Feedback Control for Stable Output Power of Magnetrons Based on Signal Reconstruction

Magnetrons have been widely used, due to their high power, high efficiency, and low cost. However, the unstable output power of magnetrons limits their further applications. In this article, based on signal reconstruction, we propose a feedback control to make magnetrons output stable power. First, we find that the output power of magnetrons can be characterized by a modified Hammerstein model. As magnetrons work for dozens of seconds, the output power can be decomposed into three components, including the direct current signal, the low-frequency disturbance (LFD), and the noise. And, the instability of the output power is dominated by the LFD and the noise. Second, the feedback control is designed by adjusting the input voltage of the power supply. It indicates that the LFD can be reduced significantly, thus improving the output power stability. Finally, a practical feedback control system is built and measured. The results show that the relative error of output power instability (REOPI) is less than 4.0% and the relative error of mean output power (REMOP) is less than 1.0% when the output power is larger than 300 W. Furthermore, the experiment shows that the maximum output power can be elevated to 900 W with the feedback control, which is higher than that of 800 W without the feedback control.