93 research outputs found
Velocity-sensorless tracking control and identification of switched-reluctance motors
International audienceWe present a solution to the speed sensorless control problem for switched-reluctance motors under parametric uncertainty. Our main results guarantee velocity tracking control for velocity references with constant reference acceleration under the assumption that the load torque, the rotor inertia, the resistance and inductances are unknown. Under a persistency of excitation condition on a function which depends only on reference trajectories, we guarantee uniform global asymptotic stability therefore, we establish conditions for the identification of the physical parameters of the system. Our theoretical findings are supported by illustrative simulation results
Nonlinear Speed Control of Switched Reluctance Motor Drives Taking into Account Mutual Inductance
A speed control algorithm is proposed for variable speed switched reluctance motor (SRM) drives taking into account the effects of mutual inductances. The control scheme adopts two-phase excitation; exciting two adjacent phases can overcome the problems associated with single-phase excitation such as large torque ripple, increased acoustic noise, and rotor shaft fatigues. The effects of mutual coupling between two adjacent phases and their contribution to the generated electromagnetic torque are considered in the design of the proposed control scheme for the motor. The proposed controller guarantees the convergence of the currents and the rotor speed of the motor to their desired values. Simulation results are given to illustrate the developed theory; the simulation studies show that the proposed controller works well. Moreover, the simulation results indicate that the proposed controller is robust to changes in the parameters of the motor and to changes in the load torque
A Complete Model Characterization of Brushless DC Motors
The modeling problem associated with brushless DC motors (BLDCMs) with nonuniform air gaps which operate in a range where magnetic saturation may exist is addressed. The mathematical model, includes the effects of reluctance variations and magnetic saturation to guarantee proper modeling of the system. An experimental procedure is developed and implemented in a laboratory environment to identify the electromagnetic characteristics of a BLDCM in the presence of magnetic saturation. It is demonstrated that the modeling problem associated with this class of BLDCM can be formulated in terms of mathematically modeling a set of multidimensional surfaces corresponding to the electromagnetic torque function and the flux linkages associated with the motor phase windings. The accuracy of the mathematical model is checked against experimental measurement
Feedback Linearization Based Nonlinear Control of SynRM Drives Accounting for Self- and Cross-Saturation
This article proposes a nonlinear controller based on feedback linearization (FL) for synchronous reluctance motor (SynRM) drives which takes into consideration the magnetic saturation. The proposed nonlinear FL control based control technique has been developed starting from the theoretical definition of an original dynamic model of the SynRM taking into consideration both the self- and the cross-saturation effects. Such a control technique permits the dynamics of both the speed and axis flux loops to be maintained constant independently from the load and the saturation of the iron core in both constant flux and variable direct axis flux operating conditions. Finally, sensitivity of the performance of the proposed FL control versus the variation of the main motor parameters has been verified. The proposed technique has been tested experimentally on a suitably developed test setup. The proposed FL control has been further compared with the classic field-oriented control (FOC) in both constant flux and variable flux working conditions
Electronic Control of Torque Ripple in Brushless Motors
Merged with duplicate record 10026.1/727 on 27.02.2017 by CS (TIS)Brushless motors are increasingly popular because of their high power density, torque to
inertia ratio and high efficiency. However an operational characteristic is the occurrence of
torque ripple at low speeds. For demanding direct drive applications like machine tools,
robot arms or aerospace applications it is necessary to reduce the level of torque ripple.
This thesis presents an in depth investigation into the production and nature of torque
ripple in brushless machines. Different torque ripple reduction strategies are evaluated and
one reduction strategy using Park's transform as a tool is identified as the promising
strategy. The unified machine theory is checked to clarify the theory behind Park's
transform; in particular assumptions made and general validity of the theory. This torque
ripple reduction strategy based on Park's transform is extended to include the effect of
armature reaction. A novel adaptive torque ripple reduction algorithm is designed. The
ineffectiveness of the conventional approach is demonstrated. Further a novel torque ripple
reduction strategy using direct measurements of the torque ripple is suggested, reducing
implementation time and allowing higher accuracies for torque ripple reduction. Extensive
measurements from the experimental system show the validity of the novel torque ripple
reduction strategies. The experimental results allow derivation of a formula for all load
situations. This formula makes it possible to further increase the reduction accuracy and
enables improved real time implementation of the torque ripple reduction algorithm.
The work presented here makes a substantial contribution towards understanding the nature
of torque ripple in brushless motors and solving the associated problems. The novel
reduction strategies form the basis for the development of intelligent dynamometers for
motor test beds. Further the torque ripple reduction method presented here can be used to
overcome manufacturing imperfections in brushless machines thus removing the cost for
precise manufacturing tools. Future designs of controllers can "build" their own correction
formula during set-up runs, providing a motor specific torque ripple correction.Automotive Motion Technology Lt
Nonlinear H-infinity control for switched reluctance machines
AbstractThe article proposes a nonlinear H-infinity control method for switched reluctance machines. The dynamic model of the switched reluctance machine undergoes approximate linearization round local operating points which are redefined at each iteration of the control algorithm. These temporary equilibria consist of the last value of the reluctance machine's state vector and of the last value of the control signal that was exerted on it. For the approximate linearization of the reluctance machine's dynamics, Taylor series expansion is performed through the computation of the associated Jacobian matrices. The modelling errors are compensated by the robustness of the control algorithm. Next, for the linearized equivalent model of the reluctance machine an H-infinity feedback controller is designed. This requires the solution of an algebraic Riccati equation at each time-step of the control method. It is shown that the control scheme achieves H-infinity tracking performance, which implies maximum robustness to modelling errors and external perturbations. The stability of the control loop is proven through Lyapunov analysis
Generalized Sensorless and Advanced Control of Synchronous Reluctance Machines
L'abstract è presente nell'allegato / the abstract is in the attachmen
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