Short Through Avoidance in AC-AC Choppers

This article discusses a new approach to improve the switching characteristics of a buck-AC chopper. Conventionally, a line voltage detection based switching algorithm is utilized for this purpose. A new switching strategy for a pulse-width modulated AC chopper has distinct advantages over a voltage detecting method, such as higher reliability, lower harmonic contents, and high efficiency. In addition, it can avoid the short through problem, which is inherent in conventional methods in the case of false zero crossing detection. Both methods are analyzed through simulation in MATLAB (The MathWorks, Natick, Massachusetts, USA). The advantage of the proposed approach is verified by experimental results using a laboratory prototype.