To address the issues of slow magnetization current tracking speed, prolonged magnetization time, and low accuracy during magnetic particle testing of ship castings, forgings, and welded components, this study designed a high-precision rapid current tracking control system. By integrating the predictive characteristics of the Newton interpolation algorithm with the robustness of PID control, a compound control algorithm with a pre-judgment mechanism was developed. An innovative three-phase zero-crossing detection circuit architecture was also implemented, combining high-speed A/D converters and CS5460 chips to optimize current tracking methods, resolving the conflict between initial tracking phase deviation and dynamic process overshoot in conventional approaches. Experimental results demonstrated that this method significantly improves magnetization speed, achieving target current tracking within 0.5 seconds with errors below 2%, meeting the design requirements for non-destructive testing in ship welding applications.

In this study, the load fluctuation of the main engine is considered to be a disturbance for the jacket coolant temperature control system of the low-speed two-stroke main diesel engine on the ships. A nonlinear PID temperature control system with satisfactory disturbance rejection performance was designed by rapidly transmitting the load change value to the controller for following the reference set value. The feed-forwarded load fluctuation is considered the set points of the dual loop control system to be changed. Real-coded genetic algorithms were used as an optimization tool to tune the gains for the nonlinear PID controller. ITAE was used as an evaluation function for optimization. For the evaluation function, the engine jacket coolant outlet temperature was considered. As a result of simulating the proposed cascade nonlinear PID control system, it was confirmed that the disturbance caused by the load fluctuation was eliminated with satisfactory performance and that the changed set value was followed.