Implementation of Bidirectional Resonant DC Transformer in Hybrid AC/DC Micro-Grid

Huang, Jingjing; Xiao, Jianfang; Chen, Wen; Wang, Peng; Zhang, Aimin

doi:10.1109/tsg.2017.2771822

Cited by 78 publications

(40 citation statements)

References 26 publications

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“…A control algorithm of the DCT is required to be as simple as possible to reduce the communication among the DCT, BIC and EMS and to simplify the systematic control. [8], [22]. Therefore, in the microgrid application, the 50% duty cycle based semi-regulated (DCSR) control is usually recommended for the DCT [8], [23].…”

Section: Lm1 Lm2mentioning

confidence: 99%

“…Hence, the co-existing AC and DC sources form the hybrid AC/DC microgrid to improve system compatibility [3], [4]. [3]- [8]. The line frequency AC transformer (ACT) is deployed in [3] to realize the galvanic isolation and to match the voltage-grade.…”

Section: Introductionmentioning

confidence: 99%

“…However, the bulky ACT hinders the efficiency and powerdensity of the hybrid AC/DC microgrid [5], [6]. Therefore, the high frequency DC transformer (DCT) has been proposed to replace the bulky ACT in the microgrid application to reduce weight and space occupation [7], [8]. In hybrid AC/DC microgrid application, DCT and bidirectional interlinking converter (BIC) must work together to improve the energy utilization by transferring the power between the AC bus and the DC bus [8].…”

Section: Introductionmentioning

confidence: 99%

“…Another one is to maintain the voltage conversion gain (VCG), i.e., keep its HV voltage (i.e., H V in Fig. 2) within the permitted range to ensure the well operation of BIC [8], [11]. A typical DCT topology is depicted in Fig.…”

Section: Introductionmentioning

confidence: 99%

“…A typical DCT topology is depicted in Fig. 3(a), which involves two H-bridge converters and one resonant high frequency transformer (HFT) to reduce the operating power loss and to improve the power-density [8], [12], [13]. Based on the resonant HFT topologies shown in Fig.…”

Section: Introductionmentioning

confidence: 99%

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Three-Step Switching Frequency Selection Criteria for the Generalized CLLC-Type DC Transformer in Hybrid AC–DC Microgrid

Huang

Zhang

2020

IEEE Trans. Ind. Electron.

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For hybrid AC/DC microgrids, the widely applied high frequency DC transformer (DCT) is usually scheduled to operate at resonant frequency with 50% duty-cycle based semi-regulated control (DCSR) to ensure the power transmission (PT), improve its power-density and simplify the system-level control. However, for a real DCT, it may exist more than one resonant frequency that exhibit totally different features, which may seriously degrade the PT ability if the inappropriate switching frequency is selected. Meanwhile, the actual values of the DCT inductances and capacitances are also changing with the power, temperature, etc., which may lead to the practical resonant frequency's variation. Thus, how to select the suitable switching frequency to guarantee the PT ability against the parameter variation becomes a challenge. In this paper, three-step switching frequency selection criteria (SFSC) are proposed. A generalized CLLC-type DCT (GCLLC-DCT) model is extracted to make the proposed approach available for the LLC-, CLL-, symmetric CLLC-and asymmetric CLLC-type topologies. For convenience, the definition of the active power transmission ratio (APTR) is introduced to help evaluate the PT ability. First, the number, value and impact variables of the resonant frequency are derived and analyzed in Step I as the preliminary. Afterwards, the optimum resonant frequency is confirmed for the GCLLC-DCT as the criterion based on the APTR in Step II. At last, the criterion in Step III is given to finally determine the switching frequency against the parameter variations. The proposed SFSC method is also validated by the experiments. IndexTerms-CLLC, DC transformer, power transmission (PT), resonant frequency, switching frequency.

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Section: Lm1 Lm2mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Three-Step Switching Frequency Selection Criteria for the Generalized CLLC-Type DC Transformer in Hybrid AC–DC Microgrid

Huang

Zhang

2020

IEEE Trans. Ind. Electron.

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Robust and low‐cost design of LLC‐type DC transformer in hybrid AC / DC nano‐grids to improve energy conversion ability

Sun

Tong

Huang

et al. 2021

Int Trans Electr Energ Syst

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In the hybrid AC/DC nano‐grid, the LLC‐type DC transformer (DCT) is widely utilized in the DC and AC bus connection system (BCS) with high frequency to improve the system power density. However, it always employs the simple open‐loop scheme for not increasing the control complexity of the nano‐grid system, which creates a big challenge on the inherent features of the DCT circuit for the energy efficiency and conversion ability. Therefore, a robust and low‐cost design approach of the LLC‐type DCT is put forward in this paper based on the specific requirements of hybrid AC/DC nano‐grid. First of all, the design challenges of the LLC‐type DCT are discussed by analyzing the functions of BCS in nano‐grid application. Then, the detailed parameter design approach is presented step‐by‐step to meet the energy efficiency and conversion requirements in the full power range. Finally, a 6 kW nano‐grid prototype is established to verify the effectiveness of the proposed design method. The results show that the designed DCT can enjoy good energy efficiency and conversion ability with simple control and hence accommodate the high‐frequency nano‐grid application.

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The Proposed Two-Stage Parameter Design Methodology of a Generalized Resonant DC Transformer in Hybrid AC/DC Microgrid with Optimum Active Power Transmission

Zhang

Lin

Zhao

et al. 2023

Holistic Design of Resonant DC Transformer on Constant Voltage Conversion, Cascaded Stability and High Efficiency

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Implementation of Bidirectional Resonant DC Transformer in Hybrid AC/DC Micro-Grid

Cited by 78 publications

References 26 publications

Three-Step Switching Frequency Selection Criteria for the Generalized CLLC-Type DC Transformer in Hybrid AC–DC Microgrid

Three-Step Switching Frequency Selection Criteria for the Generalized CLLC-Type DC Transformer in Hybrid AC–DC Microgrid

Robust and low‐cost design of LLC‐type DC transformer in hybrid AC / DC nano‐grids to improve energy conversion ability

The Proposed Two-Stage Parameter Design Methodology of a Generalized Resonant DC Transformer in Hybrid AC/DC Microgrid with Optimum Active Power Transmission

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