Simulation study of a simple flux saturation controller for high-frequency transformer link full-bridge DC-DC converters

High-Frequency Transformer Link Full-bridge DC-DC converter systems such as those used in plasma cutting applications are prone to transformer flux saturation. It can cause unit shutdown due to over-current protection or even catastrophic failure under extreme situations [1]. This is especially unacceptable in large plasma cutting applications where unexpected production stoppages can lead to severe economic loss to the customer. A simple flux control method that overcomes the disadvantages of current flux saturation control methods has been presented in [2]. Here, the transformer flux is controlled without affecting the dynamics of the main control loop. The proposed method is verified by simulating a 16 kW DC-DC full-bridge converter circuit model in ORCAD-PSPICE software. Results of this exercise show a 50% improvement in dynamic response, a 25% reduction in transformer size and weight, and improvements in system reliability and efficiency when compared with the conventional approach. It is seen that the proposed method can be retro-fitted on an existing power supply whether voltage or current controlled, with minimal change to its circuitry. In addition, it can also be extended to converter topologies like the push-pull as well.