Three-phase Flyback-Boost DC-DC converter with three-phase high frequency isolation

Abstract

This paper presents a new modulation strategy of the three-phase DC-DC Boost converter with high frequency isolation. This work has as its main objective to present a solution to deal with the forbidden region found in the study of the referred converter. The proposed modulation keeps the main characteristics of the original topology, which are: the voltage and current frequencies in the output filter are three times the switching frequency, input current ripple reduction, high frequency isolation, moreover, when the converter works within duty ratio up to 1/3, it makes it possible to precharge the output capacitor, reducing the start-up converter' currents. A theoretical analysis of the operating stages and the experimental results are presented to a prototype operating as a Flyback-Boost with switching frequency of 20 kHz, input voltage from 24 V to 120 V, output voltage from 52 V to 450 V and output power from 650 W to 2025 W.

Bidirectional isolated three‐phase dc‐dc converter using coupled inductor for dc microgrid applications

“…It can be seen that in operation at the duty cycle range 1/3 ≤ D < 2/3, the maximum current ripple value of the proposed topology is 0.0083 occurs at D = 1/2, where this value is one‐third compared with Jin and Liu 23 and half value compared with Bal et al 51 While in operation at duty cycle range 2/3 ≤ D < 1, the current ripple of studied topology is higher than that of the converter in Bal et al 52 ; when the duty cycle is equal to 5/6, and the normalized current ripple is equal to 0.0083. Furthermore, the current ripple of the previously proposed converters in previous studies 26 , 51 is higher than that of the proposed topology, according to the values shown in Figure 12A. Also, the normalized current ripple cancellation of the proposed topology occurs when the duty cycle is 1/3 and 2/3, which means that the proposed topology has a better dynamic response and smaller size inductor.…”

“…The objective of this paper is to study and develop a new TBDC with galvanic isolation for applications involving storage energy systems (battery or ultracapacitor) connected to dc microgrid. The proposed topology is derived from the topology shown in Figure 2A, 46 which is an improved version of the unidirectional step‐up dc‐dc topology presented in Oliveira and Barbi 47 …”

“…The objective of this paper is to study and develop a new TBDC with galvanic isolation for applications involving storage energy systems (battery or ultracapacitor) connected to dc microgrid. The proposed topology is derived from the F I G U R E 1 Schematic diagram of the system structure of microgrid [Colour figure can be viewed at wileyonlinelibrary.com] topology shown in Figure 2A, 46 which is an improved version of the unidirectional step-up dc-dc topology presented in Oliveira and Barbi. 47 The steps of obtaining the proposed topology are detailed as follows: (a) the original topology circuit is presented, as exposed in Figure 2A; (b) eliminate the connection between the windings (L 1 , L 2 , and L 3 ) and the switches (S 1 , S 2 , and S 3 ), and afterwards, the terminals of L 1 , L 2 , and L 3 come to be connected to the middle point of the transformer primary windings via the diodes D 7 , D 8 , and D 9 as illustrated in Figure 2B; (c) the original diodes (D 1 ´, D 2 ´, and D 3 ´) can be replaced by three switches (S 4 , S 5 , and S 6 ) connected between the coupled inductors secondary winding and load ground point, according to Figure 2C.…”