A Three Phase Active Filter based on Three Level Diode Clamp Inverter

Variable speed drives are the main source of harmonics in industrial power systems. The focus of this paper is industrial power systems in heavy industries like petro-chemical industries, steel mills, cement mills etc where medium voltage high power variable speed drives are used. A three phase shunt active filter based on three level diode clamp inverter is presented in this paper. The working principle of the three level shunt active filters, design of controller is explained. A DC bus voltage controller is developed which will not only maintain the DC bus at constant value and but also balance the DC bus voltage. The action of the active filter under steady state operation of the drive, load changes and speed changes, including regeneration is presented.