Multi-Objective Optimization for Outer Rotor Low-Speed Permanent Magnet Motor
Abstract
:1. Introduction
2. Initial Parameters
3. Comprehensive Sensitivity Analysis
3.1. Optimization Parameters
3.2. Response-Surface Analysis
3.3. Sensitivity Analysis
4. Multiple Objectives Comprehensive Optimization
4.1. Multi-Objective Program Design
- Output torque: The output torque should be satisfied first in the design. For the LSPMM, its rated torque depends on the rated power and rated speed of the motor; the greater the rated power and the lower the rated speed, the greater the motor’s torque. In this paper, the rated torque of the design is 34,107.1 Nm and the output torque is constrained to a minimum of 34,110 Nm.
- No-load back EMF: The no-load back EMF is an important factor affecting the power factor. When the back EMF point is close to the voltage amplitude and the deviation is within the voltage range of ±2%, the motor power factor is greater than 0.9; otherwise, the power factor is low. Therefore, to pursue a high power factor, the no-load back EMF should be limited to the vicinity of the rated voltage, which is 205 V to 220 V.
- Power factor: The power factor is an important factor to measure the motor efficiency. The higher the power factor, the higher the motor efficiency. Therefore, the minimum power factor is set to 0.95.
- Current density: The current density also needs to be limited. If the current density is too large, then it will increase the loss and affect the motor temperature; if it is too small, then the amount of coil material will increase. According to the traditional permanent magnet motor theory, the current density of the LSPMM is about 4–6 A/mm2.
- Output power: The power selection of the motor should be appropriate. When the power selection is too large, the efficiency and power factor will be reduced, and when the power selection is too small, the motor will be overloaded and the lifespan will be shortened. In this optimization, the LSPMM is rated at 200 kW, so the minimum output power is limited to 200,000 W.
- Core loss: Although the core loss is about 10 times smaller than the copper loss, the effect of the core loss on the motor temperature is not as large as that of the copper loss, but excessive core loss still affects motor performance. Therefore, the maximum core loss is set to 1500 W.
4.2. Optimization
5. Performance Evaluation
6. Experimental Tests
7. Conclusions
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Conflicts of Interest
References
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Parameters | Value |
---|---|
Number of poles | 30 |
Number of stator slots | 36 |
Air gap length (mm) | 3 |
Stator outer diameter (mm) | 863 |
Core length (mm) | 930 |
Pole arc coefficient | 0.7 |
PM thickness (mm) | 11 |
Number of conductors per slot | 12 |
Parameters | Range |
---|---|
Pole arc coefficient | [0.65, 0.95] |
PM thickness (mm) | [10, 15] |
Stator outer diameter (mm) | [840, 880] |
Core length (mm) | [900, 940] |
Number of conductors per slot N | [8, 10, 12] |
Air gap length (mm) | [2, 5] |
Parameters | Point 1 | Point 2 | Point 3 | |
---|---|---|---|---|
Design parameters | Pole arc coefficient | 0.92 | 0.86 | 0.89 |
PM thickness (mm) | 13 | 14 | 14 | |
Stator outer diameter (mm) | 878 | 877 | 877 | |
Core length (mm) | 922 | 936 | 932 | |
Conductors per slot | 10 | 10 | 10 | |
Air gap length (mm) | 2.1 | 2 | 2.3 | |
Performance | Efficiency (%) | 94.61 | 94.65 | 94.66 |
Thermal load (A2/mm3) | 158.6 | 156.9 | 157.6 | |
Power factor | 0.977 | 0.983 | 0.982 | |
Core loss (W) | 1274.6 | 1258.4 | 1247.6 | |
Copper loss (W) | 10,684.6 | 10,763 | 10,708.1 | |
Torque (Nm) | 34,117.1 | 34,118.5 | 34,117.8 | |
No-load back EMF (V) | 213 | 217.4 | 216.2 | |
Output power (W) | 200,094 | 200,125 | 200,123 |
Parameters | Initial | Optimization |
---|---|---|
Pole arc coefficient | 0.7 | 0.89 |
PM thickness (mm) | 11 | 14 |
Stator outer diameter (mm) | 863 | 877 |
Core length (mm) | 930 | 932 |
Conductors per slot N | 12 | 10 |
Air gap length (mm) | 3 | 2.3 |
Parameters | Initial | Optimization |
---|---|---|
Efficiency (%) | 92.62 | 94.66 |
Thermal load () | 233.7 | 157.6 |
Power factor | 0.910 | 0.982 |
Core loss (W) | 639.6 | 1247.6 |
Copper loss (W) | 15,572.8 | 10,708.1 |
Torque (Nm) | 34,110.7 | 34,117.8 |
No-load back EMF (V) | 215.2 | 216.2 |
Current density () | 4.074 | 3.690 |
Torque ripple (%) | 7.2 | 6.8 |
Air gap flux density (T) | 0.84 | 0.92 |
Parameters | Measurement | Calculation |
---|---|---|
Power factor | 0.98 | 0.982 |
Efficiency (%) | 94.2 | 94.66 |
Winding temperature (°C) | 109 | 106 |
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Du, G.; Hu, C.; Zhou, Q.; Gao, W.; Zhang, Q. Multi-Objective Optimization for Outer Rotor Low-Speed Permanent Magnet Motor. Appl. Sci. 2022, 12, 8113. https://doi.org/10.3390/app12168113
Du G, Hu C, Zhou Q, Gao W, Zhang Q. Multi-Objective Optimization for Outer Rotor Low-Speed Permanent Magnet Motor. Applied Sciences. 2022; 12(16):8113. https://doi.org/10.3390/app12168113
Chicago/Turabian StyleDu, Guanghui, Chengshuai Hu, Qixun Zhou, Wentao Gao, and Qizheng Zhang. 2022. "Multi-Objective Optimization for Outer Rotor Low-Speed Permanent Magnet Motor" Applied Sciences 12, no. 16: 8113. https://doi.org/10.3390/app12168113
APA StyleDu, G., Hu, C., Zhou, Q., Gao, W., & Zhang, Q. (2022). Multi-Objective Optimization for Outer Rotor Low-Speed Permanent Magnet Motor. Applied Sciences, 12(16), 8113. https://doi.org/10.3390/app12168113