DC-Link Voltage Constraint Strategy for DC Power Supply Film-Capacitor Drive System Based on Improved Model Predictive Control

DC-link voltage oscillation is a common problem that needs special attention in dc power supply film-capacitor drive systems. For this problem, an improved model predictive control method is presented in this article, which achieves system stability control by adding voltage stability constraint of dc-link in the cost function. First, the discrete predictive equations of motor current and LC filter voltage for permanent magnet synchronous motor are derived in this article. The system stability is proved by analyzing the system damping with voltage constraint in the meantime. The weight factor of the cost function based on exponential function is designed to accelerate the suppression of dc-link voltage oscillation in the dynamic process. Second, a full-order observer is designed for observing the LC filter inductor current, which is designed to reduce hardware costs. Third, an improved control set method is proposed to improve the steady-state performance of each control item in the cost function. Finally, a hardware platform based on DSP is built to verify the validity of the stability constraint scheme proposed in this article.