A known problem (and possibly the biggest one) in automotive body shops are the sparks caused by welding spot guns. They happen when a high valued electrical current passes through a big resistance (e.g dirty metal sheets). Although control algorithms have been proposed for more than 30 years in order to improve the welding spots quality and minimize the sparks, the time interval between sensing and actuating is still insufficient for avoiding them, since welding spot guns inverters were implemented with insulated-gate bipolar transistors (IGBTs), so far. The recent improvement in GaN-based power electronics, which support switching frequencies up to 600 KHz can represent a breakthrough in this field by reducing or even eliminating the sparks in such applications. Even more, as current and voltage sensing and control are already implemented in the TAPAS board, the entire control will be defined by software and just a minor hardware must be added as a front end, enabling a fast prototyping and testing stage.
To build a sparkless spot welding gun prototype.
The TAPAS board output (one phase only) will be connected to a transformer, capable of raising the TAPAS output current to hundreds of Amps. The secondary will be connected to the electrodes, which press two (or even three) metal sheets. Some simple but low frequency implementations are available in the internet, and will help us through this process. The control, including instant resistance measurements, will be software defined.
A simplified schematics is attached.
How Many TAPAS Boards
1 TAPAS board would be enough for the first implementation. Nonetheless, the authors would ask for 3 boards, so that we can keep track of the evolution of our prototypes (improvements might occur) and thus, present all of them operating at the same time.
this idea gets threeTAPAS dev kits