General Torque Enhancement Approach for a Nine-Phase Surface PMSM With Built-In Fault Tolerance

This article investigates maximum possible torque improvement in a two-pole surface permanent magnet synchronous machine with reduced span, which causes production of highly nonsinusoidal back electromotive force (EMF). It contains high third and fifth harmonics, can be used for the enhancement, using stator current harmonic injection. Optimal span is studied first, it shown that such value, would able to develop an insignificantly lower than full span. Next, field-oriented control algorithm, considers all nonfundamental EMF components phase number, devised. Using per ampere principles, optimal ratios between fundamental other injected are calculated then drive control. The output this way increased up 45% respect one obtainable only. Alternatively, same load torque, rms value by 45%. Last but not least, method position sensor fault mitigation introduced. based on alternative use back-EMF rotor estimation, instead enhancement. Experimental verification provided throughout relevant aspects.