Automatic Current Balancing Three-Phase LLC Symmetric Resonant Converter Using Flying Capacitors

2020 ◽  
Vol 140 (12) ◽  
pp. 949-957
Author(s):  
Masatoshi Uno ◽  
Yoshiya Tada
Keyword(s):  
Resonant Converter ◽  
Three Phase ◽  
Flying Capacitors

scholarly journals A Novel Multilevel DC-Link Three-Phase T-Type Inverter

Energies ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 4186
Author(s):  
Saddam Shueai Alnamer ◽  
Saad Mekhilef ◽  
Hazlie Mokhlis ◽  
Nadia M. L. Tan
Keyword(s):  
High Efficiency ◽  
Short Circuit ◽  
Multilevel Converters ◽  
Passive Components ◽  
Medium Voltage ◽  
Three Phase ◽  
Unbalanced Voltage ◽  
Flying Capacitors ◽  
Voltage Deviation ◽  
Current Commutation

This research proposes a four-level T-type inverter that is suitable for low-power applications. The presented topology outranks other types of inverters in terms of a smaller number of semiconductor devices, absence of passive components such as clamping diodes and flying capacitors, low switching and conduction losses, and high efficiency. The proposed topology is free from voltage deviation and unbalanced voltage occurrences that are present in other multilevel converters having clamping diodes or flying capacitors. The proposed inverter can extend to N levels using unequal dc-link voltage sources for medium-voltage application. The inverter employs the simple fundamental frequency staircase modulation technique. Moreover, this paper presents a current commutation strategy to prevent the occurrences of short circuit and minimizing the number of required switching devices and switching transitions, resulting in improving the efficiency of the inverter. This paper also analyses the theoretical converter losses showing lower switching and conduction losses when compared to existing four-level inverters. The experimental validation of the proposed inverter shows its operating feasibility and a low output voltage THD.

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 ◽  
...  
Keyword(s):  
Resonant Converter ◽  
Pwm Rectifier ◽  
Output Impedance ◽  
Cascade System ◽  
Signal Model ◽  
Impedance Model ◽  
Small Signal Model ◽  
Three Phase ◽  
Llc Resonant Converter ◽  
The Stability

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.

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