Research Of Fractional-slot Concentrated Winding PM Machines With Combined Stator Blocks

High-performance PM machines have received more and more attention in the field of industrial engineering because of their small size,high torque density and high efficiency.For wind turbines,especially large offshore wind turbines,the combined stator single-layer concentrated winding have the advantages of convenient transportation and installation,strong fault tolerance,convenient maintenance,and short manufacturing cycle,which is of great significance for the development of clean energy and energy efficiency.Firstly,the theoretical basis and mathematical model of fractional-slot PM machine are analyzed,the geometric relationship of the conventional fractional-slot PM machine is introduced,the principle of slot/pole configuration in single-layer winding,double-layer winding,concentrated winding and distributed winding fractional-slot PM machines is analyzed.From the perspective of machine energy conversion,the generation mechanism of the cogging torque of the fractional-slot machine is analyzed.Secondly,from the perspective of maximizing the winding factor,the research object of the thesis are the 12-slot/10-pole and 12-slot/14-pole fractional-slot concentrated winding PM machines with single-layer winding,the winding factor of machines in two slot/pole configurations are derived in detail,and the effect of the combined stator blocks on the winding factor of the fractional-slot machines.The finite element software was used to verify the rationality of machines,and finally the detailed parameters and design scheme of machines were determined.Finally,the finite element software is used to analyze the electromagnetic characteristics,torque characteristics and loss characteristics of the established machines,and calculate the operating efficiency of the machines separately.It is clear that the existence of the stator gap of machines with combined stator blocks will change the stator magnetic circuit,thus affecting the performance of the machine.The results show that the existence of the stator gap improves the winding factor,output torque,operating efficiency,etc.of the 12-slot/14-pole machine,compared with the 12-slot/10-pole fractional-slot concentrated winding machines,the 12-slot/14-pole counterpart is more suitable for modular transformation.