Research On Heating And Heat Dissipation Of Permanent Manet Synchronous In-wheel Motor

The permanent magnet synchronous in-wheel motor is widely used in the fieldof electric vehicles. The motor has large working current and high power density,however, it is limited by installation space and work environment, which lead to thepoor cooling conditions. So in-wheel motor must face tow problems which areheating and cooling. This paper bases on Interior Permanent Magnet Synchronousin-wheel motor as an object, the research contents are about influencing factors ofloss, reduce loss method, the key issues about loss of in-wheel motor, how drivingpart influences loss, cooling pattern design, correction about water-cooled heatrelease coefficient correction, winding equivalent model, the factors influencingtemperature field simulation, temperature distribution of in-wheel motor underdifferent conditions.First of all, combination with applications of in-wheel motor, this paperresearch for the influence factors of copper loss, iron loss and the permanent magneteddy current loss. From the Angle of temperature field simulation, this paperanalyses the load current’s influence on the size and distribution of stator and rotoriron loss. On the other hand, through the analysis of permanent magnet eddy currentloss based on interior Permanent Magnet Synchronous in-wheel motor, this papergives two ways to reduce the loss of permanent magnet eddy current.Secondly, according to the applying background of the in-wheel motor, thepaper does the research about loss of the in-wheel motor when electric vehicleswork in different conditions, finding that the main loss comes from the motoroverload running at low speed and flux-weakening operating at high speed. And it’snecessary to use specific industrial means to increase the heat sinking capacity ofrelevant components. Moreover, this paper proposes a simulation method offlux-weakening at constant power operation according to the loss situation whenmotor runs at high speed.Then, this paper will do theoretical analysis about the magnetic field in statorside and rotor side respectively finding out that the cycle of changing magnetic fielddiffers. Considering that the loss is an average value, we can’t choose thesimulation time optionally when calculating iron loss by finite element software. Inaddition, this paper also does the research about the impact on loss deriving fromthe current harmonics that PWM chopped wave introduces and change of the DCbus voltage.Furthermore, considering the limited space to the wheel hub motor, through thecomparing of different water jackets,‘Z’ axial water jacket is more suitable for the in-wheel motor. By further study, the paper finds that the traditional heat releasecoefficient calculation formula does not fit to ‘Z’ axial water jacket, so this paperproposes a thermal coefficient correction method for ‘Z’ axial water jacket.Finally, in order to make more realistic simulation of temperature field, thispaper proposes a new equivalent winding model, analysis the relevant issues basedon CFD simulation software. Additionally, this paper also points out that thetemperature of in-wheel motor must take consideration of the various affections ofboth accurate simulation of thermal Physical properties change with temperaturerise of the motor, and the heat impact of the size, distribution, loading type on thein-wheel motor temperature rise. After the simulation of motor temperature fieldunder different conditions, the result is that during the case of low speed thewinding temperature is higher, and the case of high speed the rotor temperature ishigher. Then the solution to the problem of high temperature of the in-wheel motorsis given by the way of upgrading manufacturing process and some relevant crafts.