Step‐down converter with wide voltage conversion ratio

In this study, two new high step-down DC-DC converters are proposed. The proposed converters are designed transformerless and have similar power circuits. For controlling the switches of the proposed converters, two distinct switching patterns are applied. The first switching pattern is interleaved pulse-width modulation pulses with 180° phase shifts, which are applied for the first proposed converter, therefore, the first converter has an interleaved switching pattern and its structure is symmetrical, the voltage stress on its elements decreased. On the other hand, there will be two conversion ratio equations for the first proposed converter for duty cycles larger and less than 0.5. The second switching pattern is applied to the proposed second converter; therefore, in this case, the constant voltage gain is obtained for the whole ranges of duty cycles. The sum of voltage stress on its switches and diodes are a little more than the first converter. The proposed converters are analysed for all of their operating modes. To verify the theoretical results, a prototype of the first and second proposed converter for 500/26 and 800/20.5 V, respectively, and 430 W is implemented in laboratory and the extracted results are compared with calculated ones.

Section: Resultsmentioning

confidence: 99%

“…DC-DC buck converters based on coupled inductors or transformers would be a good choice to increase the output currents. In [8][9][10][11][12], the buck converters based on coupled inductors are presented. A two-phase ultra-high step-down DC converter was presented in [8].…”

Section: Introductionmentioning

confidence: 99%

Two new transformerless high step‐down DC–DC converters

Saadatizadeh

Heris

Sabahi

et al. 2019

“…Also, in the high step-down applications, the extension of duty cycle may be insufficient. In [23][24][25][26], the coupled inductor and series capacitor techniques are simultaneously utilised to resolve the narrow duty cycle and high switch voltage spike problems. In these converters, the zero voltage switching (ZVS) condition is provided for all switches.…”

Section: Introductionmentioning

confidence: 99%

Ultra‐high step‐down ZVS synchronous buck converter with low switch voltage stress

Asghari

2020

In this study, a new zero voltage switching (ZVS) synchronous buck converter with ultra-high step-down conversion ratio is introduced. By combining coupled inductors and energy-transferring capacitors, operating duty cycle is significantly extended while the voltage stress across the switches is reduced. Thereby, extremely low voltage gain can be achieved and the conduction loss is reduced owing to using switches with lower voltage rating. Also, by applying the interleaved method and complementary pulses for switches, the current stress and the output current ripple are reduced. In the proposed converter, soft switching condition is achieved for all switches without any auxiliary circuit. As a result, the overall efficiency of the introduced converter is improved. The converter operation and its design considerations are discussed. Experimental results are presented to validate the theoretical analysis.

“…Coupled-inductor based DC-DC buck converters are good choice to obtain low voltages and high currents without preselecting extremely narrow duty cycles. In [8][9][10][11][12], high stepdown converters based on coupled inductors are presented. In [8], the improvement of the voltage gain of a buck converter with a coupled inductor considering the core size and flux linkage is presented.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, in [12], a flyback converter with coupled inductors in its structure is presented. In the presented step-down converters in [8][9][10][11][12], by decreasing the turn ratio of the secondary winding of these converters, the voltage gain will be significantly improved. However, when high turn ratios are adopted in coupled-inductor based step-down converters, large leakage inductances may occur which causes severe voltage spikes and the input current with be increased which may have undesirable effects on renewable energy devices [13].…”

Section: Introductionmentioning

confidence: 99%

Transformerless quadratic‐based high step‐down DC–DC converter with wide duty cycle range

Heris

Saadatizadeh

Rostami

2019

In this study, a quadratic-based transformerless high step-down DC-DC buck converter is presented. There are two switching patterns applied to the switches. Through the first switching pattern, the proposed converter provides a constant stepdown voltage conversion ratio for the whole ranges of duty cycles. On the other hand, by using an interleaved switching pattern for the proposed converter the input voltage will be divided equally between the primary capacitors, as a result, low voltage stress will be across the semiconductor components. This feature allows the designer to select switches and diodes with lower voltage ratings. However, with the interleaved switching pattern, the converter will have two different voltage conversion ratios for duty cycles larger and less than 0.5. Furthermore, the proposed converter is capable of providing a high range of currents without applying extremely narrow duty ratios. Theoretical analysis is provided in this study. To show the merits of the proposed converter, it is compared with other similar recently presented converters. A 430 W prototype of the proposed converter with 600 V/20 V is implemented and experimental results are presented and compared with the theoretical ones.