Topic
Small-signal model
About: Small-signal model is a research topic. Over the lifetime, 1013 publications have been published within this topic receiving 12836 citations.
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TL;DR: A simple method of tracking the maximum power points (MPPs) and forcing the system to operate close to these points is presented, and the principle of energy conservation is used to derive the large- and small-signal model and transfer function.
Abstract: Photovoltaic systems normally use a maximum power point tracking (MPPT) technique to continuously deliver the highest possible power to the load when variations in the insulation and temperature occur. It overcomes the problem of mismatch between the solar arrays and the given load. A simple method of tracking the maximum power points (MPPs) and forcing the system to operate close to these points is presented. The principle of energy conservation is used to derive the large- and small-signal model and transfer function. By using the proposed model, the drawbacks of the state-space-averaging method can be overcome. The TI320C25 digital signal processor (DSP) was used to implement the proposed MPPT controller, which controls the DC/DC converter in the photovoltaic system. Simulations and experimental results show excellent performance.
746 citations
16 Mar 2014
TL;DR: In this article, an impedance-based analysis method was proposed to analyze the grid-synchronization stability issue in paralleled three-phase converter systems, which showed that the multivariable generalized inverse Nyquist stability criterion (GINC) can be used to predict the system stability based on the grid and inverter impedances in the synchronous d-q frame.
Abstract: Grid synchronization instability issues and low frequency oscillations between synchronous generators exist in electrical power system. This kind of stability issue happens between paralleled power converters is also reported. Analysis based on small-signal model of inverters with phase-locked loops (PLL) has been proposed. Different from that approach, which needs detailed inverter and controller parameters, this paper proposes an impedance-based analysis method to analyze the grid-synchronization stability issue in paralleled three-phase converter systems. The proposed method shows that the multivariable generalized inverse Nyquist stability criterion (GINC) can be used to predict the system stability based on the grid and inverter impedances in the synchronous d-q frame. Furthermore, the instability is found to be caused by qq channel impedance interaction. Experimental results verify the analysis and the proposed method.
451 citations
TL;DR: In this paper, an accurate small-signal model for a galvanically isolated, bidirectional dc-dc converter and the implementation of a corresponding controller on a DSP as well as key methods and functions required for the digital implementation are detailed.
Abstract: The derivation of an accurate small-signal model for a galvanically isolated, bidirectional dc-dc converter and the implementation of a corresponding controller on a DSP as well as key methods and functions required for the digital implementation are detailed in this paper. The investigated dc-dc converter, an automotive dual active bridge (DAB) system, enables power transfer between a low-voltage port (ranging from 11 to 16 V) and an HV port (240 to 450 V). The nominal power rating is 2 kW. The developed small-signal model yields highly accurate results for the DAB system, but the proposed modeling procedure could also be applied to arbitrary resonant power converters with unidirectional or bidirectional power transfer.
361 citations
TL;DR: In this paper, a small-signal model for the average current-mode control method is developed, which is suitable for applications where the average inductor current needs to be controlled, as in power factor correction circuits and battery charger dischargers.
Abstract: A recently proposed average current-mode control method is analyzed. A complete small-signal model for the control scheme is developed. The model is accurate up to half the switching frequency. This control scheme is suitable for applications where the average inductor current needs to be controlled, as in power factor correction circuits and battery charger dischargers. The subharmonic oscillation, commonly found in peak current-mode control, also exists in this method. This subharmonic oscillation can be eliminated by properly choosing the proper gain of the compensation network in the current loop. Model predictions are confirmed experimentally. >
347 citations
TL;DR: In this article, an exact small-signal discrete-time model for dc-dc converters operating in constant frequency continuous conduction mode (CCM) with a single effective A/D sampling instant per switching period is presented.
Abstract: The letter presents an exact small-signal discrete-time model for digitally controlled pulsewidth modulated (PWM) dc-dc converters operating in constant frequency continuous conduction mode (CCM) with a single effective A/D sampling instant per switching period. The model, which is based on well-known approaches to discrete-time modeling and the standard Z-transform, takes into account sampling, modulator effects and delays in the control loop, and is well suited for direct digital design of digital compensators. The letter presents general results valid for any CCM converter with leading or trailing edge PWM. Specific examples, including approximate closed-form expressions for control-to-output transfer functions are given for buck and boost converters. The model is verified in simulation using an independent system identification approach.
303 citations