During the wireless charging of an automated guided vehicle (AGV), the output voltage is unstable due to changes in parameters such as coil mutual inductance and load resistance caused by external interferences and internal mismatches of the system. In this paper, an integral sliding mode control method based on an unknown input observer (UIO) containing predictive equations is designed to build an inductor–capacitor–capacitor-series (LCC-S) topology model for wireless power transfer (WPT). The observer designed by this method can perceive changes in the secondary resistance parameter and the mutual inductance of the primary and secondary coils. The design with the prediction equation speeds up the convergence of the observer to the true value. The observer’s compensation of the control system avoids the occurrence of integral oversaturation. The experimental results show that, based on the UIO-SMC system output, voltage can be accurately controlled to meet the requirement for a given voltage. The effect of suppressing disturbance is better than with SMC and PI control. When the system parameter changes, it has better voltage anti-interference performance and stronger ripple suppression.

Accurate phase information on three-phase grid voltage and currents which are supplied by PLL are needed in power system operation. Conventional three-phase synchronous reference frame-based phase locked loop is generally sufficient during balanced operation conditions. But unbalanced in input signal set causes a double-frequency ripple. The output signal is not ideal. There are lots of improved SRF-PLL methods, aiming at removing the double-frequency ripple such as DSC-PLL,MAF-PLL, but these methods may causes a certain time delay. DIF-PLL method is based on adding another signal, which has reverse polarity ripple. It may amplify the harmonic signal. In this paper, an INT-PLL method based on integral is proposed, which wont amplify the harmonics. The comparison of these methods and simulation results are given in this paper.

Due to the huge impact of temperature on mechanical and tribological properties of polymer composites, polyimide composites reinforced with glass fiber and aramid fiber were fabricated. The composites were treated by the alternate temperature from-50 °C to 150 °C with 200 cycles. The comparation of the test results were analyzed and discussed before and after alternate temperature treatment.