A fault-tolerant control technique is discussed for the Neutral-Point-Clamped (NPC) three-level inverter, which ensures that the\nNPC inverter operates normally even under device failures. A two-level leg is added to the NPC inverter; when the device open\ncircuit fault occurs, the load of this faulty phase is connected to the neutral point of this two-level leg through the bidirectional\nthyristors. An improved Space Vector Pulse Width Modulation (SVPWM) strategy called ââ?¬Å?addition and subtraction substitution\nSVPWMââ?¬Â is proposed to effectively suppress fluctuation in capacitor neutral-point voltages by readjusting the sequence and action\ntime of voltage vectors. The fault-tolerant topology in this paper has the advantages of fewer switching devices and lower circuit\ncosts. Experimental results show that the proposed fault-tolerant system can operate in balance of capacitor neutral-point voltages\nat full output power and the reliability of the inverter is greatly enhanced.
Loading....