ABSTRACT
To improve robustness to parameter uncertainties and external load torque of shaft sensorless electrical drives employing permanent magnet synchronous motors (PMSM) with forced dynamics a new more complex control system is presented. The original control structure consists of the inner loop, which is stator current control loop and the middle loop, which is shaft sensorless speed control loop based on the forced dynamics. This control structure is completed with the outer loop, based on the sliding mode control (SMC) principles. The forced dynamics control, as well as converting the non-linear PMSM into a linear element, offers higher robustness than conventional shaft sensorless speed control methods. Based on feedback linearisation a first order linear closed-loop response to speed demands with a user specified time constant is obtained. Simulation and experimental results presented show good correspondence with theoretical predictions.
Key Words: Synchronous motor control, observers, sliding-mode control, variable-structure control, cascade control, non-linear systems, feedback linearisation.
ABSTRACT
This paper describes an application of the block control and variable structure control techniques to form a stabilizing controller for an synchronous generator. This combined approach enables the inherent nonlinearities of the generator to be compensated and high level external disturbances to be rejected. Also, the control system utilizes a nonlinear observer for estimation of the mechanical torque and rotor fluxes.
Keywords. Synchronous generator, stability, variable structure control, observers.
ABSTRACT
In this paper, we propose an integrated design method of robust internal-loop compensator and synchronizing motion controller to cancel out skew motion of twin-servo system caused by different dynamic characteristics of two driving systems. And also, we focus on the modeling of the twin-servo system and propose its network representation. The proposed control method consists of separate feedback motion controller of each driving system and skew motion compensating controller between two systems. Robust tracking controller based on robust internal-loop compensator is proposed as a separate motion controller and its disturbance attenuation property is shown. Skew motion compensation scheme is also designed to maintain the synchronizing motion during high speed operation, and the stability of the whole closed loop system is proved based on passivity theory. Finally, experimental results are shown to verify control performance.
Key Words. Twin-servo system, network representation, synchronizing motion control, robust internal-loop compensator.
ABSTRACT
The problem of flux and speed control of induction motors modelled in field coordinates, is studied. First, a P-I controller is applied that satisfies the requirement of current command following. Additionally a P-D controller is applied. The P-D controller provides flux and speed command following with simultaneous rejection of the load torque. Finally, a discrete observer being suitable for on line implementation is proposed. The present results are illustrated via simulation for a M3541 Baldor industrial motor.
Key Words. AC-motors, PID Control, Nonlinear Systems, Speed/Position Control, Disturbance Rejection
ABSTRACT
For a permanent magnet DC motor the design goal of perfect position/speed control with simultaneous load torque rejection is studied, using a P-D feedback law. The problem is proved to be always solvable. The P-D feedback law solving the problem is determined. Stability properties and robustness are investigated. The above results are illustrated via simulation for a 75 watt DC motor.
Key Words. DC motor, linear systems, disturbance rejection, position control, speed control, robust control.