Control-oriented design guidelines to extend the stability margin of switching converters

On the stability of certain systems under resonance conditions

To study the stability of a nominal cyclic steady state in power electronic converters, it is necessary to obtain a linearization around the periodic orbit. In many past studies, this was achieved by explicitly deriving the Poincare map that describes the evolution of the state from one clock instant to the next and then locally linearizing the map at the fixed point. However, in many converters, the map cannot be derived in closed form, and therefore this approach cannot directly be applied. Alternatively, the orbital stability can be worked out by studying the evolution of perturbations about a nominal periodic orbit, and some studies along this line have also been reported. In this paper, we show that Filippov's method - which has commonly been applied to mechanical switching systems - can be used fruitfully in power electronic circuits to achieve the same end by describing the behavior of the system during the switchings. By combining this and the Floquet theory, it is possible to describe the stability of power electronic converters. We demonstrate the method using the example of a voltage-mode-controlled buck converter operating in continuous conduction mode. We find that the stability of a converter is strongly dependent upon the so-called saltation matrix - the state transition matrix relating the state just after the switching to that just before. We show that the Filippov approach, especially the structure of the saltation matrix, offers some additional insights on issues related to the stability of the orbit, like the recent observation that coupling with spurious signals coming from the environment causes intermittent subharmonic windows. Based on this approach, we also propose a new controller that can significantly extend the parameter range for nominal period-1 operation.

Asymptotic 2p-moment stability of stochastic linear systems

Advanced control methods for power electronics systems

The reliability and lifetime of insulated gate bipolar transistors (IGBTs) are critical to ensuring the stability and safety of power electronic systems. IGBTs are widely used in electric vehicles, renewable energy systems, and industrial automation. However, their degradation over time poses a significant risk to system performance. Therefore, this paper proposes a data-driven approach based on a Long Short-Term Memory (LSTM) network optimized by a Genetic Algorithm (GA) to predict IGBT degradation. The study examines the health monitoring of insulated gate bipolar transistors from a device physics perspective. Degradation mechanisms that alter parasitics and electro-thermal stress produce characteristic changes in the turn-off overvoltage and the on-state voltage. Using power-cycling data from packaged half-bridge modules, an LSTM-based sequence model configured by a genetic algorithm search reduces error against an identically trained baseline (RMSE = 0.0073, MAE = 0.057, MAPE = 0.726%) under the shared protocol, with the clearest advantages in the early stage of degradation. These results support predictive maintenance and health management in power-electronic systems.

The characteristics of the behavior of complex technical systems that realize the property of functional stability of these systems were studied. One of the possible statements of the problems of planning the operation of complex technical systems arising within the functional-parametric direction of risk theory is considered. It is shown that on the basis of the developed algorithms of the minimax assessment of the technical condition using the idea of ellipsoidal assessment, it is possible to implement a guaranteeing strategy for managing the risks of unauthorized influences. The proposed approach allows forecasting even with a small number of parameter measurements, does not require information about the stochastic properties of measurement errors and other obstacles, and has adaptive properties. The conditions for ensuring the functional stability of the technological process are given and practical recommendations for applying these conditions for decision-making in the practical implementation of production processes are described. Ensuring the functional stability of production processes is one of the most important tasks today. Currently, many different methods have been proposed to ensure a high level of functional stability, but this problem requires constant improvement and development of new approaches. In order to improve and develop methods of organizing production processes that ensure the functional stability of technological processes thanks to the implementation of an individual strategy for the operation of technical systems, an approach to the formation of an operation management strategy that ensures the functional stability of the relevant systems is proposed. An individual strategy for planning the operation of technical systems was studied, depending on their actual state, taking into account the features of this specific system. The proposed approach is advisable to use when planning the functionally stable operation of complex technical systems of responsible purpose, the failure of which is associated with significant material losses or catastrophic consequences.

294 fault patterns of 12-pulse waveform controlled rectifier circuit (CRC) are studied firstly; a special fault classification method according to the rectifier aberrant voltage waveforms is put forward then. 12-dimension fault patterns and the corresponding fault codes are obtained through logic pre-processing of the fault rectifier voltage waveforms. A recurrent neural network (RNN) with deviation error units is used to construct a fault mapping. The fault patterns are used as the input of the network, after being calculated by the neural network the 12-dimension fault codes are obtained to indicate the fault state of the system. Simulation and experiment study demonstrate that the proposed technique is low time consuming with high fault identification rate, it improves the performance of the existing neural network based on-line fault diagnosis methods effectively. The proposed method is suitable for the fault diagnosis of complex power electronic devices or systems.

Про проектування малочутливих прискорювально-фокусуючих систем методами практичної стійкості

In analysis and design of a power electronic system, it is essentially important to check its stability for a given system's parameters. This paper presents a computer-aided method for analyzing stability of a general class of power electronic systems. In usual operating modes of power electronic systems, the solution orbits are periodic due to the periodic switching operations of power semiconductor devices. We derive an efficient computer algorithm to determine the stability of periodic solutions of power electronic systems. The proposed method is based on the use of a transient simulator for power electronics systems. The method can check stability of any power electronics system with considering detailed switching behaviors which the transient simulator can treat.

Review of condition monitoring methods for capacitors used in power converters

This paper is concerned with the analysis of large-scale interconnected systems constructed from positive subsystems and a nonnegative interconnection matrix. We first show that the interconnected system is admissible and stable if and only if a Metzler matrix built from the coefficient matrices of the positive subsystems and the interconnection matrix is Hurwitz stable. By means of this key lemma, we further provide several results that characterize the admissibility and stability of interconnected systems in terms of the weighted L1-induced norm of each positive subsystem and the Frobenius eigenvalue of the interconnection matrix. Moreover, in the case where every subsystem is SISO, we provide explicit conditions under which the interconnected system has the property of persistence, i.e., the state of the interconnected system converges to a unique strictly positive vector (up to a strictly positive constant multiplicative factor) irrespective of nonnegative and nonzero initial states. We illustrate the effectiveness of the persistence results via formation control of multi-agent systems.

This paper investigates input-to-state-K ℒ*-stability (IS-K ℒ*-S) for hybrid dynamical systems (HDS) with external inputs. The notions of IS- K ℒ θL K θK 0-property and IS- K ℒ θ -S are proposed for HDS. The IS- K ℒ θL K θK 0-property, including input-to-state stability (ISS) and IS- K ℒ θ -S, is a more general input-to-state property and reflects the specific effects on the dynamic behavior of a HDS from its continuous/discrete-time subsystems and switching events. A HDS with IS- K ℒ θL K θK 0-property may be non-ISS. The conditions for HDS with IS- K ℒ θL K θK 0-property to achieve IS- K − θL -S are derived. These conditions are expressed by the conditions of K −-function and finite accumulative value (KLF-FAV-conditions) while satisfying the hybrid dwell time condition (HDT). Finally, a criterion of IS- K − θ -S is given by using the multiple Lyapunov-like functions and the IS- K ℒ θL K θK 0-property of subsystems.

Accurate stabilization for linear stochastic systems based on region pole assignment and its applications

Objectives: In this paper, a Field Programmable Gate Array (FPGA) based real time implementation of a closed loop controller for regulating the load voltage under line and load disturbances by generating Digital Pulse Width Modulation (DPWM) is developed. Digital Proportional Integral (DPI) controller is designed to generate the DPWM. Methods: DPWM are developed by two methods: Counter based and Delay line based. The closed loop DPWM activated DC-DC buck converter is simulated using MODELSIM and tested in real time using Xilinx Spartan 3A DSP FPGA. Findings: Hardware results show the regulated load voltage by updating the DPWM control signal duty cycle to compensate the line and load disturbances. FPGA based DPWM provides less complexity in design. Improvements: Hybrid based DPWM method with closed loop control for DC-DC Buck converter could be used for voltage regulation.

A closed loop control system based on optimal control by Linear Quadratic Regulator whose weighting matrices obtained by deterministic approach for dc-dc Buck converter is presented. State Space Averaged model of the Buck converter and LQR controller with weighting matrices determined by the desired location of poles are studied. The performance of such controller is compared with PID, Fuzzy Tuned PID, Sliding Mode and Error Compensation controllersin terms of transient and steady state responses along with load and line disturbances. In this paper systematic procedures are used for developing all the above controllers which make the system robust against load and line disturbances. The hardware results validate the simulated response and forcing out the merits over the other existing control methods. The methodology generates a fresh dimension for the case of such converter in practical applications.