SDAA195 January   2026 LMG3522R030

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Operating Principles in a Flying Capacitor Switching Cell
    1. 2.1 Switching Pattern of a 3-Level Flying Capacitor Switching Cell
  6. 3Design Considerations of a Flying Capacitor Switching Cell
    1. 3.1 Conduction and Switching Losses
      1. 3.1.1 AC Conduction Losses
      2. 3.1.2 AC Switching Losses
    2. 3.2 Passive Components Design
      1. 3.2.1 Boost Inductor Design
      2. 3.2.2 DC Link High Frequency Ripple
      3. 3.2.3 Flying Capacitor Design
    3. 3.3 Layout Considerations
    4. 3.4 Pre-Charging Network
  7. 4Experimental Results
    1. 4.1 Pre-charging of the Flying Capacitor of TIDA-010957
    2. 4.2 Steady State Operation
  8. 5Summary
  9. 6References

1 Introduction

Nowadays, power conversion systems having high-efficiency and power density in renewable energy are becoming a must. Adoption of GaN technology becomes a state-of-the-art design when targeting single-phase applications as 400V DC link rated [1, 2]. When targeting 800V systems, GaN in two-level topologies require breaking down voltage higher than 1000V, thus making it hard to find GaN transistors being able to withstand this high voltage. In traditional half bridges cell, each switching device needs to withstand the full DC bus voltage. To reduce the voltage stress presents in three-phase applications, alternative multilevel topologies need to be taken into consideration. By adding additional power components, the overall voltage stress on the device can be significantly reduced when adopting multilevel converters. As can be seen from 3, multiple topologies can be found in the literature but flying capacitor results is the most cost-effective design. The three-level flying capacitor topology is discussed in this document. A special focus is given on the implementation with Texas Instruments GaN FETs.