4. The dynamics of servo drives

Annotation: The article gives the analysis results for the servo drives dynamics, obtained from the theoretical calculations and during the development testing of the high power electric drives. Theoretical research was conducted, using the complete mathematical model of the servo drive, which included the equations of the control signal shaping path, electric motor, reducer and load. The equations of the control signal shaping network include only the characteristics of the compensating element in the assumption that all other delays in the transformation path are minimized. The electric motor equations are assumed in the classical form, taking into account the influence of the following main parameters on the motor dynamics: inductance and stator winding resistance, torque and armature reaction coefficients and rotor moment of inertia. Interaction of the motor with the multimass system of the reducer and load is presented in the form of force interaction of two masses – a reduced mass of the rotor and mass of the load through the certain equivalent rigidity of the kinematic chain. To describe the effect of gap in the kinematic connection the special computational trick, which considerably simplifies its mathematical description, is used. Efficiency of the reducer is presented in the form of the internal friction, proportional to the transmitted force. Calculation results with the application of the given mathematical model match well with the results of the full-scale testing of different specimens of servo drives, which makes it possible to use it for the development of new servomechanisms, as well as for the correct flight simulation when testing the aircraft control systems. In particular, based on the frequency response calculations of the closed circuit with the application of the given mathematical model, it is possible to define optimal parameters of the correcting circuit. Reaction on the step action with the various values of circular amplification coefficient in the circuit gives complete information on the stability regions of the closed circuit and influence of various drive parameters on these regions. Based on the conducted theoretical and experimental studies, the basic conclusions and recommendations were obtained and presented, accounting and implementation of which will provide high dynamic characteristics of the newly designed servo drives.