Electronic ballasts are open loop systems iwht respect to lamp current.The lamp current is dtermined by values of certain electrical components,all having their own manufacturing tolerances that contribute to an overall error in the lamp current.This paper prensents a concept of closed loop control of current that cancels error in lamp current resulting in constant almp current under all ballast oeprating ocnditions.The paper discusses the benefits of closed loop versus open loop control.The effectiveness of the closed loop approach is assessed by the data obtained from experimental tests.
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