-domain steady-state analysis model for MMGC, where the coupled relationships among the load, the MMGC, and the dc-side system can be fully reflected; the amplitudes and phase angles of electrical quantities, including their harmonic components, can be directly calculated. Then, the influence of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> filters on submodule capacitor are studied. The study found that the submodule capacitance is highly correlated to the filter capacitance and almost uncorrelated to the filter inductance. It is also found that the filter capacitance selection should consider the load characteristic; a larger filter capacitance is required in the inductive load supply scenario. Finally, the studies are verified by both simulation and experiment.

출력변동에 대응한 유도발전기의 역률 보상 제어

Induction generators are widely used in micro hydroelectric power plants. When the flow rate and the head change in the power plants, it becomes a parameter that changes the output of the induction generator. Induction generator has a low power factor even when operated at rated output with an inductive load. Also, if the induction generator is operated lower than the rated value or its output power is fluctuated, the change in the power factor becomes larger at a lower power factor. Therefore, a power factor compensation device such as a single capacitor or STATCOM is applied for power factor compensation. When the generator output is fluctuated, the converter voltage of STATCOM has the characteristic of fluctuating in conjunction with it. In this study, we propose the constant voltage source control method in STATCOM for power factor correction of induction generator and its feasibility is verified by the simulation in which the performance of power factor compensation by the capacitor, STATCOM without constant voltage control and STATCOM with constant voltage control are simulated and quantitatively compared. As a results, we confirmed that the STATCOM with constant voltage control can improve the power factor of induction generators a little comparing to the single capacitor or STATCOM without constant voltage control even if the generator output is fluctuated.

부하의 변동에 따른 유도전동기의 자화 전력과 무효전력의 변화 분석

Induction motor is one of the representative inductive loads. Induction motors have coils in the stator and rotor respectively. This coil is distributed in the stator and the rotor, respectively, and has a resistive component and an inductive component according to the flow of current. The slip of an induction motor depends on the rotational speed. The slip of an induction motor varies according to no-load and changes in load. As this slip changes, resistance and reactance change. In an induction motor, the power required to form a magnetic flux is magnetizing power, and the power including the component used as a leakage component of the stator or rotor in the magnetizing power is called reactive power. The ratio of reactive power to active power in an induction motor is called power factor. In order to compensate the power factor, it is necessary to accurately know the magnitude of the magnetizing power required to form a magnetic flux. In order to know the magnitude of the magnetizing power, it is necessary to find the voltage at the air gap.

Design and Control of Two-Stage DC-AC Solid-State Transformer for Remote Area and Microgrid Applications

The critical challenges with integrating renewable energy into the grid are smooth power flow control, isolation between the high-voltage and low-voltage networks, voltage regulation, harmonic isolation, and power quality regulation. This paper considers the design and construction of a two-stage DC-AC solid-state transformer based on wide bandgap (WBG) semiconductor technologies, an optimized medium-frequency transformer, and PI and dq controllers for supplying urban area electric drive systems and microgrid applications. The designed SST consists of a dual active bridge (DAB) DC-DC converter followed by a DC-AC three-phase inverter. Each stage of the SST was simulated with independent controllers. The proposed system was initially developed in MATLAB/Simulink and a laboratory prototype was constructed to verify the results experimentally. Resistive and inductive load were used to test the load disturbance to evaluate the voltage regulation performance. This work has comprehensively provided the performance of a double stage (DC-DC and DC-AC converter) by taking into consideration input voltage, load disturbance, and voltage tracking both in simulation and experiment. The dual active bridge with its controller is able to maintain the desired output reference voltage with minimal voltage ripples under input voltage fluctuations and load variations. Similarly, the three-phase DC-AC converter’s controller exhibits better performance in tracking the desired reference voltage and producing well-regulated AC voltage with low harmonic distortion.

A Proposed Supercapacitor Integrated with an Active Power Filter for Improving the Performance of a Wind Generation System under Nonlinear Unbalanced Loading and Faults

This study proposes the integration of a supercapacitor (SC) with the DC link of a three-phase four-wire active power filter (APF) by using an interfaced three-level bidirectional buck-boost converter controlled by the fuzzy control approach. APF is a flexible alternating current transmission system (FACTS) device that enhances power quality in the electrical network by reducing the load current harmonics and compensating the reactive power. Regulating the DC voltage of the APF’s DC link and absorbing fluctuations in compensated reactive power during disturbances are the major objectives of the integration of an SC circuit to APF. The studied model is a wind farm of Gabal El-Zeit with a total capacity of 580 MW, connected to unbalanced nonlinear loads. The Gabal El-Zeit wind farm is divided into three projects with a capacity of 240 MW, 220 MW, and 120 MW. The model is simulated by the MATLAB/SIMULINK program, and the effectiveness of the proposed methodology is proved by applying different types of faults such as single-line-to-ground, double-line-to-ground, and three-line-to-ground faults. In addition, an additional SC circuit with a two-level converter is connected to the generators coupled to the wind turbines to enhance the performance of the wind farm during disturbances. The results show that SC-integrated APF can reduce the harmonic distortion and compensate the reactive power for high or low inductive loads. Also, it can regulate the DC voltage and absorb the fluctuations in the reactive power during faults. Finally, the performance and the stability of the overall electric system are improved.

Automatic Power Factor Compensation

Paper present the project designed to correcting power factor for domestic, Commercial, Industrial. Which with hope to make the cost and energy usage efficient, because the energy source is depleting due to increase in population. Power factor is the ratio of real power and apparent power. This definition is mathematically represented as kW/kVA where kW is active power and kVA is apparent power (active + reactive). Reactive power is the non-working power generated by the magnetic and inductive load to generate magnetic flux. The increase in reactive power increase the apparent power so the power factor will decrease. Low pF will cause the industry to meet high demand thus making it less efficient. The main aim of this project is to increasing the current power factor of industries from 0.85 to 0.90. Power factor compensation contribute to reduction in current-dependent losses and increase energy efficiency while expanding the reliability of planning for future energy network. As technology develops, the gradual cost and efficiency penalty should reduce. Therefore, automatic power factor compensation device should become cost-effective and smaller device over time. That is the reason this project is using programmable device as it is a miniature architecture device.

Implementation of artificial neural network based control for power quality enhancement of proton exchange membrane fuel cell powered distributed generation system

In this paper, a fuel cell and battery-based distributed generation system is demonstrated. A proton exchange membrane fuel cell is the primary power generator in this decentralized system, with a lead-acid battery providing backup power. A boost converter regulates the fuel cell’s output power to ensure its optimal performance. A bidirectional buck-boost converter has been employed to integrate battery using slope compensated current control. 5-level cascaded H-Bridge inverter is used to convert available DC power into AC power while integrating DG systems with the grid and improving power quality. The artificial neural network has been trained and used to generate the estimated reference current for sinusoidal pulse width modulation techniques. The artificial neural network has been fine-tuned using the scaled conjugate gradient with the performance value 0.094056. The THD of grid current has been reduced by 12.5% and 8.14% approximately for 30 Ω resistive, 30 mH inductive load and 20 Ω resistive, 15 mH inductive load respectively. The system has been simulated in Matlab/Simulink, and the findings have been validated. The results demonstrate the effectiveness of the methodology.

実験値とデータシート値と近似式から構築した電力変換器の損失モデルの実機検証

This paper proposes a losses-analysis model of a DC-output converter based on the approximated equations from measurements and a datasheet. Target verification circuit consists of a DC-voltage source, a smooth capacitor, two half bridge legs, and a load inductor connected to the midpoints of the half bridge legs, which controls the continuous average DC current of the load inductor. A use of self-measured data, compared with the use of datasheet values, enables expanding the ranges of the considerable target parameters. Hence, lesser order approximated equations can deal with more target parameters with less calculation period than that in a conventional time domain simulation. In this study, calculation flow of losses from losses of power devices and an inductor to circuit losses was developed. Subsequently, a semiconductor losses model and inductor losses model were developed via the linear least square method. Finally, a 400V experimental system was developed to verify the accuracy of the circuit losses at 16 specified operating conditions by varying three verification parameters, switching frequency, gate resistance, and inductance. The result shows that the losses calculated using the proposed model has good accuracy with an error of 1.9% to 10.6% to the measured result.

An investigation of avalanche ruggedness and failure mechanisms of 4H SiC trench MOSFETs in unclamped inductive switching by varying load inductances over a wide range

The avalanche ruggedness of unclamped inductive switching of 1.2 kV SiC trench MOSFETs was investigated with load inductances ranging from 1 μH to 5 mH. The SiC trench MOSFETs showed an extremely high avalanche current of more than 6000 A cm−2 at 1 μH, which was 3.3 times higher than state-of-the-art 1.2 kV Si IGBTs. This indicates that modules of SiC trench MOSFETs could show higher ruggedness for parallel connections. In addition, SiC trench diodes in which only the n+ source regions were eliminated from the MOSFETs were fabricated to verify the failure mechanism by the activation of parasitic bipolar transistors. In medium-load inductances from 10 μH to 100 μH, the MOSFETs showed lower avalanche ruggedness than the diodes, and failures were caused by the activation of the parasitic bipolar transistors. For inductances outside that range, the MOSFETs showed identical ruggedness to the diodes, and the failures were caused by the source metals melting.

유도발전기의 출력 변동시 역률 보상 커패시터의 자기여자에 관한 연구

Induction generators are widely used in mini- or micro-scale hydroelectric power plants. In the case of hydroelectric power generation in which changes in flow rate and head are large, the operation of the induction generator is often lower than the rated output. An induction generator is an inductive load and has a lagging power factor, and when operated at rated output, the power factor is around 0.8. The utility recommends that the customer compensate for the low power factor. The power factor compensation is planned so that the power factor of the induction generator will be about 0.95 under the condition of operating at the rated capacity. When the output of the induction generator decreases, the reactive power required for magnetization has a low change, but the active power decreases and the power factor is further lowered. At this time, a self-excitation phenomenon in which the reactive power for power factor compensation becomes higher than the reactive power required for magnetization may occur. When the self-excitation phenomenon occurs, electrical stress is provided to the induction generator, so in order to reduce the occurrence probability, the extent to which the generator

Development of a High-Voltage Pulsed Electric Field Sterilization Power Supply Using a New Topology Circuit

Traditional thermal sterilization technology is easy to implement and safe, but it will destroy food nutrition and change food taste. Therefore, people began to turn their attention to non-thermal sterilization. High-voltage pulsed electric field sterilization technology is one of them; it has attracted much attention because of its high efficiency and little damage to food. Different types of loads will cause serious trailing of the pulse falling edge. In view of this situation, this paper proposes a new topology circuit that combines a solid-state switch with a half-bridge Marx generator. It can be used for high-voltage pulsed electric field sterilization. By improving the structure of the classical Marx circuit, the high-voltage pulse power supply of the new topology circuit has the characteristics of steep rising edge and short falling edge delay; does not require isolation inductance or isolation resistance, which solves the isolation problem between the DC charging power supply and the high-voltage terminal; and has a good voltage-clamping function and load adaptability. The working process of the topology circuit under resistive, capacitive and inductive loads and the voltage clamping effect when the solid-state switch does not work properly in the discharge process are analyzed in detail. The power supply is composed of an adjustable DC power supply, five-stage half-bridge Marx generator and control protection circuit. A field programmable gate array (FPGA) is used as the controller to generate control signals, and optical fiber isolation is used to provide control signals for the main loop. The power supply can output a high-voltage square wave pulse with a voltage amplitude of 10 kV, maximum pulse number of 1000 per second, maximum pulse width of 20 μs, pulse rise time of smaller than 300 ns and short pulse drop time, and the repeated voltage amplitude, frequency and pulse width are adjustable, which can meet the requirements of a high-voltage pulse sterilization experiment.