▌01 无线充电系统

1.背景

在昨天(2021-02-09)无线充电系统的功率与效率 的文章在 公众号(TSINGHUAZHUOQING) 发出之后，张斌给出了两点建议：

谐振电容要用c0g的，而且要注意电压电流应力，不能用x7r，其容值会变。串串补漏感和自感都可以。发射端用LCC补偿，可实现有无接收端时发射线圈都恒流，更适合比赛，现在ev无线充电也是这样做的。
利兹线的漆包要烫透（不冒黑色泡为止，沾松香水后用锡炉烫更好），否则线圈的阻会影响效率。无线充电系统有个最优负载的概念，大家可以查查文献。耦合系数k，线圈的交流阻，最优负载，三个主要因素直接影响效率。

其中关于功率部分采用LCC拓扑结构可以在无负载情况下形成输出恒流的特性会提高系统在运行动态过程中的可靠性。下面通过查找相关论文进行综述研究。

2. 研究论文：

注意：很多的文章只能够在清华校内网络上从ieeexplore.ieee.org上下载下来。

▌02 Paper Review

1. An Optimizable Circuit Structure for High-Efficiency Wireless Power Transfer

Paper Link:An Optimizable Circuit Structure for High-Efficiency Wireless Power Transfer

（1）Scaling Factor

Using word “shunt” refer to parallel .
Define the scaling factor: relative distance
$scaling\,\,factor = { {transfer\,dis\tan ce} \over {coil\,\,diameter\,\,}}$

▲ Mixed-resonant coupleing circuit with its three degenerated forms

^{▲ Mixed-resonant coupleing circuit with its three degenerated forms}

（2）Using Scatter Factor

▲ Scatter Parameter Definition

^{▲ Scatter Parameter Definition}

Definition of S21:

$\left| {S_{21} } \right| = 2 \cdot { {V_L } \over {V_S }} \cdot \left( { { {R_s } \over {R_L }}} \right)^{ {1 \over 2}}$

Power Efficiency : $\eta = \left| {S_{21} } \right|^2$

⊙ Applying LCC Compensation Network to Dynamic Wireless EV Charging System

Applying LCC Compensation Network to Dynamic Wireless EV Charging System

▲ Diagram of symmetrical T-compensated network

^{▲ Diagram of symmetrical T-compensated network}

（1）T-symmetrical compensated network

Input resistance:
$Z_i = { {X^2 } \over {Z_0 }}$

Load Current:I0
$I_0 = { {U_i } \over {jX}}$

When Z is one mutual inductance, we can substitude the second coil as reflect resistance, which value is :

$Z_r = { {\left( {\omega M} \right)^2 } \over {Z_2 }}$

Parameters:

M: Mutual inductance;

\omega

: radian(Angular, Circular) frequency;

Z_2

: The second turns load.

（2）设计副边补偿网络

▲ 接收线圈等效电路

^{▲ 接收线圈等效电路}

根据最优接收效率设计：
首先根据对称T型补偿电路公式， $Z_i = { {X^2 } \over {Z_0 }}$ ，假设 $Z_i = R_{L\_OPT\_\eta }$ ， $Z_0 = 8/\pi ^2 \cdot R_L$ （全桥整流负载），那么 $X_s = \sqrt {R_{L\_OPT\_\eta } \cdot {8 \over {\pi ^2 }}R_L }$

根据文章中（A6）大体确认：

$R_{L\_OPT\_\eta } = \omega M\sqrt { { {R_{P2} } \over {R_{P1} }}} \approx \omega M$

这部分参见下面阅读的文章中的讨论。

因此：

（3）设计原边补偿网络参数

▲ 发送线圈补偿网络示意图

^{▲ 发送线圈补偿网络示意图}

其中副边反射电阻在负载等于最佳效率电阻式对应： $R_{refav} = \omega M$

Step1： Determine the Irq:

$I_{rq} = \sqrt {P_{out} /\eta _e R_{ref} }$

Argument:

Pout: Output power;

\eta

: Primary to secondary coil efficiency
Rref: Equvalent reflect resistance from receive coil

Step2: Determine Xp:
$X_p = { {U_i } \over {I_{rq} }}$

其中: $\alpha ,\beta$ 可以取1来进行计算。

2. Maximum Energy Efficiency Tracking for Wireless Power Transfer Systems

Maximum Energy Efficiency Tracking for Wireless Power Transfer Systems

Review Detail: Review: Maximum Energy Efficiency Tracking for Wireless Power Transfer Systems

3.A Double-Sided LCC Compensation Network and Its Tuning Method for Wireless Power Transfer

A Double-Sided LCC Compensation Network and Its Tuning Method for Wireless Power Transfer

（1） Contents

A theoretical analysis of double-sided LCC compensation
ZVS tuning method
Design method and Experimental.

▲ Double-Sided LCC compensation Topology

^{▲ Double-Sided LCC compensation Topology}

▌结论

■ 相关文献链接:

无线充电系统在输出部分采用LCC拓扑结构综述研究