# Comparative Analysis of Si- and GaN-Based Single-Phase Transformer-Less PV Grid-Tied Inverter

^{*}

## Abstract

**:**

## 1. Introduction

## 2. Proposed Inverter Description and Operation Principle

#### 2.1. Proposed Topology

#### 2.2. Operation Modes Analysis

## 3. Theoretical Power Loss Model Calculation

## 4. Performance Evaluation of Si MOSFET and GaN HEMT

#### 4.1. Conduction Characteristics

#### 4.2. Switching Characteristics

## 5. Simulation Results and Discussion

#### 5.1. Efficiency Improvement

#### 5.2. Passive Component Reduction

^{3}. Accordingly, this will result in a reduction of the inductor weight as demonstrated in Figure 14. The inductor weight was reduced from 618 to 120 g.

#### 5.3. Improvement In Power Rating

## 6. Thermal Design and Simulation Analysis

#### 6.1. Model Outline

#### 6.2. Model Geometry

#### 6.3. Material Properties

#### 6.4. Heat Transfer Physics Modeling

^{2}K to simulate non-forced free flowing air. The initial temperature of the structures and surrounding air was set to room temperature i.e., 293.15 K or 20 ${}^{\circ}$C. Using these inputs and boundary conditions, COMSOL solved the heat equation in solids to obtain the temperature profiles of each model.

#### 6.5. Model Simulation and Results

^{3}and surface area of 1861 cm

^{2}for the heatsink while the GaN model had a volume of 125.6 cm

^{3}and surface area of 826.3 cm

^{2}. From the simulations for the two models, it is clear that the WBG GaN MOSFET module requires a smaller heatsink (by a factor of 0.444 for GaN in terms of surface area) for similar maximum temperatures. Thus, using GaN HEMT will consequently reduce the overall system volume. The thermal modelling clearly demonstrates that the GaN module is more efficient than the Si module in terms of heatsink size and overall heat dissipation.

## 7. Conclusions

## Author Contributions

## Conflicts of Interest

## References

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**Figure 4.**Proposed topology operational modes: (

**a**) Active state positive half- cycle; (

**b**) Zero-state positive half cycle; (

**c**) Active state negative half- cycle; (

**d**) Zero-state negative half cycle.

**Figure 5.**Forward voltages of Si MOSFET and GaN HEMT at various current and junction temperature: (

**a**) Si MOSFET and GaN HEMT forward voltage at 25 ${}^{\circ}$C junction temperature; (

**b**) Si MOSFET and GaN HEMT forward voltage at 150 ${}^{\circ}$C junction temperature.

**Figure 7.**The turn-on and turn-off waveforms of Si MOSFET and GaN HEMT at 400 V and 30 A: (

**a**) Si MOSFET Turn-on; (

**b**) GaN HEMT Turn-on; (

**c**) Si MOSFET Turn-off; (

**d**) GaN HEMT Turn-off.

**Figure 8.**Turn-on and Turn-off switching energy losses of Si MOSFET and GaN HEMT: (

**a**) Turn-On; (

**b**) Turn-Off.

**Figure 11.**The balance point where GaN HEMT losses at 500 kHz is equal to Si MOSFET losses at 50 kHz.

H5 | H6 | Proposed Topology | |
---|---|---|---|

Total number of devices | 5 | 6 | 6 |

Number of conducting devices ($v>0$) | 3 | 3 | 2 |

Number of conducting devices ($v<0$) | 3 | 2 | 2 |

Total Number of conducting devices during active modes | 6 | 6 | 4 |

Number of devices in freewheeling | 2 | 2 | 2 |

Turn-On | Turn-Off | |||
---|---|---|---|---|

Si | GaN | Si | GaN | |

dv/dt (kV/$\mathsf{\mu}$s) | 6 | 9.6 | 4.9 | 15.8 |

di/dt (kA/$\mathsf{\mu}$s) | 0.63 | 4 | 0.4 | 3 |

Current (A) | Si MOSFET | GaN HEMT | ||
---|---|---|---|---|

${\mathit{E}}_{\mathit{on}}$($\mathsf{\mu}$J) | ${\mathit{E}}_{\mathit{off}}$($\mathsf{\mu}$J) | ${\mathit{E}}_{\mathit{on}}$($\mathsf{\mu}$J) | ${\mathit{E}}_{\mathit{off}}$($\mathsf{\mu}$J) | |

0 | 0 | 0 | 0 | 0 |

5 | 109.16 | 26.86 | 73.1 | 14 |

10 | 223.17 | 28.92 | 76.5 | 14.1 |

15 | 343.9 | 53.59 | 92.3 | 14.2 |

20 | 472.86 | 105.69 | 102 | 14.1 |

25 | 604.8 | 170.94 | 109 | 14.5 |

30 | 760.32 | 264.29 | 118.3 | 14.6 |

40 | 1045.6 | 482.79 | 143.2 | 14.8 |

Parameter | Value |
---|---|

System Power | 5 kW |

Input Voltage | 400 V |

Grid Voltage | 120 V |

Grid Frequency | 60 Hz |

Switching Frequency | 50 kHz and 200 kHz |

Input Capacitance (${C}_{DC})$ | 1 mF |

Parameter | IPW60R045CP | GS66516T |
---|---|---|

${V}_{DS}$ (V) | 650 | 650 |

${I}_{D}$ (A) | 60 | 60 |

${R}_{DS}$ (m$\Omega $) | 45 | 25 |

${Q}_{G}$ (nC) | 150 | 12.1 |

${Q}_{GS}$ (nC) | 34 | 4.4 |

${Q}_{GD}$ (nC) | 51 | 3.4 |

${C}_{iss}$ (pF) | 6800 | 520 |

${C}_{oss}$ (pF) | 320 | 130 |

${C}_{rss}$ (pF) | - | 4 |

Property | Symbol | Unit | Cu | SAC396 | AIN | Si | GaN | Al |
---|---|---|---|---|---|---|---|---|

Density | $\rho $ | kg/m${}^{3}$ | 8960 | 7400 | 3260 | 2329 | 6070 | 2700 |

Heat capacity at constant pressure | ${C}_{p}$ | J/(kg K) | 385 | 220 | 740 | 700 | 490 | 900 |

Thermal conductivity | k | W/(m K) | 400 | 61.1 | 160 | 131 | 130 | 238 |

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**MDPI and ACS Style**

Alatawi, K.; Almasoudi, F.; Manandhar, M.; Matin, M.
Comparative Analysis of Si- and GaN-Based Single-Phase Transformer-Less PV Grid-Tied Inverter. *Electronics* **2018**, *7*, 34.
https://doi.org/10.3390/electronics7030034

**AMA Style**

Alatawi K, Almasoudi F, Manandhar M, Matin M.
Comparative Analysis of Si- and GaN-Based Single-Phase Transformer-Less PV Grid-Tied Inverter. *Electronics*. 2018; 7(3):34.
https://doi.org/10.3390/electronics7030034

**Chicago/Turabian Style**

Alatawi, Khaled, Fahad Almasoudi, Mahesh Manandhar, and Mohammad Matin.
2018. "Comparative Analysis of Si- and GaN-Based Single-Phase Transformer-Less PV Grid-Tied Inverter" *Electronics* 7, no. 3: 34.
https://doi.org/10.3390/electronics7030034