Discrete Sliding Mode Control with Lumped Disturbance Estimation Used for Wireless Power Transfer Transient Performance Improvement

Wireless power transfer (WPT) systems are easily affected by input voltage variation, coupling variation, and load changes, resulting in output voltage fluctuation and long settling time. To improve the transient performance, this article proposes a discrete sliding mode control method with lumped disturbance estimation (LDE-DSMC) for an LCC–S compensated WPT system. Input voltage variation, mutual inductance variation, load step, and unmodeled dynamics are uniformly treated as a lumped disturbance in the output voltage channel. The estimated disturbance is introduced into the control law for feedforward compensation, and one-step prediction is used to reduce the influence of duty cycle update delay. A hardware prototype is built for verification. Compared with PI control and adaptive feedforward control, the proposed method achieves smaller output voltage deviation and shorter settling time under different disturbances. In the single disturbance tests, the maximum output voltage deviation is reduced by at least 50%, and the settling time is shortened by at least 33%. Under the compound disturbance, the maximum output voltage deviation is reduced by 62.50% and 36.36% compared with PI control and adaptive feedforward control, respectively, while the settling time is shortened by 64.49% and 39.68%.