System Noise Suppression of Muzzle Voltage in Augmented Electromagnetic Railgun Based on VMD and the Application in Armature–Rail Contact Characteristics

The muzzle voltage is an important characteristic parameter of electromagnetic railgun. The contact resistance between the sliding armature and the copper rail surface during the launching process can be calculated by utilizing it to analyze the armature–rail contact characteristics. However, in the engineering experiments of augmented electromagnetic railgun, the detected muzzle voltage waveform will be disturbed by the system noise because of the existence of augmented rail, firing sequence of pulse forming network (PFN), and friction of armature–rail contact surface. Therefore, it is difficult to calculate the contact resistance accurately. This article presents a new noise suppression method variational mode decomposition (VMD) for suppressing the jagged noise in the muzzle voltage. A method for calculating the contact resistance is presented to analyze the armature–rail contact characteristics. A frame for analyzing the contact characteristics of the electromagnetic railgun is presented. The method can suppress the system noise by utilizing the signal mode decomposition in the time domain based on the frequency characteristics of VMD. Then, in order to analyze the armature–rail contact characteristics, the contact resistance can be calculated according to the formula derived from the theory. The results show that the method can suppress the muzzle voltage system noise effectively. And the calculated contact resistance wave is smooth, which is helpful to analyze the armature–rail contact characteristics. The noise component extracted from muzzle voltage contains pulse signals, and the time and amplitude of these pulse signals are related to PFN’s firing sequence and the changing trend of the armature–rail contact resistance. The method proposed in this article provides a new and reliable reference for monitoring the launching state of electromagnetic railgun in engineering experiments.