Switching Regulators Features in the Matching Mode Operation

Currently, various types of non-traditional and renewable sources of electrical energy are widely used. If the energy carrier of such sources is free, in the process of operation it is advisable to select the maximum possible power from them, regardless of the fact that the utilization factor of the source's electrical energy in this case may be relatively low. To obtain the maximum amount of electrical energy from the source, two conditions must be met: 1) the source must be brought to the maximum power point (МPP); 2) energy from the source must be taken continuously. As you know, to bring the source into the MPP, it is necessary that the load resistance be equal to the output resistance of the source. Otherwise, the power will be taken from the source, which is less than the maximum possible. Therefore, in cases where the load resistance differs from the output resistance of the source, a matching switching regulator is turned on between the source and the load to match the output resistance of the source with the load resistance. In this case, the input impedance of the switching regulator will be the load of the source. This resistance depends on the load resistance of the regulator, as well as on the relative time of the closed (open) state of the controlled switch S of the regulator t*. Thus, by adjusting the parameter t*, it is possible to ensure the fulfillment of the condition for removing the source into the MPP at various values of the load resistance. In this case, the maximum possible power of the source will be transferred to the load, regardless of the value of its resistance. The dependence of the output parameters of the switching regulator on the parameter t* describe its regulation characteristics. Since, when operating in the maximum power transmission mode, the internal resistance of the source and the load resistance are of the same order of magnitude, when determining the regulating characteristics of the regulator, the internal resistance of the source must be taken into account. The aim of the work is to analyze the control characteristics of the regulator, which operates in the mode of transferring maximum power from the source of electrical energy to the load, as well as to determine the conditions under which it is possible and advisable to operate in this mode. These issues were analyzed using the example of the two most common switching regulator circuits - step-down and step-up regulators. It is shown in the work that, in contrast to the up-type switching regulator, in the down-type regulator, the energy from the power source is taken in discrete portions. Therefore, it can ensure the selection of maximum power from the source only in the t* = 1 mode at a certain value of the load resistance. To ensure continuous extraction of energy from the source, at the input of the switching regulator of the step-down type, it is necessary to install a capacitance of sufficient value. In this case, the circuit can provide maximum power transfer from the source at different load resistances. The paper presents the adjusting characteristics of the analyzed circuits for the case of their operation in the mode of transferring maximum power from the power source to the load, which makes it possible to determine the parameter t* at which the power source is output to the MPP. It is shown that each of the considered circuits can provide the output of the power supply to the MPP only in a certain range of variation of the load resistance of the regulator. For each regulator, an appropriate range of variation of the t* parameter is indicated, depending on whether the power source is a voltage source or a current source.

Design and Analysis of the Voltage Controller for the Non Isolated Boost DC-DC Convertor

In this paper, a controller has been presented by the root locus method based on the state space average model of the boost switching regulator with all of the converter’s parameters and uncertainties. In this model, the load current is unknown and the inductor, capacitor, diode and active switch are non ideal and have an on-state resistance. Furthermore, an on-state voltage drop has been considered for diode and active switch. By neglecting the load current and assuming the ideal elements the simplified model of the regulator has been caddied out. By these complete and simplified models, a step by step method has been proposed to design a single input single output (SISO), second order controller based on roots locus method. In this regard the controller's electronic circuit has been introduced by operational amplifiers. At the end, by simulation of the complete closed-loop system in MATLAB Simulink environment and comparing its results by the results of the regulator and controller circuits in PLECS, the accuracy of the designed controller performance has been shown.

Derivative-Free Direct Search Optimization Method for Enhancing Performance of Analytical Design Approach-Based Digital Controller for Switching Regulator

Although an analytical design approach-based digital controller—which is essentially a deadbeat controller—shows zero steady-state error and no intersampling oscillations, it takes a finite number of sampling periods to settle down to a steady-state value. This paper describes the application of a derivative-free Nelder–Mead (N–M) simplex method to the digital controller for retuning of its coefficients intelligently to ensure improved settling and rise times without disturbing the deadbeat controller characteristics (i.e., no ripples between the sampling periods and no steady-state error). A switching-mode buck regulator working at 1 MHz in continuous conduction mode (CCM) is considered as a plant. Numerical simulation results depict that the N–M algorithm-based optimized digital controller not only shows improved steady-state and transient performance but also guarantees rigorous robustness against model uncertainty and disturbance as compared to its traditional counterpart, as well as the other optimized digital controller fine-tuned through other derivative-free metaheuristic optimization techniques, such as the genetic algorithm (GA). A system generator-based hardware software co-simulation is also performed to validate the simulation results.