# Comparative Verification of Radiation Noise Reduction Effect Using Spread Spectrum for Inductive Power Transfer System

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## Abstract

**:**

## 1. Introduction

## 2. Radiation Noise Reduction Method

#### 2.1. Generation Method of Pseudorandom Numbers

_{z−p}and X

_{z−q}are the present values of X

_{z}delayed by periods of p and q, respectively (p > q). In this paper, p = 7 and q = 1 are used. Note that the number of bits of the pseudorandom number is seven.

#### 2.2. Probability Distributions for Reduction Method

## 3. Design of Transmission Coil

#### 3.1. SS Compensation Method

_{1}is the primary voltage, R

_{eq}is the equivalent load resistance, r

_{1}is the equivalent series resistance of the primary winding, r

_{2}is the equivalent series resistance of the secondary winding, L

_{1}is the primary inductance, L

_{2}is the secondary inductance, C

_{1}is the primary compensation capacitor, C

_{2}is the compensation capacitor on the secondary side, L

_{m}is the mutual inductance, and ω is the angular frequency of the power supply. Note that the voltage V

_{1}is the fundamental component of the output voltage of the inverter.

_{eq}indicates that equivalent load resistance considering the full-bridge rectifier. Then the equivalent load resistance is given by [16]:

_{DC}

_{,2}is the DC voltage on the secondary side and P

_{2}is the output power.

_{DC}

_{,1}is the DC voltage on the primary side and k is the coupling coefficient.

#### 3.2. SP Compensation Method

**V**

_{1}is the fundamental component of the output voltage of the inverter.

_{eq}indicates the equivalent load resistance considering the full-bridge rectifier. Then the equivalent load resistance is given by [16]:

## 4. Experimental Results

#### 4.1. Experimental Setup

#### 4.2. Operation Waveform

_{1}varies. However, constant output voltages were obtained for all operation methods. In the waveforms with SP compensation, a similar characteristic was obtained as shown in Figure 8. Besides, when the operating frequency was higher than the resonant frequency due to the operation of spread spectrum, zero-voltage switching (ZVS) was achieved because the current flowed in the direction to discharge the parasitic capacitance of the MOSFETs, which would turn-on after the dead time, during the dead time. In contrast, ZVS was not achieved when the transmission frequency was lower than the resonant frequency.

#### 4.3. Radiation Noise Measurement Conditions

#### 4.4. Efficiency Evaluation

## 5. Conclusions

## Author Contributions

## Funding

## Conflicts of Interest

## References

- Hui, S.Y.R.; Zhong, W.; Lee, C.K. A Critical Review of Recent Progress in Mid-Range Wireless Power Transfer. IEEE Trans. Power Electron.
**2014**, 29, 4500–4511. [Google Scholar] [CrossRef] - Shimode, D.; Mura, T.; Fujiwara, S. A Study of Structure of Inductive Power Transfer Coil for Railway Vehicles. IEE Jpn. J. Ind. Appl.
**2015**, 4, 550–558. [Google Scholar] [CrossRef] [Green Version] - Hayashi, Y.; Chiku, Y. Contactless DC Connector Concept for High-Power—Density 380-V DC Distribution System. IEE Jpn. J. Ind. Appl.
**2015**, 4, 49–58. [Google Scholar] [CrossRef] - Kusaka, K.; Orikawa, K.; Itoh, J.; Hasegawa, I.; Morita, K.; Kondo, T. Galvanic Isolation System with Wireless Power Transfer for Multiple Gate Driver Supplies of a Medium-voltage Inverter. IEEJ J. Ind. Appl.
**2016**, 5, 206–214. [Google Scholar] [CrossRef] - Mizuno, T.; Ueda, T.; Yashi, S.; Ohtomo, R.; Goto, Y. Dependence of Efficiency on Wire Type and Number of strands of Litz Wire for Wireless Power Transfer of Magnetic Resonant Coupling. IEEJ J. Ind. Appl.
**2014**, 3, 35–40. [Google Scholar] [CrossRef] - Trung, N.K.; Ogata, T.; Tanaka, S.; Akatsu, K. Analysis and PCB Design of Class D Inverter for Wireless Power Transfer Systems Operating a 13.5 MHz. IEEJ J. Ind. Appl.
**2015**, 4, 703–713. [Google Scholar] - Boys, J.T.; Covic, G.A.; Xu, Y. DC Analysis Technique for Inductive Power Transfer Pick-Ups. IEEE Trans. Power Electron.
**2003**, 1, 51–53. [Google Scholar] [CrossRef] - Ministry of Internal Affairs and Communications. Inquiry of Technical Requirements for Wireless Power Transfer System for EVs in Technical Requirements for Wireless Power Transfer System in Standards of International Special Committee on Radio Interference (CISPR); Ministry of Internal Affairs and Communications: Tokyo, Japan, 2015.
- Jo, M.; Sato, Y.; Kaneko, Y.; Abe, S. Methods for Reducing Leakage Electric Field of a Wireless Power Transfer System for Electric Vehicles. In Proceedings of the 2014 IEEE Energy Conversion Congress and Exposition (ECCE), Pittsburgh, PA, USA, 14–18 September 2014; pp. 1762–1769. [Google Scholar]
- Kim, H.; Cho, J.; Ahn, S.; Kim, J.; Kim, J. Suppression of Leakage Magnetic Field from a Wireless Power Transfer System using Ferrimagnetic Material and Metallic Shielding. In Proceedings of the 2012 IEEE International Symposium on Electromagnetic Compatibility, Pittsburgh, PA, USA, 6–10 August 2012; pp. 640–645. [Google Scholar]
- Campi, T.; Cruciani, S.; Feliziani, M. Magnetic Shielding of Wireless Power Transfer Systems. In Proceedings of the 2014 International Symposium on Electromagnetic Compatibility, Tokyo, Japan, 12–16 May 2014; pp. 422–425. [Google Scholar]
- Maikawa, K.; Imai, K.; Minagawa, Y.; Arimitsu, M.; Iwao, H. Magnetic Field Reduction Technology of Wireless Charging System. In JSAE Annual Congress Autumn 2013; JSAE: Tokyo, Japan, 2013. [Google Scholar]
- Kusaka, K.; Inoue, K.; Itoh, J. Reduction in Radiation Noise Level for Inductive Power Transfer System with Spread Spectrum. In Proceedings of the International Electric Vehicle Technology & Automotive Power Electronics Japan Conference, Yokohama, Japan, 25–30 May 2016. No. 20169063. [Google Scholar]
- Inoue, K.; Kusaka, K.; Itoh, J. Reduction in Radiation Noise Level for Inductive Power Transfer Systems using Spread Spectrum Techniques. IEEE Trans. Power Electron.
**2018**, 33, 3076–3085. [Google Scholar] [CrossRef] - Kusaka, K.; Inoue, K.; Itoh, J. Comparative Verification of Radiation Noise Reduction Effect using Spread Spectrum for Inductive Power Transfer System. In Proceedings of the 31st International Electric Vehicles Symposium & Exhibition & International Electric Vehicle Technology Conference 2018 (EVS 31 & EVTeC), Kobe, Japan, 30 September–3 October 2018. No. 20189223. [Google Scholar]
- Bosshard, R.; Kolar, J.W.; Muhlethaler, J.; Stevanovic, I.; Wunsch, B.; Canales, F. Modeling and η-α-Pareto Optimization of Inductive Power Transfer Coils for Electric Vehicles. IEEE J. Power Electron.
**2014**, 3, 50–64. [Google Scholar] - Kusaka, K.; Inoue, K.; Itoh, J. Radiation noise reduction using spread spectrum for inductive power transfer systems considering misalignment of coils. In Proceedings of the 2017 IEEE Energy Conversion Congress and Exposition (ECCE), Cincinnati, OH, USA, 1–5 October 2017; pp. 5507–5514. [Google Scholar]

**Figure 1.**Maximum allowable radiation noise for inductive power transfer (IPT) system of 7 kW or less for use in electric vehicles (EVs) in Japan (under discussion).

**Figure 3.**Probability distributions for proposed methods. Changing range of switching frequency of inverter is from 80 kHz to 90 kHz: (

**a**) is the proposed method I (SSUD), and (

**b**) is the proposed method II (SSBD).

**Figure 4.**Equivalent circuits for designing the IPT systems: (

**a**) is the SS compensation method, and (

**b**) is the SP compensation method.

**Figure 5.**Circuit configuration of prototype: (

**a**) is the series-series (SS) compensation method, and (

**b**) is the series-parallel (SP) compensation method.

**Figure 6.**Transmission coils with rated power of 3 kW. Lower side is transmitter coil, upper side is receiver coil. White winding on the secondary side is used as SS compensation method. Red winding on secondary side is used as SP compensation method.

**Figure 7.**Operation waveforms with SS compensation: (

**a**) is the constant frequency operation, (

**b**) is the spread spectrum with a uniform distribution (SSUD), and (

**c**) is the spread spectrum with a biased distribution (SSBD).

**Figure 8.**Operation waveforms with SP compensation: (

**a**) is the constant frequency operation, (

**b**) is the SSUD, and (

**c**) is the SSBD.

**Figure 9.**Measurement environment of radiation noise: (

**a**) is the measurement point A, (

**b**) is the measurement point B. The distance from the edge of the transmission coils to each measurement position is 500 mm.

**Figure 10.**Radiation noise at measurement point A in y-z plane with SS compensation: (

**a**) is the conventional method with constant frequency, (

**b**) is the proposed method I: SSUD, and (

**c**) is the proposed method II: SSBD.

**Figure 11.**Radiation noise at measurement point A in y-z plane with SP compensation: (

**a**) is the conventional method with constant frequency, (

**b**) is the proposed method I: SSUD, and (

**c**) is the proposed method II: SSBD.

Symbol | Value | |
---|---|---|

Input DC voltage | V_{in} | 420 V |

Rated power | P | 3.0 kW |

Coupling coefficient | k | 0.20 |

Primary inductance | L_{1} | 392 H |

Secondary inductance | L_{2} | 401 μH (SS) 24.2 μH (SP) |

Primary capacitance | C_{1} | 8.96 nF |

Secondary capacitance | C_{2} | 8.78 nF (SS) 145 nF (SP) |

Transmission distance | l | 150 mm |

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**MDPI and ACS Style**

Kusaka, K.; Inoue, K.; Itoh, J.-i.
Comparative Verification of Radiation Noise Reduction Effect Using Spread Spectrum for Inductive Power Transfer System. *World Electr. Veh. J.* **2019**, *10*, 40.
https://doi.org/10.3390/wevj10020040

**AMA Style**

Kusaka K, Inoue K, Itoh J-i.
Comparative Verification of Radiation Noise Reduction Effect Using Spread Spectrum for Inductive Power Transfer System. *World Electric Vehicle Journal*. 2019; 10(2):40.
https://doi.org/10.3390/wevj10020040

**Chicago/Turabian Style**

Kusaka, Keisuke, Kent Inoue, and Jun-ichi Itoh.
2019. "Comparative Verification of Radiation Noise Reduction Effect Using Spread Spectrum for Inductive Power Transfer System" *World Electric Vehicle Journal* 10, no. 2: 40.
https://doi.org/10.3390/wevj10020040