# A New High-Gain DC-DC Converter with Continuous Input Current for DC Microgrid Applications

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## Abstract

**:**

## 1. Introduction

_{O}. In [12], a voltage doubler circuit was introduced by the authors. With the help of diodes and switched capacitors, the voltage at the output could be increased significantly. In [13], a new DC-DC Luo converter having positive output voltage was introduced. Only switched capacitors and diodes were employed for increasing gain. Coupled inductor-based topologies are also popular to achieve very high gain. To achieve the desired gain, the coupled inductor’s turn ratio is adjusted, but this results in higher input current ripple. The high-gain converters proposed in [14,15,16,17] addressed the problems associated with coupled inductor topologies. New boost converters with a voltage multiplier cell (VMC) were proposed by the authors in [18,19,20]. VMC can be incorporated with conventional converters like boost, SEPIC, and conventional quadratic boost (CQBC) to increase the gain. A VMC employing switched capacitors suffers from the problem of high charging current, which results in additional power losses. Moreover, the number of components also increases when a VMC is used, leading to an increase in the cost and decrease in the reliability of the converter. Another family of converters are interleaved boost converters. These converters produce high gain at smaller duty ratios. An interleaved converter needs several VMCs [21,22,23,24] at the output to increase the voltage. In [25], a three-port DC-DC converter suitable for solar PV applications was proposed by the authors. In [26], an extendable switched inductor based high-gain converter was proposed by authors. The converter in [26] had continuous input current and reduced stress across switches, but many inductors were used to achieve high gain. In [27], a new hybrid switched-capacitor high-gain converter for DC microgrids was proposed. In [28], a modified SEPIC converter was proposed for solar PV applications. In [29], a boost converter with a VMC was explained and discussed. However, the converter had many voltage-multiplier levels, but the converter still provided low voltage gain. A new high-gain converter with built-in transformers and a VMC was proposed in [30]. In [31], a non-isolated high-gain converter with switched capacitors and voltage doublers was proposed by the authors. In [32], a new QBC with a voltage doubler and a single switch was proposed by the authors. Some other recently developed high-gain converters have been proposed by authors in [33,34,35]. Although these converters have high gain, the number of passive components is high. The main novelty of the converter proposed in the current study is that it has a quadratic gain with only four passive elements. The other features of the converter are:

- Continuous input current;
- Quadratic voltage gain with reduced voltage stress across switches;
- High efficiency and easy control.

## 2. Structure and Working of the Proposed Converter

_{1}and D

_{2}are reverse-biased. The conduction diagram is given in Figure 2. In this operation mode, both the capacitors discharge and transfer their energy to the inductors and to the load, respectively, while both inductors store energy, and the inductor current subsequently increases linearly.

_{2}and L

_{1}:

## 3. Design of Passive Components and Stress across Switches

#### 3.1. Design of Inductors

_{1}and L

_{2}are:

#### 3.2. Design of Capacitor

#### 3.3. Voltage Stress across Switches

_{1}and S

_{2}is less than V

_{O}.

## 4. Comparison Assessment with Other Converters

_{O}. Similarly, the converter proposed in [28] had three inductors and three capacitors; still, the gain was limited and stress across the switch was high. As can be observed in Figure 5, our proposed high-gain structure has a gain of 8 times at D = 0.6. The gain rapidly increases from 0.7 to 0.8 duty ratio. Apart from higher gain, the converter utilizes only 8 components, and hence losses in the ON state and parasitic resistance would be low. Figure 6 gives the normalized voltage stress across the switch of the converter. It can be observed that the two switches of the converter had different voltage stresses across them. As compared with other structures, the switch S

_{1}had the lowest stress across it. The stress across switch S

_{2}was less than V

_{O}but was higher than S

_{1}. Further, it can be observed that the stress across S

_{2}also was less than in the converters proposed in [28] and the conventional quadratic boost converter (CQBC) proposed in [11].

## 5. Experimental Results

_{O}was equal to 80 V, which was proximate to the theoretical value. The voltage across the capacitor was found to be 40 V, which was half the V

_{O}. The converter was operating in continuous conduction mode, as evident from the waveforms of the inductor currents shown in Figure 8b. The voltage stress across switch S

_{1}was found to be 40 V, and the stress across the switch S

_{2}was found to be 65 V, as observed in Figure 8c. The stress across both switches was less than V

_{O}, which was an improvement over the other conventional topologies, thereby improving the efficiency. The converter had a continuous input current, which is its main advantage. The average input current I

_{in}and output current I

_{O}were found to be 1.5 A and 0.4 A, respectively. Furthermore, the input current had a very low voltage ripple, which eliminated the need for any input filter.

_{1}was 27 V, which was almost the same as that of the calculated value. The inductor currents and voltage across switches are shown in Figure 9b,c.

## 6. Efficiency Calculation

_{O}is found to be 82.1 V for V

_{in}= 24 V and D = 0.4, which is very close to the experimental value of 80 V.

## 7. Conclusions

_{in}= 24 V. The merits of converter make it worthy for renewable energy applications for an output power in the range of 200–300 W.

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Conflicts of Interest

## References

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**Figure 8.**Experimental results at V

_{in}= 24 V, D = 0.4. (

**a**) V

_{O}, V

_{C1}, and V

_{in}. (

**b**) I

_{L1}and I

_{L2}. (

**c**) V

_{O}, V

_{ds1}, and V

_{ds2}. (

**d**) I

_{o}, I

_{in}, and V

_{gs}.

**Figure 9.**Experimental results at V

_{in}= 10 V, D = 0.65. (

**a**) V

_{O}, V

_{C1}, and V

_{in}. (

**b**) I

_{L1}and I

_{L2}. (

**c**) V

_{O}, V

_{ds1}, V

_{ds2}.

Topology | Inductors | Capacitors | Switches | Diodes | Total Components | Voltage Gain $({\mathit{V}}_{\mathit{o}}/{\mathit{V}}_{\mathit{i}\mathit{n}})$ | Normalized Voltage Stress $({\mathit{V}}_{\mathit{S}}/{\mathit{V}}_{\mathit{i}\mathit{n}})$ |
---|---|---|---|---|---|---|---|

[4] | 2 | 3 | 1 | 3 | 9 | $\frac{1+D}{\left(1-D\right)}$ | $\frac{1}{1-D}$ |

[6] | 2 | 3 | 1 | 4 | 10 | $\frac{3+D}{2\left(1-D\right)}$ | $\frac{1}{1-D}$ |

[7] | 4 | 6 | 1 | 3 | 14 | $\frac{3D}{\left(1-D\right)}$ | $\frac{1}{1-D}$ |

[9] | 4 | 1 | 2 | 7 | 14 | $\frac{1+3D}{\left(1-D\right)}$ | $\frac{1+D}{1-D}$ |

[10] | 2 | 2 | 1 | 3 | 8 | $\frac{D\left(2-D\right)}{{\left(1-D\right)}^{2}}$ | $\frac{2}{\left(1-D\right)}$ |

[11] | 2 | 2 | 1 | 3 | 8 | $\frac{1}{{\left(1-D\right)}^{2}}$ | $\frac{1}{{\left(1-D\right)}^{2}}$ |

[28] | 3 | 3 | 1 | 3 | 9 | $\frac{D}{{\left(1-D\right)}^{2}}$ | $\frac{D}{{\left(1-D\right)}^{2}}$ |

Proposed | 2 | 2 | 2 | 2 | 8 | $\frac{1+D-{D}^{2}}{{\left(1-D\right)}^{2}}$ | ${S}_{1}\left[\mathrm{P}\right]=\frac{1}{1-D}$ ${S}_{2}\left[\mathrm{P}\right]=\frac{1}{{\left(1-D\right)}^{2}}$ |

Elements | Rating/Model |
---|---|

V_{in} | 24 V, 10 V |

P_{o} (max) | 150 W |

f_{s} | 50 kHz |

R (Load) | 250 Ω, 300 Ω |

Inductors | L_{1} = L_{2} = 330 µH, ESR = 0.2 Ω |

Capacitors | C_{1} = C_{2} = 33 µF 200 V, ESR = 0.15 Ω |

S_{1} and S_{2} | SPW52N50C3 |

D_{1} and D_{2} | SF8L60USM |

Gate Drivers IC | TLP250H |

Microcontroller | STM32 Nucleo H743ZI2 |

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**MDPI and ACS Style**

Ahmad, J.; Zaid, M.; Sarwar, A.; Lin, C.-H.; Asim, M.; Yadav, R.K.; Tariq, M.; Satpathi, K.; Alamri, B.
A New High-Gain DC-DC Converter with Continuous Input Current for DC Microgrid Applications. *Energies* **2021**, *14*, 2629.
https://doi.org/10.3390/en14092629

**AMA Style**

Ahmad J, Zaid M, Sarwar A, Lin C-H, Asim M, Yadav RK, Tariq M, Satpathi K, Alamri B.
A New High-Gain DC-DC Converter with Continuous Input Current for DC Microgrid Applications. *Energies*. 2021; 14(9):2629.
https://doi.org/10.3390/en14092629

**Chicago/Turabian Style**

Ahmad, Javed, Mohammad Zaid, Adil Sarwar, Chang-Hua Lin, Mohammed Asim, Raj Kumar Yadav, Mohd Tariq, Kuntal Satpathi, and Basem Alamri.
2021. "A New High-Gain DC-DC Converter with Continuous Input Current for DC Microgrid Applications" *Energies* 14, no. 9: 2629.
https://doi.org/10.3390/en14092629