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When direct torque control (DTC) is applied to permanent-magnet synchronous motor (PMSM) drives, the relationship between the torque and stator flux linkage is important for high-efficiency drives because DTC requires them as references. In the stator flux linkage synchronous frame (M–T frame), the torque is described by a simple equation using the T-axis current. However, the M-axis current is neglected in the equation. This paper derives the relationship between the M-axis current and the stator flux linkage, and proposes a maximum torque per ampere (MTPA) control strategy for direct torque controlled PMSM drives using the above relationship. The proposed method does not require the q-axis inductance, which often varies due to the magnetic saturation. The simulation and experimental results verify that the MTPA condition can be obtained with the proposed method. [ABSTRACT FROM AUTHOR]

This paper proposes a maximum torque per ampere control strategy for direct-torque-controlled interior permanent magnet synchronous motor drives. The proposed method is based on the solutions of a quartic equation, a motor model in the d-q rotating frame often used for the synchronous motor controllers, and a well-known equation for maximum torque per ampere control. Therefore, the proposed method does not use a lookup table that depends on parameters of the motor and that has to be created in advance. In addition, the proposed method can use the estimated parameters. Particularly, the variations of the d- and q-axes inductances can be estimated when the inductances are modeled as the functions of the d- and q-axes current. The simulation results validate that the proposed method can achieve the maximum torque per ampere control. In addition, the simulation and experimental results verify the accuracy improvement of the maximum torque per ampere control with the iterated calculation. [ABSTRACT FROM AUTHOR]

This paper proposes a novel method of using maximum torque per ampere (MTPA) control for direct torque control (DTC) of a permanent-magnet synchronous motor (PMSM) in the stator flux linkage synchronous (M-T) frame. The stator flux vector estimation of DTC enables use of the M-T frame. Consideration of the magnetic saturation and cross-coupling effects in PMSMs requires significant complexity in most of the mathematical models using the rotor synchronous ($d-q$) frame. In the M-T frame, the mathematical model for MTPA control requires only three parameters that can be determined from only three measured points. The validity of the proposed method is confirmed by experimental results. [ABSTRACT FROM AUTHOR]

A mathematical model is proposed for the maximum torque per ampere (MTPA) control law of a permanent-magnet synchronous motor (PMSM) in the stator flux linkage synchronous frame (M-T frame). The mathematical model takes into consideration magnetic saturation and cross-magnetization effects. In taking into consideration magnetic saturation effects, most of the mathematical models in the d\mbox-q frame are complex. The M-T frame has several advantages, such as the simplicity of the flux-weakening control law and its applicability to various motors. In this paper, the control characteristics of a PMSM in the M-T frame are analyzed, and a mathematical model for estimating the MTPA control trajectory in the M-T frame is proposed. In addition, a method of simply determining the parameters for the mathematical model is proposed. The validity of the proposed model is confirmed by comparing the analytical and experimental results. [ABSTRACT FROM PUBLISHER]

This paper describes an approach in improving the performance of the position sensorless control of an interior permanent-magnet synchronous motor using parameter identification. The model-based sensorless method requires accurate motor parameters. At low speed, the resistance variation degrades the accuracy of position estimation. The identified parameter is used in the sensorless drive system to improve the accuracy of position estimation. In this paper, the resistance is identified online, but the offline identified value of the q-axis inductance is used. The experimental results reveal the effectiveness of applying parameter identification to the sensorless drive system. [ABSTRACT FROM PUBLISHER]

This paper proposes a novel control scheme for maximum power operation of synchronous reluctance motors. The proposed scheme consists of a combination of maximum torque per ampere control, maximum torque per flux control, flux-weakening control, and torque limiting. The first three control methods are based on a mathematical model in a rotating reference frame that is synchronized with the stator flux linkage. The final method utilizes a reactive torque calculated as the inner product of the flux and current vectors. The proposed control scheme is suitable for direct torque control (DTC) or flux-oriented control. In this paper, the scheme is applied to a DTC-based motor-drive system. The validity of the control scheme is verified by simulation and experimental results. [ABSTRACT FROM AUTHOR]