Calculation Of Comprehensive Physical Fields And Design Of Water-cooling System In Explosion-proof Motor

The explosion-proof motor with water-cooling system is an essential part ofthe coal cutters for the thin seam, and its development trend is toward theincreasement of the power density. But the more the power density is, the morethe loss per unit volume is, and then the temperature of the motor will be higher.If the temperature rise is greater than the value of permissible temperature rise, itcould cause insulation layer damaging, which triggers various troubles such asdischarge and short circuit. Eventually it leads to motor burning out. Socalculation of the temperature field is necessary to insure safety operation of themotor.In the paper, a100kW explosion-proof motor of YBCM190-4series withwater-cooling system is taken as an example. Firstly, the electromagnetic field iscalculated for the motor, then, by the extracting flux density, the iron losses andcopper losses are worked out, also the additional losses on each parts are calculated.The losses can be changed into the heat generation rates for the corresponding partsin the temperature field.Secondly, based on the theory of computational fluid dynamic, thetemperature field model of the explosion-proof motor with water-cooling systemcreated at actual size is calculated by the finite volume method. Because themotor has a complex structure, the whole model couldn’t be created. According tothe structure of cooling system of motor, a method from the part to the whole isused. Then based on the field-circuit coupled method, the part models areconnected by the suitable boundary conditions. Calculation and analysis of thetemperature field and picking up the highest temperature are to ensure the motor work in the safe condition.Last, the influence of cooling system to the motor temperature is studied intwo ways. Under the condition of same flow and heat sources, the influence ofwater flow velocity to the motor temperature is studied by rebuilding the model.On the other hand, under the condition of same structure of the motor except forcooling structure, the effect of different cooling structures to the temperature isstudied by the numerical calculation. The study results are beneficial to theoptimization design for explosion-proof motor with cooling system.