DC Filter Design Research Articles

Filter Design and Optimization of Electromechanical Actuation Systems Using Search and Surrogate Algorithms for More-Electric Aircraft Applications

In this article, the dc filter design and optimization problem is studied for dc electrical power distribution systems onboard more-electric aircraft. Component sizing models are built to serve as the basis of the optimization whose objectives are mass and power loss of this filter. A categorization strategy of search and surrogate algorithms is proposed and used for the target multiobjective optimization problem (MOOP). A genetic algorithm is utilized as a search algorithm to identify potential best solutions based on a set of filter sizing functions (subject to constraints). In addition, two machine learning (ML) algorithms are considered as surrogate algorithms to address the same optimization problem. In the ML training process, a constraint violation model is applied since there are various constraints in optimization, and this kind of classification model is relatively difficult to train. A support vector machine is applied for the constraint violation model; after that, two artificial neural networks are trained as the final surrogate model for mapping design variables to filter performance. To address these issues, a novel category of search and surrogate algorithms is proposed. Both algorithms are explored to solve the filter MOOP, and their optimization results are compared at the end.

DC-side harmonic analysis and DC filter design in hybrid HVDC transmission systems

Hybrid high-voltage direct current (HVDC) transmission is a new transmission structure that uses line commutated converter (LCC) at the rectifier side and voltage source converter (VSC) at the inverter side. This study proposes a method to calculate DC side harmonic currents of hybrid HVDC transmission systems and design filters to mitigate DC-side low-frequency voltage pulsations. First, an equivalent harmonic analysis model of modular multilevel converter (MMC) is deduced according to the relationship among different harmonic components. The harmonic voltage expressions at DC side of 12-pulse LCC are deduced by combining the three-pulse harmonic voltage source model and FFT decomposition. On this basis, the expressions for harmonic currents are derived by multiplying the harmonic voltage transfer function and transfer admittance equation of DC network and are solved for the inverse Laplace transform. Two different types of DC filters are designed according to the requirements of DC filter on decaying specific order harmonic currents. The influence of partial element decay on the transfer characteristic of filter is analyzed, and appropriate partial component dissipation parameters are applied. The decay pole near the harmonic resonance frequency is configured to achieve reasonable DC-filtering results. Simulation results of a hybrid HVDC transmission system demonstrate the effectiveness of the proposed analysis model and filter design method.

Front-End Buck Rectifier With Reduced Filter Size and Single-Loop Control

This paper presents a transformerless solution for front-end rectification, which is particularly suitable for traction applications, requiring high voltages to be stepped down to appropriate dc voltage. The proposed topology is based on pulsewidth-modulation buck rectifier (current source inverter topology) and is capable of rectification and stepping down of single-phase ac supply, in a single stage. A new control scheme is proposed to achieve constant dc output voltage and sinusoidal source current, irrespective of large ripples in the dc inductor current. The proposed scheme is configured in single-loop voltage control mode. The relevant small-signal model is derived from the large-signal model using multiorder decomposition. An elaborate procedure of dc filter design is discussed, for circuit operation with minimum energy storage. All analytical results are validated by numerical simulation for sinusoidal and distorted source voltage. Experimental verification is achieved through a 1.2-kW grid-connected laboratory prototype.

Study on DC Filter’s Performance of Different Match Properties in Materials Engineering

When the cell pack is tested, it need low ripple charging current to ensure the tester accuracy. It is very necessary to set proper DC filter which has excellent filtering characteristic and wide input/output range. The inner resistance of a cell pack is very small but the system is indefinite. If the DC filter is designed by the type of traditional matched filter, the flat-fading would inevitably occur. This would reduce the power transmission efficiency. This paper discussed the design philosophy of the non-matched filter and proposed a non-matched Chebyshev DC filter design method aimed at the special resistive-capacitive property of the cell pack. The method is proved to be correct and feasible by simulation.

Measurement of harmonic currents and evaluation of the DC filter performance of the New England-Hydro-Quebec Phase I HVDC project

Measurements were conducted to determine the cause of increased telephone interference and to evaluate the DC filter performance. The measurements revealed unexpected high levels of three-pulse harmonic currents in the DC pole conductors. The cause is attributed to imbalances within the six-pulse bridges caused by the converter transformer and valve stray capacitances to ground. The conventional model of the converter power circuit used as the basis for the DC filter design does not reproduce the measured three-pulse harmonics.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

DC filter design methods for HVDC systems

This paper discusses the design of dc filters for use in conjunction with small dc smoothing reactors in HVDC systems. Analytical techniques for calculating the steady-state and transient interactions between the converters, smoothing reactor, dc filter, and dc line are also given.