An Energy Router Based on Multi-Winding
High-Frequency Transformer
Xianzhuo Liu, Zedong Zheng, Kui Wang, Yongdong Li
Department of Electrical Engineering
Tsinghua University Beijing, China
liu-xz14@mails.tsinghua.edu.cn
Abstract—The paper proposed a multi-port active bridge Reference [8] proposes a solid state transformer (SST) used (MAB) converter applied to household energy router (ER), where in zonal DC microgrid. Distributed generation (DG) devices, a multi-winding high-frequency transformer is used for the DC and AC loads are all connected to the DC bus through isolation and energy redistribution. The ER can provide both DC converters. However all the devices or loads of this system are and AC ports with adjustable voltages, thus can be used for not electric isolated and the voltage range is limited by the DC various distributed renewable generations and energy storage bus’ voltage.
access. This work also provides simplified equivalent model and control strategy of the multi-active bridge (MAB) using in the multi-winding high-frequency transformer. At the end of this paper, results of the simulation and part of the experiment have done are given.
Reference [9] presents a multi-winding high-frequency transformer applied in a multi-level converter. The main advantages of this multi-winding high-frequency transformer are:
? The generations and loads matching to the system are electric isolated; ? The transformer can access various voltage level by changing each winding’s parameter; ? The transformer with single iron core would reduce the volume and weight of the system; ? Every two ports can match to each other via the transformer directly, thus the power flow will pass two converters at most, which can improve the efficiency of the system. Reference [10] shows a quad-active-bridge (QAB) converter based multi-port SST integrating distributed generation and storage. However, the expressions and control methods related would become highly more complex with the increase of port amounts.
Reference [11] puts forward a more feasible power balancing control method of MAB, and we proposed a power and voltage combined control method basing on it.
In this paper, a MAB converter based Energy Router is proposed, where a multi-winding high-frequency transformer is used for isolation and power control. The simplified equivalent model and expressions of the high-frequency isolation unit is given. A power and voltage combined control method is put forward. Simulation and experiment are implemented to verify the analysis and proposed control method.
Keywords—Household energy router; MAB; multi-winding high-frequency transformer;
I. INTRODUCTION
In the recent decades, to face the contradiction between the shortage of traditional fossil energy and the growth of load, the renewable and distributed generation technologies have been developed rapidly. However, with a large amount of renewable and distributed generation devices accessing in, the traditional grid is going to face the problems of stability and reliability. To solve these problems, the “Energy Internet” concept was proposed recently, and has drawn a wide attention of researchers over the world [1-4]. The Energy Internet aims at finding a way to dispatch the power more intelligent, also to utilize the renewable and distributed energy more efficient and flexible. As the core part of the Energy Internet, Energy Router’s structure design and control strategy also become one of the research hotspots [5,6].
The present Energy Router proposed are mostly with two ports, which is not suitable for accessing variable sources and loads with different voltage. Some multi-port Energy Routers by paralleling devices or converters on the DC bus are also proposed, which are not flexible for the power flow control, and the devices voltages range are limited.
Reference [7] gives an AC-AC Energy Router based on MMC (modular multi-level converter) topology, which can reduce the volume and cost of traditional transformer. But MMC is very complex and it’s still difficult to balance the voltages of flying capacities.
978-1-4673-9550-2/16/$31.00 ?2016 IEEE3317
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