Abdur Rahman

This paper proposes an improvement for the loss minimization control (LMC) of an interior permanent magnet synchronous machine (IPMSM). The LMC is also referred to as the maximum efficiency (ME) control because the maximum efficiency is obtained by minimizing both the core and copper losses. In conventional LMC methods, core loss is represented by a constant equivalent resistance. However, several recent studies showed that the core loss resistance can vary significantly with both load current and speed. If these variations are not included in the LMC, the true maximum efficiency of the motor cannot be achieved. The proposed method of this paper represents the equivalent core loss resistance as a function of load current and speed. It was observed that, by considering the derivative of core loss resistance with respect to current in the LMC trajectory calculation, the total electrical loss of the controlled IPMSM can be reduced. The proposed LMC was experimentally tested on a high-speed IPMSM and compared to the existing LMC and conventional maximum torque per ampere (MTPA) control. A detailed analysis was carried out to identify the operating conditions where the loss minimization control can outperform MTPA in high-speed IPMSMs.

The open-winding permanent magnet synchronous machines (OW-PMSMs) have recently been gaining more attention because of their fault-tolerant capability and power quality comparable to a 3-level converter-driven system. This paper reviews the common configurations of OW-PMSM when used as a generator, highlighting its shortcomings and benefits. The OW-PMSM with a common DC bus was found to be a promising direct-drive generator solution for wind energy conversion (WEC) systems considering fault tolerance, DC bus utilization, and power quality when appropriate control algorithms are in place. The presence of the zero-sequence current is the key disadvantage of the common DC bus configuration. The review highlights the algorithms that have been proposed to suppress the zero-sequence current of the OW-PMSM under healthy and various fault conditions, especially the open-circuit fault of semiconductor switch. Shutting down remotely located wind turbines because of faults, until they can be repaired, may not make economic sense. The OW-PMSM can offer the opportunity, to run a WEC system even under fault conditions albeit with low output power. This paper will assess the literature gaps in the existing control techniques that prevent the extension via a comprehensive review.