Comparative Study of PM-Assisted SynRM and IPMSM on Constant Power Speed Range for EV Applications

Performance Analysis of Synchronous Reluctance Motor with Limited Amount of Permanent Magnet

“…From the above discussions, with limited PM volume (less than common IPM motors), the selection of torque and power is closely related to desired motor speed range and needs to be chosen carefully by simultaneously considering the mechanical and electromagnetic characteristics of the motors and their applications. Although these motors are ideally infinite speed [16], the actual start-and end-points of the constant power region. The pink ones are for Model 3 and the blue ones are for Models 1 or 5.…”

“…From the above discussions, with limited PM volume (less than common IPM motors), the selection of torque and power is closely related to desired motor speed range and needs to be chosen carefully by simultaneously considering the mechanical and electromagnetic characteristics of the motors and their applications. Although these motors are ideally infinite speed [16], the actual From the above discussions, with limited PM volume (less than common IPM motors), the selection of torque and power is closely related to desired motor speed range and needs to be chosen carefully by simultaneously considering the mechanical and electromagnetic characteristics of the motors and their applications. Although these motors are ideally infinite speed [16], the actual operating speed is limited.…”

“…Although these motors are ideally infinite speed [16], the actual From the above discussions, with limited PM volume (less than common IPM motors), the selection of torque and power is closely related to desired motor speed range and needs to be chosen carefully by simultaneously considering the mechanical and electromagnetic characteristics of the motors and their applications. Although these motors are ideally infinite speed [16], the actual operating speed is limited. In addition, the selection of the PM positions and directions, e.g., moving PM from q-axis to d-axis in this paper, is the key to improve the performance of SynRMs with limited PM used.…”

“…The PM flux linkage also contributes to torque production so that the total torque increases. However, the volume/size of the added PM needs to be limited to avoid the motor becoming an interior permanent magnet synchronous motor (IPMSM) [16], which could also increase the cost. Nevertheless, the volume/size of the PM should not be too small to achieve the desired torque and power density, or to be vulnerable to irreversible demagnetization [10].…”

“…The multiple flux barrier design allows the torque density of this motor to reach 28.1 Nm/L with PM taking only 0.95% of the motor volume by assuming sufficient cooling is applied, as shown in Table 1. However, as mentioned in Reference [16], the low PM volume and high excitation current could lead to its negligible contribution in torque production due to the low PM-torque-to-total-torque ratio and high probability of irreversible demagnetization with field-weakening applied. In addition, since the armature current I s is far from the characteristic current I ch on d-axis [24], the constant power speed range (CPSR) could become relatively low for PMa-SynRM with a little amount of PM.…”