A Controlled High-Voltage DC Source for Power Semiconductor Components Testing

The presented high-voltage DC source was designed to enable laboratory measurements of reverse and forward characteristics in non-conducting state of power semiconductor components. It also enables to measure the minimum triggering current or control voltage in dependence of the voltage on main electrodes for SCR, triac or voltage-controlled semiconductor devices such as MOSFET and IGBT, respectively. The source consists of a high-voltage switching converter, voltage and current measuring subsystems and electrically insulated linearmode current source. Control and measuring tasks inside the source are performed by means of an 8-bit Microchip microcontroller 18F452. The switching converter is comprised of a flyback step-up transformer and four identical secondary modules connected in series. The flyback transformer is carefully constructed to minimize its stray capacitance and leakage inductance. These parasitic components cause high-frequency oscillations and make setting of the precise output voltage even more difficult. In proposed aiming of improving the output-voltage control, the turn-on speed of the switching MOSFET is decreased and, consequently, the charging current of the transformer parasitic capacitors is limited.