# Research on High Power Factor Single Tube Variable Structure Wireless Power Transmission

^{1}

^{2}

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## Abstract

**:**

## 1. Introduction

## 2. System Structure and Operation Process

_{1}is the compensation capacitor, L

_{1}is the resonant inductance, and V

_{T1}is the switch tube. The input DC voltage V

_{g1}is the stable DC voltage output after the input voltage of the total system passes through the voltage converter. For the convenience of analysis, all components in the circuit are assumed to be ideal components. Figure 3 is the topology of parallel resonance of the traditional transmitter, where C

_{2}is the compensation capacitor, L

_{2}is the resonant inductance, and V

_{T2}is the switching tube. The modal waveforms diagram of the transmitter circuit is shown in Figure 4. The input DC voltage V

_{g2}is the stable DC voltage output after the input voltage of the total system passes through the voltage converter. The modal waveforms diagram of the transmitter circuit is shown in Figure 5. For the convenience of analysis, all components in the circuit are assumed to be ideal components. The modal analysis of the two circuits is shown in Table 1.

## 3. Circuit Model Analysis

_{P}is the equivalent inductance, R

_{P}is the equivalent resistance, U

_{OC}is the open-circuit voltage of the side, i

_{P}is the inductance current, L

_{S}is the inductance of the side, C

_{S}is the compensating capacitor of the side, and R is the load, which equals to $R=\frac{{\pi}^{2}{R}_{L}}{8}$. The secondary equivalent impedance is ${Z}_{S}=j\omega {L}_{S}+\frac{R}{1+j\omega {C}_{S}R}$ [20].

_{P}= L

_{1}+ X

_{P}/ω.

_{P}is shorted. Inductance L

_{1}is in charge state and the initial current is zero. According to Kirchhoff’s voltage law, we have

_{0}, t

_{1}] is

_{1}is

_{1}and capacitor C

_{1}will realize resonance. According to Kirchhoff’s voltage law and current law, it can be known that

_{P(t1)}= i

_{P}

_{MAX}, u

_{CP(t1)}= U

_{i}, the current and voltage of the inductance L

_{1}are formulated, respectively, as

_{CP}flowing through the capacitor C

_{P}is

_{S}

_{1}is equal to the current flowing through the inductance L

_{1}for the parallel resonant circuit of the IDC transmitter, such that

_{S}

_{2}equals to the sum of the current flowing through the capacitor C

_{1}and the inductance L

_{1}

## 4. The Simulation Analysis

#### 4.1. Simulation Analysis of Input Current

_{L1}and i

_{L2}are the same, and the conclusion drawn above can be achieved that parallel resonant circuits for the IDC transmitter are equivalent to resonant circuits for the traditional transmitter through this simulation.

_{S2n}is the input current waveform in practice for the traditional circuit. i

_{S1n}is the input current waveform in practice for the IDC circuit. i

_{S2′n}is the input current waveform under ideal conditions for the traditional circuit. The reason for the difference between these two waveforms is that there is a deviation between the theoretical situation and the actual situation. In theoretical analysis, the switch tube is often considered an ideal element, and the parasitic capacitance in the switch tube is ignored, resulting in the i

_{S2′n}waveform. However, in practice, there is a parasitic capacitor inside the open light tube, and when the circuit is in the resonant state, the parasitic capacitor will release power to the resonant circuit, thus mitigating the degree of the sudden change of the input current and smoothing the current waveform. This discovery is proposed for the first time in this paper, and it is hoped that it will be used as a reference for future research and analysis.

_{S1n}and i

_{S2n}in the figure are the same as those derived from the theoretical model, and the input current waveforms of the resonant unit are significantly different. It can be seen from the figure that there is no difference in the input circuit waveforms of the two kinds of circuits in the time period [t

_{0}, t

_{1}]. This is because the capacitor current of the switch tube is shorted at this time, so the capacitor current is zero. For the traditional parallel resonance, the input current i

_{S2n}in the time period (t

_{0},t

_{1}) is equal to the inductance current i

_{L2}. When the switch tube is opened in the time period (t

_{1},t

_{2}), the resonant input current generated by the power exchange between capacitor and inductance is equal to zero. However, for the IDC parallel resonant circuit, the input current i

_{S1n}is always equal to the inductive current i

_{L1}, so that there will be no sudden change, and the current waveform is smoother. There is no current oscillation brought by the original circuit, and the current oscillation will cause great damage to the power supply. The IDC circuit protects the power supply and improves the charging efficiency.

#### 4.2. Simulation Analysis of Ripple Suppression

_{1}and current flows into the inductance. When the switch tube is cut off, the inductance L

_{1}and the compensation capacitor C

_{1}begin to resonate. When the capacitor C

_{1}transfers all the power to the inductance L

_{1}, the current will flow backward into L

_{1}. Since the input current i

_{S1}is equal to the inductance current i

_{L1}, the input current will increase in the opposite direction, which will cause the ripple in the circuit.

_{S2n}is the input current waveform before phase-shift and i

_{S2′n}is the input current waveform after phase-shift. Through comparison, it can be seen that the input current amplitude of the traditional topology has not been improved after the phase-shift, and the waveform has a mutation and distortion. Its fundamental properties have not been changed, and it seems to be more fluctuant without any help to the stability of the whole system. Figure 17 shows the input current waveform of the IDC at 180 degrees phase-shift under static condition. In the figure, i

_{S1n}is the input current waveform before the phase-shift of the IDC, and i

_{S1′n}is the input current waveform after the phase-shift of the IDC. It can be seen from the figure that the peak value of the input current of the parallel resonant circuit of the IDC decreases significantly after the phase-shift of 180 degrees, and the current is similar to the sine wave, which is very smooth. This is of great help to the stability of the whole system, which can greatly improve the system’s efficiency and reduce the loss of power supply.

_{S2O}is the input current waveform before phase-shifting in the traditional topology, and i

_{S2 ‘o}is the input current waveform after phaseshifting in the traditional topology. It can be seen that the amplitude does not change much after phase-shifting in the traditional topology, and the mutation and conflict of the current become more serious. As shown in Figure 19, i

_{S1o}is the input current waveform before phase-shifting in the IDC topology, and i

_{S1′o}is the input current waveform after phase-shifting in the IDC topology. It can be seen that the current amplitude drops significantly, and the waveform becomes smooth after phase-shifting in the IDC topology.

## 5. Experimental Verification

## 6. Conclusions

## Author Contributions

## Funding

## Data Availability Statement

## Acknowledgments

## Conflicts of Interest

## References

- Yang, Y.; Wan, C.; Shen, X. Design of bidirectional DC-DC power supply software. J. Southwest Univ. (Nat. Sci. Ed.)
**2017**, 39, 175–180. [Google Scholar] - Li, H.; Wang, C.; Yue, R. Research on single tube radio energy transmission circuit based on SiC device. Proc. CSEE
**2020**, 40, 1808–1817. [Google Scholar] - Huang, X.; Zhao, J.; You, X. An improved interleeway control method based on input-series-output shunt phase-shifting full-bridge converters. Trans. China Electrotech. Soc.
**2020**, 35, 81–90. [Google Scholar] - Sun, Y.; Liao, Z.; Ye, Z. Study on frequency splitting characteristics of MCR-WPT system based on vibration theory. Trans. China Electrotech. Soc.
**2018**, 33, 240–248. [Google Scholar] - Cheng, L.; Cui, Y.; Yan, G. Research on magnetic coupled resonant radio energy transmission frequency tracking control. Power Electron.
**2014**, 48, 3–6. [Google Scholar] - Li, Y.; Zhang, Y.; Yang, Q. Analysis and experimental verification of maximum power efficiency of magnetic coupled resonant radio energy transmission system. Trans. China Electrotech. Soc.
**2016**, 31, 18–24. [Google Scholar] - Pan, C.; Liu, K.; Zheng, Y. Transmission characteristics of series-parallel radio energy system with mutual inductance parameters. Trans. China Electrotech. Soc.
**2016**, 31, 39–44. [Google Scholar] - Li, J.; Cheng, B. Research on magnetic coupled resonance type serial radio energy transmission system. J. Shaoyang Univ. Nat. Sci. Ed.
**2018**, 15, 46–54. [Google Scholar] - Pan, C.; Liu, K.; Zheng, Y. Research on the performance of electromagnetic coupled resonant radio energy transmission system. Power Electron.
**2017**, 51, 113–115. [Google Scholar] - Zhou, H.; Sun, L.; Wang, S. Analysis of resonant mode of magnetically coupled resonant radio energy transmission system. Electr. Mach. Control
**2016**, 20, 65–73. [Google Scholar] - Li, Y. High-efficiency class E inverter power for magnetic coupled resonant radio energy transmission system. Trans. China Electrotech. Soc.
**2019**, 34, 21–27. [Google Scholar] - Wang, H.; Wang, A. Research on Relay Structure of Magnetic Coupling Resonance Wireless Power Transmission System. J. Northeast. Univ. Nat. Sci. Ed.
**2016**, 37, 913–917. [Google Scholar] - Ahn, D.; Hong, S. Wireless Power Transfer Resonance Coupling Amplification by Load-Modulation Switching Controller. IEEE Trans. Ind. Electron.
**2015**, 62, 898–909. [Google Scholar] [CrossRef] - Li, Z.; Wei, Z.; Xia, J. Modeling and analysis of magnetic coupled resonant radio energy transmission system. Electr. Appl. Energy Effic. Manag. Technol.
**2017**, 22, 12–16. [Google Scholar] - Zhao, J.; Zhou, S.; Cui, Y. Research and implementation of design method of LCL magnet-coupled resonant radio energy transmission system. High Volt. Eng.
**2019**, 45, 234–241. [Google Scholar] - Zhao, J.; Zhou, S.; Cui, Y. Study on stability of magnetic coupled resonant serial radio energy transmission power. Adv. Technol. Electr. Eng. Energy
**2018**, 37, 20–29. [Google Scholar] - Cheng, Z.; Lei, Y.; Song, K. Design and loss analysis of loosely coupled transformer for an underwater high-power inductive power transfer system. IEEE Trans. Magn.
**2015**, 51, 8401110. [Google Scholar] - McDonough, M. Integration of inductively coupled power transfer and hybrid energy storage system: A multiport power electronics interface for battery-powered electric vehicles. IEEE Trans. Power Electron.
**2015**, 30, 6423–6433. [Google Scholar] [CrossRef] - Lee, S.Y.; Hsieh, C.H.; Yang, C.M. Wireless front-end with power management for an implantable cardiac microstimulator. IEEE Trans. Biomed. Circuits Syst.
**2012**, 6, 28–38. [Google Scholar] - Cai, H.; Shi, L.; Li, Y. Harmonic-based phase shifted control of inductively coupled power transfer. IEEE Trans. Power Electron.
**2014**, 29, 594–602. [Google Scholar] [CrossRef] - Gonzalez, J.; Alatise, O.; Hu, J. An investigation of temperature-sensitive electrical parameters for SiC power MOSFETs. IEEE Trans. Power Electron.
**2017**, 32, 7954–7966. [Google Scholar] [CrossRef] [Green Version] - Chen, K.; Zhao, Z.; Yuan, L. The impact of nonlinear junction capacitance on switching transient and its modeling for SiC MOSFET. IEEE Trans. Electron Devices
**2015**, 62, 333–338. [Google Scholar] [CrossRef]

**Figure 15.**Relationship between circulation size, phase-shifting angle, and switching frequency. (

**a**) Anlarged; (

**b**) Zoom out.

**Figure 31.**Waveform of 180° phase-shifting input current under load condition of traditional topology.

Mode | Separate Topological Transmitter | Traditional Topological Transmitter |
---|---|---|

Stage 1 | i_{L1} increases linearly when the switch is on. | Switch tube continuation diode conduction. |

Stage 2 | When the switch is off, i_{L1} decreases and C_{1} accumulates charge. | When the switch is on, i_{L2} increases linearly. |

Stage 3 | The switch is closed and the capacitor charges the inductance. | The switch tube closes and the inductance and capacitor enter the resonant state. |

Stage 4 | The switch tube is turned on with zero voltage, and the inductance current is continued through the continuing diode, which is reduced to zero, and stage 1 is repeated. | The inductance charges the capacitor in reverse, and the voltage withstand of the switch reaches its maximum. |

Stage 5 | Capacitor discharges, voltage resistance of switch tube is reduced. | |

Stage 6 | The inductance charges the capacitor, the voltage drop of the switch is zero, and the continuation secondary leads on. | |

Stage 7 | The switch tube realizes zero voltage conduction. |

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

Switching frequency | 206 kHz |

Receiving/Transmitting resonant inductance | 7 µH |

The receiver compensates the capacitance | 0.094 µF |

load | 15 Ω |

The coupling coefficient | 0.3 |

Input Current/A | Output Voltage/V | Output Current/A | Transmission Efficiency/% | |
---|---|---|---|---|

Traditional PP system | 1.05 | 5.25 | 2.01 | 83.75 |

IDC PP-type system | 1.03 | 5.21 | 2.02 | 85.15 |

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**MDPI and ACS Style**

Yang, Y.; Zhang, X.; Luo, L.; Xie, S.; Zhou, Q.
Research on High Power Factor Single Tube Variable Structure Wireless Power Transmission. *World Electr. Veh. J.* **2021**, *12*, 214.
https://doi.org/10.3390/wevj12040214

**AMA Style**

Yang Y, Zhang X, Luo L, Xie S, Zhou Q.
Research on High Power Factor Single Tube Variable Structure Wireless Power Transmission. *World Electric Vehicle Journal*. 2021; 12(4):214.
https://doi.org/10.3390/wevj12040214

**Chicago/Turabian Style**

Yang, Yi, Xuejian Zhang, Lei Luo, Shiyun Xie, and Qingshan Zhou.
2021. "Research on High Power Factor Single Tube Variable Structure Wireless Power Transmission" *World Electric Vehicle Journal* 12, no. 4: 214.
https://doi.org/10.3390/wevj12040214