Design of high-efficiency synchronous reluctance motor and drive for circulation pumps

Circulation pumps can be defined as integrated structures comprising a hydraulic pump, electric motor, and variable speed drive. These pumps are utilized to convey heating or cooling fluids with sufficient pressure for residential, industrial, and office buildings. The utilization of high-efficiency motors and drives in these systems, which account for a significant portion of the overall energy consumption of electrical machines worldwide, contributes to the reduction of energy costs and carbon emissions. Due to their reliability and simple construction, induction motors (IM) have been the most preferred motor type in pump applications to date. However, as these motors fail to comply with the new energy efficiency standards set by the European Union, there is a growing inclination towards high-efficiency permanent magnet synchronous motors (PMSM). PMSMs are motors with high energy density that meet energy efficiency standards. Nevertheless, the magnets used in the rotor structure contain rare elements not found in our country, reducing motor manufacturability and increasing system costs. In high-temperature applications, demagnetization can lead to torque losses. In this context, synchronous reluctance motors (SynRM) stand out for their structures that do not contain rare and sensitive elements, positioning them in the high-efficiency class. Despite their significant potential to meet these standards, SynRMs are not widely preferred in the industry due to their low power factor and relatively complex control algorithms. In the scope of this thesis, the design and production of a 750 W SynRM for circulation pumps have been conducted. A power factor-corrected (PFC) motor drive has been designed, controlled by a field-oriented control algorithm. The PFC circuit has enhanced motor drive performance, preventing the adverse impact of the low power factor of synchronous reluctance motors on the grid. The developed field-oriented control algorithm ensures stable motor control, determining the current vector angle at which the motor operates most efficiently and elevating the motor efficiency to the IE5 class. The practical demonstration within the thesis showcases the high potential of SynRMs in transitioning from IM motors to PMSM motors to meet efficiency standards.