A DAB Converter with Common-Point-Connected Winding Transformers Suitable for a Single-Phase 5-Level SST System

Yun, Hyeok-Jin; Kim, Ho‐Sung; Kim, Myoungho; Baek, Ju-Won; Kim, Hee-Je

doi:10.3390/en11040928

Cited by 4 publications

(4 citation statements)

References 38 publications

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“…As the MMC-PET consists of different power stages, each stage has its own control system. Different control targets should be achieved simultaneously, the power transferred between power stages should be balanced [12], [13]. MMC controller achieves different tasks internally such as keeping the cell voltage at a certain level and regulates the circulating currents flowing between the three phases.…”

Section: Mmc-pet Control Systemmentioning

confidence: 99%

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A Modified Phase Shift Control of the Dual Active Bridge-Based Modular Power Electronic Transformer to Minimize the LVdc Side Voltage Ripples Under Unbalanced Load Conditions

et al. 2022

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Power Electronic Transformers (PETs) are considered as an emerging solution for power conversion due to their benefits over the low frequency power transformers (LFPTs) such as lower size, multi-port structure and different control functionalities. However, unbalanced load conditions may limit the reduction of size due to using bulky capacitors to absorb the resulting 2 nd harmonic voltage oscillations. This paper aims to provide a solution to this problem in the Dual Active Bridge (DAB)-based Modular Multilevel Converter Power Electronic Transformers (MMC-PET). In this study, a modified phase shift control strategy for the DAB isolation stage is presented. In this strategy, the duty cycle is allowed to change sinusoidally around the operating point. This consequently transfers the power oscillations to the HV side where their effect is less significant. The system is simulated using Matlab-Simulink under different unbalanced load conditions. Besides, the theoretical analysis and the simulation results are experimentally validated using a laboratory prototype. According to the obtained results, the proposed controller succeeded to reduce the voltage ripples from 7.5% to 0.2% and this helps in replacing large Aluminum electrolytic capacitors with low size film capacitors and consequently reducing the system overall size and volume which is a great benefit.INDEX TERMS Dual active bridge, modular multilevel converter, Power electronic transformer,resonant controller.

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Section: Mmc-pet Control Systemmentioning

confidence: 99%

“…So, the Proportional Integral Resonant (PIR) controller has been introduced. PIR controller consists of both PI and R parts as indicated by its transfer function G P IR (s) in (12). Fig.…”

Section: B the Proposed Phase Shift Controlmentioning

confidence: 99%

A Modified Phase Shift Control of the Dual Active Bridge-Based Modular Power Electronic Transformer to Minimize the LVdc Side Voltage Ripples Under Unbalanced Load Conditions

et al. 2022

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“…When the voltage A bi-directional H-bridge converter was suggested with high frequency isolation for PV/ESS. Dual active bridge (DAB) converters have been widely used in various renewable devices with high efficiency, high performance, galvanic isolation, and an inherent soft switching function [8,9]. There are two H-bridges in a DAB converter and a single transformer operating in high frequency.…”

Section: Introductionmentioning

confidence: 99%

Soft Start-Up Control Strategy for Dual Active Bridge Converter with a Supercapacitor

Kim

Jeong³

et al. 2020

Energies

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Renewable energy needs are steadily on the rise. Bidirectional DC/DC converters are essential in charging and discharging various storage batteries, such as PV/ESS (photovoltaic/energy storage system). A dual active bridge (DAB) converter, in particular, transfers power in both directions by phase shift using a soiled state transformer (SST). To reduce switching inrush current in batteries under high voltages, a soft start-up is demonstrated during the initial switching operation. When a supercapacitor (SC) is used as a battery, the reverse power caused by the inrush current appears under high voltage at the DC-link side. This causes serious electrical damage to the PV/ESS’ boost converter and inverter. To suppress peak overshoot voltage and stabilize soft start-up transients, we propose a three-step soft start-up controller and algorithm for bidirectional DAB converter implementation at virtual ESS and UPS. The step-by-step control strategy by OLDC (open loop duty control), OLPSC (open loop phase shift control), and OLFC (open loop frequency control) provides a stable soft start-up operation. In the initial stage of the OLDC, the duty ratio is gradually increased by the PWM (Pulse width modulation) signal. In the middle stage, a phase difference is seen as per the voltage of the SC. The OLPSC is performed to reduce the phase difference. In the final stage, the OLFC is performed to smoothly control the small phase difference. The overshoot or inrush current is drastically suppressed toward the DC-link and SC module. Consequently, we demonstrate a proposed controller and algorithm with prototype 5 kW DAB converter.

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“…Meanwhile, since the allowable weight and volume of a traction transformer are restricted, the solid-state transformer (SST) (also known as the Power Electronic Transformer, Energy Router, Intelligent Universal Transformer, etc.) has been one of the main elements in the EI, FREEDM, and microgrids [5]. Compared with traditional transformers, the SST has several advantages, such as low weight, low volume, unity power factor, fault isolation, bidirectional power flow capability, high controllability, etc.…”

Section: Introductionmentioning

confidence: 99%

The Stability Analysis of a Multi-Port Single-Phase Solid-State Transformer in the Electromagnetic Timescale

et al. 2018

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This paper proposes an overall practical stability assessment for a multi-port single-phase solid-state transformer (MS3T) in the electromagnetic timescale. When multiple stable subsystems are combined into one MS3T, the newly formed MS3T has a certain possibility to be unstable. Thus, this paper discusses the stability assessment of the MS3T in detail. First and foremost, the structure of the MS3T and its three stage control strategies are proposed. Furthermore, the stability analysis of each of the MS3T’s subsystems is achieved through the closed loop transfer function of each subsystem, respectively, including an AC-DC front-end side converter, dual active bridge (DAB) with a high-frequency (HF) or medium-frequency (MF) transformer, and back-end side incorporating DC-AC and dc-dc converters. Furthermore, the practical impedance stability criterion in the electromagnetic timescale, which only requires two current sensors and one external high-bandwidth small-signal sinusoidal perturbation current source, is proposed by the Gershgorin theorem and Kirchhoff laws. Finally, the overall stability assessment, based on a modified impedance criterion for the MS3T is investigated. The overall practical stability assessment of the MS3T can be validated through extensive simulation and hardware results.

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A DAB Converter with Common-Point-Connected Winding Transformers Suitable for a Single-Phase 5-Level SST System

Cited by 4 publications

References 38 publications

A Modified Phase Shift Control of the Dual Active Bridge-Based Modular Power Electronic Transformer to Minimize the LVdc Side Voltage Ripples Under Unbalanced Load Conditions

A Modified Phase Shift Control of the Dual Active Bridge-Based Modular Power Electronic Transformer to Minimize the LVdc Side Voltage Ripples Under Unbalanced Load Conditions

Soft Start-Up Control Strategy for Dual Active Bridge Converter with a Supercapacitor

The Stability Analysis of a Multi-Port Single-Phase Solid-State Transformer in the Electromagnetic Timescale

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