Detection and Compensation of Interturn Short Circuit in Interior Permanent Magnet Synchronous Machines Under Two-Level Voltage Source Inverter Limitations

In this article, proof of concept of interturn short circuit (ISC) detection and shorted turns current reduction with
d
-axis current injection along with torque compensation is shown. This article evaluates the feasibility of implementing the detection and compensation of an ISC in an interior permanent magnet synchronous machine fed by a two-level voltage source inverter (VSI). First, the proposed method detects the ISC fault using a current observer capable of detecting a specific disturbance related to the ISC. Then, once the ISC is detected, the possibility of compensating for an ISC is evaluated. With a two-level VSI, the options for fault compensation are somewhat limited; however, a significant reduction in the shorted turns current can be achieved by adequately injecting
d
-axis current to cancel out the magnetic flux from the permanent magnet. Moreover, a small
q
-axis current can be injected with minimum flux to use the saliency torque. Experimental results obtained from a prototype manufactured specifically for ISC testing proof the feasibility of the proposed technique.