Average-value Model Research Articles

Improved Based on "Self-Adaptive Turning Rate" Model Algorithm

For tracking the object with tracking nonlinear, high maneuvering target，traditional interactive multiple model self-adaptive filter algorithm was usually adopted．The turning rate estimate was very important. However，the performance of turning rate algorithm was not so satisfactory in the model．Thus，a new the average value turning rate algorithm based on self-adaptive turning model was proposed．Aiming at additional device for turning rate estimation turning model, the parameters α and β were introduced to adjust the roughness of turning rate．Aiming at target constant turning movement and orthogonal turning rate unequal, estimates, turning rate was used the average value model to reduce the noise and error influence. Simulation results showed that the proposed algorithm was more suitable for the objects with Nonlinear, high maneuvering target tracking and could remarkably reduce the sample，and thus achieve much better tracking performance. DOI: http://dx.doi.org/10.11591/telkomnika.v11i6.2602

Detailed and Averaged Models for a 401-Level MMC–HVDC System

Voltage-source-converter (VSC) technologies present a bright opportunity in a variety of fields within the power system industry. New modular multilevel converters (MMCs) are expected to supersede two- and three-level VSC-based technologies for HVDC applications due to their recognized advantages in terms of scalability, performance, and efficiency. The computational burden introduced by detailed modeling of MMC-HVDC systems in electromagnetic-transients (EMT)-type programs complicates the study of transients especially when these systems are integrated into a large network. This paper presents a novel average-value model (AVM) for efficient and accurate representation of a detailed MMC-HVDC system. It also develops a detailed 401-level MMC-HVDC model for validating the AVM and studies the performance of both models when integrated into a large 400-kV transmission system in Europe. The results show that the AVM is significantly more efficient while maintaining its accuracy for the dynamic response of the overall system.

Dynamic Average-Value Modeling of 120° VSI-Commutated Brushless DC Motors With Trapezoidal Back EMF

The 120° voltage source inverter driven brushless dc (BLDC) motors are very common in many applications. This paper extends the previous work and presents an improved dynamic average-value model for such BLDC motor-drive systems. The new model is explicit and uses a proper qd model of the permanent magnet synchronous machine with nonsinusoidal rotor flux. The model utilizes multiple reference frame theory to properly include the back EMF harmonics as well as commutation and conduction intervals into the averaged voltage and torque relationships. The commutation angle is readily obtained from the detailed simulation. The proposed model is demonstrated on a typical industrial BLDC motor with trapezoidal back EMF waveforms. The results of studies are compared with experimental measurements as well as previously established models, whereas the new model is shown to provide appreciable improvement.

Dynamic modelling and characterisation of vehicular power system considering alternator iron core and rectifier losses

Modelling and simulation of automotive electrical power systems is indispensable. For the purpose of system-level large-signal transient studies and small-signal frequency-domain analysis, the very fast switching transients can be neglected resulting in computationally efficient average-value modelling. Although most existing/traditional models do not consider the machine and rectifier losses, the analytical derivation of average-value models for a wide range of operating conditions and taking the systems' losses into account is very challenging. This study extends the recently developed parametric approach and presents a new dynamic average modelling and accelerated characterisation of the most common type of automotive power systems including claw-pole alternator, rectifier and energy-storage subsystems. Such alternator/rectifier systems are particularly known to have significant losses and are difficult to represent using conventional models that are available in the literature. The new model takes into account the rectifier conduction losses as well as the rotational and core losses of the alternator, while avoiding laborious analytical derivations and crude approximations. The final model is verified against the experimental results and a detailed switch-level implementation of the system in time and frequency domains. Very significant computational gains and excellent accuracy of the new model are demonstrated.

Dynamic Average Modeling of Front-End Diode Rectifier Loads Considering Discontinuous Conduction Mode and Unbalanced Operation

Electric power distribution systems of many commercial and industrial sites often employ variable frequency drives and other loads that internally utilize dc. Such loads are often based on front-end line-commutated rectifiers. The detailed switch-level models of such rectifier systems can be readily implemented using a number of widely available digital programs and transient simulation tools, including the Electromagnetic Transient (EMT)-based programs and Matlab/Simulink. To improve the simulation efficiency for the system-level transient studies with a large number of such subsystems, the so-called dynamic average models have been utilized. This paper presents the average-value modeling methodologies for the conventional three-phase (six-pulse) front-end rectifier loads. We demonstrate the system operation and the dynamic performance of the developed average models in discontinuous and continuous modes, as well as under balanced and unbalanced operation.

Dynamic Average-Value Modeling of Hybrid-Electric Vehicular Power Systems

This paper extends the concept of dynamic average-value modeling to power-electronic-intensive hybrid-electric vehicular power trains. Hybrid vehicles with plug-in capability are becoming increasingly important in the study of emerging smart power grids, and their simulation using digital programs has gained widespread attention. This paper demonstrates the usefulness of averaging in preserving the dynamic characteristics of the vehicular system while reducing the computational intensity of its simulation on an Electromagnetic Transients Program-type simulator. This paper presents an example of averaging for modeling, simulation, and system-level studies of a power-split gear hybrid drive-train.

Aircraft Power System Stability Study Including Effect of Voltage Control and Actuators Dynamic

This paper describes a stability analysis of aircraft ac frequency-wild power systems with constant power loads (CPL). In contrast to previous publications, the proposed analysis method employs the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$dq$</tex> modeling approach instead of the state-space averaging (SSA) and average-value modeling (AVM) methods to derive power-electronic converter models for stability studies. This results in lower order models and allows the modeling of vector-controlled converter elements where the SSA and AVM methods are not easily applicable. The resulting model can be combined with models of other power system elements expressed in terms of synchronously rotating frames (generators, front-end converters, vector-controlled drives, etc.). The paper analyzes the stability of frequency-wild power systems for both load and parameter variations and takes into account controlled generator voltage dynamics and electromechanical actuator dynamics. The stability margins are assessed and compared with those for power systems with the ideal voltage source and the ideal CPLs. The study is supported by intensive time domain simulations that support the theory.

Discrete-time modelling of digitally-controlled multiphase converters

Digital controllers are often used in interleaved multiphase DC-DC converters for voltage regulator modules. A dynamic, discrete-time model is required for frequency-domain characterisation and subsequent controller design. An exact, small-signal model for a general multiphase converter is presented that is suitable for direct digital design. The proposed model is verified for a dual-phase buck converter, using hardware measurements and numerical simulation. The open loop control-to-output and the closed-loop transfer functions predicted by the proposed method match those extracted from an average-value model and network analyser, respectively.

Definitions and Applications of Dynamic Average Models for Analysis of Power Systems

Modeling and analysis of power and power-electronic systems' transients using digital programs enables testing new design concepts in modern electric grid and many industrial and commercial products and applications. This paper gives an overview of dynamic average-value modeling techniques for representing static switching converters for the system-level studies. Concepts and desirable properties of averaged models for conducting large-signal time-domain transient studies and small-signal frequency-domain analysis for control design tasks are discussed. Basic approaches for developing average models for dc/dc and dc/ac converters are briefly reviewed and summarized. Finally, the desirable properties of the average-value models are demonstrated through an example system.

Posicast control within feedback structure for a DC–DC single ended primary inductor converter in renewable energy applications

In this paper, modeling, analysis, design, simulation and control of a single ended primary inductor converter (SEPIC) are discussed for renewable energy applications. Because the traditional control methods such as proportional–integral–derivative (PID) and classical half-cycle Posicast controllers based on feedforward are sensitive to noise and variations in natural frequency, a Posicast control with feedback structure is proposed and designed to reduce or rejection undesirable sensitivity greatly, to suppress measurement noise and to eliminate the overshoot in the output response. The SEPIC converter is modeled using average value modeling analysis. Dynamic modeling and simulation are accomplished using MATLAB Simulink™ 7.2.

Improved dynamic average modelling of brushless excitation system in all rectification modes

This study presents an improved dynamic average model for brushless excitation system in synchronous generators. The model is based on an efficient voltage-behind-reactance model of the exciter and the average value modelling of rotating rectifier in all rectification modes. The excitation current is assumed to change at a constant rate during the averaging period. The model is validated through comparison of the proposed average model and the experimental results.

Numerical Dynamic Characterization of Peak Current-Mode-Controlled DC–DC Converters

Peak current-mode (PCM) control of pulsewidth-modulated (PWM) dc-dc converters is highly desired for its fast dynamic response and automatic overload protection. Dynamic characterization of PCM converters is mainly conducted via average-value modeling. However, deriving the average-value models of PCM converters is challenging when the component parasitics and different conduction modes are considered. This paper extends a recently developed computer-aided methodology to the PCM converters and presents an accurate dynamic average-value model that considers the parasitics and true averages of nonlinear waveforms. The proposed model is functional in all operational modes and is validated in large-signal transient studies and small-signal characterizations.

MPC of Switching in a Boost Converter Using a Hybrid State Model With a Sliding Mode Observer

In this paper, a model of a DC-DC (boost) converter is first expressed as a hybrid/switched/variable-structure system state model for the purpose of applying recently developed hybrid optimal control theory to control switching in a boost converter. Switching control is achieved by forming the embedded form of the hybrid state model, which enables the derivation of a control that solves for the switching function that minimizes a user-defined performance index. This approach eliminates the need to form average-value models and provides flexibility to balance competing objectives through appropriate weighting of individual terms in the performance index. Since, in practical situations, both the source voltage and the load resistance vary with time in unknown and unmeasurable ways, we introduce a sliding mode observer based on an enlarged state model which allows implicit estimation of the unknown variables. The combined optimal switching control and sliding mode observer are applied to a boost converter in which several nonidealities and losses are represented. The results of time-domain simulation and hardware experiments are used to validate and compare the response of the hybrid optimal control-sliding mode observer to that of a traditional current-mode control strategy.

Numerical Validation of Parametric Average-Value Modeling of Synchronous Machine--Rectifier Systems for Variable Frequency Operation

The derivation of accurate dynamic average-value models for synchronous machine-rectifier systems is challenging. A recently proposed parametric approach uses a computer-aided procedure for constructing the required averaged models, wherein the key nonlinear functions are extracted from a detailed (valve-by-valve) simulation. This letter shows that by using a judicious selection of parametric functions, a model obtained at a fixed generator speed is also valid for variable speeds. This is an important feature that makes this approach applicable to systems where electromechanical dynamics and variable speed operation is required.

Computer-Aided Dynamic Characterization of Fourth-Order PWM DC–DC Converters

Average-value modeling of dc-dc converters has been an area of active research for many years. Developing accurate average-value models of higher order converters is further complicated by the presence of parasitics and waveform nonlinearity. This paper extends the numerical state-space averaging to the fourth-order capacitor-based switching stages. The proposed model takes into account conduction losses associated with switching-stage components and is seamlessly functional in all operational modes. The proposed model is validated with a hardware prototype and detailed simulation and is shown to accurately predict large-signal time-domain transients as well as small-signal frequency-domain characteristics.

Average-Value Modeling of Brushless DC Motors With 120° Voltage Source Inverter

This paper describes average-value modeling of brushless dc (BLDC) motor-inverter systems, which is challenging due to the complicated switching patterns of the stator currents. A new average-value model (AVM) that appropriately includes commutation and conduction subintervals of the BLDC motor with a 120deg inverter is presented. The proposed model is explicit and uses a proper qd model of the permanent magnet synchronous machine. The required commutation angle is represented as a nonlinear algebraic function, which is readily obtained from the detailed simulation. The studies conducted are based on two typical industrial motors with different electrical time constants, and include hardware measurements, detailed simulation, and comparison with a previously published AVM. The proposed model is shown to be more accurate in terms of both large and small-signal analysis and is applicable to both types of motors.

Numerical Validation of Parametric Average-Value Modeling of Synchronous Machine–Rectifier Systems for Variable Frequency Operation

The derivation of accurate dynamic average-value models for synchronous machine-rectifier systems is challenging. A recently proposed parametric approach uses a computer-aided procedure for constructing the required averaged models, wherein the key nonlinear functions are extracted from a detailed (valve-by-valve) simulation. This letter shows that by using a judicious selection of parametric functions, a model obtained at a fixed generator speed is also valid for variable speeds. This is an important feature that makes this approach applicable to systems where electromechanical dynamics and variable speed operation is required.

Averaged-Switch Modeling of Fourth-Order PWM DC–DC Converters Considering Conduction Losses in Discontinuous Mode

This manuscript addresses dynamic average-value modeling for fourth-order pulse-width modulation (PWM) DC-DC converters in discontinuous capacitor-voltage mode. Although significant literature is devoted to analysis of the inductor-based switching stage of second-order DC-DC converters in discontinuous current mode, much less has been published regarding the discontinuous voltage mode in the capacitor-based switching stage in fourth-order converters. Accurate average-value models are further complicated by the presence of non-ideality in the switching stage components. This manuscript presents a full-order average-value model for the capacitor-based switching stage, taking into account conduction losses according to the energy conservation principle. The proposed model is validated with a hardware prototype and detailed simulation and is shown to accurately predict large-signal time-domain transients as well as small-signal frequency-domain characteristics.

Parasitics Realization in State-Space Average-Value Modeling of PWM DC&amp;#x2013;DC Converters Using an Equal Area Method

Average-value modeling of pulsewidth-modulation dc-dc converters is often based on the assumption of piecewise-linear waveforms of the circuit variables, whereas considering parasitics introduces waveform nonlinearity and complicates the model derivation. This paper presents a new approach that considers averaging with nonlinear waveforms using the equivalent area method, and proposes a state-space averaged model that is fairly accurate and seamlessly functional in both continuous and discontinuous conduction modes. The resulting average-value model is applicable for large-signal transient studies as well as for linearization and subsequent small-signal analysis. The proposed model is validated with a hardware prototype and a detailed simulation, and is shown to be an improvement over previously established models in the time and frequency domains.

Averaged modelling of switched-inductor cells considering conduction losses in discontinuous mode

Many PWM DC-DC converters contain a switched-inductor cell for which an average-value model is required. However, the presence of parasitics associated with the cell's components complicates the development of accurate averaged models, especially for the discontinuous conduction mode. Here is described an improved full-order, large-signal averaged switching cell. The proposed averaged cell takes into account conduction losses as required by the energy conservation principle and provides a more accurate duty-ratio constraint. The final model shows improvement over several previously established averaged cells in predicting large-signal, time-domain transients as well as small-signal, frequency-domain characteristics