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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. [ABSTRACT FROM AUTHOR]

Magnetic components, such as inductors and transformers, enable short-term energy storage and transfer and are essential for many power electronic converters. Physics-based models of magnetic systems, such as finite element-based models and/or high-fidelity magnetic equivalent circuit (HFMEC) models, accurately represent the magnetic device. However, these models are computationally intensive and hard to formulate. In this paper, an HFMEC approach for laminated and solid magnetic cores is set forth that avoids conventional geometrical simplifications and assumptions of uniform flux density. The proposed dynamic HFMEC model accurately captures the effects of magnetic saturation, high frequency eddy currents, corner effects, and 3-D effects. The resulting full-order HFMEC models introduce a large set of state variables. Automated linear and nonlinear order-reduction techniques are introduced to extract the desired essential system dynamics, thus preserving both model accuracy and computational efficiency. The resulting reduced-order models are validated with hardware measurements and the original full-order HFMECs in both time and frequency domains. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Brushless dc (BLDC) motors controlled by Hall-effect sensors are widely used in various applications and have been extensively researched in the literature, mainly under the assumption that the Hall sensors are ideally placed 120 electrical degrees apart. However, this assumption is not always valid; in fact, sensor placement may be significantly inaccurate, especially in medium- and low-precision BLDC machines. This paper shows that misplaced Hall sensors lead to unbalanced operation of the inverter and motor phases, which increases the low-frequency harmonics in torque ripple and degrades the overall drive performance. The paper also presents several average-filtering techniques that can be applied to the original Hall-sensor signals to mitigate the effect of unbalanced placement during steady-state and transient operations. The pro- posed methodology is demonstrated by modeling and hardware, and is shown to achieve dynamic performance similar to that of a BLDC motor with accurately positioned Hall sensors. [ABSTRACT FROM AUTHOR]

Recently, there has been renewed interest in modeling of electrical machines for the Electro-Magnetic Transient Program (EMTP)-type programs, with the goal of improving the machine-network interface. In this paper, we present a new voltage-behind- reactance induction machine model for the EMTP-type solution and power system transients. In the proposed model, the stator circuit is represented in abc phase coordinates and the rotor subsystem is expressed in qd arbitrary reference frame. Similar to the recently proposed synchronous-machine voltage-behind-reactance model and the established phase-domain model, simultaneous solution of the machine-network electrical variables is achieved. Efficient numerical implementation of the proposed model is presented, in which one time-step requires as little as 108 flops, taking 1.6 μs of CPU time. Case studies of induction machine start-up transients demonstrate that the proposed model is more accurate and efficient than several existing EMTP machine models. [ABSTRACT FROM AUTHOR]

Over the past several years, there has been renewed interest in modeling electrical machines using phase (abc) variables. This paper considers modeling induction machines using phase variables in a voltage-behind-reactance (VBR) formulation. Specifically, three VBR models are proposed wherein the rotor. electrical subsystem is modeled using flux linkages as state variables expressed in the qd reference frame. The stator electrical dynamics are represented in abc phase coordinates that enable direct interface of the machine model to an external network. Such a direct interface is advantageous when the machine is fed from a power electronic converter and/or when the modeling is carried out using circuit-based simulators. Computer studies of an induction machine demonstrate that the proposed VBR models achieve a 740% improvement in computational efficiency as compared with the traditional coupled-circuit phase-domain model. [ABSTRACT FROM AUTHOR]

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 120° 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 hard. ware 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. [ABSTRACT FROM AUTHOR]

This paper presents modeling and control design of a wind-hybrid power system that includes a battery storage and a dumpload. The proposed control scheme is based on the Takagi-Sugeno (TS) fuzzy model and the linear quadratic regulator. The TS fuzzy model expresses the local dynamics of a nonlinear system partitioned into sub systems by linguistic rules. A possibility auto-regression model is presented that provides optimally partitioned sub systems based on the observed time series. The controllers for each sub system are designed by the linear quadratic regulator. In the simulation study, the proposed controller is compared with the conventional proportional-integral controller and shown to be more effective against disturbances caused by the wind speed and the load variations. Thus, a better power quality is achieved on the given site. [ABSTRACT FROM AUTHOR]

Analytical average-value modeling of pulsewidth modulation dc-dc converters is usually based on the piece-wise linear waveforms of the circuit variables and neglects the parasitics that give rise to waveform nonlinearities and complicate model derivation. This letter presents a straightforward but powerful methodology that considers the true averaging of nonlinear waveforms and produces a fairly accurate large-signal transient model that is functional in both operational modes. Based on the proposed modeling approach, a fast procedure for extracting the small-signal frequency-domain characteristics is set forth. The key model parameters are established numerically using the detailed simulation, which streamlines the analysis. The resulting average-value model is validated with a hardware prototype, a detailed simulation, and several previously established models in time and frequency domains. [ABSTRACT FROM AUTHOR]

State-space average-value modeling of pulsewidth modulation converters in continuous and discontinuous modes has received significant attention in the literature, and various models have been developed. This paper presents a new approach for generating the state-space average-value model. In the proposed methodology, the so-called duty-ratio constraint and the correction term are extracted numerically using the detailed simulation and are expressed as nonlinear functions of the duty cycle and average-value of the fast state variable. The parasitic effects of circuit elements are readily included. The resulting average-value model is compared to a hardware prototype, a detailed simulation, and several previously published models. The proposed model is shown to be very accurate in predicting the large-signal time-domain transients as well as the small-signal frequency-domain characteristics. [ABSTRACT FROM AUTHOR]

The analytical derivation of the average-value models (AVMs) for synchronous-machine-fed rectifier systems depends on many factors and is challenging in general. Various models presented in the literature rely on a single operating mode and a dc filter configuration. A recently proposed parametric approach utilizes a detailed simulation as a basis to establish an AVM that uses a proper full-order qd generator model. This paper presents a procedure to extract the appropriate nonlinear algebraic functions to represent the rectifier averaged behavior. In contrast to existing methods, the proposed procedure does not require significant analytical derivations and/or computational resources and results in a highly accurate dynamic AVM. The proposed methodology is validated with the results of detailed simulation and hardware experiment, and is shown to be very accurate in predicting the large-signal time-domain transients as well as the small-signal frequency-domain characteristics. [ABSTRACT FROM AUTHOR]