Overview

In the initial stages of motor design, if only the magnetic design is completed and the design proceeds to the later stages, rework may occur when it is discovered that the part temperature and stress do not meet the requirements. Such rework can be reduced by running multifaceted evaluations from the initial design stages, including not only magnetic design but also thermal and stress.
By using the templates included in JMAG-Express, you can create motor models and evaluate design plans both quickly and easily. In addition, by combining the prepared scenarios, you can run magnetic design, thermal design, and structural design all at the same time.
In this example, the part temperature and stress are evaluated at the same time for the motor design plan, and a design plan that meets the requirements is explored.

Design Requirements, Design Variables

Table 1 shows the design requirements, Fig. 1 shows the rotor core and geometry that are the design variables, and Table 2 shows the cooling specifications.
The rotor core slit depth and the cooling jacket flow velocity are also design variables.

Initial Design Plan Evaluation

Fig. 2, Fig. 3, and Fig. 4 show the efficiency map, average temperature of each part, and maximum stress position, respectively, for a rotor core slit depth of 0.5 mm and a cooling jacket flow velocity of 0.5 msec. Table 3 shows the maximum stress value.
From Fig. 2, it can be seen that the maximum torque exceeds the requirement of 280 Nm and the efficiency at the rated point exceeds the requirement of 95%.
On the contrary, Fig. 3 shows that the coil temperature is 130 deg C, and Fig. 4 and Table 3 show that the maximum stress occurs at the bridge where it exceeds 200 MPa. This indicates that adjustments are necessary in terms of the temperature and stress.

Design Plan Adjustments

The design variables are adjusted based on the results of the initial design plan.
In this example, the evaluation is run again with the rotor core slit depth changed to 1.5 mm and the cooling jacket flow velocity changed to 2 msec.
Fig. 5, Fig. 6, and Fig. 7 show the obtained efficiency map, average temperature of each part, and maximum stress position, respectively. Table 4 shows the maximum stress value.
From Fig. 5, it can be seen that the maximum torque exceeds the requirement of 280 Nm and the efficiency at the rated point exceeds the requirement of 95 %.
Fig. 6 shows that the coil temperature is 130 deg C or less, and Fig. 7 and Table 4 show that the maximum stress occurs at the bridge, where it is 200 MPa or less. From this, it can be seen that the design plan meets the requirements after the adjustments have been made.