强耦合条件下非接触滑环工作特性分析与控制

Working Characteristic Analysis and Control of Contactless Slipring System Under Strong Coupling Condition

非接触滑环系统中旋转变压器工作气隙一般小于10mm,耦合系数一般大于0.5,属于强耦合条件。在此工作条件下,非接触滑环系统对耦合系数变化敏感度较小,但变换器中谐波含量较大,导致基波近似分析方法误差增加。为此,文中推导出串/串补偿时非接触谐振变换器原、副边电流精确的表达式。此外,为消除3次谐波,采用无中线的三相星形结构。建立了三相系统的数学模型,研究了三相系统的控制策略,并指出采用不对称控制方式调宽时,实现软开关的调节范围比对称控制方式更大。最后,搭建了一台200 W的原理样机,实验结果验证了理论分析的有效性与正确性。

The air gap of the rotating transformer in the contactless slipring system (CSS)is usually less than 10mm and the coupling coefficient is usually more than 0.5.It belongs to the strong coupling condition.Higher coupling coefficient could help CSS reduce the sensitivity of coupling coefficient to parameter variation.But it will also increase the harmonic content in the resonant tank and the errors of fundamental harmonic approximation (FHA)method.In order to solve these problems,this paper deduces accurate expressions of the primary and secondary currents for the S/S compensated contactless resonant converter.In addition,this paper adopts the three-phase system,which is star-connected with an open neutral point to eliminate the third harmonic.The mathematical model and control strategy of the three-phase system are studied.It is pointed out that the asymmetrical control has a wider range of adjustment than the symmetrical control in the realization of soft switching.Finally,experimental results on a 200W prototype are presented to evaluate the effectiveness of theoretical analysis.