Surge detection of magnetic suspension fluid machinery based on rotor axial displacement signal and normalized second-order generalized integrator-frequency locked loop with prefilter

A surge detection method according to rotor axial displacement signal and normalized second-order generalized integrator-frequency locked loop with prefilter (SOGI-FLL-WPF) is proposed to solve the surge detection problem of magnetic suspension fluid machinery, which has important practical significance. To improve the anti-disturbance performance of surge detection, SOGI is introduced as a prefilter. As a prefilter, SOGI can eliminate the interference in the surge signal, and normalized SOGI-FLL can estimate the amplitude and frequency of the surge signal. Normalized SOGI-FLL and prefilter are combined to form normalized SOGI-FLL-WPF. First, the disturbance transfer model between rotor axial displacement signal and pressure signal is deduced. Then, the surge is detected by normalized SOGI-FLL-WPF. This method has the merit of fast response, small computation, and good disturbance resistance without additional detection units. Finally, the test is implemented on 105 kW and 150 kW magnetic suspension blowers. The results demonstrate that the proposed method can quickly detect surge signal after the surge occurs.