Search

Your search keyword '"Li, Wuhua"' showing total 196 results
Start Over Author "Li, Wuhua" Journal ieee transactions on power electronics
196 results on '"Li, Wuhua"'

10. Improved Short-Circuit Protection Method for SiC MOSFET Split-Output Power Module Achieving Ultra-Low Fault Dissipated Energy

Author

Gao, Hongyi, Hai, Dong, Jin, Yuting, Zheng, Fujun, Zhu, Ankang, Luo, Haoze, Li, Wuhua, and He, Xiangning

Abstract

Due to ultrafast switching speed and high-frequency switching of silicon carbide (SiC) metal-oxide-semiconductor field-effect transistor (mosfets), crosstalk effect, high turn-on losses and electromagnetic interference are becoming constraints to the efficient and safe applications of SiC mosfets. The split-output structure has attracted widespread attention due to its advantages of overcoming the above constraints by integrating decoupling inductors. Thereby, it fully exploits the potential benefits of SiC mosfets. In this article, the effects of the split inductors on short-circuit characteristics of split-output power module are analyzed. An analytical model of the split-output power module is established to compare the electrical characteristics of the split inductors under normal operation and short-circuit faults. A dedicated short-circuit protection method is proposed based on the detection of the voltage pulse duration across the split inductors. The protection method is validated by hard switching fault and fault under load experiments. The results show that the short-circuit power device can be shut down when the short-circuit current is much lower than the continuous drain current. Besides, the short-circuit energy of the power device has the same order of magnitude as the dissipated energy under normal switching, which avoids degradation and even destruction of SiC mosfets under short-circuit faults.

Published
2024
Full Text
View/download PDF

11. Accurate Multiport Network Model for Forced Oscillations Analysis and Suppression of Multichip IGBT Power Modules

Author

Zhu, Ankang, Gao, Hongyi, Ye, Shuoyu, Xia, Yuanye, Zhu, Xiaohui, Luo, Haoze, Li, Wuhua, and He, Xiangning

Abstract

In this article, a multiport network approach is proposed to analyze the forced oscillations issue for the multichips power module. First, experimental results indicate the presence of multiple resonance points caused by forced oscillations during the switching process of multichip power modules. Due to the complex distribution of parasitic parameters within the module, it is challenging to establish an accurate analytical model. Therefore, this article proposes a method based on multisoftware collaborative simulation to extract the corresponding impedance of different chip ports. In addition, the impact of bus parasitic inductance and chip capacitances on port impedance is obtained. Compared with the experimental result, the error of dominant frequency obtained by the proposed model is less than 3%. Furthermore, the sensitivity of the spatial near-field spectrum to bus voltage and load current is studied based on experimental results. Finally, the suppression methods for forced oscillations are proposed based on the aforementioned theoretical analysis from the perspectives of both chips and packaging. The effectiveness of proposed methods is verified through experimental results.

Published
2024
Full Text
View/download PDF

12. Optimal Circulant Modulation for Submodule Voltage Ripple Minimization With Inherent Balancing Capability in Modular Multilevel DC–DC Converters

Author

Fan, Shiyuan, Xiang, Xin, Gu, Yunjie, Yang, Huan, Li, Wuhua, Zhao, Rongxiang, He, Xiangning, and Green, Timothy C.

Abstract

The modularity of the modular multilevel dc-dc converters (MMDCs) makes them a competitive candidate in medium voltage applications but brings the submodule (SM) voltage balancing issue. This article proposes an optimal circulant modulation method for minimizing the SM voltage ripples with inherent balancing capability proven at the same time, which allows smaller SM capacitors and avoids the high-frequency communication for SM voltage balancing. First, the optimal switching pattern is strictly derived providing a general method to theoretically minimize the SM capacitor voltage ripple. Then the switching matrix of the optimal circulant modulation is formulated by introducing the generalized-circulant matrix. It verifies the circularity and full-rank feature of the optimal switching matrix, which promises the uniformity of SM actions and the inherent balancing of SM voltages. Finally, full-scale simulations and down-scaled experiments are both provided with the isolated LLC-based MMDC model and prototype. The results show that the proposed optimal circulant modulation can reduce the SM capacitor voltage ripple by 37% compared with the existed method, and it also promises the inherent SM voltage balancing and SM uniformity.

Published
2024
Full Text
View/download PDF

13. Analysis and Design for Medium Voltage Dual Active Bridge Converter Based on Series-Connected SiC MOSFETs

Author

Chen, Runtian, Li, Chushan, Fang, Heng, Lu, Rui, Li, Chengmin, Yao, Wenxi, Li, Wuhua, and He, Xiangning

Abstract

In this article, a series-connected SiC MOSFETs-based medium voltage (MV) dual active bridge (DAB) converter featuring a low voltage difference among devices and high efficiency is proposed. In the developed DAB converter, the zero voltage switching-on characteristic is used to redesign the voltage balancing snubber circuits of the series-connected SiC MOSFETs. The snubber resistance is greatly reduced, whereas the snubber capacitance is increased, which realizes good voltage sharing and low switching-off loss of SiC MOSFETs. Furthermore, the operating modes and the operating characteristics of MV DAB converter with large snubber capacitors are derived in detail. Based on the above analysis, snubber capacitance and auxiliary inductance are optimized, taking into account the losses and voltage imbalance in the series-connected SiC MOSFETs. Finally, a 4 kV/1 kV experimental prototype is built and tested, and an experiment with up to 100 kW transmission power has been carried out. The results show that a maximum efficiency of 98.7% has been reached and the maximum voltage difference among SiC MOSFETs does not exceed 4%.

Published
2023
Full Text
View/download PDF

21. High-Efficient Operation for Modular Multilevel Resonant DC–DC Converters in Medium Voltage Applications With Wide Input Range and Wide Load Condition

Author

Sheng, Jing, Xiang, Xin, Li, Boliang, Lu, Rui, Li, Chushan, Zhang, Xiaotian, Li, Wuhua, and He, Xiangning

Abstract

The modular multilevel resonant dc–dc converters (MMRDCs) are becoming one of the most attractive candidates in medium voltage applications, but they would usually face technical challenges in high-efficient operation with wide input range and wide load condition. First, this article provides an elaborate review of the voltage control dimensions in MMRDC, and their corresponding operation principles, regulation capabilities, and efficiency influences for MMRDC are also analyzed respectively. Then for the wide input range, a tailored voltage regulation method combining both phase shift angle control and inserted submodule number control is proposed, and the optimal regulation principles of these two control dimensions are further investigated to realize high-efficient operation for MMRDC with wide load condition. Finally, the effectiveness of the proposed strategy is demonstrated through a simulation model and a full-scale MMRDC prototype with 9–18 kV input and 60 kW power rating.

Published
2023
Full Text
View/download PDF

35. A family of isolated interleaved boost and buck converters with winding-cross-coupled inductors

Author

Li, Wuhua and He, Xiangning

Subjects
Electric current converters -- Design and construction, Clamping circuits -- Design and construction, Inductors -- Design and construction, Electric current converter, Business, Electronics, Electronics and electrical industries
Abstract

A boost-type converter is derived by inserting a third winding of the winding-cross-coupled inductors (WCCIs) between the secondary winding and the output diode of the interleaved flyback converter in this paper. A family of isolated interleaved boost or buck dc/dc converters with WCCIs is summarized by employing the four main types of interleaved structures, which is suitable for step-up or step-down isolated distribution power systems. Then, an interleaved flyback-boost converter with WCCIs and an active clamp circuit is analyzed as an example to explore the advantages of the derived converters. The active clamp scheme is adopted to recycle the leakage energy and to suppress the turn-off voltage spikes on MOSFETs. And only one set of active clamp circuit is necessary for the interleaved two phases. Zero voltage transition (ZVT) soft switching performances are achieved for all MOSFETs during the whole switching transition. Furthermore, the output diode turn-off current falling rate is controlled by the inherent leakage inductance of the WCCIs, and the output diode reverse-recovery problem is alleviated. A clear picture is made in this paper of the general law and structure of the isolated interleaved dc/dc converters with WCCIs. At last, a 650 W prototype with 48 V-to-180 V is built and tested to verify the theoretical analysis in this paper. Index Terms--Active clamp, interleaved converter, winding-cross-coupled inductor (WCCI).

Published
2008

36. A family of interleaved dc-dc converters deduced from a basic cell with winding-cross-coupled inductors (WCCIs) for high step-up or step-down conversions

Author

Li, Wuhua and He, Xiangning

Subjects
Electric current converters -- Design and construction, Inductors -- Design and construction, Clamping circuits -- Design and construction, Power electronics -- Research, Electric current converter, Business, Electronics, Electronics and electrical industries
Abstract

A basic cell with winding-cross-coupled inductors (WCCIs) and interleaved structure is proposed in this paper. A family of dc-dc converters is deduced from the proposed basic cell, which is suitable for high step-up or step-down conversions. The passive-lossless clamp scheme is derived from the active clamp scheme to recycle the leakage energy and to suppress the voltage spikes caused by the leakage inductance. The advantages of the derived interleaved boost converter with WCCIs and passive-lossless clamp circuits are analyzed as an example. The voltage gain is extended and the switch voltage stress is reduced to minimize the conduction losses. The rectifier reverse-recovery problem is alleviated by the leakage inductance. Furthermore, a series of dc-dc converters with WCCIs and passive-lossless clamp circuits are summarized for high efficiency, high power and high step-up or step-down applications. A clear picture is made in this paper on the general law and structure of the WCCIs for dc-dc conversion in high step-up or step-down applications. At last, the simulated and experimental results of a 1 kW 40 V-to-380 V prototype with WCCIs and passive-lossless clamp circuits verify the significant improvements in performance. Index Terms--Basic cell, passive-lossless clamp, winding-cross-coupled inductor (WCCI).

Published
2008

38. Design and analysis of isolated ZVT boost converters for high-efficiency and high-step-up applications

Author

Li, Wuhua, Liu, Jun, Wu, Jiande, and He, Xiangning

Subjects
Electric current converters -- Design and construction, Inductors -- Design and construction, Power electronics -- Research, Electric current converter, Business, Electronics, Electronics and electrical industries
Abstract

The fundamental limitations of the current topologies for isolated high step-up dc-dc conversion are summarized. The primary-parallel-secondary-series structure is employed in this paper to handle the large input current, sustain the high output voltage and extend the voltage gain. A novel active clamp boost converter with coupled-inductors is proposed for high step-up applications. The third windings of the coupled-inductors have the function of voltage gain extension and the switch voltage stress reduction. The active clamp circuit serves for the interleaved two phases, which reduces the circuit complexity. Both the main and the auxiliary switches of the proposed converter are zero voltage transition performances during the whole switching transition. Meanwhile, the leakage energy is recycled by the active clamp circuit. The rectifier voltage stress is reduced by the primary-parallel-secondary-series structure. The rectifier reverse-recovery problem is alleviated by the leakage inductance. Experimental results for a 40-V-to-760-V converter verify the significant improvements in efficiency. Index Terms--Active clamp, coupled-inductors, isolated boost converter.

Published
2007

39. An interleaved winding-coupled boost converter with passive lossless clamp circuits

Author

Li, Wuhua and He, Xiangning

Subjects
Electric current converters -- Equipment and supplies, Clamping circuits -- Design and construction, Inductors -- Equipment and supplies, Power electronics -- Research, Electric current converter, Business, Electronics, Electronics and electrical industries
Abstract

An interleaved winding-coupled boost converter is proposed in order to realize ZCS turn-on condition and to achieve high step-up gain. The voltage gain is extended easily and the voltage stress on the switches is reduced with different turns ratios of the coupled inductors. The output diode reverse-recovery problem is alleviated due to the inherent leakage inductor of the winding-coupled inductors. The simple but effective passive lossless clamp circuits are introduced to limit the voltage stress on the switches when they turn off so that the low-voltage, high-performance devices with low conduction resistor can be used in the proposed converter to reduce the relative losses. The leakage energy is ultimately recovered to the load. The high efficiency of 90.7% at full load and the maximum efficiency of 92.6% are achieved in a 1-kW 40-V-input-to-380-V-output prototype for front-end application. There is more than 10% efficiency improvement with the passive lossless clamp circuits compared to the case with RCD dissipated snubbers. The efficiency of 5% improvement at full load is achieved with the proposed converter with passive lossless circuits compared to the conventional interleaved boost converter. Index Terms--Interleaved boost, passive lossless clamp, winding-coupled inductors.

Published
2007

40. Inherent SM Voltage Balance for Multilevel Circulant Modulation in Modular Multilevel DC–DC Converters.

Author

Fan, Shiyuan, Xiang, Xin, Sheng, Jing, Gu, Yunjie, Yang, Huan, Li, Wuhua, He, Xiangning, and Green, Timothy C.

Subjects
DC-to-DC converters, VOLTAGE, CIRCULANT matrices, RADIAL distribution function, BRIDGE circuits, CAPACITORS
Abstract

The modularity of a modular multilevel dc converter (MMDC) makes it attractive for medium-voltage distribution systems. Inherent balance of submodule (SM) capacitor voltages is considered as an ideal property, which avoids a complex sorting process based on many measurements thereby reducing costs and enhancing reliability. This article extends the inherent balance concept previously shown for square-wave modulation to a multilevel version for MMDCs. A switching duty matrix dU is introduced: it is a circulant matrix of preset multilevel switching patterns with multiple stages and multiple durations. Inherent voltage balance is ensured with a full-rank dU. Circulant matrix theory shows that this is equivalent to a simplified common factor criterion. A nonfull rank dU causes clusters of SM voltage rather than a single common value, with the clusters indicated by the kernel of the matrix. A generalized coprime criterion is developed into several deductions that serve as practical guidance for design of multilevel circulant modulation. The theoretical development is verified through full-scale simulations and downscaled experiments. The effectiveness of the proposed circulant modulation in achieving SM voltage balance in an MMDC is demonstrated. [ABSTRACT FROM AUTHOR]

Published
2022
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results