| Permanent magnet synchronous motors(PMSMs)are widely used in various industries,especially in the automobile industry.A large number of losses was generated by PMSMs during the operation,which makes the temperature of the motor rise continuously.Some studies indicate that overheating is the primary cause of motor degeneration.The life of PMSMs,peak operating time and peak operating power will be increased when the effective cooling methods applied.With the development of the electric vehicle industry,the motor will be more efficient and compact,so the thermal management system of PMSMs should be more efective.Water cooling is the main cooling method of PMSMs of electric vehicles,which also is the most widely used and mature scheme at present.The temperature rise of the water-cooled motor is not only related to the loss,but also related to the channel of the cooling fluid and the operation parameters of the water-cooled system.There is important application value when the efficient cooling channel and the appropriate operation parameters of the water-cooled system are invesgated.In this paper,the cooling performance of 30-k W PMSM under different cooling channels and operation parameters is studied by means of simulation.The effectiveness of the simulation model is verified by compared with the experimental results.The main work and innovation points of this paper are as follows:(1)A simplified equivalent model of 30 k W PMSM is established,and the loss and heat generation rate of each part are calculated.The temperature distribution characteristics of each part in 30 k W water-cooled PMSM are simulated.The effectiveness of the simulation model is verified by compared with the experimental results.(2)Based on the simulation results of the initial water-cooled motor,five different cooling channels are designed,and the heat disspating performance of 30-kw PMSM is simulated when these five cooling channels are adopted.The distribution of flow rate and temperature as well as the influence on pressure drop are analyzed under the case of differrant cooling channels equipped,which provides a reference for encapsulating high thermal conductivity material in the highest temperature area of motor.The results show that the temperature and pressure drop of the motor will be reduced by adding multiple inlets and outlets,and the uneven distribution of flow velocity will be caused by branches in the water channel.The temperature rise of the motor will be effectively reduced by potting high thermal conductivity material.(3)In order to determine the optimal operating parameters of the motor,the temperature distribution on the 30-kw PMSM under the operating conditions of different cooling water flow rate,cooling medium and internal operating pressure of the motor are studied.The synergism between the temperature gradient field and the flow field of cooling fluid of 30-kw PMSM under different operating parameters are analyzed by using the field synergy principle,and the mechanism of heat dissipation enhancement with different operating parameters was explained by using this theory.The results show that the flow rate and the type of cooling medium have a great influence on the temperature rise and synergy between flow field and temperature gradient field of the motor.Although temperature rise of the rotor will be effectively reduced by increasing the air pressure inside the motor,it has little effect on the synergy between flow field and temperature gradient field of the motor. |
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