• 조명전기설비학회논문지
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• 제22권12호
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• pp.64-70
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• 2008

종래의 준 랜덤 주파수 캐리어(PRC : Pseudo-Randomized Frequency Carrier) 변조기법을 3상 H-브리지 멀티레벨 인버터(HBML: H-Bridge Multi-Level Inverter)에 적용하는 경우, 스위칭 주파수의 2배 주파수 영역에서 큰 스펙트럼 클러스터가 그대로 존재하는 문제점이 있다. 본 연구에서는 서로 2배의 주파수 비율을 갖는 2개의 고정주파수 삼각파 캐리어와 3단계 멀티플렉서(MUX : Multiplexer)를 이용하여 종래의 PRC기법의 고조파 스펙트럼 확산 효과를 개선하였다. 제안된 기법은 1.5[kw]급 3상 HBML인버터 구동시스템에 적용하였으며, 종전의 방법과 제안된 방법의 전압 및 전류 고조파 스펙트럼을 비교 검토하였다.

• Journal of Electrical Engineering and Technology
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• 제10권5호
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• pp.2018-2030
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• 2015

A two stage ac drive configuration consisting of a single-phase line commutated rectifier and a three-phase voltage source inverter (VSI) is very common in low and medium power applications. The deterministic pulse width modulation (PWM) methods like sinusoidal PWM (SPWM) could not be considered as an ideal choice for modern drives since they result mechanical vibration and acoustic noise, and limit the application scope. This is due to the incapability of the deterministic PWM strategies in sprawling the harmonic power. The random PWM (RPWM) approaches could solve this issue by creating continuous harmonic profile instead of discrete clusters of dominant harmonics. Insufficient filtering at dc link results in the amplitude distortion of the input dc voltage to the VSI and has the most significant impact on the spectral errors (difference between theoretical and practical spectra). It is obvious that the sprawling effect of RPWM undoubtedly influenced by input fluctuation and the discrete harmonic clusters may reappear. The influence of dc link fluctuation on harmonics and their spreading effect in the VSI remains invalidated. A case study is done with four different filter capacitor values in this paper and results are compared with the constant dc input operation. This paper also proposes an ingenious RPWM, a ripple dosed sinusoidal reference-random carrier PWM (RDSRRCPWM), which has the innate capacity of suppressing the effect of input fluctuation in the output than the other modern PWM methods. MATLAB based simulation study reveals the fundamental component, total harmonic distortion (THD) and harmonic spread factor (HSF) for various modulation indices. The non-ideal dc link is managed well with the developed RDSRRCPWM applied to the VSI and tested in a proto type VSI using the field programmable gate array (FPGA).