Jon Anzola

Partial power converters (PPCs) have proven to be efficient, high-density solutions that reduce electrical stress. However, due to their lack of maturity, PPCs still require an extensive analysis of their reliability. Despite their capability of varying the voltage level between its terminals, similarly to a power transformer, they cannot provide galvanic isolation between both sides. Then, in the event of a ground fault, the entire system becomes highly exposed. Therefore, this paper presents a ground fault detection method for PPC-based solutions. The approach relies on a grounding resistor that is sequentially linked between the positive, negative, and midpoint terminals of the DC systems, grounded by three different switches. The paper provides a detailed explanation of the methodology and the necessary components to perform the diagnosis. A simulation setup conducted in MATLAB-Simulink is presented, along with its results. Afterwards, an experimental 50-kW Input-Series-Output-Parallel PPC test bench is used under both healthy and faulty scenarios to validate the methodology. The results conclude that this method not only detects the ground faults, but it also discerns its location, reducing the maintenance work.

Predicting core losses is a difficult task for designing magnetic components. Under triangular current waveforms the classical approaches work with duty cycles close to 0.5 but are inaccurate for high and low duty cycles. In this work the composite waveform hypothesis is tested, using data from the MagNet database for N87 material at 25 ºC (3312 data points). Limitations of the composite waveform hypothesis are discussed and a technique to expand the loss space is presented. The new approach based in an extended loss space is validated against the classical improved Generalized Steinmetz Equation, reducing the root mean square and 95 percentile errors by 5.85 and 6.96 times, allowing to predict core losses accurately even at high and low duty cycles. A direct correlation between the expanded loss space and the Steinmetz parameters from the improved Generalized Steinmetz Equation is proven, allowing to represent the core losses as functions of these parameters and generating the composite improved Generalized Steinmetz Equation. The proposed methodology for core loss prediction is validated making use of all data available from the MagNet database (10 materials, 4 temperatures, 59423 data points), achieving better results than the commonly used improved Generalized Steinmetz Equation.

This article studies the new benefits that partial power processing brings to Silicon (Si) devices compared to wide-bandgap technologies. To prove this, the proposed case study consists of an on-board charger (OBC) application in which a Si-based partial power converter (PPC) is compared with a Silicon Carbide (SiC) based full power converter (FPC). The OBC application considers three different technologies of lithium-ion batteries and the main comparison metrics are: semiconductor switching, temperature rise of semiconductors, volume and device losses (efficiency). This last one is oriented to energy losses (Wh) and not to power losses (W) as classical design. An analytical model is used to compute switching and conduction losses. Depending on the operating point, switching events are segregated into zero voltage switching (ZVS), incomplete ZVS and hard switching. It is shown that the Si-based PPC may enter non-ZVS in certain operating conditions. However, its efficiency remains above 99 %, producing up to 5 times lower energy losses than the SiC-based FPC. Also, the case temperature of the semiconductors is halved and a reduction in the volume and electrical stress of the devices is achieved. This permits a global multi-objective optimization. The results are experimentally validated using a 3 kW prototype of SiC-based FPC and Si-based PPC.

This paper proposes an approach for analyzing the benefits that partial-power-processing-based converters can bring to fully electric maritime applications. With the aim of making the system modular and scalable to different powers/energies, series-connected partial power converters are proposed. Serializing these converters entails significant overvoltage issues, and this paper tackles them for one series-connected module failure case. A reliability analysis has been carried out considering that the components of the battery system follow an independent and identical distribution in terms of failure probability. Furthermore, a redundancy factor has been added to allow a certain failure rate in what is known as a fault-tolerant system. Finally, to demonstrate the high efficiency of partial power converters, a 3 kW prototype is tested at different working points that model the charging process of a battery. The experimental results show a peak efficiency of 99.36%.

This paper discusses the possibility of achieving partial power processing with non-isolated DC–DC topologies. To this end, partial power converter architectures are seen as an interesting solution for reducing the power processed by the converter. We observed via simulations that single-inductor non-isolated topologies cannot achieve partial power processing since the obtained current and voltage waveforms were the same as those found in a full-power converter. However, when using double inductor non-isolated topologies, reduced current and improved efficiencies were achieved. In order to confirm the results obtained from the simulations, single- and double-inductor topologies were tested experimentally. Finally, it was concluded that a double-inductor non-isolated topology can improve its performance by using partial power processing.

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This paper focuses on the design of a charging unit for an electric vehicle fast charging station. With this purpose, in first place, different solutions that exist for fast charging stations are described through a brief introduction. Then, partial power processing architectures are introduced and proposed as attractive strategies to improve the performance of this type of applications. Furthermore, through a series of simulations, it is observed that partial power processing based converters obtain reduced processed power ratio and efficiency results compared to conventional full power converters. So, with the aim of verifying the conclusions obtained through the simulations, two downscaled prototypes are assembled and tested. Finally, it is concluded that, in case galvanic isolation is not required for the charging unit converter, partial power converters are smaller and more efficient alternatives than conventional full power converters.

This paper presents a review of advanced architectures based on the partial power processing concept, whose main objective is to achieve a reduction of the power processed by the converter. If the power processed by the converter is decreased, the power losses generated by the power converter are reduced, obtaining lower sized converters and higher system efficiencies. Through the review 3 different partial power processing strategies are distinguished: Differential Power Converters, Partial Power Converters and Mixed strategies. Each strategy is subdivided into smaller groups that entail different architectures with their own advantages and disadvantages. Also, due to the lack of agreement that exists in the sources around the naming of the different architectures, this paper seeks to stablish a nomenclature that avoids confusion when indexing this type of architectures. Regarding Partial Power Converters an extensive application oriented description is also developed. Finally, the main conclusions obtained through the review are presented.