Design And Performance Analysis Of Heat Dissipation System Based On Heat Pipe Applying To Motor Of New Energy Vehicle

With increasing environmental pollution and worsening shortage of oil resource loss,the exploitation and application of the new energy vehicle have attracted more and more attention.Motor,which dominantly affects the vehicle’s performance,is the critical component of new energy vehicle.Compared with it in traditional industry,motor in new energy automobile demands higher requirements on the power density,while the ascension of power density imposes severe challenges for the design of motor heat dissipation system.Objective of this research is the MD15 inner rotor type permanent magnet synchronous motor(PMSM)manufactured by a certain company.In this research,we found that the high temperature area of the inner rotor type PMSM mainly focused on the end winding,and that excessive increasing temperature would reduce the lifespan of winding insulation.In order to cooling the motor’s end winding,reducing the increased motor temperature,and improving the lifespan of winding insulation,a motor heat dissipation solution was proposed.It conducted out the heat rapidly from the end winding using the heat pipe.In this scheme,the critical sections including the layout of the heat pipe,the connection between the heat pipe and motor,the parameters of the flow channel were optimal designed.In this way,we determined the combination of heat pipe and motor.,connecting the heat pipe at one with the end cover,and putting the other end into the motor internal glued with end winding by electronic potting resin.Meanwhile,we presented two kinds of motor heat dissipation structures,including the tailstraight type and the tail-bended type.Then we determined the assembly process.Subsequently,we optimized the design of the flow channel’s twist number,the cross section width and height had been made,to decrease pressure loss guaranteeing a certain heat dissipation capacity.Motor was modeled by a 3D-designing software and was adapted on the basis of simulation accuracy: we ignored the rotor and shaft structures,and simplified the tiny features on the end cover.Subsequently,MD15 motor model and two finite element models(FEM)of the motor with dissipation structure based on heat pipe were established.Based on which,we determined the boundary conditions including inlet flow rate,the outlet pressure and the motor surface heat dissipation conditions.The working loss,which further acted as heat source applied to relating parts,was calculated under the rated condition.Otherwise,coefficient of thermal conductivity of different parts were determined after literature review and repeated tests.In the end,upon analyzing accuracy of models,we determined RNG k-epsilon turbulence model,standard wall function and the y plus value of 30 in the near-wall grid.At the same time,its simulation results were shown to be independent of the grid size.Results of FEM simulation showed that the best achiever was the tail-bended type,which could reduce the rising temperature of end winding by 15.3℃.Following was the tail-bended type,while the decline of rising temperature was 14.8℃.However,in consideration of assembly process,we adapted the structure of the tail-straight type.Proximately to the simulation model,results showed that the most decline of rising temperature was nearly 15℃.Therefore,our test showed that the heat dissipation system based on heat pipe could effectively reduce the winding temperature of the motor,which providing a new train of thought for the design of the heat dissipation system on PMSM.