Inductance Analysis of Interior Permanent Magnet Motor (DP)

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Overview This example shows the analysis of an IPM (Interior Permanent Magnet) motor, which is often used in areas where high efficiency is needed, such as air conditioners and automobiles (See Figure 1). Since reluctance as well as torque generated in the magnet exists in an IPM, it is essential to perform the simulation allowing for magnetic saturation in order to obtain its characteristics. To obtain high controllability, it is also important to evaluate the motor's inductance accurately. Figure 1 - Time domain response The procedure for calculating the inductance of an interior permanent magnet motor is as follows: 1. Calculate the current and voltage characteristics with load 2. Calculate the inductance of the d-axis and q-axis 3. Evaluate of reluctance torque and magnet torque Figure 2 shows the relationship between the inductance of the d- and q-axes and the advance phase angle of the currents as calculated using JMAG. Figure 3 shows the sum of the magnet torque calculated from its inductance and reluctance torque, and the results obtained by normal torque calculation conducted independently. As can be seen, they are almost coincident, which shows the accuracy of the inductance calculation. Figure 2 - Relationship between inductance and advance phase angle Enlarged View Figure 3 - Relationship between reluctance torque and advance phase angle of currents Enlarged View Analysis of induced voltage with load The advance phase angle is 0 degrees. Animation of induced voltage analysis. For a more realistic view, see the full animation file (176 kB). The advance phase angle is 60 degrees. Animation of induced voltage analysis. For a more realistic view, see the full animation file (150 kB).