A Fast Dielectric Response Measurement Instrument With Dynamic Power Supply Tracking and Active Suppression of Temperature Fluctuations

This article proposes a fast frequency domain dielectric spectroscopy test scheme for diagnosing oil-paper insulation. The high-voltage output section introduces dynamic power supply tracking (DPST) and cascading techniques to generate high-voltage excitation signals. The DPST can increase the amplifier's voltage slew rate (SR) from 13 V per microsecond to 36.3 V per microsecond without crossover distortion. In the microcurrent measurement section, the error active suppression structure of bias current and bias current under time-varying temperature conditions is proposed to improve the temperature stability of the measurement circuit. The fast testing technology shortens the test period by 65% in the low-frequency band by using the method of multifrequency signal synthesis and partial cycle waveform fitting. The experimental results show that the total harmonic distortion and noise (THD+N) of the output voltage of the instrument are less than or equal to 0.078%. The voltage range is 780 Vpp. The standard deviation of current is less than 1.5%, and the standard deviation of tan δ is less than 1.7%, which verifies the stability of the designed instrument.