scholarly journals Impedance Modeling and Stability Analysis for Cascade System of Three-Phase PWM Rectifier and LLC Resonant Converter

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 3050 ◽  
Author(s):  
Rutian Wang ◽  
Yuyang Wu ◽  
Guoqing He ◽  
Ying Lv ◽  
Jiaxing Du ◽  
...  

In this paper; the impedance model of PWM rectifier and LLC resonant converter are deduced, and the stability analysis of cascade system is studied. The principle of three-phase PWM rectifier is introduced; and the small signal model in d-q coordinate system is deduced. The expression of dc side output impedance model for PWM rectifier is derived. The LLC resonant converter is operated in a fixed-frequency state, and the LLC resonant converter is modeled as a small signal model. On this basis, the input impedance model expression of the LLC resonant converter is derived. According to the impedance stability criterion, it can seen that the amplitude of input impedance is greater than the amplitude of output impedance in a certain frequency domain. In addition, the Nyquist curve is not around the point (−1,0), which can judge that the cascade system is stable. In simulation software, a cascade system simulation is built and corresponding simulation curves are obtained, which verifies the stability of the cascade system.

2019 ◽  
Vol 66 (8) ◽  
pp. 6493-6504 ◽  
Author(s):  
Zhikang Shuai ◽  
Yang Li ◽  
Weimin Wu ◽  
Chunming Tu ◽  
An Luo ◽  
...  

2021 ◽  
Author(s):  
Jermaine Stern

The project verifies the performance of a control system designed for a Series Resonant Converter (SRC). A discrete small-signal model of an SRC was derived and used to design the control system. An accurate control system was designed in the frequency domain to eliminate the need for trail-and-error [sic] methods or other time domain methods. A PSPICE simulation of a regulated SRC circuit was used to test the control system. A prototype of the regulated SRC was developed to verify the simulated results. The tests performed demonstrated that the control system design provides a quick response. The tests determined that when a step input is applied to the reference input the control system adjusts the SRC's output voltage to the new reference input value. Also, the control system is able to regulate output load voltage in the presence of sudden load changes.


2019 ◽  
Vol 28 (04) ◽  
pp. 1950063
Author(s):  
Jianguang Ma ◽  
Xueye Wei ◽  
Liang Hu ◽  
Junhong Zhang

This paper proposes a small-signal modeling method for building an LLC half-bridge resonant converter. In recent years, the LLC half-bridge resonant converter has attracted the attention of many researchers because of its high-power conversion efficiency and high-power density. Generally, the LLC half-bridge resonant converter consists of many passive components, including stray and parasitic elements, resulting in a high-order system. Because the fundamental harmonic approximation (FHA) method for an LLC resonant converter only considers the fundamental harmonic and neglects higher harmonics, it is not accurate and introduces large errors in a higher-order system. In this paper, according to the operation principle of the LLC half-bridge resonant converter, a small-signal model is established. Based on the small-signal model, the input-to-output and control-to-output transfer function is derived. The experimental result verified that the proposed model yields a high accuracy, thereby highlighting the usefulness and versatility of the proposed model over other existing models.


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