A discrete time-domain model for fast simulation of MMC circuits

2016 ◽  
Author(s):  
Feng Zhang ◽  
Xu Yang ◽  
Kangping Wang ◽  
Guangzhao Xu ◽  
Lang Huang ◽  
...  
Keyword(s):  
Discrete Time ◽  
Time Domain ◽  
Domain Model ◽  
Fast Simulation

Modeling and Analysis of Small Scale High-Voltage Charging Circuit under Discrete Time Domain

2011 ◽  
Vol 130-134 ◽  
pp. 3386-3391
Author(s):  
Yong Qiang Wang ◽  
Yi Di Wu ◽  
Yun Yan Wang ◽  
Chang Lin Liu
Keyword(s):  
Discrete Time ◽  
High Voltage ◽  
Time Domain ◽  
Low Voltage ◽  
Research Topic ◽  
Domain Model ◽  
Small Scale ◽  
Large Signal ◽  
Modeling And Analysis ◽  
Highly Nonlinear

Small scale high-voltage flyback charging circuit is the key unit of the initiating experiment device of slapper detonator, which converts the initiating energy from low voltage to high voltage and stores the energy in a high voltage capacitor. It is a highly nonlinear system, of which the research topic is the process of the establishment of the output voltage—an area which belongs to large signal transients. This has made the research of this topic difficult and progress slowly. In this paper, in order to study the characteristics as well as the rules of the charging process for the purpose of design optimization, the discrete time domain model of the flyback charging circuit is built and simulated. Experimental results are given and show that the model presented in this paper is instrumental for the optimization of the high voltage charging circuit.

scholarly journals Discrete Time Domain Modeling and Control of a Grid-Connected Four-Wire Split-Link Converter

Electronics ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 506
Author(s):  
Jeroen D. M. De Kooning ◽  
Dimitar Bozalakov ◽  
Lieven Vandevelde
Keyword(s):  
Discrete Time ◽  
Time Domain ◽  
Controller Design ◽  
Domain Model ◽  
Domain Modeling ◽  
Modeling And Control ◽  
Current Harmonics ◽  
Voltage Unbalance ◽  
Zero Sequence ◽  
Time Domain Modeling

Distributed generation (DG) allows the production of renewable energy where it is consumed, avoiding transport losses. It is envisioned that future DG units will become more intelligent, not just injecting power into the grid but also actively improving the power quality by means of active power filtering techniques. In this manner, voltage and current harmonics, voltage unbalance or over-voltages can be mitigated. To achieve such a smart DG unit, an appropriate multi-functional converter topology is required, with full control over the currents exchanged with the grid, including the neutral-wire current. For this purpose, this article studies the three-phase four-wire split-link converter. A known problem of the split-link converter is voltage unbalance of the bus capacitors. This mid-point can be balanced either by injecting additional zero-sequence currents into the grid, which return through the neutral wire, or by injecting a compensating current into the mid-point with an additional half-bridge chopper. For both methods, this article presents a discrete time domain model to allow controller design and implementation in digital control. Both techniques are validated and compared by means of simulation results and experiments on a test setup.

Chatter Stability of Serrated Milling Tools in Frequency Domain

2021 ◽  
pp. 1-26
Author(s):  
Nima Dabiri Farahani ◽  
Yusuf Altintas
Keyword(s):  
Frequency Domain ◽  
Discrete Time ◽  
Time Domain ◽  
Angular Distance ◽  
Domain Model ◽  
Chatter Stability ◽  
Stability Diagrams ◽  
Time Marching ◽  
The Stability ◽  
Milling Tools

Abstract Serrated milling tools are widely used for chatter suppression in roughing difficult-to-cut Titanium and Nickel alloys in the aerospace industry. Due to the complexity of chip generation and serration wave geometries ground on the flutes, the chatter stability diagrams are predicted with time marching numerical simulation or semi-discrete time-domain methods, which are computationally too costly to use in practice. This paper presents a frequency domain model of milling dynamics with variable delays caused by the flute serrations. The endmill is divided into discrete cylindrical elements, each having a different radius from the cutter axis. As the cutter rotates and cuts metal, the angular distance between the subsequent tooth varies as a function of serration amplitudes and feedrate; hence the regenerative delays vary. The angular delays and effective directional factors are averaged for each tooth to form a time-independent but serration-dependent characteristics equation for all discrete cutter elements. The stability of the resulting characteristic equation of the system is solved using Nyquist theory and compared against the experimental results and existing time marching and semi-discrete time-domain solutions. The proposed analytical model predicts the stability charts about thirty times faster than the time-domain models while providing acceptable accuracy.

scholarly journals Prediction of deepwater riser VIV with an improved time domain model including non-linear structural behavior

2021 ◽  
Vol 236 ◽  
pp. 109508
Author(s):  
Sang Woo Kim ◽  
Svein Sævik ◽  
Jie Wu ◽  
Bernt Johan Leira
Keyword(s):  
Time Domain ◽  
Domain Model ◽  
Structural Behavior ◽  
Non Linear ◽  
Deepwater Riser
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