Review and Selection Strategy for High-Accuracy Modeling of PWM Converters in DCM

Mao, Yu-Jun; Lam, Chi-Seng; Sin, Sai-Weng; Wong, Man-Chung; Martins, Rui P.

doi:10.1155/2018/3901693

Cited by 7 publications

(4 citation statements)

References 21 publications

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“…Note however when one considers other operating modes, such as DCM, or other control schemes, such as current mode control, the low order averaged models lack sufficient accuracy at high frequencies. A wide range of models have been presented to model converters in DCM, for example, see [10] for a recent historical overview of these models.…”

Section: Voltage Mode Transfer Functionsmentioning

confidence: 99%

Exact Dynamic Modeling of PWM DC-to-DC Power Converters—Part I: Continuous Conduction Mode

Simmons¹,

Tymerski²

2021

JPEE

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A general approach is presented by which the exact frequency response of any transfer function of switched linear networks can be determined. This is achieved with a describing function approach using a state space equation formulation. This work presents a somewhat simplified set of equations to one previously given by one of the authors. To demonstrate application of the general formulation, the frequency responses of switched networks used as PWM DC-to-DC converters operating in continuous conduction mode (CCM) under voltage mode control are derived. (The accompanying paper, Part II, will present results for converters operating in discontinuous conduction mode (DCM)). From the general sets of equations developed here, both the control to output and input source variation to output frequency responses are derived. The describing function approach enables exact frequency response determination, even at high frequencies where the accuracy using average models may be compromised. Confirmation of the accuracy of the derived models is provided by comparing the responses with those obtained using the commercial simulator PSIM on a PWM boost converter. The magnitude and phase responses are shown to match perfectly over the full range of frequencies up to close to half the switching frequency. Matlab code that implements the models is given such that the user can easily adapt for use with other PWM converter topologies.

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Section: Voltage Mode Transfer Functionsmentioning

confidence: 99%

Exact Dynamic Modeling of PWM DC-to-DC Power Converters—Part I: Continuous Conduction Mode

Simmons¹,

Tymerski²

2021

JPEE

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“…The small signal modeling of converters operating under DCM has progressively evolved over the years. An excellent, comprehensive review of the developed techniques of the past two decades has been presented in [4]. There it is seen that methods involving state space averaging, or alternatively, circuit averaging, result in the most accurate results.…”

Section: Introductionmentioning

confidence: 99%

Exact Dynamic Modeling of PWM DC-to-DC Power Converters—Part II: Discontinuous Conduction Mode

Simmons¹,

Tymerski²

2021

JPEE

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This paper follows on from the first paper, Part I, where a general formulation of a describing function approach to frequency response determination of switched linear networks, such as PWM converters, was simplified and updated. The models assume a piecewise linear state space equation description of the system and results in a closed form solution for the sought after frequency response. In Part I, model derivation was demonstrated for the case of PWM converters operating in the continuous conduction mode (CCM). This operating mode does not feature any state dependent switching times. In this paper, Part II, frequency response models for any transfer function for PWM converters operating in discontinuous conduction mode (DCM) are derived based on the theory presented in Part I. This operating model features state dependent switching times. The describing function models developed are exact and therefore, in terms of accuracy, are to be preferred over averaged models which are widely used. The example of a boost dc-to-dc converter operating in DCM is simulated to obtain the control to output and input to output frequency responses and are compared with the models derived here. Excellent agreement between the simulated and model responses was found. Matlab code implementing the analytical models is also presented which the user can adapt for any other PWM converter topology. The models derived here may be used as a basis from which simplified models may be derived while still preserving required accuracy.

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“…To be useful, these models must be subsequently linearized. Although they are widely used in the industry with good results, they have two disadvantages: (a) the model is valid in a narrow working range and (b) two different models are needed depending on the converter operation mode (continuous or discontinuous), which represents a great inconvenience [4]. Therefore, to check the overall performance of the control system, repeated simulations must be carried out at various operating points, with different values of load and disturbances, changing the model as appropriate to each case, which represents a very annoying drawback.…”

Section: Introductionmentioning

confidence: 99%

Application of Statecharts in Buck-Boost DC-DC Converter Simulation

Cendoya

Toccaceli

2021

Wseas Transactions on Electronics

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A very attractive and relatively simple option to simulate a DC-DC converter is to use a hybrid model. In this case, the need to use very small simulation steps (as those necessary to simulate models carried out at the physical level) is avoided. Furthermore, unlike the averaged state-space models, it has the advantage that the model is valid throughout the entire working range of the converter and for both conduction modes (continuous and discontinuous). By simulating several renewable energy conversion systems incorporating DC-DC converters, the authors have discovered the true potential of this modeling method. Despite its inherent advantages, this approach to DC-DC converters simulation is not as widely adopted as it should be. This work tries to encourage the reader of its use in certain typical situations. In this article the implementation of the hybrid model of the DC-DC Buck-Boost converter, using Statechart techniques, is performed. This model was written in the Stateflow language, a tool from the MATLAB®/Simulink environment, and allowed the creation of a building block formed by the described converter model with adequate interfaces to the SimPowerSystem and Simulink environments. The block is validated by comparing simulation results, realized under different operating conditions, with calculations done employing well-known and proven formulas. As an example of the use of the presented block, a buck-boost DC-DC converter with voltage and current control loops is simulated, corroborating its correct performance

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Review and Selection Strategy for High-Accuracy Modeling of PWM Converters in DCM

Cited by 7 publications

References 21 publications

Exact Dynamic Modeling of PWM DC-to-DC Power Converters—Part I: Continuous Conduction Mode

Exact Dynamic Modeling of PWM DC-to-DC Power Converters—Part I: Continuous Conduction Mode

Exact Dynamic Modeling of PWM DC-to-DC Power Converters—Part II: Discontinuous Conduction Mode

Application of Statecharts in Buck-Boost DC-DC Converter Simulation

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