| The permanent magnet vernier machine can realize the function of low speed and large torque by using vernier effect.Its structural and functional advantages have attracted the attention of many scholars in recent years.However,the structural characteristics of too many poles of the magnet on rotor will lead to problems such as large slot pole fit,increased magnetic flux leakage between poles,and weakened rotor core strength.Therefore,it is of engineering significance to design a permanent magnet machine that can be applied to low-speed and large-torque working situations,so that it can overcome these shortcomings,and also have high efficiency and high output performance.Firstly,the development and current status of permanent magnet vernier machines,consequent-pole machines and hybrid-excited machines are introduced and summarized.Then,a novel hybrid-excited consequent-pole permanent-magnet vernier machine(HECP-PMVM)topology has been proposed.Based on the principles of electromagnetics and motor design theory,the topology and the characteristics of the magnetic circuit are analyzed to help design the machine.Secondly,to verify the effectiveness and superiority of proposed topology of the HECP-PMVM,the way that Halbach array enhanced consequent-pole machine is studied by comparing four different permanent magnet configurations based on finite element method.In order to summarize the law and obtain more suitable parameter value,the influence of several important structural parameters on electromagnetic performance about the output torque,cogging torque,back electromotive force,total harmonic distortion(THD)and other indicators is studied.So the overall structural design of the HECP-PMVM can be optimized.Thirdly,related theories about the no-load and load characteristics,and inductance characteristics on direct-axis and quadrature-axis of HECP-PMVM are introduced and studied.By using the finite element simulation software and data processing tools such as Matlab,the structure and performance characteristics of HECP-PMVM are further analyzed and summarized.Finally,by building loss and efficiency calculation model of HECP-PMVM,copper loss,hysteresis loss,eddy current loss,and mechanical loss in different working status are analyzed so that efficiency map can be drawn.Moreover,a eight-heat-source equivalent thermal circuit model with closed-loop feedback has been proposed to calculate the temperature rise of HECP-PMVM based on theory of heat transfer and thermal circuit method.Accuracy of the calculation model is verified by comparing with the result of the finite element method.In order to verify the feasibility and effectiveness of the thermal design of HECP-PMVM,the temperature rise of machine in different situations such as rated condition,speed changing condition and lockedrotor condition is studied and evaluated. |
