Chattering-Free Terminal Sliding Mode Control of DOC Outlet Temperature with Active Disturbance Compensation

Precise control of the diesel oxidation catalyst (DOC) outlet temperature is critical for reliable diesel particulate filter (DPF) regenerations. This paper proposes a novel and composite control strategy for the DOC outlet temperature control based on a representative identified transfer function model, which requires only a nominal value of the input gain parameter. By integrating a PID-type sliding variable with a non-singular terminal sliding mode (TSM) manifold through the second-order sliding mode technique, the strategy provides a continuous and chattering-free control signal. A linear extended state observer (LESO) is designed for real-time estimation and compensation of the lumped total disturbances. Feedforward compensation (FFC) is also integrated to proactively counteract the effects of exhaust flow and inlet temperature variations, thereby reducing the burden on the LESO. The disturbance rejection control scheme is designed by combining the LESO, the chattering-free terminal sliding mode (CTSM), and the FFC. Its stability is proved by using the Lyapunov method. Comprehensive co-simulations conducted in a high-fidelity GT-Power/MATLAB environment demonstrated that the proposed control scheme achieves superior performance with respect to set-point tracking and disturbance rejection. This work provides an effective solution for robust temperature control in DPF regeneration processes. It can also be applied to other types of robust process control systems attributed to its ease of implementation.