0.1Hz VLF cosine square-wave puncture test systems, Owing to have good equivalence with the systems of power frequency withstand voltage and have small size, light weight, etc, can effectively detect defects of XLPE insulated power cables. But now polarity switching circuit of ultra-low frequency device is designed with second order damped shocks with energy loss, resulting in inconsistent positive and negative polarity voltage. That will lead to the accumulation of space charge of XLPE power cable, making the whole performance of the system decreases. To solve the above problem, this paper proposes the use of feedback in polarity switching circuit to solve this problem. By matlab / simulink simulation showing that this method can complement the loss of polarity energy ,making positive and negative polarity of the voltage reach agreement. Simulation results and theoretical analysis of the design are the same.
