Showing papers by "Bangyin Liu published in 2015"
TL;DR: In this article, the authors proposed a power decoupling method based on a four-switch three-port dc/dc/ac converter in dc microgrid, which can decouple the lowfrequency ripple power which is necessary for the ac port and undesirable for the dc source with small capacitor.
Abstract: This paper presents a power decoupling method based on a four-switch three-port dc/dc/ac converter in dc microgrid. The proposed topology has three interfaces which can be connected with a dc source, a capacitor, and an ac port. With a corresponding power flow control method, this converter can decouple the low-frequency ripple power which is necessary for the ac port and undesirable for the dc source with small capacitor. The proposed topology is compact and cost-effective because, compared with the H-bridge inverter, no extra switches or devices are required. With the model of the proposed dc/dc/ac converter, a power control method with two inductors' current control is presented for power decoupling. In addition, the control parameters are designed as well. Experimental results on the laboratory prototype verified the feasibility of the proposed topology and the designed power control method.
71 citations
TL;DR: In this article, the operation modes and characteristics under continued conductive and discontinued conductive modes are analyzed based on state-plane analysis and the boundary of two conductive mode is figured out, and the iteration calculation model of the LLC converter is proposed to predict the resonant current during start-up progress, and time constant of the existing soft start method is optimized using iteration algorithm.
Abstract: There is a current spike in LLC resonant converter during start-up and frequency modulation method is adopted to limit the resonant current usually, which controls switching frequency decreasing from specific high frequency to steady-state frequency in exponential pattern with a time constant tau. However, it is hard to determine the crucial parameter of time constant of the exponential switching frequency sweep curve, due to the complexity in analyzing dynamic process of the converter. In this paper, the operation modes and characteristics under continued conductive mode and discontinued conductive mode are analyzed based on state-plane analysis and the boundary of two conductive modes is figured out. Then, the iteration calculation model of the LLC converter is proposed to predict the resonant current during start-up progress, and time constant of the existing soft start method is optimized using iteration algorithm. Using the proposed iterative design method, the current stress of LLC resonant converter is limited, as well as guaranteeing the response speed of output voltage.
46 citations
01 Jan 2015
TL;DR: A power decoupling method based on a four-switch three-port dc/dc/ac converter in dc microgrid that can decouple the low-frequency ripple power which is necessary for the ac port and undesirable for the dc source with small capacitor.
Abstract: This paper presents a power decoupling method based on a four-switch three-port dc/dc/ac converter in dc micro- grid. The proposed topology has three interfaces which can be connected with a dc source, a capacitor, and an ac port. With a corresponding power flow control method, this converter can decouple the low-frequency ripple power which is necessary for the ac port and undesirable for the dc source with small capacitor. The proposed topology is compact and cost-effective because, compared with the H-bridge inverter, no extra switches or devices are required. With the model of the proposed dc/dc/ac converter, a power control method with two inductors' current control is presented for power decoupling. In addition, the control param- eters are designed as well. Experimental results on the laboratory prototype verified the feasibility of the proposed topology and the designed power control method.
19 citations
Patent•
20 May 2015
TL;DR: In this article, a current-limiting method and a currentlimiting circuit of an LLC resonant converter are presented to adjust the switching frequency of the converter under the working condition of abruptly adding resistance-capacitance load, thus limiting the current shock of a resonant circuit and solving the false triggering problem of overcurrent protection.
Abstract: The invention discloses a current-limiting method and a current-limiting circuit of an LLC resonant converter. According to the current-limiting method, the controlled quantity of switching frequency output in a PI adjusting step is detected so as to judge whether a frequency modulation step is added for current-limiting operation. The provided current-limiting circuit comprises a comparing trigger circuit and a current injection circuit. The current-limiting circuit can correspondingly adjust the switching frequency of the LLC resonant converter under the working condition of abruptly adding resistance-capacitance load, thus limiting the current shock of a resonant circuit, protecting the power element of the resonant circuit and solving the false triggering problem of overcurrent protection. According to the current-limiting method and the current-limiting circuit for frequency modulation, the structure is simple, the cost is low, the response speed of frequency modulation is high under the condition of abruptly adding resistance-capacitance load, and the current of the resonant circuit can be limited in an expected current set value.
6 citations
29 Oct 2015
TL;DR: Experimental results show the performance of the proposed grid-connected inverter is as expected, with low leakage current and no need for split capacitors.
Abstract: A transformer-less grid-connected inverter is presented for photovoltaic generation system. The proposed inverter topology features low leakage current and no need for split capacitors. The topology, basic operating principles and pulse-width modulation scheme for the proposed inverter are described. Moreover the characteristic of leakage current of the proposed topology is analyzed. Experimental results show the performance of the proposed grid-connected inverter is as expected.
1 citations