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The electrochemical impedance spectroscopy (EIS) measurement is a method used for offline battery impedance spectrum measurement, which usually requires a specialized and costly equipment. Recent work presented an online method to measure the AC impedance of batteries by utilizing the DC-DC power converter that usually follows the battery for regulation purposes. In this method, the duty cycle of...
Harmonic Quasi Resonant (HQR) control is widely adopted to suppress the harmonic currents for LCL-filtered inverters in stiff grid. However, inverters with HQR control may observe instability when the point of the common coupling (PCC) behaves uncertain impedance or the HQR control frequency is out of the bandwidth of the system control loop. Besides, it could not effectively eliminate the harmonics...
In this paper we present a distributed control method for minimizing the operation cost in DC microgrid based on multiagent system. Each agent is autonomous and controls the local converter in a hierarchical way through droop control, voltage scheduling and collective decision making. The collective decision for the whole system is made by proposed incremental cost consensus, and only nearest-neighbor...
In this article, a design methodology for DC-DC converters with high insulation capabilities (up to 30kV) is proposed. The objective is to provide a power transmission function for IGBT drivers. To achieve this, a DC-DC full-bridge series-series (FB-SS) resonant converter with a high air gap transformer is selected and studied. This high air gap transformer (loosely coupled transformer (k)) is used...
This paper proposes a dual voltage regulations of single switch flyback converter using variable frequency control. By adding an adjusted filter to secondary windings, each output shows different tendency according to the switching frequency. This means that even if the switching duty is same, the output voltage might be not equal at the different switching frequency. So the output voltage can be...
An algorithm based on new circulated current model is proposed to analyze the circulating current in the multiphase LLC converter. First of all, a virtual-open concept is introduced and LLC phases are decoupled from each other, Thus, A circulating current model can be achieved from fundamental harmonic approximation (FHA). Secondly, the ac voltages on the equivalent resistor of different phases are...
This paper introduces a new design methodology for high-frequency resonant dc-dc converters utilizing the recently proposed impedance control network (ICN) converter architecture. This design methodology guarantees zero voltage switching (ZVS) and near zero current switching (ZCS) of all transistors across the entire operating range of the converter. As compared to previous ICN converter design techniques,...
Current trends in power distribution systems are focused on distributed architectures instead of centralized approach. Distributed architectures are more complex since a network of power electronic converters is required to distribute power with appropriate performance. One of the main issues deals with the control loop design of the converters when they are loaded by other converters downstream....
Grid-connected inverters (GCIs) are power electronics interfaces to connect distributed energy resources into the grid. In order to improve the performance of distributed energy resources as well as maintain the high power quality of the grid, it is important to understand the characteristic of GCIs with appropriate controllers depending on its applications. This paper presents a study on the effect...
The inductive performance of non-magnetic thin metallic layers is investigated with the objective of designing convenient loads for domestic induction heating applications. Thin layers of copper and aluminum with thicknesses ranging from one hundred of nanometers to tens of micrometers are fabricated using the phase vapor deposition (PVD) technique. Performance of layers of different thicknesses and...
Voltage feed-forward control (VFFC) is widely used due to its good low-frequency-harmonics suppression and easy implementation, however, it will worsen system stability under the weak grid condition. In this paper, the stability of single-phase grid-connected inverter with VFFC is studied based on impedance analysis method. With this method, the instability mechanism and the unstable area caused by...
In this paper, the stability of solid state transformer (SST)-paralleled inverters system is investigated by using the unified impedance-based stability criterion (UIBSC). Theoretical analysis reveals that the output impedance characteristics of SST are frequency-dependent and multiple resonances can happen in the SST-paralleled inverters system. A lead-lag controller and a negative impedance feedback...
To address the instability issue in renewable systems of a radial-line structure with multiple current-controlled interface inverters, this paper proposes a practical stability criterion to easily analyze the system stability and a controller parameter design method to guarantee stable system operation with good oscillation damping performance. The proposed impedance-based sufficient stability criterion...
High frequency is the major catalyst for size reduction in the advancement of power conversion technology. It is essential to understand the EMI characteristic of high frequency converter since the EMI filter typically occupies one third of total system volume. This paper presents an insight view of CM/DM noise transformation in Flyback converter for low power adapter applications. The so-called mixed-mode...
To efficiently power multi-core processors in today's computing devices, integrated voltage regulator (IVR) shows significant energy saving ability by dynamic voltage and frequency scaling. One key aspect in developing IVR is to design power inductors with small size and small loss at very high frequency. However, the challenge in very high frequency magnetic characterization is a major obstacle to...
The DC power delivery system is becoming an appealing research topic and real world solution due to its higher energy efficiency compare with AC delivery system. It has already been applied in data centers, commercial buildings, electrical vehicle charge stations and micro grid systems, etc. Among many new issues that need to be addressed for the DC power delivery system, ultra-fast and accurate protection...
To investigate the instability issues of three-phase voltage source converters (VSCs) connected to a weak grid, this paper develops a modeling method based on the harmonic-balance approach. The nonlinear coordinate transformation in the control system would generate two sideband components. If the grid is not strong while the bandwidth of phase-locked loop (PLL) is high enough, the sideband components...
This paper shows a gate driver design for 1.7 kV SiC MOSFET module as well a Rogowski-coil based current sensor for effective shortcircuit protection. The design begins with the power architecture selection for better common-mode noise immunity as the driver is subjected to high dv/dt due to the very high switching speed of the SiC MOSFET modules. The selection of the most appropriate gate driver...
This paper presents an active islanding detection method which has zero non-detection zone. This method is the advanced version of the conventional slip mode frequency shift islanding detection method (SMS IDM). In this method the parameters of SMS IDM change based on the local load impedance value. The parameters value are calibrated periodically by measuring the impedance of the local load. The...
This paper proposes an improved impedance (Z) source inverter topology. Compared to the traditional impedance-source inverter, it can reduce Z-source inverter device voltage stress significantly to perform the same voltage boost, and provides the controllable and stable output power in all load condition. The control strategy of the proposed Z-source inverter is exactly the same as the traditional...
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