Effect of nonlinear modal interaction on control performance: use of normal forms technique in control design. I. General theory and procedure

1998 ◽  
Vol 13 (2) ◽  
pp. 401-407 ◽  
Author(s):  
Gilsoo Jang ◽  
V. Vittal ◽  
W. Kliemann
Keyword(s):  
General Theory ◽  
Normal Forms ◽  
Control Design ◽  
Control Performance ◽  
Modal Interaction ◽  
Nonlinear Modal Interaction

scholarly journals Improved Self-Sensing Speed Control of IPMSM Drive Based on Cascaded Nonlinear Control

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2205
Author(s):  
Muhammad Usama ◽  
Jaehong Kim
Keyword(s):  
Fuzzy Logic Controller ◽  
Control Design ◽  
Speed Control ◽  
Current Control ◽  
The Self ◽  
Pole Placement ◽  
Motor Drive ◽  
Control Performance ◽  
Control Loop ◽  
Maximum Torque

This paper presents a nonlinear cascaded control design that has been developed to (1) improve the self-sensing speed control performance of an interior permanent magnet synchronous motor (IPMSM) drive by reducing its speed and torque ripples and its phase current harmonic distortion and (2) attain the maximum torque while utilizing the minimum drive current. The nonlinear cascaded control system consists of two nonlinear controls for the speed and current control loop. A fuzzy logic controller (FLC) is employed for the outer speed control loop to regulate the rotor shaft speed. Model predictive current control (MPCC) is utilized for the inner current control loop to regulate the drive phase currents. The nonlinear equation for the dq reference current is derived to implement the maximum torque per armature (MTPA) control to achieve the maximum torque while using the minimum current values. The model reference adaptive system (MRAS) was employed for the speed self-sensing mechanism. The self-sensing speed control performance of the IPMSM motor drive was compared with that of the traditional cascaded control schemes. The stability of the sensorless mechanism was studied using the pole placement method. The proposed nonlinear cascaded control was verified based on the simulation results. The robustness of the control design was ensured under various loads and in a wide speed range. The dynamic performance of the motor drive is improved while circumventing the need to tune the proportional-integral (PI) controller. The self-sensing speed control performance of the IPMSM drive was enhanced significantly by the designed cascaded control model.

Multi-Wave Flutter Vibrations in Mistuned Cascades with Tip-Shroud Friction

2020 ◽  
Author(s):  
Johann Gross ◽  
Malte Krack
Keyword(s):  
Single Mode ◽  
Wave Form ◽  
Modal Interaction ◽  
Modal Interactions ◽  
Multiple Wave ◽  
Aero Engine ◽  
Wave Forms ◽  
Nonlinear Modal Interaction ◽  
The Rich ◽  
Tip Shroud

Abstract Measurements taken during aero engine tests and in the field showed that flutter vibrations of shrouded blades can feature rich wave content (multi-wave flutter vibrations). In a previous work, we demonstrated that this behavior can be explained by the nonlinear interaction of aeroelastically unstable traveling wave modes. The resulting vibrations are quasi-periodic. In the present work, we show that the nonlinear modal interaction is not strictly needed, but actually mistuning alone can explain the multi-wave form of flutter vibrations. The resulting vibrations are periodic and dominated by only a single mode shape of the mistuned system. However, unrealistically high mistuning intensities are needed to obtain significant contributions of multiple wave forms under the considered strong inter-blade coupling. Thus, we conclude that mistuning cannot explain the rich wave content observed in the measurements. Moreover, mistuning tends to hamper the nonlinear modal interactions and, thus, the occurrence of quasi-periodic multi-wave flutter vibrations. This implies that intentional mistuning is not only useful to stabilize flutter, but might also play an important role in developing flutter-tolerant blade designs.

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