Embedded digital protection for IPMSM drives

This paper presents the development, real-time implementation, and experimental testing of a new embedded digital protection for three phase (3φ) interior permanent magnet synchronous motor (IPMSM) drives. The proposed digital protection is established through extracting the high frequency sub-band contents present in the d-q-axis components of the currents drawn by an IPMSM. the desired high frequency sub-band contents are extracted using the wavelet packet transform (WPT). These extracted high frequency sub-band contents contain signature information that allow detecting and classifying transient disturbances occurring in IPMSM drives. Such a structure of the d - q WPT-based digital protection simplifies its implementation, and facilitates its embedding within the controller of an IPMSM drive. Performances of the proposed digital protection are investigated experimentally on a laboratory 5-hp IPMSM drive. Experimental test results for various fault and non-fault transient disturbances demonstrate fast and accurate detection, classification, and responses. Performance features, along with simple implementation of the d - q WPT-based digital protection support its application in IPMSM drives.