# Design Methodology and Circuit Analysis of Wireless Power Transfer Systems Applied to Electric Vehicles Wireless Chargers

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## Abstract

**:**

## 1. Introduction

## 2. Design Methodology for WPT System

#### 2.1. The Resonant WPT System for SS Topology

- Static charging: this mode involves charging the vehicle at specific locations with the engine turned off, either at home or in charging stations.
- Stationary charging: Vehicles can be charged in dedicated zones such as traffic lights while the engine of the vehicle is still running. This mode is particularly useful for public transportation, such as taxis and buses.
- Dynamic charging: This mode involves charging the vehicle when it is in motion, and the road is equipped with electronics to facilitate the charging process.

- The off-board part is situated on the ground outside the vehicle and spans from the Electric Vehicle Supply Equipment (EVSE) to the primary coil.
- The on-board part is located within the vehicle and extends from the receiving coil into the battery of the vehicle.

#### 2.2. Calculation of the Design-Related Parameters

#### 2.2.1. The Design Parameters of the Pad

- The wire diameter ${w}_{d}$, which is selected according to the current of the coil.
- The pitch of the coil represents the height of one complete turn.

- Above Ground Mounting involves mounting the pad assembly on the surface.
- Flush Ground Mounting involves mounting the pad assembly within the surface, with the top of the pad flush with the surface.
- Buried Mounting involves mounting the pad with the top of the pad below the surface.

#### 2.2.2. The Electrical Parameters and the Transferred Power Expression

#### 2.3. Magnetic Core and Shielding Plate: Analysis and Design

#### 2.3.1. Magnetic Core

- Scenario 1: circular coreless model.
- Scenario 2: circular core model using ferrite bars.
- Scenario 3: circular core model using a ferrite plate.

#### 2.3.2. Shielding Plate

#### 2.4. Design Methodology for WPT System for SS Compensation Topology

#### 2.4.1. Flow Chart of Pad Dimension Optimization

#### 2.4.2. The Results of Coil Dimensions and Design Parameters for a 3.7 kW WPT System

- Minimizing the length of the cable (Equation (16)).
- Verifying the bifurcation condition (Equation (35)).

## 3. Verification and Analysis of the Magnetic Design

#### 3.1. Finite Element Modeling

#### 3.2. The Distribution of Magnetic Flux Density

#### 3.3. Types of Losses of the Magnetic Coupler

#### 3.3.1. Losses of the Litz Wire Coil

#### 3.3.2. Losses of the Ferrite Core

#### 3.3.3. Losses of Aluminum Shield

## 4. Circuit Analysis of the WPT System

#### 4.1. Presentation of the Simulation Circuit

#### 4.2. Simulation Results for 3.7 kW

- Number of turns = 19.
- Mutual inductance = 74.8 $\mathsf{\mu}\mathrm{H}$.
- Dimensions of ferrite bars = 230 (mm) × 30 (mm) × 20 (mm).
- Dimensions of the aluminium plate = 600 (mm) × 600 (mm) × 1 (mm).

#### 4.3. Bifurcation Phenomenon in WPT System

_{s}refers to the secondary quality factor.

## 5. Conclusions

- The importance of ferrite and aluminum in the system.
- The exact dimensions of the ferrite and aluminum plate bars.
- A clear methodology based on FEA software that provides optimized pad dimensions such as the length of the litz wire needed for coil construction, the outer diameter Dout, the inner diameter Din, and the number of turns N.
- The study incorporates a circuit analysis to confirm the identified dimensions and enhance the efficiency of the system.

## Author Contributions

## Funding

## Acknowledgments

## Conflicts of Interest

## References

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**Figure 7.**Circular models: (

**a**) circular coreless model; (

**b**) circular model using ferrite bars; (

**c**)circular model using a ferrite plate.

**Figure 10.**The magnetic field distribution on the YZ plane was simulated under the same conditions: (

**a**) case 1: circular coreless model; (

**b**) case 2: with ferrite and aluminum.

Ferrite | (mm) |
---|---|

Dimensions of ferrite bar | 225 × 30 × 20 |

Dimensions of ferrite plate (radius × thickness) | 250 × 20 |

**Table 2.**The coupling coefficient values for three cases with variations of the gap from 100 mm to 200 mm.

Gap Variation (mm) | The Coupling Coefficient | ||
---|---|---|---|

Case 1 | Case 2 | Case 3 | |

100 | 0.254742 | 0.369677 | 0.385042 |

120 | 0.209370 | 0.305432 | 0.316385 |

140 | 0.173810 | 0.253880 | 0.261800 |

160 | 0.145391 | 0.212085 | 0.217908 |

180 | 0.122344 | 0.178019 | 0.180967 |

200 | 0.103442 | 0.149973 | 0.153215 |

Parameters | (mm) |
---|---|

Dimensions of ferrite bars | 230 × 30 × 20 |

Dimensions of ferrite plate | 600 × 600 × 1 |

N = 11 | N = 13 | N = 16 | N = 17 | N = 18 | N = 19 | |
---|---|---|---|---|---|---|

$M(\mu \mathrm{H})$ | 26.38 | 36.13 | 54.86 | 62.40 | 68.07 | 74.80 |

${P}_{trans}\left(\mathrm{k}\mathrm{W}\right)$ | 1.4 | 1.92 | 2.92 | 3.29 | 3.61 | 3.97 |

Title 1 | Title 2 |
---|---|

${D}_{in}$ | 285 mm |

${L}_{1}$ | 239.30 µH |

${L}_{2}$ | 239.24 µH |

$M$ | 74.80 µH |

$k$ | 0.31 |

${C}_{1}$ | 14.65 nF |

${C}_{2}$ | 14.65 nF |

Operating Frequency | Strand Gauge | Strand Diameter | Number of Strands | Nominal Outside Diameter | Construction Type |
---|---|---|---|---|---|

50 KHz to 100 kHz | AWG 38 | 0.1007 mm | 1050 | 0.189 inches | 2 |

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## Share and Cite

**MDPI and ACS Style**

Bouanou, T.; El Fadil, H.; Lassioui, A.; Bentalhik, I.; Koundi, M.; El Jeilani, S.
Design Methodology and Circuit Analysis of Wireless Power Transfer Systems Applied to Electric Vehicles Wireless Chargers. *World Electr. Veh. J.* **2023**, *14*, 117.
https://doi.org/10.3390/wevj14050117

**AMA Style**

Bouanou T, El Fadil H, Lassioui A, Bentalhik I, Koundi M, El Jeilani S.
Design Methodology and Circuit Analysis of Wireless Power Transfer Systems Applied to Electric Vehicles Wireless Chargers. *World Electric Vehicle Journal*. 2023; 14(5):117.
https://doi.org/10.3390/wevj14050117

**Chicago/Turabian Style**

Bouanou, Tasnime, Hassan El Fadil, Abdellah Lassioui, Issam Bentalhik, Mohamed Koundi, and Sidina El Jeilani.
2023. "Design Methodology and Circuit Analysis of Wireless Power Transfer Systems Applied to Electric Vehicles Wireless Chargers" *World Electric Vehicle Journal* 14, no. 5: 117.
https://doi.org/10.3390/wevj14050117