483 results found
Yuan H, Lam HS, Beniwal N, et al., 2023, Modulation Methods for Balancing the Capacitor Voltages of N-Level Diode-Clamped Converters, IEEE Transactions on Industrial Electronics, Vol: 70, Pages: 11887-11897, ISSN: 0278-0046
Diode-clamped converters (DCCs) suffer from the inherent capacitor voltage imbalance problem. Most software-based voltage-balancing methods fall into the space vector modulation category and the carrier-based pulsewidth modulation category. Despite their effectiveness for the three-level DCCs, it is not easy to extend them to a general n-level topology. In this article, a new modulation method of a category called good-switching (GS) PWM is proposed for balancing the capacitor voltages. The proposed method requires no parameter-tuning effort and is extremely simple to design even for the n-level topology regardless of the number of phases. It is also potentially applicable to other multilevel converters. The principle, the implementation, and the stability analysis of GS-PWM are elaborated for a generic n-level DCC. A modified GS-PWM scheme and an on-off control scheme are proposed to reduce the switching transitions for further realizing the advantages of the GS-PWM. Particularly, the on-off control can be extended to many other voltage-balancing methods. Simulation and experiments with a five-level DCC validate the proposed methods.
Yuan H, Lam HS, Beniwal N, et al., 2023, Direct-Switch Duty-Cycle Control of Grid-Connected n-Level Neutral-Point-Clamped Converter, IEEE Transactions on Industrial Electronics, Vol: 70, Pages: 8624-8633, ISSN: 0278-0046
Capacitor voltage imbalance is a well-recognized issue for neutral-point-clamped (NPC) converters. Hardware solutions increase the system cost and complexity, while existing software solutions generally involve sophisticated algorithms, making it difficult to extend them for more voltage levels and full power-factor range. In this article, a new control method, termed direct-switch duty-cycle control (DSDCC), is proposed and generalized for the grid-connected n-level NPC converter. This method has the advantage of balancing the capacitor voltages for the full range of power factors on the ac side. The main significance of the DSDCC is that it can achieve near-optimal performance with simple and fast control implementation for two reasons. First, the DSDCC is based on the model directly concerning switches' duty cycles, which can easily generate gating signals for the converter with only one carrier. Second, instead of searching for an optimal control solution, near-optimal switch duty cycles are derived such that the controller design can be greatly simplified. The extremely fast execution time of the proposed control algorithm is only about 3% of that of model predictive control for five-level NPC (5L-NPC) converters. Experimental results are included to validate the proposed method with a 5L-NPC converter.
Liang HWR, Yang Y, He L, et al., 2023, A Multi-Hysteresis Control for Minimizing Battery Charging Time Within Industrial JEITA Guidelines, IEEE Transactions on Industrial Electronics, Vol: 70, Pages: 8416-8425, ISSN: 0278-0046
In common industrial practices, the Japan Electronics and Information Technology Industries Association (JEITA) guideline is widely adopted for battery temperature regulations. However, the conventional JEITA-compliant temperature-regulated current control (TRCC) is generally designed without considering the charging speed. To address this issue, a multi-hysteresis TRCC (MTRCC) is proposed in this article. The proposed MTRCC is designed based on the conventional JEITA-compliant TRCC by dividing the hysteresis band for each temperature reference from one to multiple. As a result, the number of charging current levels is increased from three to multiple, such that the charging speed can be improved according to the analysis. The proposed control inherits the simple and effective temperature regulations of the conventional control, while enhancing the charging speed without additional hardware costs. This approach has potential to be an alternative of the state-of-the-art TRCC in JEITA guidelines for single-cell charging applications. Empirical results validate that the proposed MTRCC (with four hysteresis bands) can achieve faster charging than the conventional control at four different ambient temperatures and the charging speed improvement is more significant when the ambient temperature is higher.
Zhou J, Li Z, Lee CK, et al., 2023, A Weather-Independent and Renewable Power Supply With Wireless Power Transfer Feature for Powering Online Monitoring Systems in Smart Grid, IEEE Transactions on Industrial Electronics, Vol: 70, Pages: 6414-6424, ISSN: 0278-0046
The merge of the power and information infrastructures in the smart grid requires an increasing number of sensors and online monitoring systems on the high-voltage transmission towers. These systems are traditionally powered by small solar panels or wind turbines that are weather-dependent. This new contribution involves a full analysis of a complete weather-independent power supply to replace existing approaches. For the first time, the complete system comprising the energy harvesting, wireless power transfer (WPT) and output power stages are practically evaluated using printed circuit board (PCB) resonators embedded in a 35-kV composite insulator. We leverage the nearly constant current, transresistance, and voltage gains characteristics of the PCB domino-resonator structure under different self-oscillating frequencies and propose a coordinated control scheme of transmitter-side and receiver-side converters to regulate the constant current (CC) or constant voltage (CV) through the entire charging process. Any current surge caused by the burst operation of the active rectifier on the receiver side triggers a transition between different self-oscillating operations on the transmitter side, leading to operating region extension of the active rectifier. Thus, the proposed system can easily adjust the output to follow different battery charging profiles without wireless communication between the transmitter and receiver.
Hui SYR, Yang Y, Zhang C, 2023, Wireless Power Transfer: A Paradigm Shift for the Next Generation, IEEE Journal of Emerging and Selected Topics in Power Electronics, Vol: 11, Pages: 2412-2427, ISSN: 2168-6777
The first generation of wireless power transfer (WPT) standard Qi, launched in 2010, contains a wide range of transmitter and receiver designs with the aim of maximizing compatibility to attract many manufacturers to share the same standard. Such compatibility feature (i.e., interoperability) has not only attracted over 400 company members in the Wireless Power Consortium (WPC), but also facilitated a fast-growing wireless power market for a decade. The WPC is now expanding the scope of WPT applications to mid-power and high-power applications up to several kilowatts while the Society for Automobile Engineers (SAE) also set the SAE standard for wireless charging of electric vehicles (EVs) up to tens of kilowatts. Without compromising compatibility, the authors share in this article their views on the need for a paradigm shift from compatibility to optimal performance in terms of maximum energy efficiency for the entire charging process and minimum charging time. This paradigm change is imminent and important in view of the increasing power of WPT applications. Several enabling technologies essential to the paradigm shift will be addressed.
Wu J, Li S, Tan SC, et al., 2023, Frequency Folding for LLC Resonant Converters in EV Charging Applications, IEEE Transactions on Power Electronics, Vol: 38, Pages: 5041-5054, ISSN: 0885-8993
To realize a wide voltage variation of electric vehicles (EV) battery packs, the conventional LLC converter needs to operate over a wide frequency range, which generally complicates the magnetics design and decreases the efficiency when the operating frequency is far away from the resonant frequency. Responding to the challenge, a frequency folding technique is proposed and explained with an exemplary new LLC converter. The proposed converter utilizes both the inductive region and the capacitive region of the conventional LLC converter through a one-shot operation of the relay during the whole charging process. As the battery voltage increases, the converter switches from the capacitive region to the inductive region. Throughout the charging process, the operating frequency is effectively reduced, and zero-voltage switching is maintained, resulting in a relatively higher overall efficiency. A detailed description on the design procedure of the proposed converter is described. A scaled-down 400-W prototype with 200 V input and 120 V-210 V output range verified the advantages of the proposed concept and measured efficiency of 98% at the maximum output power.
Yan Z, Huang Y, Tan S-C, et al., 2023, A Self-Adaptive-Step-Size Incremental-Resistance-MPPT Technique for Reverse-Electrodialysis System, IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, Vol: 70, Pages: 3814-3824, ISSN: 0278-0046
Yuan H, Lam HS, Beniwal N, et al., 2023, Cooperative Voltage-Balancing Control for Medium-Voltage Electric-Spring System Based on Diode-Clamped Converter and Dual Active Bridges, IEEE Transactions on Power Electronics, ISSN: 0885-8993
Electric spring (ES) is an emerging smart grid technology for stabilizing the voltage and frequency in a power network. Being fast demand-side-management technology, ES has recently been extended to the medium-voltage (MV) level in an AC-DC power conversion system that connects the distribution line of 6.6/11/22 kV to a DC grid of 800 V. To interface with the MV power grid, a diode-clamped converter (DCC) and multiple dual active bridges (DABs) can be employed to construct the MV-ES system. The balance of the capacitor voltages is crucial for DCCs, and thereby also for the MV-ES system. Conventional voltage-balancing approaches for DCCs generally compromise the quality of the grid-side voltage and current, which is undesirable especially in high-voltage high-power occasions. In this paper, a voltage-balancing control solution is proposed for the MV-ES system via cooperation of the DCC and DABs. By taking advantage of the DABs in voltage balancing, the DCC can adopt simple modulation and ensure grid-friendly voltage and current injection into the grid. The proposed voltage-balancing solution is verified using simulations in a five-level system and with practical experiments for a three-level system.
Yuan H, Lam HS, Liang G, et al., 2023, Fault-Tolerant Control of Electric-Spring Enabled Solid-State Transformer Under Dual Active Bridge Failure, IEEE Journal of Emerging and Selected Topics in Power Electronics, ISSN: 2168-6777
The electric-spring (ES) technology is recently integrated into a solid-state transformer (SST) to support the power grid at the distribution voltage level and provide an 800-V dc grid for large-scale electric vehicle (EV) charging infrastructure. The ES-enabled SST (ES-SST) studied here consists of a diode-clamped converter (DCC) and several dual active bridges (DABs). The failure of one DAB could pose a big challenge on the balance of the dc-link capacitors and threatens the operation of the whole system. Existing voltage-balancing methods are not suitable for the faulty ES-SST due to the highly uneven distribution of the capacitor output power. In this paper, a fault-tolerant control method is proposed to keep the capacitor voltages balanced under the DAB failure and maintain the operation of the system. The proposed control features a modulation algorithm to maximize the balancing capability of the DCC, the insertion of a zero-sequence voltage offset in the ac voltages, and deliberate generation of reactive power. A numerical tool is also developed to predict the operability of the faulty system and design the controller. Simulation and experiments are conducted to verify the proposed control.
Yang Y, Zeng J, Hui SYR, 2023, A Fast Primary-Side Current and Voltage Control for Direct Wireless Battery Chargers, IEEE Journal of Emerging and Selected Topics in Power Electronics, ISSN: 2168-6777
In traditional wireless power transfer (WPT) systems, constant current (CC) and constant voltage (CV)-based battery charging control strategies are applied to DC-DC converters on the receiver sides. In this study, the receiver-side control paradigm is shifted to the transmitter side and lumped as a primary-side current and voltage control that can (i) rapidly determine the mutual inductances between the coupled coils regardless of misalignment (within tens of milliseconds), (ii) eliminate DC-DC converters on the receiver sides, (iii) implement constant frequency operations, and (iv) automatically select current or voltage control mode without battery management chips and radio frequency (RF) communication. The combination of these four features offers a simple solution to reduce the complexities and sizes of receiver circuits for next-generation wireless battery chargers (WBCs). Only additional calibration circuits with limited components are required on the load ends. Both simulation and experimental results have validated the effectiveness of the proposed primary-side control for WBCs operating in both CC and CV modes. Practical results also showcase the automatic smooth transition from the CC mode to the CV mode.
Li K, Tan S-C, Hui SYR, 2022, Interleaved Buck-Type Rectifier With Pseudo-DC-Link Capacitors for Automatic Current Balancing, IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, Vol: 69, Pages: 12676-12687, ISSN: 0278-0046
Lam HS, Yuan H, Tan S-C, et al., 2022, Bidirectional AC-DC Modular Multilevel Converter With Electric Spring Functions for Stabilizing Renewable AC Power Grid at the Distribution Voltage Level, IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS, Vol: 10, Pages: 7589-7600, ISSN: 2168-6777
Zeng J, Chen S, Yang Y, et al., 2022, A Primary-Side Method for Ultrafast Determination of Mutual Coupling Coefficient in Milliseconds for Wireless Power Transfer Systems, IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 37, Pages: 15706-15716, ISSN: 0885-8993
Wu J, Li S, Tan S-C, et al., 2022, Fixed-Frequency Phase-Shift Modulated Capacitor-Clamped LLC Resonant Converter for EV Charging, IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 37, Pages: 13730-13742, ISSN: 0885-8993
Jiang Y, Yang Y, Tan S-C, et al., 2022, Power Loss Minimization of Parallel-Connected Distributed Energy Resources in DC Microgrids Using a Distributed Gradient Algorithm-Based Hierarchical Control, IEEE TRANSACTIONS ON SMART GRID, Vol: 13, Pages: 4538-4550, ISSN: 1949-3053
Beniwal N, Farivar GG, Lam HS, et al., 2022, Dual-Layer Pulsewidth Modulation Technique for Average Neutral Point Current Control in Neutral-Point-Clamped Converters, IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 37, Pages: 11762-11773, ISSN: 0885-8993
Lam HS, Li P, Chen B, et al., 2022, Exponential modulation integral observer for online detection of the fundamental and harmonics in grid-connected power electronics equipment, IEEE Transactions on Control Systems Technology, Vol: 30, Pages: 1821-1833, ISSN: 1063-6536
Harmonic current estimation is required in active power filters for compensation purposes. The most efficient way of calculating the total harmonic current up to the infinite order is to subtract the fundamental component from the distorted current. Direct determination of the fundamental component of a distorted current of mains frequency was realized recently with a third-order modulation integral observer. This article shows that using an exponential modulation function (Exp-MF) for the integral observer will: 1) significantly enhance the robustness of the observer against noise and 2) automatically remove the low-frequency envelope arising from the D/A and A/C sampling processes compared to previous polynomial modulation function. These new and advantageous features are supported with detailed analysis and experimental verification. The robust observer can be implemented in grid-connected power electronics circuits that require the instantaneous information of the fundamental and/or harmonic currents. Practical comparative tests with the adaptive notch filter and recursive discrete Fourier transform (DFT) methods in an active power filter have confirmed the good performance under both the steady and dynamic states of the proposed Exp-MF integral observer.
Jiang Y, Yang Y, Tan S-C, et al., 2022, A High-Order Differentiator Based Distributed Secondary Control for DC Microgrids Against False Data Injection Attacks, IEEE TRANSACTIONS ON SMART GRID, Vol: 13, Pages: 4035-4045, ISSN: 1949-3053
Li H, Li S, Xiao W, et al., 2022, A Modulation Method for Capacitance Reduction in Active-Clamp Flyback-Based AC-DC Adapters, IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 37, Pages: 9455-9467, ISSN: 0885-8993
Liang H-WR, Yang Y, Hui SYR, 2022, Improvement of Lithium-Ion Battery Charging From the State-of-the-Art Industrial JEITA Guidelines to a Hybrid Temperature-Regulated Current Control, IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 37, Pages: 6412-6423, ISSN: 0885-8993
Lee ATL, Jin W, Tan S-C, et al., 2022, Single-Inductor Multiple-Output (SIMO) Buck Hybrid Converter for Simultaneous Wireless and Wired Power Transfer, IEEE JOURNAL OF EMERGING AND SELECTED TOPICS IN POWER ELECTRONICS, Vol: 10, Pages: 2163-2177, ISSN: 2168-6777
Yan S, Hui SYR, 2022, A Simple Multi-Vector Predictive Direct Power Control Using Geometric Modulation, IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 37, Pages: 2899-2908, ISSN: 0885-8993
Li K, Yuan H, Tan SC, et al., 2022, Overshoot Damping and Dynamics Improvement in Wireless Power Transfer Systems Via Receiver-Side Controller Design, IEEE Transactions on Power Electronics, Vol: 37, Pages: 2362-2371, ISSN: 0885-8993
Buck converters have been extensively used for output regulation in the receiver of series-series compensated wireless power transfer (WPT) systems. Nonetheless, there are two major challenges in the controller design of this class of WPT systems. First, due to the current-source nature and finite dc-link capacitance, a right-half-plane (RHP) zero exists in the WPT receiver, reducing its stability margin and causing limited system dynamics. Second, this RHP zero can cause an overshoot issue in the WPT system. Without proper treatment, this overshoot may largely increase the voltage/current stress of the system and even cause catastrophic failure. However, existing solutions to the above two issues suffer from long communication delays or significantly compromised output regulation, degrading system performance. In this article, the slow dynamics and the overshoot issue of the WPT system are elaborated in theory and a solution is proposed by adding a feedforward path of the dc-link voltage in the receiver's controller. No communication is involved in the proposed control method, and only trivial computation is added to the controller. The proposed method is examined on a WPT prototype. The experimental results show that the two issues of the WPT system can be simultaneously solved by the proposed method while the output regulation of the system is not compromised.
Fang Y, Qu J, Pong BMH, et al., 2022, Quasi-Static Modeling and Optimization of Two-Layer PCB Resonators in Wireless Power Transfer Systems for 110-kV Power Grid Online Monitoring Equipment, IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, Vol: 69, Pages: 1400-1410, ISSN: 0278-0046
Chen J, Gallo AJ, Yan S, et al., 2022, Cyber-attack detection and countermeasure for distributed electric springs for smart grid applications, IEEE Access, Vol: 10, Pages: 13182-13192, ISSN: 2169-3536
With increasing installations of grid-connected power electronic converters in the distribution network, there is a new trend of using distributed control in a cyber layer to coordinate the operations of these power converters for improving power system stability. However, cyber-attacks remain a threat to such distributed control. This paper addresses the cyber-attack detection and a countermeasure of distributed electric springs (ESs) that have emerged as a fast demand-response technology. A fully distributed model-based architecture for cyber-attack detection in the communication network is developed. Based on a dynamic model of ES with consensus control, a local state estimator is proposed and practically implemented to monitor the system. The estimator is fully distributed because only local and neighboring information is necessary. A countermeasure for the distributed ESs to ride through the cyber-attack and maintain regulatory services in a microgrid is demonstrated successfully. Experimental results are provided to verify the effectiveness of the proposed cyber-attack detection method and its ride-through capability.
Wang H, Zhang C, Yang Y, et al., 2022, A Comparative Study on Overall Efficiency of Two-Dimensional Wireless Power Transfer Systems Using Rotational and Directional Methods, IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, Vol: 69, Pages: 260-269, ISSN: 0278-0046
Wong CPG, Lee ATL, Li K, et al., 2022, Precise Luminous Flux and Color Control of Dimmable Red-Green-Blue Light-Emitting Diode Systems, IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 37, Pages: 588-606, ISSN: 0885-8993
Li K, Tan S-C, Hui SYR, 2021, Efficient Hybrid-Modulated Single-Stage Wireless Power Receiver With Continuous DC Current, IEEE TRANSACTIONS ON POWER ELECTRONICS, Vol: 36, Pages: 13504-13514, ISSN: 0885-8993
Lee CK, Liu H, Tan S-C, et al., 2021, Electric spring and smart load: technology, system-level impact and opportunities, IEEE journal of emerging and selected topics in power electronics, Vol: 9, Pages: 6524-6544, ISSN: 2168-6777
Increasing use of renewable energy sources to combat climate change comes with the challenge of power imbalance and instability issues in emerging power grids. To mitigate power fluctuation arising from the intermittent nature of renewables, electric spring has been proposed as a fast demand-side management technology. Since its original conceptualization in 2011, many versions and variants of electric springs have emerged and industrial evaluations have begun. This paper provides an update of existing electric spring topologies, their associated control methodologies, and studies from the device level to the power system level. Future trends of electric springs in large-scale infrastructures are also addressed.
Yuan H, Li S, Tan S-C, et al., 2021, Sensor Count Reduction for Single-Phase Converters With an Active Power Buffer Using Algebraic Observers, IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, Vol: 68, Pages: 10666-10676, ISSN: 0278-0046
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