Analysis,Design And Control Of The Magnetic-geared Power Split Motor

New energy vehicles have been the development trend of the automotive industry.The hybrid electric vehicle(HEV)is considered as a transitional product between traditional autos and the pure electric autos.Hence,techniques of the HEV have been valued as hotspots.Power split device(PSD)of the series-parallel HEV can make the internal combustion engine(ICE)run consistently in a high-efficient situation.However,internationally,dominant techniques of the HEV have been monopolized by the Toyota Corporation for several years.The PSD of the Toyota hybrid system(THS)contains a generator and a planetary gear,which suffers some inherent drawbacks,such as the mechanical abrasion and the backlash.Therefore,the pure electrical hybrid sy stem has been proposed as a promising candidate.Meanwhile,the magnetic gear has been widely concerned by scholars in the field of electric machines.Unlike the mechanical gears,their magnetic counterpart can help to avoid the mechanical abrasion.which makes the whole system more reliable.Precisely.there is a neat analogy between the kinematic features of the planetary gear and the coaxial magnetic gear(CMG).Such an analogy implies that the magnetic-geared power split motor(MGPSM).which combines a permanent magnet synchronous motor(PMSM)and a CMG,can function as the PSD of the hybrid system.The principle of the MGPSM is studied in this paper.A complete set of the analysis method for this motor is raised,and the mathematical model is established.Additionally,some unique features of the MGPSM are also revealed and utilized to improve the motor performance.All these work sets a foundation for the further research and industrial applications.The main research achievements are as following:1.The structure and operation principle of the MGPSM are analyzed.Some design rules and requirements for the HEV application are summarized.The shortcoming of the existing MGPSM structure is revealed and clarified for the first time.2.An exciting feature,namely the torque reduction of the MGPSM due to the skewing rotor can be avoid,is discovered.Such feature is unique,because the skewing technique always reduces the torque performace of the common PMSM when it is used to suppress the torque ripple.The principle of this phenomenon is also explained in this paper.3.On the basis of the above mentioned feature.a kind of complemcntary MGPSM is proposed to improve the asymmetrical magnetic circuit.By proper design of the shift angles.complementary structure can help to reduce the torque ripple with keeping the average torque.A principle prototype of the complementary MGPSM is manufactured to validate the analysis results.4.The power dimension equation of the MGPSM is established,which reflects the influences of the main parameters.By the power dimension equation.an improved split ratio optimization method for the MGPSM is achieved.which counts the core saturation.Not only the basic principle.but also the manufacturing and assembling techniques are studied.With these novel techniques,an engineering prototype of 12 kW has been designed and manufactured.5.The mathematical model of the MGPSM in the d-q coordinate is established.The dual-rotor motion is decoupled,so the motion of the effective component in the no-load air gap magnetic field can be oriented.Therefore,the motion control strategy of the MGPSM can be developed as the counterpart of a common PMSM.The Matlab software is used to develop the simulation of the whole power split system,which contains a MGPSM and an ICE.6.An experimental platform for the hybrid powertrain is constructed.The above mentioned engineering prototype of the MGPSM is controlled to split the mechanical power from the ICE,and the distribution of the power flows can be regulated by the developed algorithm.The expriments involve the stable and dynamic performance of the hybrid powertrain,and the torque coordination algorithm has been implemented to improve the system performance.Furthermore,the efficiency of the MGPSM has also been evaluated.The measured results agree well with the simulated results.