Modulation Rectifier Research Articles

Eigenfrequency Identification Scheme for Strongly Coupled Series-Parallel Compensated Wireless Power Transfer System

This brief proposes an eigenfrequency identification scheme (EIS) based on circuit theory in time domain for a series-parallel compensated wireless power transfer (SP-WPT) system with the pure capacitance filter. In the SP-WPT system, the high nonlinear features (HNFs), including the strong magnetic coupling and diode rectifier influence the system operation by causing the distortion and discontinuity of the voltages and currents. Thus, the effectiveness of fundamental harmonic approximation is influenced, especially when the impact of HNF becomes serious under the strong magnetic coupling and light load conditions. Consequently, the time domain analysis is developed for the diode rectifier-equipped strongly coupled SP-WPT system. Three operation modes of the diode rectifier are analyzed in detail, where the influence of constant dc-link voltage is investigated. Besides, the two eigenfrequencies of the SP-WPT system can be analytically calculated by using the coupling coefficient, k and resonant frequency in the proposed EIS, which reveals the relationship between k and the operation characteristic of the system. Eigenfrequency is the inherent characteristic of the system, which is different from odd and even frequency. Finally, the effectiveness and accuracy of the proposed EIS are verified by experiments on an SP-WPT platform.

Fractional-Order Linear Active Disturbance Rejection Control Strategy for Grid-Side Current of PWM Rectifiers

To further improve the performance of linear extended state observer (LESO), a novel fractional-order linear extended state observer (FOLESO) is proposed in this paper. By incorporating a fractional-order term into the framework of traditional LESO, the design of FOLESO is more flexible and thereby the disturbance estimation error can be further reduced. Based on the proposed FOLESO, a fractional-order linear active disturbance rejection control (FOLADRC) strategy has been designed for grid-side current control of three-phase voltage-type pulse width modulation (PWM) rectifiers. In this way, the harmonic suppression property can be enhanced without sacrificing the tracking performance, and the ideal grid-side current can be achieved. Furthermore, the detailed design process, implementation mode and parameter tuning of FOLADRC are also given in this paper. The theoretical analysis and experimental results show that the proposed method is effective and superior to the traditional PI control or linear active disturbance rejection control (LADRC) strategy.

Finite-Time Adaptive Fuzzy Control for Three-Phase PWM Rectifiers With Improved Output Performance

For three-phase pulse width modulation (PWM) rectifiers, system uncertainties, such as load disturbances, parametric uncertainties, and grid disturbances, may result in significant DC-link voltage fluctuations, degrade the quality of grid currents, and even lead to system instability. To address this issue, a modified dynamic model of the PWM rectifier with system uncertainties is established, and a finite-time adaptive fuzzy control (FTAFC) method with the dual-loop structure is proposed. In the outer voltage loop, a finite-time adaptive law is used to maintain stable DC-link voltages despite load disturbances. In the inner power loop, an adaptive fuzzy technique is used to estimate and compensate system uncertainties, thus ensuring finite-time power tracking. It is confirmed that all signals of the closed-loop system are finite-time bounded. The experimental and simulation results demonstrate the effectiveness of the proposed method.

Current and transconductance mode full/half‐wave rectifiers realized with only one active block

SummaryThis research paper introduces a novel active building block for full/half‐wave (inverse) rectifier circuits, eliminating the need for passive elements. The paper presents two alternative implementations: a current mode approach utilizing MO‐CFTA (multiple output current follower transconductance amplifier) and a transconductance mode approach utilizing MO‐VDTA (multiple output voltage differencing transconductance amplifier). Both circuit configurations exhibit favorable zero‐crossing characteristics and exceptional linearity. The transconductance mode rectifier enables electronic control of the output current signal by adjusting the applied bias currents. The circuits are designed with simplicity and compactness in mind, making them highly suitable for integration into IC circuits. The analysis investigates the impact of non‐idealities and parasitic effects, although the absence of passive elements results in minimal parasitic effects. Simulation results conducted using 0.18‐μm CMOS technology and a ±0.9‐V supply voltage align closely with the theoretical predictions. Furthermore, Monte Carlo simulations and corner analysis are employed to evaluate the circuit's robustness. To validate the feasibility of the proposed solution, experimental tests are performed using commercially available components. The designs are implemented on Cadence Virtuoso, and post‐layout measurements are conducted to further verify the proposed solutions.

Parallel Power Sharing Control of Multi-Controllable Rectifiers in a High-Power DC Fast Charging Station

The increase in demand for the fast charging of electric vehicles (EVs) has promoted research and the application of high-power direct current (DC) fast charging stations, and research on the stability control of charging stations with a parallel structure of multi-controllable rectifier modules is of great significance. Taking into account the dynamic and steady-state performance, the parameters of the dual-loop controller based on virtual impedance control are designed to realize the power sharing of multi-controllable rectifier modules. The constant power load model of EV charging at a constant current is established, and the load capacity of the cascaded system of converters is studied by using the impedance analysis method. The experimental and simulation results verify the effectiveness and correctness of the power sharing control strategy and the cascaded system stability analysis.

Evolution Game Analysis of Chemical Risk Supervision Based on Special Rectification and Normal Regulation Modes

Chemical safety is closely related to public health, safety, and environmental concerns. Strengthening chemical safety supervision is not only vital for ensuring safe production but also plays a crucial role in maintaining overall social safety. This paper aims to analyze the evolutionary game strategies between chemical enterprises and government regulators under different regulatory modes, namely, ‘special rectification’ and ‘normal regulation’. The results indicate that under the ‘special rectification’ pattern, the strategic choices of chemical enterprises regarding safety investment rely on the cost–benefit analysis of safety non-investment. Conversely, in the ‘normal regulation’ mode, the decision to invest in safety is based on the comparison between the cost of safety investment and the cost of not investing in safety. Increasing government sanctions encourages chemical enterprises to prioritize safety investment under both supervision modes. Notably, while punishment significantly impacts safety investment behavior under the ‘normal regulation’ mode, it exhibits negligible influence under the ‘special rectification’ pattern. These research findings provide valuable decision-making support for government agencies tasked with effectively supervising the safety production of chemical enterprises.

Confluence of Integrated Magnetics and TCM for a ZVS Based Higher Order Differential-Mode Rectifier

Two driving performance metrics in modern power-electronic systems are power density and efficiency: usually, improvement in one result in sacrificing the other. In this paper, triangular conduction mode (TCM) is used alongside integrated magnetics to achieve both performance metrics simultaneously. TCM is implemented by extending the switch current high enough to reverse direction and provide enough energy at the onset of the deadtime to discharge the parasitic capacitance of the SiC MOSFET. The elevated current ripple is alleviated by distributing the rectifier low-frequency current among parallel interleaved sub-modules. Taking advantage of the symmetrical topology of the differential mode Ćuk rectifier (DMCR), an integrated interleaved magnetic (IIM) structure is proposed to house all the inductors in a module. In doing so flux cancellation technique is used between the Ac-and Dc-side inductors to reduce the losses and size while using a custom core structure to control the flux coupling between the interleaved windings. A step by step design algorithm is presented to manage the different types of coupling within IIM. Challenges in design, fabrication, and testing of the system are analyzed and appropriate solutions are presented in each section. The solutions are supported by mathematical analysis to optimize the power stage design and validated by circuit as well as finite element simulations. An experimental setup is assembled to test this concept and multiple time-domain and parametric results are presented for proof of the concept in rectifier mode and single module mode.

Robust Feature Rectification of Pretrained Vision Models for Object Recognition

Pretrained vision models for object recognition often suffer a dramatic performance drop with degradations unseen during training. In this work, we propose a RObust FEature Rectification module (ROFER) to improve the performance of pretrained models against degradations. Specifically, ROFER first estimates the type and intensity of the degradation that corrupts the image features. Then, it leverages a Fully Convolutional Network (FCN) to rectify the features from the degradation by pulling them back to clear features. ROFER is a general-purpose module that can address various degradations simultaneously, including blur, noise, and low contrast. Besides, it can be plugged into pretrained models seamlessly to rectify the degraded features without retraining the whole model. Furthermore, ROFER can be easily extended to address composite degradations by adopting a beam search algorithm to find the composition order. Evaluations on CIFAR-10 and Tiny-ImageNet demonstrate that the accuracy of ROFER is 5% higher than that of SOTA methods on different degradations. With respect to composite degradations, ROFER improves the accuracy of a pretrained CNN by 10% and 6% on CIFAR-10 and Tiny-ImageNet respectively.

Modeling and adaptive control strategy of hybrid microgrid based on virtual synchronous generator

AbstractAiming at large system operation fluctuations caused by the technical control of virtual synchronous generators, this article studies the introduction of interface converter control power, builds a virtual synchronous generator (VSG)‐based hybrid microgrid model and adaptive control strategy. Finally it optimizes it with fuzzy logic to obtain an fuzzy logic controller (FLC) based adaptive VSG control strategy. The experimental results show that under the FLC‐based adaptive VSG control strategy, in the reverse current mode, the system regression time is 0.37 s, and the DC bus voltage is 6.5 V; In the rectification mode, the system regression time is 0.49 s, and the DC bus voltage is 2.1 V. The results obtained are faster than the traditional VSG control strategy, and the DC bus voltage is 42.48%–68.66% lower. In summary, the suggested control approach is effective and reliable under the two operation modes, which can make the system operate safely and stably.

Disturbance Decoupling for a Single-Phase Pulse Width Modulation Rectifier Based on an Extended H-Infinity Filter

The growing utilization of single-phase pulse width modulation (PWM) rectifiers in various applications has spurred interest in detecting and monitoring faults in these devices. In particular, voltage and current sensors play a crucial role in the control loop of these rectifiers. However, sensor faults can significantly affect the converter’s performance and availability. This paper introduces a novel and efficient method for detecting and decoupling sensor faults in single-phase PWM rectifiers. The proposed method utilizes residual generation and incorporates an extended filter within the rectifier. Unlike conventional filters, the presented fault detection and isolation (FDI) method effectively eliminates the influence of disturbances on the residual signal. This feature helps prevent false alarms in the monitored system, ensuring reliable fault detection. To evaluate the effectiveness of the approach, hardware-in-the-loop and simulation tests were conducted. The results from these tests provide substantial evidence supporting the efficacy of the proposed method. The hardware-in-the-loop experiments involved real-world implementation, validating the practicality and reliability of the approach. Meanwhile, simulation tests allowed for a comprehensive analysis of system behavior and performance under various fault scenarios. The findings demonstrate the rapid and dependable nature of the proposed method for detecting and decoupling sensor faults in single-phase PWM rectifiers. By effectively mitigating the impact of disturbances on the residual signal, false alarms are minimized, ensuring accurate fault detection. The experimental validation highlights the practical applicability and effectiveness of the proposed approach, making it a valuable contribution to fault detection in single-phase PWM rectifiers.

Modelling of Bidirectional Three-Phase Four-Wire Three-Level NPC MLC under Single-Loop Current Sensorless Control

Single-loop current sensorless control allows for abolishing of the instantaneous current measurement in the control system using only a single control loop with voltage feedback to stabilise the DC-bus voltage. This approach eliminates current sensors in the control circuit, benefiting from saving space on the printed circuit board and minimising power dissipation in the current measurement circuitry. This paper focuses on the single-loop current sensorless control applied to bidirectional three-phase four-wire three-level NPC MLC by simulation analysis and demonstrates the performance of the proposed current control algorithm in the rectifier and inverter modes and the step response with power direction change and grid-voltage change. In capacitor voltage balancing, an additional controller is applied, which is capable of compensating for the voltage asymmetry caused by adding a 2.5 kOhm resistor in parallel to one of the DC-bus capacitors. Our results demonstrate good performance of the proposed control method both in the inverter and rectifier modes, showing stable current shape in the low power and full power modes with acceptable harmonics content, meeting the requirements of the IEC 61000-3-2 standard for Class A devices. The analysis showed that the proposed control approach is suitable for industrial application.

CMOS readout FEE based TV-BLR module for CdZnTe pixel detectors in high count rate applications

In this study, a time-variant baseline restorer (TV-BLR) circuit was designed and implemented to address the poor frequency selectivity issue in the shaping units of most state-of-the-art readout electronics for CdZnTe/CdTe detectors used in biomedical imaging applications. The proposed circuit improves image quality by canceling the artifacts that result from poor temporal and energy resolution in PET imaging. The proposed circuit consists of a Charge Sensitive Preamplifier (CSP) followed by a classical pole-zero compensation circuit. Two stages of integrators are added and a frequency rectifier module named the TV-BLR circuit has been built. The open-loop amplifier for the CSP is a single-ended input stage amplifier, designed for low-power applications with a maximum power consumption of 43 µW from a 1.2 V supply voltage, verified through post-layout Monte Carlo simulations. The TV-BLR increases the selectivity of the shaping filter, lowers the equivalent noise charge (ENC), and restores the baseline of the circuit to only 143 µV dc-offset. It also extends the counting rate behavior of the system by handling the time-over-threshold (ToT), which depends on the tail current (Itail) of the comparator stage. The circuit was designed, simulated, and validated for an input dynamic of 2–12.5fC, providing an energy range of 55.1–354.3 keV. The design has a charge-to-voltage conversion factor of 56.7 mV/fC with a 4% non-linearity error for an input detector capacitance of 200 fF, while achieving an optimal ENC of 57.4 e − RMS ± 0.1 e−/fC with 13.27 ns peaking time. Process Voltage Temperature (PVT) analysis was performed to validate the simulation results and performance metrics of the design. The proposed design improves energy resolution and avoids energy losses due to the readout system.

Robust Sensor Fault Detection for a Single-Phase Pulse Width Modulation Rectifier

Maintaining safe and efficient operation in a single-phase pulse width modulation (PWM) rectifier that employs current sensors relies heavily on accurate sensor readings. However, several factors such as environmental conditions, aging, or damage can lead to sensor faults. Therefore, it is imperative to implement robust fault detection methods to ensure reliable system operation. The use of unknown input observer techniques is one such method that involves analyzing the differences between actual and estimated states to detect and identify faults in the system. This paper presents the development of a fault detection method that employs an unknown input observer with high sensitivity to faults and disturbance rejection to achieve robust fault detection. The method involves modeling the system as a state-space model and designing an observer to estimate the system’s state variables based on input and output measurements. The deviations between the actual and estimated states are then analyzed to detect and identify sensor faults, without the need for additional hardware, making it a cost-effective solution. Hardware-in-the-loop tests confirm the effectiveness of the proposed method.

An Autonomous Electric Power System with a Permanent Magnet Synchronous Generator

The article deals with an autonomous electric power system (AEPS) with a permanent magnet synchronous generator (PMSG), storage battery (SB), and a static reversible converter (RC). The autonomous system has a transformer galvanic isolation between the AC and DC voltage networks. The converter operates in two modes: as a rectifier (the generator is in operation) and as an inverter (the generator is out of service). In the rectifier mode, the converter operates as an active voltage rectifier (AVR), which charges (recharges) the storage battery and stabilizes the generator voltage to form the main network. In the inverter mode, the converter operates as an autonomous voltage inverter to form a backup network. The autonomous electric power system structures were analyzed, and its two rational versions with the lowest current load of the converter have been selected based on the analysis results. One version of the structure, which contains, apart from the converter, an additional magnetizing device that stabilizes the generator voltage, operates with a DC network voltage of 250 ± 75 V. The other option does not contain an additional magnetizing device (MD) and operates with a DC network voltage of 600–640 V. For both versions, the automatic control system operating modes with stabilizing the generator voltage and charging the storage battery have been studied by simulating them on a computer.

PROPORTIONAL INTEGRAL QUASI RESONANT CONTROLLER FOR ZERO-SEQUENCE CIRCULATING CURRENT AND RIPPLES SUPPRESSION IN PARALLEL THREE-PHASE PWM RECTIFIERS

Parallel three-phase pulse with modulation (PWM) rectifiers with common sc and ac buses are widely used in power systems due to their many advantages such as flexibility, sinusoidal grid currents, lower switching frequency, and good reliability. However, this topology suffers from zero-sequence circulating current (ZSCC) generated by numerous reasons including filters inductors unbalanced, unequal dead time, and losses of synchronism between the control of each rectifier, which will distort the ac-side currents and increase power losses. This paper proposes both an adjusted space vector pulse width modulated (ASVPWM) method and proportional integral quasi resonant controller (PIQRC) method not only to force the ZSCC to be zero but also to reduce its ripples, which results in low frequency harmonic components in the ac side currents. This twofold objective can be achieved by adjusting the zero-vector duty ratios of ASVPWM to suppress the ZSCC and by using PIQRC to mitigate its predominant harmonics. Finally, the superiority and efficiency of the proposed control method in terms of ZSCC suppression and current ripple reduction are verified through comparative analysis with the conventional ZSCC-PI controller.

Virtual Vector-Based Direct Power Control of a Three-Phase Coupled Inductor-Based Bipolar-Output Active Rectifier for More Electric Aircraft

Direct power control (DPC) has gained increasing attention in recent years as a simple and efficient control strategy for pulse width modulation (PWM) rectifiers. In this paper, the idea of DPC is introduced into the three-phase coupled inductor-based bipolar-output active rectifier (TCIBAR) for the first time, and a virtual vector-based direct power control (VVB-DPC) strategy is proposed for TCIBAR to realize the bipolar DC power supply for more electric aircraft (MEA). First, the mathematical model of the TCIBAR is deduced, and the basic principle of the classic DPC strategy is reviewed. On this basis, the limitations of the classic DPC strategy in TCIBAR control are analyzed. Second, a set of virtual vectors are derived to establish a novel virtual-vector switching table. Based on the virtual-vector switching table, the hysteresis power control of TCIBAR can be realized without affecting the DC-side neutral-point potential of TCIBAR. Finally, a neutral-point potential control method based on DPC architecture is studied and integrated into the VVB-DPC strategy to maintain the bipolar DC voltage balance of TCIBAR under unbalanced load conditions. The VVB-DPC strategy is experimentally studied on a TCIBAR prototype, and the experimental results verify the feasibility and effectiveness of the proposed strategy.

A Novel ZVS/ZCS Push-Pull LC Resonant DC-DC Converter for Energy Sources

In this paper, a novel soft switching push-pull LC resonant DC-DC converter for energy sources is presented. In a high step-up converter, the input of primary side possesses low voltage and high current, so the losses caused by the current account for most of the total power loss. At the same time, the high-voltage stress of the high-voltage output components on the secondary side is also a major problem. Therefore, a high-gain isolated push-pull converter with a secondary-side resonant circuit is proposed, so that the primary-side switches have zero voltage switching (ZVS) and the secondary-side diodes have zero current switching (ZCS). The push-pull structure can reduce the number of active switches, so that the total power loss on the primary side can be reduced. The converter has a resonant tank circuit arranged between the secondary side of isolation transformer and the high-voltage output rectification module. The high-voltage output rectifier module adopts a full-bridge architecture suitable for high-voltage coupling connection. The low-side power switching module adopts a push-pull architecture suitable for low-voltage and high-current applications. The resonant tank circuit uses an inductor–capacitor (LC) structure to improve the resonant tank circuit, which achieves soft switching during power transfer, increasing the efficiency of the converter and improving the electromagnetic compatibility. The main advantage of this technology is that the secondary-side leakage inductance of transformer and the resonant capacitance are connected in series to achieve ZVS for switches and ZCS for diodes. Finally, a prototype of a high-gain push-pull resonant converter was established. The converter was operated at a fixed switching frequency of 135 kHz and a duty cycle of approximately 0.5. The efficiency of the converter can reach 97.1% under experimental tests at an output voltage of 400 V and a rated output power of 500 W.

Sliding mode approach for control and observation of a three phase AC-DC pulse-width modulation rectifier

Introduction. For AC-DC conversion systems, the electrical systems typically use thyristor or diode bridge rectifiers, which have relatively poor performance. Nowadays, three-phase pulse-width modulation rectifiers are widely applied in various applications for their well-known intrinsic benefits, such as adjustable DC link voltage, unity power factor, bidirectional power flow and very low total harmonic distortion. Purpose. The objective of this work is to achieve better stability and dynamic performance using sliding mode strategy for control and observation. Methods. For that purpose, first a sliding mode controller is introduced on the DC-link side to ensure a fast and accurate response of the output load voltage. Then, the sliding mode approach is employed to control the quadrature and direct components of power to maintain the input power factor at unity. Finally, this approach is used to design two observers for grid voltage estimation and online variation of load resistance. To overcome the problem associated with the use of the classical low-pass filter, an adaptive compensation algorithm is used to compensate the attenuation of the amplitude and phase delay of the observed grid voltages. This algorithm is based on the use of the two low-pass filters in cascade and ensures the minimization of chattering. Results. Comparative studies have been carried out between sliding mode control method for controlling the three-phase AC-DC pulse-width modulation rectifier and other conventional techniques. The validation by simulation and the tests carried out gave very satisfactory results and proved the effectiveness and feasibility of the sliding mode for both control and observation of three phase pulse-width modulation rectifier.

An Enhanced Current Differential Protection for AC Transmission Lines Connecting MMC-HVDC Stations

The peculiar fault current signatures of modular multilevel converter-based high voltage dc transmission (MMC-HVdc) system degenerate the operating performance of conventional current differential protection (CDP). CDP may incur low sensitivity or maloperations, especially when MMC-HVdc stations operate in rectifier mode. The performance problem of CDP in the presence of MMC-HVdc stations is analyzed. To address this issue, an enhanced CDP (ECDP) based on amplitude and phase correction factors is presented. The basic principle of ECDP is illustrated and the performance comparison between CDP and ECDP is provided. Furthermore, to avoid unwanted operations caused by abnormal data under external faults, abnormal data index is designed to identify abnormal data. Saturation index is proposed to improve the security of ECDP in the case of CT saturation. Compared with CDP, ECDP has a faster respond speed for internal faults. ECDP can perform well under different operation modes of MMC-HVdc station and various fault conditions. Therefore, ECDP is a promising candidate to protect transmission lines connecting MMC-based converter stations. The performance of ECDP is evaluated using PSCAD/EMTDC and RTDS.

Presynchronization Control for Grid-Connected Inverters Without Grid Voltage Sensors

The grid voltage sensorless control for grid-connected inverters samples the line current to estimate the voltage at the point-of-common-coupling and achieve grid synchronization. The sensorless control tends to enlarge in-rush currents and fails to connect to the grid. For addressing this issue, this letter proposes a presynchronization control strategy to achieve a fast and reliable connection to the grid. By applying periodic pulses with a designed duty cycle, the converter operates in the rectifier mode with unit power factor before being connected to the ac grid as an inverter. The initial phase of the ac grid can thereby be estimated by the sampled current, where a synchronous reference frame phase-locked loop is applied to obtain the current phase. The proposed strategy is validated by experimental tests.