An official website of the United States government
Development of the new generation of high power and high frequency power electronic switches along with the need for compact controllable converters for utilization of distributed energy resources in the grid, have led to significant developments in the area of solid state transformers in the last years. The design process of a high frequency transformer as the main element in the solid state transformer is illustrated in this article. A multi winding transformer for multiport SST application is designed, studied and built in this research. In a MPSST several windings feed the core. As the result, coupling coefficient between each pair of windings, become an important factor which is studied in this study. Since the transformer is designed for high frequency applications, the power loss in the wire and core of the transformer increases as the result of higher skin effect and eddy current loss in high frequency. Three important factors in the design of HF transformer for MPSST are discussed in the paper. First, four different possible core materials are compared based on their flux density, frequency range, loss and price. Then the cable selection is illustrated and finally, different winding placement and distribution on the same core are suggested and the inductance and coupling coefficient matrices are calculated using ANSYS Maxwell 3D simulation. The transformer is built in the lab and the inductance values matches the expected values from the simulation.
more »
« less
Exploring the Leakage Inductance of Transformers Used in Dual Active Bridge
Battery Energy Storage Systems (BESS) are critical to achieving reliability and efficiency in the modern electric grid. Dual Active Bridges (DAB) are often proposed for such integration since they can allow multiple sources and electrical isolation via a high-frequency transformer. In defined applications, DABs rely on the magnetizing and leakage inductance of their high-frequency transformers to achieve their performance requirement. In this paper, the inductance parameters of two types of two-winding transformers are investigated using the Finite Element Analysis (FEA) software ANSYS Maxwell. The variation of the inductance values due to the windings' distribution and core geometry was studied by establishing a parametric analysis. Prototypes were built and tested to compare the inductances actual measurements versus the simulation results. Exploring the possibility of characterizing the inductances of a transformer from a simulation standpoint is of interest in order to construct customized transformers with the optimal characteristic required in a specific DAB design.
more »
« less
- Award ID(s):
- 1757207
- PAR ID:
- 10139120
- Date Published:
- Journal Name:
- 2019 North American Power Symposium (NAPS)
- Page Range / eLocation ID:
- 1 to 6
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
null (Ed.)High frequency modular power converters are increasingly becoming popular due to their small size and weight. Targeting the input-series and output-parallel (ISOP) dual active bridge (DAB) DC-DC converters, this paper proposes a control scheme based on optimal triple phase-shift (TPS) control for both power sharing control and RMS current minimization. This achieves balanced power transmission, even under mismatched leakage inductance of a DAB module of the ISOP. In order to obtain the optimal zones of operation for the converter, the RMS current was minimized using the Lagrange multiplier method to obtain the optimal duty cycles. The power balancing was added to compensate unbalanced power sharing for variations in model parameters or module shutdown. Analyses and simulation results through MATLAB/Simulink are presented to validate the proposed controller.more » « less
-
null (Ed.)In this study, design of a 330kW single-phase transformer (corresponding to 1MW three-phase) operating at 50kHz is presented. Possible core materials and their performances are investigated under high switching frequency operation. Core volume, area, configuration, and market availability are studied to achieve the optimal compact and cost-effective transformer model. Next, transformer winding type, size, placement, and cost are analyzed. These steps will result in a complete transformer electromagnetic design and modelling. Afterwards, a 3D transformer model is created and simulated using a Finite Element Analysis (FEA) tool. ANSYS Maxwell-3D is used to simulate the magnetics, electrostatics, and transients of the designed transformer. This model is integrated with a power electronics circuit in ANSYS Simplorer to make a co-simulation for the entire system. Results obtained will include core maximum flux density, core/copper losses, leakage/magnetizing inductances, windings parasitic capacitances, and input/output voltage, current, and power values. Finally, the systems' overall efficiency is calculated and presented.more » « less
-
This article introduces an innovative four-port dual-path inductor designed to deliver two distinct inductance values to the resonator of a voltage-controlled oscillator (VCO). The switching between the inductor’s two excitation modes, even and odd, is determined by the differential excitation’s input polarity, eliminating the need for a series switch. Thus, the inductor has a high-quality factor ( Q ) in both modes. The inductances in these modes can be independently set based on desired frequencies. This inductance change achieves coarse frequency tuning, while fine-tuning is realized by a conventional 2-bit capacitor bank with a small-size varactor. This inductor is well suited for designing multiband VCOs aimed at widely spaced operation frequency bands. Apart from the inductance change, a particular case of mode-switching capacitor is employed to extend to another frequency band in between the low and middle bands, achieving triple-band oscillation. As a result, this article presents two VCOs designed using the proposed inductor: one in class-D biasing in a 65-nm CMOS process and another with class-B biasing in a 180-nm BiCMOS process. Both VCOs successfully oscillate across three distinct frequency bands, centered at 19, 28, and 36 GHz, while maintaining outstanding phase noise and minimal power consumption. Measurement results show good match with simulation, resulting in a peak figure of merit (FoM) of 185.7 dBc/Hz at 18.5 GHz, and occupy 0.088- mm2 (250 × 350 μ m) area in both processes.more » « less
-
Abstract Power electronics–based converters for photovoltaic (PV) systems are susceptible to overcurrents; it is important to design their controllers to reduce the transient current for all viable operating conditions. To design a current controller and find the maximum transient current via simulation‐based techniques, the exact values of the system parameters, initial states, and inputs are required. However, they are not precisely known in practice, some system parameters such as inductances may change over time, and output power and load are variable. The uncertainty in the parameter (filter inductance) and input of the system (injected power) should be considered in the analysis of a PV system controllers as it can degrade their performance, which are designed for the system nominal parameters. This paper employs reachability analysis for a grid‐connected PV system to (1) find the maximum transient current, (2) devise an improved PI current controller and (3) compare the maximum transient current in PI‐ and internal model control (IMC)‐based controllers with uncertain‐but‐bounded input power and inductance error. Simulation and experimental studies showcase the results.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/NAPS46351.2019.9000267
