Characteristics of Space Charge Accumulation Under Unipolar Square Wave Voltage

In this article, the characteristics of space charge accumulation in insulating materials under unipolar square wave voltage are studied. Taking silicone elastomer as the research object, the effects of amplitude, frequency, and duty cycle of square wave voltage on the space charge characteristics of the material are studied. According to the relationship between the interface electric field and space charge, a recursive model describing the process of space charge accumulation under unipolar periodic square wave voltage is derived. Under the unipolar square wave voltage, the space charge accumulation gradually reaches stability. Comparing the calculated results of average volume charge density with the experimental results, it shows that the model proposed in this article can effectively describe the charge accumulation process. The criterion of charge accumulation reaching stability is put forward, and the time of charge accumulation reaching stability under different waveform parameters is obtained. With the increase of the electric field, the shorter the time required for charge accumulation to reach stability. With the increase of the duty cycle, the time for charge accumulation to reach stability first decreases and then increases. The time for charge accumulation to reach stability at different frequencies is basically the same.