VP5-03 Investigation of Flux Barrier Design on Flux Weakening Capability of Consequent Pole Reverse Salient PM Machines
Creators: Qinglin Zhou
Ya Li
Shichuan Ding and Jun Hang
Publisher: name: IEEE
Year: 2025

Introduction Permanent magnet (PM) synchronous machines (PMSMs) are widely used in electric vehicles due to their high efficiency, high power density, and compact size. Due to the use of PM material, it is difficult to regulate the air gap flux density directly. Negative d-axis current is adopted to achieve field-weakening operation in vector control method, which results a potential irreversible demagnetization risk of PMs [1]. Different from the traditional PMSMs with relatively higher q-axis inductance, the reverse salient PM (RSPM) machines show a larger d-axis inductance and lead to reduced negative d-axis current [2]. When using maximum torque per ampere (MTPA) control strategy, the d-axis current of RSPM changes from positive to negative, which means it has a flux intensifying region [3][4]. This feature endows the PM with a strong resistance to demagnetization [5], making it feasible to reduce requirements for PM [6]. Consequent pole machines can reduce the number of PMs used and has a larger d-axis inductance [7]. This paper proposed consequent pole RSPMs with different q-axis flux barriers and investigates the flux weakening capability under different structures. Machine Topologies The consequent pole machines with different q-axis barriers are shown in Fig. 1. Preliminary Electromagnetic Performance In vector control method, MTPA is used when the operation speed is lower than base speed. The smaller copper loss leads to higher efficiency. Because of the relatively higher base speed, the high-efficiency (≥90%) region of the machines with central barrier are shifted to the higher speed region, as shown in Fig. 2. Conclusions This paper investigates six consequent pole machines with different q-axis flux barriers, including one layer, two-layer, three-layer arc flux barriers, and trapezoid central barriers. The basic electromagnetic performances show that multi-layer structure can achieve the reverse salient characteristic and improve the flux weakening capability. Due to the extended base speed, topologies with trapezoid central barrier have higher efficiency in high-speed region.References: Y. Liu, K. Ma, H. Gao and Z. Zhang, IEEE Trans. Ind. Electron., vol. 71, no. 8, pp. 8503–8513 (2024) R. H. Moncada, J. A. Tapia and T. M. Jahns, 2009 IEEE Energy Conversion Congress and Exposition, pp. 2368-2373(2009) Bianchi N, Bolognani S and Jang J H. , IEEE Trans. Power Elec., 22(06): 2466-2475( 2007) Kan A, Minoru A, Shinji W., IEEE Trans. Ind. Appl., 126(07): 827-834(2006) M. Kashif and B. Singh, 2021 IEEE International Power and Renewable Energy Conference (IPRECON), Kollam, India, , pp. 1-4(2021) T. Kato, N. Limsuwan and C.-Y. Yu, K. , IEEE Trans. Ind. Appl., vol. 50, no. 3, pp. 1748–1756(2014) Y. Li, H. Yang,and H. Lin, IEEE T. Transp. Electr., vol. 9, no. 1, pp. 819–832(2023)
Introduction Permanent magnet (PM) synchronous machines (PMSMs) are widely used in electric vehicles due to their high efficiency, high power density, and compact size. Due to the use of PM material, it is difficult to regulate the air gap flux density directly. Negative d-axis current is adopted to achieve field-weakening operation in vector control method, which results a potential irreversible demagnetization risk of PMs [1]. Different from the traditional PMSMs with relatively higher q-axis inductance, the reverse salient PM (RSPM) machines show a larger d-axis inductance and lead to reduced negative d-axis current [2]. When using maximum torque per ampere (MTPA) control strategy, the d-axis current of RSPM changes from positive to negative, which means it has a flux intensifying region [3][4]. This feature endows the PM with a strong resistance to demagnetization [5], making it feasible to reduce requirements for PM [6]. Consequent pole machines can reduce the number of PMs used and has a larger d-axis inductance [7]. This paper proposed consequent pole RSPMs with different q-axis flux barriers and investigates the flux weakening capability under different structures. Machine Topologies The consequent pole machines with different q-axis barriers are shown in Fig. 1. Preliminary Electromagnetic Performance In vector control method, MTPA is used when the operation speed is lower than base speed. The smaller copper loss leads to higher efficiency. Because of the relatively higher base speed, the high-efficiency (≥90%) region of the machines with central barrier are shifted to the higher speed region, as shown in Fig. 2. Conclusions This paper investigates six consequent pole machines with different q-axis flux barriers, including one layer, two-layer, three-layer arc flux barriers, and trapezoid central barriers. The basic electromagnetic performances show that multi-layer structure can achieve the reverse salient characteristic and improve the flux weakening capability. Due to the extended base speed, topologies with trapezoid central barrier have higher efficiency in high-speed region.References: Y. Liu, K. Ma, H. Gao and Z. Zhang, IEEE Trans. Ind. Electron., vol. 71, no. 8, pp. 8503–8513 (2024) R. H. Moncada, J. A. Tapia and T. M. Jahns, 2009 IEEE Energy Conversion Congress and Exposition, pp. 2368-2373(2009) Bianchi N, Bolognani S and Jang J H. , IEEE Trans. Power Elec., 22(06): 2466-2475( 2007) Kan A, Minoru A, Shinji W., IEEE Trans. Ind. Appl., 126(07): 827-834(2006) M. Kashif and B. Singh, 2021 IEEE International Power and Renewable Energy Conference (IPRECON), Kollam, India, , pp. 1-4(2021) T. Kato, N. Limsuwan and C.-Y. Yu, K. , IEEE Trans. Ind. Appl., vol. 50, no. 3, pp. 1748–1756(2014) Y. Li, H. Yang,and H. Lin, IEEE T. Transp. Electr., vol. 9, no. 1, pp. 819–832(2023)