A Novel Control Strategy to Mitigate the Parameter Saturation Problems in Synchronous Reluctance Machines

The objective of this paper is to propose a new control strategy for synchronous reluctance machines (SyRM) to mitigate the parameter saturation problems. The paper also highlights the reasons for the difference in the saturation behavior between the permanent magnet motors (PM) and the SyRM using the FEA flux distribution results. The synchronous reluctance machine is devoid of rotor magnets (in contrast with the PM machines) and it solely relies on reluctance portion to produce torque. This gives the SyRM machines the advantage of lower cost and more reliability compared to PM machines. But the lack of magnets in SyRM causes the motor parameters to saturate more quickly compared to the PM machines. The optimal control of the SyRM machine is thus strongly dependent on the controller’s ability to adapt to the fast changing saturation in the SyRM machine. The control strategy proposed in the paper uses a reference current generation block that optimizes the reference current for the saturation that would occur in the machine at any point in operation. A d-q voltage and current sign estimator reduces the controller iterations considerably to reach to a solution. The simulation and experimental results are presented for a 30 slot 4-pole SyRM machine.