基于幅频自校准的高精度LVDT模拟器设计

Design of High Accuracy LVDT Simulator Based on Amplitude-frequency Calibration

摘要:

电路模拟LVDT传感器在航空发动机测试中有着广泛的应用,相对于机械传感器其降低了使用难度和维护费用；传统模拟器由于电路中变压器的影响,仿真精度较差导致系统测试准确性降低,研制高精度LVDT模拟器存在着较大的工程需求；文章从LVDT传感器工作原理出发,基于乘法型DAC芯片实现了电路合成模拟LVDT传感器；同时在模拟器中设计自动校准单元,利用离线拟合并存储到FPGA中的模板曲线对不同通道进行在线校准,消除了变压器幅频响应的影响,提高了模拟器在宽频率范围内的仿真精度；文章通过理论推导证明了模板曲线的有效性,通过测试数据验证了该模拟器在0.36~10 kHz范围内可达到优于0.1%的设计精度；该模拟器能够逼真模拟LVDT传感器的电气行为,已成功应用于某型号发动机控制系统的地面仿真测试平台中,达到了预期效果。

Abstract:

Electronically simulated LVDT sensor is widely used in the aviation engine test field, which lowered use difficulty and maintenance charge relative to mechanical sensor. Conventional simulator’s poor accuracy lowered the test accuracy because of transformers. So there are big engineering requirements in designing high-accuracy LVDT simulator. From LVDT simulator’s working principles, the paper realized to simulate LVDT sensor based on multiplying DAC chips. Simultaneously we designed auto-calibration unit and utilized fitting template curve to on-line calibration stored in FPGA, which eliminated the impact of amplitude-frequency response and increased simulation accuracy in wide frequency range. The validity of the template curve was proved by theoretical deduction. The excelled 0.1% design accuracy in 0.36~10 kHz range was verified by test data. The simulator can simulate LVDT sensor’s electrical character, which has been used successfully in some aircraft engine control system simulation test platform, achieving expected effect.