航空发动机测速电机低转速精准测量方法

Method of Low Rotational Speed Measurement for Aeroengine Tachometer Motor

在航空发动机转速较低时,测速电机输出信号的杂波较大且频率较低,严重制约转速测量精度。提出一种信号调理和半周期测量相结合的策略:首先将正弦输出信号规整为方波信号,将转速测量范围内的信号幅值稳定到一个固定值;其次通过高低时间间隔对信号半周期进行测量,以提高测量响应频率。采用直接测频法和测量周期法对50～2 500 rpm转速范围的测量精度进行考察,表明直接测频法绝对误差小于2 rpm,测量周期法绝对误差小于3 rpm,但测量周期法更适用于低转速测量。

When the rotational speed of aeroengine tachometer motor is low,the output signal is with large clutter and low frequency,which seriously restricts the accuracy of the rotational speed measurement.A strategy is proposed combining signal modulation and semiperiod measurement.Firstly,the sinusoidal output signal is modulated as a square wave signal,and the amplitude of the signal in the range of rotational speed measurement is stabilized to a fixed value.Secondly,the semiperiod of the signal is measured through high and low time intervals,so as to improve the measurement response frequency.The measurement accuracy of 50~2 500 rpm rotational speed range is investigated by using direct frequency measurement method and measurement period method.The results show that the absolute error of former and latter is less than 2 rpm and 3 rpm,respectively,but the measurement period method is more suitable for low rotational speed measurement.