HPG Pulsed Welding Generator Subsystems

Physical Sciences : Civil Engineering

Available for licensing


  • Raymond Zowarka, Jr. , Center for Electromechanics
  • J.H. Koo , KAI, LLC
  • Jonathan Hahne, B.S. , Center for Electromechanics
  • David Prater , Center for Electromechanics
  • Charles Penney, B.S. , Center for Electromechanics
  • Bryan Bunkowski , Center for Electromechanics
  • Siddharth Pratap, Ph.D. , University of Texas at Austin
  • Ben Rech , KAI, LLC

Background/unmet need

Modern industrial processes abandoned homopolar generator (HPG) technology designs for welding applications in the past due to their high cost of production and inefficiency. However, design improvements since then have made HPG technology not only comparable to current industrial methods, but also superior in cost efficiency and productivity. The development of commercially viable HPG pulse welding of bridge girders can dramatically impact the bridge production industry. Steel and transportation industries can benefit as well from implementing the HPG pulse welding process for efficient production of high-performance bridge steel.

Invention Description

Researchers at The University of Texas Center for Electromechanics and their business partner Koo and Associates, Inc. were awarded a Phase II SBIR grant from the U.S. Department of Transportation to further the development of a full-scale HPG pulse power welding system for the production of high-performance bridge steel. Although HPG technology has been applied to the production of railroad rails and assorted metallurgy samples, this development is the first application of HPG to bridge girders.

The inventors improved upon the efficiency issues in both the HPG technology itself as well as current methods for bridge girder welding, verifying HPG technology as the most profitable welding method to date. Improvements included addressing magnetic field leakage problems and removing the need for high-power and high-pressure hydraulic auxiliary systems previously needed to operate the bearings in pulse welders. The Submerged Arc Welding (SAW) method requires hundreds of brushes, pneumatic cylinders to actuate each brush, and cumbersome tubing schemes to route pressurized gas to the cylinders in the generator. The inventors have made improvements to the sliding electric contact design to eliminate the need for these excessive parts, effectively simplifying the design, lowering costs, and increasing production speed.


  • Easily serviceable
  • Cheaper and faster design than SAW method that mechanically requires hundreds of brushes
  • Elimination of costly high-pressure hydraulic auxiliaries and intricate sump pump systems needed for bearings
  • Elimination of low-profile pneumatic cylinders and cumbersome piping systems needed for electric contact brushes
  • Can retain features from previous designs (trailing arm, electromagnetic assist, etc.)


  • Simple, elegant, and cost-effective design
  • Ceramic rolling element bearings superior to currently used steel rolling element bearings
  • Radially stiff and circumferentially compliant mounting that allows for the use of ceramic bearings
  • Unique mechanical actuation scheme
  • Improved sliding electric contact brushes within the generator
  • Built from inexpensive commercially available parts
  • Experimentally tested at full pulsed duty rating

Market potential/applications

Bridge manufacturing industries are the main beneficiaries of current HPG pulse welding systems. However, HPG pulsed welding has previously been used to produce railroad rails and assorted metallurgy samples, demonstrating that HPG technology has a diverse range of applications. While current developments made in HPG technology are relevant to any transportation industry, future HPG technology can potentially apply to any manufacturing process involving the use of high performance steel, such as architectural, environmental, and urban industries.

Development Stage

Beta product/commercial prototype

IP Status

  • 1 U.S. patent application filed