The relations between the simulation circuit parameters and the linear motor parameters were achieved by analyzing the equivalent circuit of the linear motor and the simulation circuit of piston displacement self-sensor. The experimental study on the linear motor parameters was carried out. The results show that the force coefficient

the equivalent inductance and resistance are constant when the moving magnets oscillate in an operating region. The force coefficient decreases slightly when the moving magnet is close to the top dead position(TDP). The equivalent inductance and resistance of the linear motor are constant in a certain current range. The experiment was conducted to investigate the output characteristics of the self-sensor. The results show that the output waveform is hardly influenced by the fluctuating of the equivalent inductance and resistance

and the output amplitude is influenced by the force coefficient. In order to improve the output precision of the self-sensor

it is suggested that the parameters of the self-sensor' circuit should be slightly adjusted to avoid the output waveform distortion

and the output of the self-sensor should be corrected when the piston is close to TDP.