HV HIPOT design for dielectric strength testing

In this study, a high-voltage tester was designed to detect post-production faults and quality control of high-voltage cables. It is also used to detect defects in cables caused by crushing, breaking, and bending. The device's input voltage is three-phase 380V (AC), and the output voltage is 80-100 kV (AC) with an adjustable frequency between 20-400 Hz. The device is called High Voltage (HV) high potential (HIPOT). HV HIPOT tests aim to check the high-voltage material's isolation by measuring the product's dielectric strength. This device combines a 3-phase auto transformer, AC DC converter, DC-AC converter, High voltage transformer, and RLC resonant tank. First, for safety reasons, an autotransformer is used to set the input voltage to 40V (AC) while detecting the resonant frequency. Next, the input AC voltage is converted to DC voltage using a three-phase full-wave rectifier to supply the DC-AC converter. As a DC-AC converter, the driver board is designed. The driver board consists of a power inverter, control, and measurement circuit. An intelligent power module (IPM) and a digital signal controller (DSPIC33FJ64MC204) are used in the inverter part of the driver board. According to the output voltage and current measurement value, DSPIC generates a PWM signal with a carrier frequency of 20-400Hz and applies it to the IPM. The inverter feeds the high-voltage transformer, which is used to supply the RLC resonant circuit. According to the calculated R, L, and C values of the resonant circuit, the Q gain ratio of the output voltage is determined. Then the output voltage applies to the material for testing isolation, and the driver observes the current flowing. Even with a tiny current flowing, the resonance is disturbed; if the wires are not well insulated, the test will fail. The presented system is modeled and examined using MATLAB/Simulink. The simulation results confirm that the proposed circuit offers high stability and efficiency. Keywords: High-Potential, Isolation Testing, Inverter, Frequency Modulation, RLC Resonant Tank