Finite‐Time Convergence Sliding Mode Control Strategy for an LLCL Filter–Based Battery Energy Storage Power Conversion System

ABSTRACT A modified finite‐time convergence sliding mode control method is presented in this paper for the power conversion system integrated with LLCL filter applied in battery energy storage system. The presented control strategy mainly possesses several merits including restricted convergence time to the equilibrium and strong robustness to uncertainties of filter parameters. The state error model for LLCL filter is established first as a preliminary step to sliding mode control design. Then, sliding surface and approaching rule are determined to obtain the dedicated control law for output voltage generated by the voltage source converter. Stability prove is theoretically conducted by using Lyapunov criterion followed by the upper limit calculation of corresponding convergence time, which reveals that finite‐time tracking control can be realized. In addition, parameter varying for the control functions is numerically analyzed in order to provide a reference for further control design. At last, experimental and performance verification is carried out based on a prototype with a rated apparent power 2100 VA. The steady state and transient waveforms can confirm the feasibility and correctness of the sliding mode control strategy and theoretical analysis presented in this paper.