Short-circuit fault tolerant compensation for PMAC machines
A new technique has been developed for suppressing the effects of short-circuit faults in permanent-magnet (PM) AC machines. The approach uses tailored current excitation of adjacent healthy motor windings to divert magnetic flux from the shorted winding, resulting in a significant reduction of the short-circuit current and braking torque. This represents a valuable contribution, since the problem of managing internal short-circuit winding faults is a major impediment to the wider adoption of permanent magnet machines in a wide variety of variable-speed drive applications. Among its major benefits is the fact that the proposed control makes it possible to maintain a significant percentage of the motor’s average torque while minimizing the short-circuit current.
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| (a) Flux diversion concept | (b) Modular PM motor structure |
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| (c) Prototype candidate motor | |
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| (d) Drive board with current sensing capability | (e) DSP controller with 12 PWM and 8 A-D |