A High Frequency Loading Control Strategy Based on Proportional Resonant Control and Stability Analysis for Electric Load Simulators

By applying proportional resonant (PR) control to the load torque control of electric load simulators (ELS), the surplus torque caused by the active motion of the system under test can be suppressed effectively, achieving high precision loading. But under the high frequency loading condition, which means that the resonant frequency of PR controllers is high according to the loading frequency, the stability of the system with the PR controller is usually difficult to be ensured, and this limits the increasing of the loading frequency. In order to solve this problem, this paper designs and analyzes an ELS with the PR controller. The speed controller of ELS is designed firstly in this paper, to establish foundation for applying PR controllers. For PR controllers, the stability of the system is analyzed in discrete domain through Nyquist diagrams. Furthermore, a phase compensation term is added into the PR controller, and the parameters of PR controllers are designed reasonably based on the stability analysis, to provide ELS enough stability margin and smooth dynamic response under high frequency loading conditions, achieving high frequency and high precision loading. Experimental results on ELS are provided and validate the effectiveness of the proposed method.