In this paper we deal with the dynamical behavior modeling, design and simulation of a two-cell DC-DC Buck converter driven DC motor. The angular velocity of the motor is controlled with a feedback loop through a Digital Pulse Width Modulation (DPWM). The stress of the switches of the converter are also balanced between the cells. Discrete time approach is used to obtain accurate information on the stability and to detect possible subharmonic oscillations quasi-periodic behavior and chaotic regimes. Under certain operating conditions, the switching model can be approximated by a three dimensional piecewise constant vector field and the corresponding the discrete time model is nonlinear map. We present a number of analytical, numerical and graphical tools that may be useful to study the dynamical behavior and stability of the fixed point of the map. Stability conditions are derived in terms of parameters. These results are confirmed by two-dimensional bifurcation diagrams.

Stability analysis of two-cell Buck converter driven DC motor with a discrete-time closed loop

A hierarchical control structure is presented for the output feedback control of nonlinear systems approximated by piecewise linear models. At the lowest level, traditional output feedback control techniques are used to design robust local controllers for each operating segment. The low-level control is then enhanced by the use of a supervisory level, which combines clustering and binary tree classification techniques from artificial intelligence to identify the transitions between the models. The controller is trained on typical operating scenarios. The structure is applied to the case of a nonlinear DC servomotor with a piecewise linear model of the thyristor converter dynamics. >

An application of expert hierarchical control to piecewise linear systems

In the previous chapter, we presented the principle of directly linked DC-DC converters either with two switches or in full-bridge topology. They enable the energy transfer to be controlled between a DC voltage generator and a DC current receptor, or between a DC current generator and a DC voltage receptor. To make matters simpler, we have used the word “source” to cover the functions of both generator and receptor.

Operation and Characteristics of Directly Linked Choppers

Applying Popov's stability criterion to the correct transfer function for the system studied in the work P.B. Anjaneyulu et al. (see ibid., vol.IE-31, no.2, p.175-80, (1984)), suitable conditions for stability are derived. From these conditions, the stability region obtained is larger than that given in the mentioned work. These results can be verified by using Lyapunov's second method. >

Comments on "Stability analysis, design, and simulation of a closed-loop converter-controlled DC drive" by P.B. Anjaneyulu, et al

For Part I, see ibid., vol.3, no.2, June 1988, pp.305-314. Having developed the general mathematical model of an isolated self-dual excited synchronous machine in part I, the author derives the small displacement equations for the two alternative excitation systems. A novel analytical method is developed for the small displacement model of the self-dual excited synchronous machine that requires less CPU time than previously. This method is general and take into account the variation of the firing angle and the automatic feedback control circuit during small disturbances. The coefficients of the characteristic equation and the eigenvalues are calculated to study the dynamic stability of the system. The effects of the ratio of the two field currents, the inertia constant, the power factor, and the gain and time constant of the feedback control circuit on the dynamic stability of the system are investigated. The results obtained show that the self-dual excited synchronous machine with the two field windings having MMF ratios between 0.75 and 1.5 presume better dynamic stability bounds than the conventional self-excited synchronous machine. In the range where the other proposed excitation system can be compared with the conventional machine, it has been found that the developed system has the same dynamic stability response with the advantage that the effect of automatic voltage regulator is implicitly included with a smaller time constant. Including the change of the firing angle during the small disturbance, a pronounced effect on the dynamic stability of the system results. >

Analysis of self-dual excited synchronous machine. II. Small perturbation model and dynamic behaviour

A method for the design of controllers for closed-loop converter-controlled dc drives is given. Popov's stability criterion has been applied for analyzing stability in the large of the drive system. The paper includes experimental and digital simulation results of a dc drive.

Stability Analysis, Design, and Simulation of a Closed-Loop Converter-Controlled DC Drive

A new pulse delay circuit for converter control is described. The circuit is versatile in the sense that- it can be used for many converter configurations employing line and forced commutations.

S. S. Prabhu

Papers

Stability Analysis, Design, and Simulation of a Closed-Loop Converter-Controlled DC Drive

A novel pulse delay circuit for converter control