Wide Variable Frequency Phase-Locked Loop for More Electric Aircraft

More Electric Aircraft (MEA) utilize electrical systems to replace some of the traditional mechanical, hydraulic, and pneumatic systems, significantly enhancing the overall efficiency of the systems and have become the main development trend in the future aviation field. The aircraft’s electrical power has evolved from the traditional constant-frequency 400 Hz AC power supply to a higher variable-frequency 360 ~ 800 Hz AC power supply for aviation. Therefore, researching how to achieve wide-range frequency phase-locking of AC power sources, enabling the aircraft power supply to operate stably at different frequencies, thereby reducing aircraft weight and improving the efficiency of MEA, is a challenge faced in the future. The Improved Enhanced Phase-Locked Loop (EPLL) has the advantages of simple structure, robust performance, elimination of dual-frequency ripple, and strong anti-interference capability for high-frequency harmonics. This paper, based on the EPLL, incorporates a Frequency-Locked Loop (FLL) circuit, utilizing the high tracking accuracy of the FLL to estimate the frequency of the input signal, and adds the estimated value to the phase-locked loop circuit, reducing the time required for the phase-locked loop to reach a steady state and the overshoot, thereby meeting the wide-range frequency conversion requirements of MEA. Finally, an FLL-assisted EPLL model simulation was built in the MATLAB/Simulink software for comparative analysis, verifying the correctness and effectiveness of the proposed model.