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A Pseudo Randomly Triggered Integer Cycle Control (PRT-ICC) for AC Loads to Reduce THD, EMI and RFI

Md. Rashedul Amin, Shahriyar Masud Rizvi, Jerry J Cupal


Several proportional voltage control techniques exist for AC loads. The most popular of these are phase control (PC), cycle control (CC) (including integral cycle control (ICC) and fractional cycle control (FCC)) and pulse-width modulation (PWM)). Phase control utilizes triggering for loads away from zero voltage or zero current and generates odd harmonics with amplitudes higher than ICC and PWM. Integral cycle control, causes more harmonics (both even and odd) overall and higher supply distortion, but generates smaller-amplitude higher-frequency harmonics and reduced THD and EMI/RFI (due to zero-point switching) as compared to phase control and pulse width modulation. By triggering the AC cycles in cycle control pseudo-randomly but in proportion to voltage regulation requirement, THD and EMI/RFI can be further reduced even compared to PWM. Largest sub-harmonic components have smaller-amplitudes as compared to conventional ICC and are further away from fundamental frequency, (which are too near the fundamental frequency in conventional ICC). Overall, the PRT-ICC produces least harmonics, sub-harmonics and EMI/RFI among all comparable AC voltage controllers. It should greatly reduce the need for filters and shielding, reduce flickering and improve longevity of motors.

Cite this Article

Md. Rashedul Amin, Shahriyar Masud Rizvi, Cupal Jerry J. A pseudo randomly triggered integer cycle control (PRT-ICC) for AC loads to reduce THD, EMI and RFI. Journal of Embedded Systems and Applications. 2015; 3(3): 22–39p.

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