Direct torque control (DTC) is considered one of the simplest and fastest control strategies used in motor drives. However, it produces large torque and flux ripples. Replacing the conventional two-level hysteresis torque controller (HTC) with a four-level HTC for a three-level neutral-point clamped (NPC) inverter can reduce the torque and flux ripples in interior permanent magnet synchronous motor (IPMSM) drives. However, the torque will not be controlled properly within the upper HTC bands when driving the IPMSM in the medium and high-speed regions. This problem causes the stator current to drop, resulting in poor torque control. To resolve this problem, a simple algorithm based on a torque error average calculation is proposed. Firstly, the proposed algorithm reads the information of the calculated torque and the corresponding torque reference to calculate the torque error. Secondly, the average value of torque error is calculated instantaneously as the reference torque changes. Finally, the average value of the torque error is used to indicate the operation of the proposed algorithm without the need for motor speed information. By using the proposed algorithm, the torque can be controlled well in all speed regions, and thus, a better stator current waveform can be obtained. Simulation and experimental results validate the effectiveness of the proposed method.
In high-performance motor drives, a highly efficient system is required. The IPMSM machine is and wide constant-power operating range. Advanced control techniques are required for achieving considered one of the highly efficient machines in the industry for its high-power density, high a superior control of the IPMSM drives. Among these techniques is the well-known DTC which reliability, and wide constant-power operating range. Advanced control techniques are required for is presented in this paper. To reduce the torque and flux ripples, a four-level HTC has replaced achieving a superior control of the IPMSM drives. Among these techniques is the well-known DTC the conventional two-level HTC for IPMSM drives fed by a three-level NPC inverter. Although, which is presented in this paper. To reduce the torque and flux ripples, a four-level HTC has replaced a great ripples reduction of both torque and stator flux has been achieved by using the four-level the conventional two-level HTC for IPMSM drives fed by a three-level NPC inverter. Although, a HTC, there is a poor torque response when the IPMSM operates in medium and high-speed regions. great ripples reduction of both torque and stator flux has been achieved by using the four-level HTC, To alleviate this issue, a simple algorithm to improve the torque capability of an IPMSM in medium there is a poor torque response when the IPMSM operates in medium and high-speed regions. To and high-speed regions is proposed. The proposed method modifies the conventional four-level alleviate this issue, a simple algorithm to improve the torque capability of an IPMSM in medium and HTC based on the torque error average calculation without requiring speed information. By using high-speed regions is proposed. The proposed method modifies the conventional four-level HTC the proposed algorithm, the torque was controlled well in all speed regions, and hence, a better based on the torque error average calculation without requiring speed information. By using the stator current waveform was achieved. The proposed method attains the advantage of classical proposed algorithm, the torque was controlled well in all speed regions, and hence, a better stator DTC in the simplicity of implementation and a very quick dynamic response. In addition, there is current waveform was achieved. The proposed method attains the advantage of classical DTC in the no calculation burden in implementing the proposed method under various operating conditions. simplicity of implementation and a very quick dynamic response. In addition, there is no calculation The simulation and experimental results indicate that the proposed four-level HTC for the 3L-DTC burden in implementing the proposed method under various operating conditions. The simulation drives improves the torque response in the medium and high-speed regions and compensates the and experimental results indicate that the proposed four-level HTC for the 3L-DTC drives improves stator current. Moreover, the NP of the three-level NPC inverter is balanced in the steady-state and the torque response in the medium and high-speed regions and compensates the stator current. transient-state operations. Therefore, the proposed algorithm can be considered as a good choice for Moreover, the NP of the three-level NPC inverter is balanced in the steady-state and transient-state high-performance applications utilizing IPMSM drives. operations. Therefore, the proposed algorithm can be considered as a good choice for high-AuthorperformContributions:ance applicatConceptualization,ions utilizing IPMmethodologySM drives. and formal analysis, S.S.H.; experimental validation, S.S.H.; writing\u2014original draft preparation, S.S.H.; writing\u2014review and editing the final manuscript, S.S.H. Author Contributions: Conceptualization, methodology and formal analysis, S.S.H.; experimental validation, S.S.H.; writing\u2014original draft preparation, S.S.H.; writing\u2014review and editing the final manuscript, S.S.H. and FKu.n-Bd.iLn.g; :reTshouisrcreesseaanrcdh swupaesrsvuispipono,rtKed.-Bb.yL. KAolrleaauEthleocrtsr ihcaPvoew reeradCoarnpdoraagtrieoend( Gtorathnet Npuob. lRis1h9eXdOv0e1r-s2io0n) aonf dthae grantmanus(2c0riRptTR. P-B146008-03) from the Railroad Technology Research Program funded by the Ministry of Land, Infrastructure and Transport of the Korean government. Funding: This research was supported by Korea Electric Power Corporation (Grant No. R19XO01-20) and a grant Acknowledgments: The authors would like to thank Power Electronics Laboratory colleagues of Electrical and (20RTRP-B146008-03) from the Railroad Technology Research Program funded by the Ministry of Land, Computer Engineering Department, Ajou University, South Korea. Infrastructure and Transport of the Korean government. Conflicts of Interest: The authors declare no conflict of interest. Acknowledgments: The authors would like to thank Power Electronics Laboratory colleagues of Electrical and Computer Engineering Department, Ajou University, South Korea.
