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Control of Grid Connected AC-DC Converters with Minimized DC Link Capacitance under Unbalanced Grid Voltage Condition
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| Author(s) |
J. George Hwang; Peter W. Lehn; Manfred Winkelnkemper |
| Abstract |
Due to the limited lifetime of electrolytic capacitors, use of film capacitors is gaining popularity in
AC-DC converter applications. In order to constrain both cost and converter volume while using film
capacitors, small DC link capacitance values must be employed. Two challenges are associated with
converters that have small DC link capacitors. First, such converters are highly susceptible to transient
over/under voltages on the DC link. Secondly, even minor grid voltage imbalance can cause large 2nd
harmonic DC link voltage ripple to appear, possibly interfering with the load. This paper details a
control scheme that overcomes both these problems. A feedforward matrix is employed to generate a
set of reference current commands that are processed by high bandwidth stationary frame current
controllers. A novel DC link voltage controller combines load feedforward with a resonant term to
reduce transient over/under voltages and improve immunity to 2nd harmonic voltage ripple under
unbalanced grid conditions. Experimental results demonstrate the efficacy of the proposed converter
controller. |
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| Filename: | Unnamed file |
| Filesize: | 481.4 KB |
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| Type |
Members Only |
| Date |
Last modified 2008-01-18 by System |
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