Research on real-time online detection of breaking time for unipolar contactor

A new method that implements the real-time online detection of breaking time for unipolar contactor is proposed. First of all, fast Fourier transformation (FFT) was employed to determine the characteristic band of arcing moment. After that, the optimal wavelet function was chosen based on the characteristic band, which is applied to feedback the contact instantaneous opening moment. Finally, this paper proposes time and frequency domain criterions to detect the changing point of break operation and finds out that it obtains excellent transient response capability at the time of sudden changes of the contact voltage. Hardware control modules are adopted to verify that the breaking time feedback loop based on the Mallat algorithm can achieve the real-time online feedback for the breaking time of the unipolar contactor. For achieving zero-current breaking, which is of practical significance especially for the batch control, thus eliminating the disadvantage that traditional schemes require prior measurement of the breaking batch contactors.