Novel AC-AC converter


The 60Hz transformer has been around for more than 100 years. It does one job, convert one AC voltage to another. Using power electronic AC/AC converter to replace this has the potential advantage of lower size and more functionalities. However, today there is a short coming in the AC/AC converter topology/circuit. This invention intends to address this issue.

Technology description

Researchers at The University of Texas at Austin have developed a circuit design that can be used to converter AC voltage to another AC voltage with high efficiency >98%, using small number of semiconductor switches and is very robust from control point of view. Therefore, it can be used to make a compact transformer to replace the 100-year-old transformer design.

  • Soft switching to achieve low losses
  • Simple control for high reliability
  • Small number of semiconductors for lower cost and high efficiency
  • Many control functions can be implemented in addition to AC/AC conversion:
    • Voltage regulation
    • Reactive power support
    • Short circuit protection
    • DC output capability


  • High efficiency: The efficiency can be up to 98%.
  • High density: reduce weight by a factor of 3 compared with 60Hz transformer
  • Lower cost
  • Support very high voltage AC/AC (4160V to 13.8 kV)
  • The invention can also be applied to DC/DC solutions

Figure 1: One embodiment of the the design. Two split phase outputs operate just like today's LFT, powering tow loads. Lr and Cr1 from one resonant loop, while Lr and Cr2 form another. Q3, Q4, Q5, and Q6 are controlled to provide the two sine output waveforms.