Lumped-parameter Thermal Model Analysis For PMSM

PMSM has been widely applied for simple structure, reliable operation, low loss, high efficiency and power weight ratio. Theraml analysis of PMSM is very important for motor design, machine control as well as motor fault-tolerant system design. The lumped-parameter thermal model method studied in this paper can calculate the motor temperature rise rapidly in the process of parametic analysis and optimization of the machine.A lumped-parameter thermal model including the mounting plate is established to predict the temperature rise for permanent magnet synchronous motors (PMSM). With dc test method proposed in this paper, these thermal parameters are tested: the equivalent thermal resistance between housing and ambient, the equivalent thermal resistance between end caps and ambient, the equivalent thermal resistance between mounting plate and ambient; the equivalent thermal conductivity between winding and lamination; the interface gap between housing and lamination, and the interface gap between mounting plate and end caps. The sensitivity of thermal parameters is studied to identify the key part which will influence the thermal performance. The steady performance of the thermal model is validated by experiments on a test motor. The results indicate that the thermal model and tested parameters can calculate the temperature of motors accurately, with less than5%error under the rated condition. The thermal model and thermal parameter data of test can provide reference for design and thermal analysis of motors with similar structer. In addition, the motor is analized with ANSYS finite element method. The analysis results show that LPTN (lumped-parameter thermal network) method have a similar accuracy to the FEA method. Therefore, with the advantage of fast speed and easy model, LPTN method can be used widely for motor design and motor temperature calculation.A software is programmed using Matlab, realizing the function of inputing motor paramters, establishing thermal model, calculating thermal resistances, and displaying temperature results. The software provides different cooling methods:natural cooling, forced wind cooling, and forced water cooling. The software can calculate temperature rise rapidly, which can be used in motor parameters optimization and cooling system design.