空间低温制冷控制器的缓启动电路建模分析

Modeling analysis of slow-startup circuits of space cooling controller

随着大功率空间低温斯特林制冷机的出现,制冷控制器仍采用传统缓启动和LC储能滤波串联抑制电路会产生不平稳/大超调的启动电流,造成制冷机控制器过流保护并对卫星电源及其他设备造成可能的浪涌破坏。在不增加元器件的情况下,提出一种具有启动电流反馈功能的缓启动和LC储能滤波电路配合方式。首先通过采用非线性器件MOSFET的低频微变等效模型对新旧配合电路进行了数学建模。之后针对小电感小电容和大电感大电容两种应用模式下的数学模型进行了简化和分析,在小电感小电容模式下新旧配合电路均可简化为无超调的一阶系统,在大电感大电容模式下传统配合电路为具有振荡特性的二阶系统,而新的配合电路仍为一阶系统,可以满足大电感大电容模式下启动电流无超调要求。最后通过Multisim仿真对比分析和实际试验证明了新的配合电路的合理性和有效性,试验表明启动电流均匀平稳无超调,启动电流峰值抑制约50%。

With more powerful space stirling cooler coming out, if the controller still uses traditional slow-startup and LC energy storage and filtering series circuits, an unstable and large overshoot start-up current will be caused, which leads to the controller overcurrent protection and potential surge damages to satellite power and other devices. Under the condition of not adding components, a slow-startup circuit connecting LC energy storage and filtering circuit cooperative way with start-up current feedback function was proposed. Firstly, the new and old cooperative circuits with low frequency equivalent model of nonlinear MOSFET were modeled. Secondly, the models both in the condition of small inductance and small capacitance and in the condition of large inductance and large capacitance were simplified and analyzed. In the condition of small inductance and small capacitance, both cooperative circuits can be simplified to non-overshot first-order system. In the condition of large inductance and large ＇capacitance, the traditional cooperative circuits was simplified to second-order system with oscillation characteristics. However, the new cooperative circuits is still first-order system, which satisfies the requirements of non-overshoot start-up current in the condition of large inductance and large capacitance. Finally, the simulation contrastive analysis and experimental verification was used to proof the new cooperative circuits rationality and effectiveness. The test shows the start-up current stable and no overshoot and the peak of the start-up current is restrained up to about 50%.