Energy Efficiency Improvement of a Single-Phase AC Spot Welding Machine by Using an Advanced Thyristor Switched Detuning Capacitor Bank

The operation of an ac spot welding load invokes serious power quality problems, such as voltage fluctuation, poor power factor, and harmonic distortion, resulting in additional power dissipation of the transformer and reducing in the operational energy efficiency. This paper proposes a fast reactive power compensating solution to improve the overall power quality of a single-phase ac spot welding machine by using an advanced thyristor switched capacitor (TSC) for detuning harmonic filtering and power factor correction bank. This study evaluates the specific improvement results regarding power dissipation, harmonic loss factor, maximum permissible load current, and top-oil temperature rise of the transformer. Based upon the implementation and experimental results, it shows that the proposed solution can effectively improve the operational energy efficiency as well as the power quality of the system. From the calculated curves, the improvement results with different TSC capacities under different operation conditions can be estimated.