Low-Cost, Multi-Input, Single Resonant Tank LLC Converters

Technology #34179

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Researchers
Seyed Milad Tayebi, Ph.D.
Issa Batarseh, Ph.D.
External Link (www.ece.ucf.edu)
Haibing Hu, Ph.D.
Managed By
Raju Nagaiah
Research Associate 407.882.0593
Patent Protection
US Patent US10630190B2
Publications
Design and analysis of a dual-input single-resonant tank LLC converter for PV applications
2018 IEEE Applied Power Electronics Conference and Exposition (APEC), San Antonio, TX, 2018, pp. 476-483, DOI: 10.1109/APEC.2018.8341054

Key points

  • Enables several PV panels and battery storage to interface with the same resonant tank
  • Uses fewer circuit components than existing designs, resulting in lower cost
  • Improves system reliability

Abstract

Researchers at the University of Central Florida have developed a new multi-input power DC-DC converter that uses a single LLC resonant tank to transfer energy and perform power conversion from multiple sources. With other technologies, the number of switches and circuit components increases with each added power source, thus raising total costs and reducing reliability. In comparison, the new UCF technology allows several photovoltaic (PV) panels and battery storage to share the same resonant tank without the need for more circuit components. Thus, it provides a more reliable and cost-effective means of improving power density for conventional inverters, microinverters, and motor controllers.

Technical Details

The UCF power converter comprises a single LLC resonant tank that includes an inductor, a capacitor, and the magnetizing inductance of a transformer. Bridge circuits can receive power from two or more PV panels and external batteries. The power converter employs a phase-shift pulse width modulation (PWM) control to implement independent maximum power point tracking (MPPT) for each PV panel. Zero-voltage-switching (ZVS) occurs in all switches over the entire range of source voltage and load conditions. Also, voltage stress across switches does not exceed the input PV voltage. To demonstrate the performance of the topology, the researchers built a 500-W prototype with an input voltage range between 25 V to 50 V and an output voltage regulated at 440 V DC. Experimental results show that the converter can achieve peak efficiency of 95.8 percent while maintaining a wide input voltage range and implementing MPPT for each PV panel.

Partnering Opportunity

The research team is looking for partners to develop the technology further for commercialization.

Stage of Development

Prototype available.

Benefit

  • Achieves high power density and conversion efficiency while reducing costs
  • Interfaces with multiple power sources without increasing the number of circuit components
  • Operates over a wide range of PV voltages

Market Application

  • PV microinverters
  • Mini-inverters

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