Abstract: An important implementation method of self-sensing active magnetic bearings（SAMB） is to extract the current ripple properties in the output of switching power amplifiers and estimate the rotor displacement. In the SAMB system, the current ripple properties in the output of switching power amplifier are not only related with rotor displacement, but also affected by system operation status and system parameters, which induce rotor displacement estimation errors. Furthermore, this phenomenon is more severe at high frequencies. For the current harmonic amplitude demodulation type SAMB, how does the duty cycle affect the current harmonic amplitude demodulator’s output under different system operation status, especially at high frequencies, was firstly analyzed by utilizing the inductance model, current ripple model and current harmonic amplitude demodulator’s output model. Then the effects of different system parameters on rotor displacement estimation errors were discussed. Finally, the associated conclusions were validated through experiments on an eight-pole radial SAMB platform.