Control of a Three-Phase to Single-Phase Back-to-Back Converter for Electrical Resistance Seam Welding Systems

Abstract

DC link back-to-back converters are widely used in industrial applications. This interest comes from their power factor unity capability on the utility grid and to maintain regulated output parameters, thanks to the decoupling between the grid and the load side. In this paper, a 150 KVA prototype of DC link back-to-back converter for electrical resistance seam welding applications is described. The focus of the paper is on the control strategy developed to absorb constant power from the three-phase utility grid. The key idea is to allow the voltage on the DC bus to vary in order to avoid the propagation at the input side of the pulsed power required by the load. An estimation procedure of the load parameters is presented too. The effectiveness of this control scheme has been proved by simulations and tests.

The Performance of the BTB-VSC for Active Power Balancing, Reactive Power Compensation and Current Harmonic Filtering in the Interconnected Systems

“…In fact, this type of configuration is the most used for WECS and MAECS [6,12,[18][19][20][21][22]. To achieve the objectives described above, control of the BTB-VSC is developed considering synchronous coordinates such as the rotating (dq0) [6,7,12,14,15,18,22,25,27,31] and stationary (αβ0) [17,23,29,31], as well as the time-domain or conventional (abc) [9,26,30], reference frame. Typically, depending on the used reference frame, the adopted control structure is chosen.…”

“…Most of the reported works use the BTB-VSC as an auxiliary topology, that combined with other proposed topology, is capable of active power transmission, reactive power compensation, voltage or frequency control and current harmonic compensation [26,[29][30][31]. Certainly, each one of the reviewed topologies has advantages and disadvantages that can be addressed from different points of view and it is not the objective of this work to compare them.…”