A Dual Current Probe Method With Enhanced Low-Frequency Sensitivity for High-Voltage Dynamic Capacitance Measurement

High-voltage electronic components are being actively developed, particularly in response to advancements in electric vehicles. The specifications of components such as high-voltage capacitors and power semiconductors are increasing, and their capacitance varies with voltage conditions. Traditional bias tees for high-voltage measurements require higher specifications, increasing physical risks. To enable contactless measurement, an inductive approach using two current probes to extract impedance has gained attention. However, this method suffers from reduced accuracy and sensitivity at lower frequencies, especially for components with high impedance at low frequencies, such as capacitors. This article proposes a method utilizing additional capacitance to enhance measurement accuracy at 100 kHz without requiring extra equipment. The approach was validated through capacitance measurements of multilayer ceramic capacitors (MLCCs) under dc bias voltages, showing a mean square error of up to 7.25% compared to vendor-provided values at voltages up to 500 V.