This paper proposes an open switch faults detection and localization algorithm for shunt three

phase active filter topology. It mainly details converter configuration and examines a simple and

reliable optimised fault diagnosis method. The con verter topology is based on classical three-leg

active power filter topology. A ne w fault diagnosis method is proposed, based on classical

currents measurements. It includes combinatory logic to analyse and validate error signals. A

Hysteresis Control is applied before and after fault detection, which avoids any controller

reconfiguration. Simulation results obtained with Matlab/Simulink/Plecs tools prove the

effectiveness of this method. -This paper proposes an open switch faults detection and localization algorithm for shunt three

phase active filter topology. It mainly details converter configuration and examines a simple and

reliable optimised fault diagnosis method. The con verter topology is based　on classical three-leg

active power filter topology. A ne w fault diagnosis method is　proposed, based on classical

currents measurements. It includes combinatory logic to analyse and validate error signals. A

Hysteresis Control is applied before and after fault detection, which avoids any controller

reconfiguration. Simulation results obtained　with Matlab/Simulink/Plecs tools prove the

effectiveness of this method.