一种基于磁隔离技术的输出电压误差反馈电路

An Output Voltage Feedback Circuit Based on Magnetic Isolation Technique

在航天星、船等特殊场合,开关变换器的闭环控制要求磁隔离反馈输出电压信号,但通常采用主变压器绕组反馈或专用磁隔离芯片实现的方案存在稳定性低、可靠性差和成本高的缺点。提出一种基于磁隔离技术的电压误差反馈电路,有效解决了上述问题。通过时序图详细分析了所提电路的工作原理,并计算工作波形。同时,探讨磁隔离电路中三极管驱动脉宽的低成本实现方式及磁环的设计要点。基于所推导的增益关系式和小信号模型,分析磁隔离电压误差反馈电路的特性及实现闭环负反馈的补偿器结构,并以单管正激为例设计系统闭环环路。最后,根据分析进行实验,实验结果验证了所提磁隔离电压误差反馈电路的可行性与有效性。

In some applications, such as spacecraft and satellite, output voltage of switching converter requires to be magnetic isolated feedback, which is usually achieved by the scheme of main power transformer winding feedback or magnetic isolation ASIC adoption.However,there exist the disadvantages of low stability ,poor reliability and high cost. To solve above problems, a novel circuit with magnetically isolated voltage error feedback is presented.The working principle and mathematical model of proposed circuit are analyzed in detail according to the timing diagram.Implementation of transistor drive signal and design of toroidal magnetic core are discussed.Based on the derived gain and small signal model of proposed circuit, this paper analyzes its characteristics and compensation structure, and closedloop design of single-switch forward circuit is further presented.Finally,experimental results verify the feasibility and effectiveness of proposed magnetically isolated circuit.