Petar Crnošija

Microcomputer implementation of optimal algorithms for closed-loop control of a hybrid stepper motor drives

Optimal control algorithms for closed-loop control of a hybrid stepper motor drive and their microcomputer implementations are discussed. An analytical expression for the average torque of a two-phase hybrid stepper motor with bipolar supply and current controller is developed. Approximate and exact expressions for the optimal control angle of a two-phase hybrid stepper motor with bipolar supply and current controller are derived. An actual hybrid stepper motor drive and the microcontroller-based implementation of the proposed optimal control algorithms are described. The experimental results obtained by positioning of a two-phase hybrid stepper motor drive with phase current controller and incremental encoder suggest that the proposed optimal control algorithms provide maximum acceleration and minimum positioning time of the hybrid stepper motor drive.

Microcomputer implementation of optimal algorithms for closed-loop control of hybrid stepper motor drives

This paper discusses optimal algorithms for closed-loop control of hybrid stepper motor drives and their microprocessor implementation. The torque characteristics and the optimal control angle of hybrid stepper motor drives with added series resistance and reluctant stepper motor drives have been described in detail in the literature. The specific contribution of the paper to this field of research consists of the analysis of the torque characteristics and the optimal control angle of hybrid stepper motor drives with a chopper amplifier and current controller. Analytical expressions for the average torque and the optimal control angle of a two-phase hybrid stepper motor with chopper amplifier and current controller have been developed. An actual hybrid stepper motor drive and the microcontroller-based implementation of the suboptimal and exact optimal control algorithms have been described. The experimental results obtained by positioning a two-phase hybrid stepper motor drive with chopper amplifier, phase current controller, and incremental encoder suggested that the derived optimal control algorithm provided maximum acceleration and minimum positioning time of the hybrid stepper motor drive.

Application of model reference adaptive control with signal adaptation to PM brushless DC motor drives

The performance of permanent magnet brushless DC motor (PMBDCM) drives degrades with parameter and load variations. An overview of adaptive methods and advantages of model reference adaptive control in the context of providing a solution to these problem, is presented. Model reference adaptive control in general form and modified signal adaptation algorithms are introduced. Model reference adaptive control with signal adaptation algorithms has been applied to compensate parameter sensitivity and influence of load torque in it permanent magnet brushless DC motor (PMBDCM) drive. Dynamic simulation results show significant reduction in the error caused by variations in parameters and load torque.

Design and stability of self-organizing fuzzy control of high-order systems

The paper describes a model reference-based self-organizing fuzzy control scheme which is suitable for high-order systems of well-known structure. The conditions for stability of the learning process, which may be used for determination of the learning coefficient values, have been worked out. The way of improving the system response in the initial stage of learning by using the referent model-based method of presetting a fuzzy control surface is described. The proposed fuzzy control method has been tested in the angular speed control loop of a DCM servo drive. The results obtained have shown the feasibility and marked effectiveness of the self-organizing fuzzy control scheme indicating a better performance of the system with the preset fuzzy controller than with a blank fuzzy rule-table in the initial stage of learning.

Optimization of PM Brushless DC Motor Drive Speed Controller Using Modification of Ziegler-Nichols Methods Based on Bodé Plots

The most commonly used methods for design of the industrial speed controllers are: experimental, root locus, frequency and optimization methods. The most commonly used experimental methods are Ziegler-Nichols methods: stability margin and step response function. Ziegler-Nichols methods are applied for design of speed controller of PM brushless DC motor drive. Both methods give the controller parameters, which result in relatively high overshoot in response to reference signal. Therefore, optimal speed controller parameters are determined by modification of Ziegler-Nichols methods based on Bodes frequency diagrams. Thereby, controller integral time constant is increased and controller gain is reduced (increased) to achieve faster and better load torque compensation than traditional controller synthesis based on compensation of maximum time constant of drive. Desired overshoot in response to reference change is achieved by adding a first order filter at the drive input. Synthesis results and responses are given in this paper

Transient performance based design optimization of PM brushless DC motor drive speed controller

Using standard integral criteria for optimization of speed controller parameters in an electric motor drive result in relatively high overshoot in speed response. Besides that, the speed controllers integral time constant is much higher than maximum drive time constant, which is unfavorable for load torque compensation, in this paper the speed controller parameters of a permanent magnet (PM) brushless direct current (DC) motor drive are obtained in terms of the overshoot in speed response. A dependence of overshoot in speed on speed controllers gain coefficient and integral time constant is derived and graphically presented for easier adoption of the derived results in industrial and research laboratory settings. It is further demonstrated that faster and better load torque compensation is achieved with smaller values of integral time constant and larger values of speed controller gain coefficient A desired speed overshoot is achieved by adding a filter at drive input. Responses on both reference and load torque variations of PM brushless DC motor drive validates the proposed design approach. The results are obtained using Matlab program package for simulation and optimization of the PM brushless DC motor drive.

Fuzzy rule-based model reference adaptive control of permanent magnet synchronous motor drive

The paper presents a model reference adaptive control scheme using fuzzy logic adaptation mechanism to generate additional signal to the system input. The proposed method has been applied to the linearized model of the angular speed control system of a vector controlled chopper-fed permanent magnet synchronous motor (PMSM) drive. Simulation results indicate that a good adaptation is achieved even for large parameter variations. Marked simplicity and digital character of the method make it very suitable for microcomputer implementation.<<ETX>>

Overshoot controlled servo system synthesis using bode plot and its application to PM brushless DC motor drive

The design of current and speed controllers remains to a large extent a mystery to many engineers in the motor drives field. An attempt is made in this paper to simplify the design of the current and speed controllers using Bode plots. This paper outlines the theoretical background behind the techniques of symmetric optimum and dominant time constant compensation methods. The techniques are compared and contrasted using the overshoot and phase margin criteria. An application of these techniques to controller design for permanent magnet brushless DC motor (PMBDCM) drive system is made and verified with simulation. In order to apply these techniques to PMBDCM drive for the design of the current and speed controllers, the model of the motor drive is given for the benefit of the reader. The current and speed controller synthesis of a PMBDCM drive is achieved with the presented technique. Simulation results demonstrate for reference (current or speed) changes, symmetric optimum and dominant time compensation methods perform similarly. But for a load torque disturbance, the adverse effect on the speed is compensated faster only with the symmetric optimum method.

Application of the MRAC with simplified discrete parameter adaptation algorithm for control of the DC electromotor drive

The application of the simplified model reference adaptive control algorithm with parameter adaptation, to the DC motor drive has been considered. DC motor drive, with a basic control loops and changeable moment of inertia belongs to the class of the higher order systems with changeable parameters. In a way to preserve the desired system behaviour, even in the case of system parameter change, the simplified MRAC algorithm with parameter adaptation was developed and applied for control of the DC motor drive. The algorithm is based on the classical model reference adaptive control approach with parameter adaptation, including few simplifications. The simplifications are as follows: the reference model and the state vector were reduced to the third order, only output variable was used in the algorithm and the total number of the algorithm coefficients was reduced to seven. The satisfactory behaviour of the adaptive control algorithm was preserved by using differences of the output variable instead of its derivatives. Furthermore, an adaptive control algorithm was normalized for the usage in the whole range of reference signal changing. Adaptive control coefficients were obtained by off line optimization, for the extreme amount of the changeable system parameter. Therefore, the same coefficients could be used in whole range of the system parameter variation. The simplified MRAC algorithm with parameter adaptation was implemented in the dSPACE DS1102 micro controller platform based on microprocessor TMS320C37. This controller is used for control of the DC motor drive with a changeable moment of inertia. Finally, it was evident from the experimental results that the application of the MRAC with the simplified discrete parameter adaptation algorithm significantly decreases the influence of the plant parameter variations and the influence of disturbance to the system behaviour.

Robustness of PM Brushless DC Motor Drive Adaptive Controller with Reference Model and Signal Adaptation Algorithm

This paper covers an application of MRAC with modified signal adaptation algorithm with optimal error weighting coefficients in a permanent magnet brushless DC motor drive with significant parameter changes in moment of inertia, armature resistance and flux linkage coefficient. Optimal values of the error weighting coefficients are determined for third order reference model, using Matlab and simplex optimization method. Presented results show that one set of optimal error weighting coefficients can compensate for any parameter change reducing the error from 41-57% to 4-8% in relation to a reference model thus showing that MRAC with modified signal adaptation algorithm is robust