Variable Structure Speed Controller Research Articles

Variable Structure Speed Controller Guaranteeing Robust Transient Performance of an IPMSM Drive

This paper proposes a variable structure speed controller (VSSC) that guarantees the robust transient performance against the external disturbances and parameter uncertainties of an interior permanent magnet synchronous motor (IPMSM) drive. Unlike the conventional VSSC applied to the IPMSMs, the proposed nonlinear compensating control term not only assures the robustness against the system uncertainties, but also implements the maximum torque per ampere technique. Furthermore, the convergence and stability of the proposed VSSC are fully proven through the Lyapunov theory by introducing reasonable bounded uncertainties which determine a feasible range for the system dynamics. The effectiveness of the proposed scheme is investigated through the simulation using MATLAB/Simulink and experiment using a prototype IPMSM drive system with a TI TMS320F28335 DSP. Finally, the proposed VSSC can ensure faster and more robust transient response than the conventional proportional-integral speed controller under the dynamic load conditions including the uncertainties.

High-performance discrete-time chattering-free sliding mode-based speed control of induction motor

This paper presents a new approach to induction motor (IM) speed controller design with indirect field-oriented control structure. The designed discrete-time variable structure (VS) speed controller uses elements of reduced-order and full-order (integral) sliding mode (SM) control, and acts as a nonlinear equivalent of conventional PI control. The controlled plant is approximated by a first-order dynamical model. Therefore, the proposed approach leads to an output feedback-based SM control (SMC) system. To improve its disturbances rejection and tracking capability, the controller is supplied with a first-order disturbance compensator based on the switching function measurement. The proposed VS control structure provides a high-performance chattering-free discrete-time SMC system. Numerous experiments have been carried out to test the proposed control method and to compare its performance with the conventional PI control approach. The experimental results demonstrate high tracking accuracy and robustness of the proposed system.

A Robust Adaptive Sliding Mode Control for PMLSM with Variable Velocity Profile Over Wide Range

An adaptive robust variable structure speed controller is designed for wide range of desired velocity control of a Permanent Magnet Linear Synchronous Motor (PMLSM). This is performed for comprehensive nonlinear model of PMLSM including non-idealities such as detent force, parameter uncertainty, unpredicted disturbance and nonlinear friction. The proposed method is based on the robust Sliding Mode Control (SMC) in combination with an adaptive strategy for a wide range of velocity. The simulation results are provided for the above mentioned comprehensive model of PMLSM with a variable velocity profile. Moreover, as an evaluation criterion, a Proportional-Integral (PI) controller is designed whose parameters are optimally tuned by the Particle Swarm Optimization (PSO) algorithm for better comparison.

Adaptive control schemes for improving dynamic performance of efficiency-optimized induction motor drives

Model Based Control (MBC) is one of the energy optimal controllers used in vector-controlled Induction Motor (IM) for controlling the excitation of motor in accordance with torque and speed. MBC offers energy conservation especially at part-load operation, but it creates ripples in torque and speed during load transition, leading to poor dynamic performance of the drive. This study investigates the opportunity for improving dynamic performance of a three-phase IM operating with MBC and proposes three control schemes: (i) MBC with a low pass filter (ii) torque producing current (iqs) injection in the output of speed controller (iii) Variable Structure Speed Controller (VSSC). The pre and post operation of MBC during load transition is also analyzed. The dynamic performance of a 1-hp, three-phase squirrel-cage IM with mine-hoist load diagram is tested. Test results are provided for the conventional field-oriented (constant flux) control and MBC (adjustable excitation) with proposed schemes. The effectiveness of proposed schemes is also illustrated for parametric variations. The test results and subsequent analysis confer that the motor dynamics improves significantly with all three proposed schemes in terms of overshoot/undershoot peak amplitude of torque and DC link power in addition to energy saving during load transitions.

Integral variable structure controller with grey prediction for synchronous reluctance motor drive

A novel sliding mode speed controller with grey prediction compensator is presented for a synchronous reluctance motor (SynRM). The sliding mode control (SMC) is insensitive to system uncertainties and disturbances when they are within expected limits. SMC systems produce chattering when uncertainty values are overestimated, or steady-state error when underestimated. Alternatively, they use computationally expensive variable-structure speed controllers to estimate external load disturbance bounds. A mathematically simple and computationally efficient grey prediction compensator is used for the variable structure speed controller. Background, theory and methodology are discussed. Experimental results verify that the SMC with grey prediction significantly reduces chatter and steady-state error.

Robust variable structure speed control for induction motor drive

In order to eliminate the effect of parameter variation on field-oriented control for induction motor drive, an adaptation algorithm for tuning the rotor time-constant is proposed. Based on the adaptive observation of the rotor flux linkages, the rotor time-constant is adapted to obtain an exact indirect-field-oriented control (IFOC). In this proposed algorithm, a related function to the variation of the rotor time-constant is designed, then the accurate slip frequency needed for IFOC is obtained from this error function through a PI-type (proportional-integral) filter. Furthermore, a novel variable structure speed control with integral sliding surface is proposed under the adaptive field-oriented operation. By means of the variable structure speed control, the dynamics of motor speed have the property of an exponentially convergent rate. Using the proposed adaptive field-oriented control and the variable structure speed control, the IFOC is robust to the variation of the rotor time-constant and the speed control is insensitive to parameter uncertainty and load disturbance. Finally, some simulation and experimental results are presented to validate the effectiveness.

Robust control of induction motor drive with rotor time-constant adaptation

In this paper, an indirect field-oriented induction motor drive with a rotor time-constant adaptation is presented. Since the deviated rotor time-constant of an induction motor makes the indirect field-orientation inaccurate, an adaptation mechanism is proposed to tune the rotor time-constant to establish a complete indirect field-oriented control for an induction motor drive. With the rotor time-constant adaptation, the indirect field-oriented control has the robustness property for decoupling torque and flux components. In order to further insure the robustness of the servo control, a novel variable-structure speed controller is proposed under the adaptive field-orientation operation. A novel sliding surface with an integral component for the variable structure speed controller is designed, and exponential convergence in speed-tracking control is obtained. Using the proposed variable-structure speed controller, the insensitivity for parameter uncertainty and disturbance load is provided. Finally, a simulation and experimental results are demonstrated.

A new switching surface sliding-mode speed control for induction motor drive systems

In this paper, a sliding-mode speed controller based on a new switching surface is proposed for induction motor systems. With this variable structure control switching surface, the exponential stability is guaranteed for the speed servo control and insensitivity to uncertainties and disturbances are obtained as well. Moreover, an adaptive variable structure speed control is studied to relax the need for the bound of disturbance in variable structure control. The insensitivity or robustness of the proposed method for general speed servo systems is maintained, and the dynamic performances are improved as well. Finally, the validity of proposed scheme is demonstrated by computer simulations and experimentations.

An output feedback sliding mode speed regulator for DC drives

Synthesis of the switching surface equation in a variable structure speed controller is accomplished by using a phase lead type compensator. In addition, the switching control is designed using only the sign of the switching surface function and an estimate of the maximum value of the equivalent sliding control. As a result, the proposed variable structure controller relies only upon output feedback. The problem of control chattering is addressed by substituting a saturation function for the switching control. The practical significance of the work is demonstrated by designing a robust speed regulator for a DC drive, without direct acceleration measurement or the use of a state estimator. Results from a control experiment complement the discussion.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

SLIDING MODE SPEED CONTROLLER FOR TRAPEZOIDAL BRUSHLESS MOTORS

ABSTRACT This paper describes the application of a variable structure speed controller for a non sinusoidal brushless permanent magnets motor drive. Our trapezoidal brushless motor model changes the working conditions for every phase commutation and moreover it allows to simulate the different structural motor configurations. Controller synthesis is carried out using sliding mode theory with a pole assignment technique. During the sliding motion the state point is forced to reach a prescribed surface due to an active change of the control action. The order of the system is therefore reduced and moreover the dynamic behaviour of the closed-loop system is imposed. Results by digital computer simulation prove parametric variation insensitivity, disturbance rejection, fast transient responses, no overshoot and absence of speed ripples during phase commutations.

A comparative study of a Luenberger observer and adaptive observer-based variable structure speed control system using a self-controlled synchronous motor

An analysis of the state-observer-based robust speed control of a self-controlled synchronous motor (SCSM) is presented. A variable-structure control technique is utilized to achieve robust (parameter-insensitive) characteristics. The speed and acceleration signals required for the implementation of the variable-structure speed control (VSSC) are dynamically estimated with state observers. Two kinds of observers-the Luenberger full-order observer and an adaptive observer-are explored. The results obtained illustrate that Luenberger observers do not estimate the system states accurately when the system parameters vary. This inaccuracy in the state estimation results in a deterioration of the VSSC performance. Therefore, the possibility of using an adaptive state observer (ASO) is investigated. It is shown that the ASO estimates the system parameters and the system states simultaneously, thus making VSSC possible. The design methods and simulation results are presented to demonstrate the potential of the scheme. >