双电源水位控制系统中模/数转换的实现

Implementation of A/D Conversion in Water Level Control with Double Power Supply

针对双电源供电测控系统中电源切换和电池供电时存在电压纹波较大以及电压值随着时间的推移而变小，从而引起A／D转换结果和实际测量之间误差较大的问题，提出了一种即时校准A／D转换的方法．在检测过程中实时检测供电电压的变化情况，计算电压系数，并根据该系数对实际检测结果进行校正，以减小供电电压对A／D转换的影响．在水位控制系统中对该方法进行了实验验证．结果表明，在150～950mm水位测量过程中，在不同的供电电压下，检测偏差在1%左右．该方法具有很强的稳定性，完全满足多电源供电系统中对测量精度的要求．

In measuring and control system with multi-power supply, power switch makes the power voltage wave greater, and the voltage of batters decreases as time goes on, these elements cause the measured value deviate from the real value which may cause the failure of the control system. In order to resolve this problem, a new A/D conversion method based on real-time adjusting is proposed. This method measures the voltage of power supply and calculates the voltage coefficient which is used to adjust the measured voltage to reduce the influence of voltage undulation on A/D conversion. This method has been testified in water level control system designed by the authors. The test results show that within the water level range of 150 mm to 950 mm, the measuring errors are about 1% under different supply voltage. It is proved that the new A/D conversion method is stable and meets accurate measuring requirement of multiple power supply system.