英语翻译According to the detailed circuit analyses in [17],the v

英语翻译According to the detailed circuit analyses in [17],the voltage gain ( V G ) of the high step-up converter and the corresponding switch voltage ( DS v ) can be represented as ) where D is the duty cycle of the switch (Q).Because the voltage gain ( V G ) is less sensitive to the coupling coefficient (k),(4) and (5) can be rewritten with k = 1 as/ (2 )/(1 ) V d pv G =V V = + n D (5)/(1 ) DS pv v = V D (6)According to (5) and (6),one can obtain /( 2) DS d v =V n + (7) By analyzing (7),the switch voltage ( DS v ) is not related to the input power source ( pv V ) and the switch duty cycle (D) if the values of the output voltage ( d V ) and the turns ratio (n) are fixed.Thus,it can ensure that the maximum sustainable voltage of the switch (Q) is constant.As long as the input voltage is not higher than the switch voltage rating,the high step-up converter can be applied well to low-voltage PV power sources even with large voltage variations.