Motor winding equivalent model, establishment method and motor temperature field analysis method

Abstract

The invention relates to a motor winding equivalent model and an establishment method thereof, and a motor temperature field analysis method. The establishment method of the motor winding equivalent model comprises steps of enabling a conductor, an insulating material and an impregnating material in a winding in a motor groove to be equivalent to a cuboid model; splitting the cuboid model into a plurality of T-shaped equivalent thermal network models according to the heat flow direction; calculating the equivalent heat conductivity coefficient of the winding in each heat flow direction by combining the heat conductivity coefficient of the impregnated material, the air heat conductivity coefficient, the conductor heat conductivity coefficient, the heat conductivity coefficient of the insulating material and the volume ratio of each material in the cuboid model in the cuboid model; and calculating the first thermal resistance, the second thermal resistance and the third thermal resistance of each T-shaped equivalent thermal network model in the heat flow direction by utilizing the equivalent heat conductivity coefficient. According to the establishing method, both the heat conductivity coefficient of the material and the heat transfer path are considered, meanwhile, the influence of the air gap in the winding is considered, the defects that winding modeling is difficult, and thecalculated amount is large are overcome, and complexity of a winding model is reduced.

Description

technical field [0001] The invention belongs to the field of new energy electric vehicles, and in particular relates to an equivalent model of a motor winding and a method for establishing it, and a method for analyzing a temperature field of a motor. Background technique [0002] When designing a motor for a new energy electric vehicle, it is always hoped to increase the output power of the motor in the continuous working state as much as possible in a limited volume, that is, to increase the power density of the motor in the continuous working state. However, the maximum output power of the motor in continuous working state is determined by the inverter power of the motor and the maximum operating temperature, which is also called the insulation level of the motor. In addition, the expected insulation life of the motor is halved for every 10°C increase in motor winding temperature. For permanent magnet synchronous motors, high temperature will weaken the magnetism of perm...

AI Technical Summary

Problems solved by technology

A common treatment method is that the winding in the slot is equivalent to the conductor layer and the insulating layer arranged at intervals, and the conductor and the insulating material are designed in the shape of a "gate", and the wall of the "gate" is parallel to the wall of the slot; such The effective model uses conductors and insulating materials to overlap and arrange each other until the entire slot is filled, which can effectively predict the problem of temperature gradients in the windings in the slot from the inside to the outside, but two conditions must be met: (1) The windings and insulation in the motor slot are uniform distribution, (2) The insulation in the motor slot is completely impregnated, and there is no air cavity in the slot; however, the actual winding model is difficult to meet these two conditions. In the actual motor model, the windings in the slot are placed randomly and discretely and to a certain extent air cavity; in addition, the equivalent layered thickness and number of layers of the conductor need to be determined through repeated iterations. At the same time, it must be considered as close as possible to the actual winding, and the feasibility and convenience of the subdivision during software calculations must also be considered, which greatly increases the modeling difficulty

Another method is to directly equate the conductor and all insulating materials as a whole. According to the experimental test results combined with empirical formulas, the winding in the slot is equivalent to a radial thermal conductivity of 0.5-1.0W / (m.K). For a thermal conductor with uniform material, it is necessary to rely on experience and experiments to continuously correct thermal parameters for this model, and the axial thermal conductivity is usually directly equal to the thermal conductivity of the conductor; however, this is a simplified processing method and the operation is relatively simple, but in the motor In the thermal design stage, the temperature rise results obtained by this model are less accurate

[0005] In summary, in the actual motor model, the winding placement in the slot is random and discrete, and it is difficult to perform solid modeling on it, with a large amount of calculation and low calculation accuracy.

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