Jonathan Robinson

Bio: Jonathan Robinson is an academic researcher from Siemens. The author has contributed to research in topics: Inductor & Converters. The author has an hindex of 1, co-authored 3 publications receiving 1 citations.

Design and Verification of Compact Inductor for Interleaved AC/DC Converter

Abstract: Interleaving concepts with coupled inductors can be utilized for the reduction of passive component size, losses, and material cost. With coupled inductors, not all harmonics are attenuated and additional filter stages may be necessary. The paper presents an inductor designed to reduce both switching harmonics circulating within the coupled inductor as well as higher order harmonics injected into the grid. Analytical equations are derived for both conventional and the proposed inductors to show the benefits and the results are demonstrated with a lab prototype.

Modeling and Design of Common Mode and Differential Mode Filter for PWM Converters

Abstract: This paper presents a method to model a back-to-back converter and the additional passive filter system. The mathematical modeling method followed the step of converting the three-phase system to single phase systems by separating the differential mode (DM) and common mode (CM) noise circuit for the design of the filter components separately. The model accounts for parasitic components in the converters and presents an indirect method of estimating parasitic capacitance for CM filter design. Design rules for the different components are summarized. Results from a lab prototype are presented and show good correspondence to the model.

On Optimal Construction of Interleaved Converter for minimum Circulating Current

Abstract: This paper analyses the effects of increasing the number of parallel interleaved converters on the overall performance of the converter. The circulating current flowing within the parallel modules has direct relation with the number of parallel modules connected in order to construct the converter. In this paper an effort is made to identify an optimal situation in terms of number of parallel modules in case the designer has a choice to select. The paper shows that three parallel converters results into the lowest peak circulating current. The mathematical analysis to support this statement is presented in this paper, assuming the constant DC link voltage, switching frequency and module inductance for the parallel individual module and the total power of the whole converter is constant. It is shown in the paper that the maximum peak of the circulating current occurs during the zero crossing of the modulation reference. A method of reducing the circulating current by control of the modulation index is presented and shows a >50% reduction in THD. The results are confirmed by laboratory testing.

Coupled Inductors for High-Frequency Drives With Parallel-Connected Inverter Legs

Abstract: In this article, coupled inductors with cross-coupled windings are described and designed for voltage source converters with parallel-connected inverter legs in each phase. The nature of the cross-coupled windings produces a very low effective series output inductance, related to the intralimb leakage inductance rather than the higher interlimb leakage. The effective inductance between the parallel inverter output terminals can be made high to reduce circulating currents and is related to inductor magnetizing inductance. These two features make the use of parallel inverters attractive for generating multilevel high-frequency fundamental pulsewidth modulation output voltages with a very low fundamental voltage drop across the coupled inductors. Sample magnetic designs are presented for a three-phase system using three inverter legs connected in parallel in each phase. The effective output inductance of the cross-coupled winding arrangement is compared with that of the coupled windings on separate limbs without cross-coupling and is shown to be 97% smaller. The performance of the two inductor winding arrangements is demonstrated with simulation and experimental results of an 11 kW (300 Vdc, 208 Vac/30 A) laboratory prototype operating with fundamental frequencies in the kilohertz range up to 5 kHz.

Comparison Between Interconnected Filter Blocks for Three-Phase AC–DC Interleaved Converters

Abstract: Three-phase ac filters occupy more than 30%–40% of the total power electronics (PEs) system volume. With interleaved operation, the size of three-phase line harmonic filters can be reduced at the expense of high circulating current between channels. Additional filter for circulating current mitigation is required, which contributes to incremental volume. The challenge is to achieve a truly optimized and modular solution for interleaved converters, while effectively blocking circulation. Two concepts are considered, i.e., magnetic and electrical interconnection between filter blocks for parallel converters. These interconnecting methods are integrated with conventional filter structures, such as the LCL filter, to achieve filter building block (FBB) configurations. A design procedure is formulated for the two FBB configurations to compare the loss-volume map of each FBB. Brief experimental and analytical comparison is performed to distinguish between the two topologies. It is found that from modularity point of view, the electrically interconnected FBB can be a favorable option and candidate for high power applications.

Common- and Differential-Mode Conducted Emissions Measurements using Conventional Receivers versus FFT-Based Receivers

Abstract: Electromagnetic interference (EMI) instrumentation has significantly evolved over the last thirty years. In this paper, the classical architecture of a conventional receiver is described and compared with the newest architecture of a Fast-Fourier-transform (FFT) based receiver. Additionally, different ways to measure the modal emissions, that is, the common and differential modes, with both types of receivers are described. In a conventional receiver, modal emissions can be measured using an external noise separator. In a dual-port FFT-based receiver, this can be done in the digital domain. Both receivers have been used to measure a device under test emitting non-stationary interference.

Analytic calculation of touch and leakage currents of non-isolated EV chargers using a fast common mode calculation method and non-ideal passive component models

Abstract: Non-isolated charging systems suffer from tremendous touch currents due to the significant extension of the common mode coupling path by the electric vehicle. Since safety limits are very tough, the selection of converter topology, modulation scheme and filters with respect to touch current behavior is a very ambitious process. With the aim to ease integral system design, research is done for common mode analysis methods, eliminating the demand for long duration time domain simulations. A time saving method to analyze the touch current behavior in common mode domain is applied on a single stage charging system setup by a 3-level converter, filter system and a major coupling path. Furthermore, this paper improves that time-saving failure current prediction method by including the influence of non-ideal passive component models on the calculation result. All calculation results are compared to laboratory measurements. Border conditions from corresponding standards are used to define the required frequency range. Besides the touch current, which typically occurs during the failure condition of a broken protective earth conductor, the leakage current flowing in the protective earth conductor during normal operation is analyzed. Finally, this paper points out the influence of an internal common mode bypass via the filter system on the touch and leakage current.

Alternate Filter Structures for Circulating Current and Conducted Noise Mitigation

Abstract: This letter presents a family of filter topologies for circulating current and conducted emissions mitigation, applicable with parallel and interleaved converters. The proposed alternative topologies are aimed at reducing the overall filter volume using magnetic integration or topological variations. In general, they are classified into three distinct forms, namely in-directly coupled, localized, and direct phase to phase coupled topologies. The emphasis is on pure common mode harmonics but can be extended to differential mode components as well. A quantitative comparison among the variants is made on the basis of simulation/experimental findings and references aiding the designer to select the structure best suited for a particular application.