Resistance spot welding is an inexpensive and efficient way of joining metals. It has extensive applications in household appliances and in automotive industries. In traditional spot welding machines 50 Hz welding transformers are commonly used. The drawback associated with these transformers is that they are both heavy and bulky. The advantage of using high frequencies is the reduction in the size of the transformer. The thesis presents development of high frequency welding machines having a high operating frequency of 10 kHz and compares conventional AC 50Hz welding machines as well as resistance spot welding machines having an operating frequency of 1 and 10 kHz. The research results obtained power consumption of RSW system. It is an object of the present thesis is to design transformer 2D FEA model and simulate analysis influence of leakage inductance and magnetic coupling factors for the leakage fluxes on power consumption and output current of RSW system.

• Acknowledgments
  • 1 Problems of development of high frequency resistance spot welding systems (RSW system)
  • 1.1. Brief description of the electric resistance welding systems
  • 1.2. The electrical circuit and advantages of high frequency resistance spot welding systems.
  • 1.3. Characteristics of the RSW system transformer design and its modes of operation in high frequency resistance spot welding systems
  • 1.4. The purpose and objectives of the thesis
    • 2 The development of an equivalent circuit of the RSW system
  • 2.1 . The main assumptions adopted for the development of the equivalent circuit of RSW system
  • 2.2 . Equivalent circuit of three-winding transformer
  • 2.3 . Experimental study of equivalent circuit of three-winding transformer
    • 3 Numerical finding of equivalent circuit parameters of the three-winding transformer
  • 3.1. Equations and 2D FEA model of the RSW systems transformer
  • 3.2. Calculations of the transformer impedances and the magnetic coupling factor for the leakage fluxes of two-winding transformers
    • 4 Influence of the transformer design on power consumption of RSW systems
  • 4.1. Analysis of influence of leakage inductances and magnetic coupling factors for the leakage fluxes on power consumption and output current of RSW systems
  • 4.2. Comparison of power consumption by high frequency resistance spot welding system which have different designs of transformers
• Bibliography