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Interior permanent magnet synchronous motors (IPMSMs) are often used in applications that demand high performance. Interest has increased in designing IPMSMs in the enlargement high-efficiency operation area. Designing to meet such specifications can be difficult and time consuming. Combining a genetic algorithm (GA) with the coarse mesh finite element method (FEM) can automate the process and reduce the time it takes to design an IPMSM to meet such specifications. This study describes the motor design and explores the usefulness of designing motors having the large high-efficiency operation area using the GA combined with the coarse-mesh FEM. [ABSTRACT FROM AUTHOR]

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 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]

Permanent-magnet (PM) synchronous motor (PMSM) with rare-earth PMs is most popular for automotive applications because of its excellent performance such as high power density, high torque density, and high efficiency. However, the rare-earth PMs have problems such as high cost and limited supply of rare-earth material. Therefore, the electric motors with less or no rare-earth PMs are required in electric vehicle (EV) and hybrid electric vehicle (HEV) applications. This paper proposes and examines a PM-assisted synchronous reluctance motor (PMASynRM) with ferrite magnets that has competitive power density and efficiency of the rare-earth PMSM employed in HEV. The PMASynRM for automotive applications is designed taking into account the irreversible demagnetization of ferrite magnets and the mechanical strength. The prototype PMASynRM has been manufactured, and several performances such as torque, output power, losses, and efficiency are evaluated. Furthermore, the performances of the high-power PMASynRM are estimated based on the experimental results of the prototype PMASynRM, and the possibility of the application of the proposed PMASynRM to EV and HEV is discussed. [ABSTRACT FROM PUBLISHER]

Although motors that use rare-earth permanent magnets typically exhibit high performance, their cost is high, and there are concerns about the stability of the raw material supply. This paper proposes a permanent-magnet-assisted synchronous reluctance motor (PMASynRM) with a ferrite magnet that does not use rare-earth materials considering productivity. The performance of the proposed PMASynRM is evaluated based on the finite-element method and an experiment using a prototype machine. The analysis results reveal that the proposed PMASynRM has the same power density and an equivalent efficiency as rare-earth permanent-magnet synchronous motors for hybrid electric vehicles (2003 Toyota Prius). Furthermore, some experimental results are presented in order to validate the analytical results. As a result, the proposed PMASynRM was found to achieve high-power-density and high-efficiency performance. [ABSTRACT FROM AUTHOR]

Although motors that use rare-earth permanent magnets (PMs) typically exhibit high performance, high costs and concerns about the stability of raw material supplies are leading to their decreased production. However, the performance of such motors is not easily matched without the use of rare-earth PMs. This paper proposes and examines a PM-assisted synchronous reluctance motor with ferrite magnets that has the same power density as rare-earth PM synchronous motors. A suitable rotor structure for high torque and high power is discussed with respect to the demagnetization of ferrite magnets and the mechanical strength. [ABSTRACT FROM PUBLISHER]

This paper examines the control performance of permanent-magnet synchronous motor drive systems based on current control and direct torque control (DTC) when flux-weakening control is applied. The control law in the M–T frame, which is used in the DTC, requires only armature resistance, whereas the control law in the d–q frame, which is used in current control, requires many motor parameters for flux-weakening control. The experimental results clarify the influence of parameter variation on the control characteristics of flux weakening and torque limiting. The DTC-based motor drive system combined with the control laws in the M–T frame has several advantages, including insensitivity to parameter variation, simplicity of calculation, and stable control. [ABSTRACT FROM AUTHOR]

The importance of reducing the amount of rare earth materials used in high-performance permanent magnets has been established. However, the performance of such motors will not be easy to match without the use of rare earth materials. Although the torque characteristic of the motor can be improved by shortening the air gap length of the motor, there is a mechanical limitation on the gap length. In this paper, a 3-D air gap structure of the motor is proposed to improve the torque characteristics without shortening the gap length. The 3-D air gap structure is demonstrated to be equivalent to shortening the actual gap length to approximately 70% of the original length. Some disadvantages in the 3-D air gap structure are also described. [ABSTRACT FROM PUBLISHER]

A mechanical sensorless drive system for an interior permanent-magnet synchronous motor, for which parameters including the inverter are identified, is proposed in this paper. The rotor position is estimated by a signal-injection sensorless scheme at standstill. The resistance, including the on-resistance of the insulated-gate bipolar transistor, the voltage error caused by the dead time of the inverter, and the d-axis and q-axis inductances are identified at standstill using the estimated position. After the motor starts by the signal-injection sensorless control, the sensorless scheme changes to a scheme based on the extended electromotive force estimation, which uses the identified parameters. The magnet flux linkage is also identified under the sensorless operation. The effectiveness of the proposed method is verified by several experimental results. [ABSTRACT FROM AUTHOR]

The influence of permanent-magnetic flux variation and magnetic saturation on sensorless control for interior permanent-magnet synchronous motors with concentrated windings is evaluated. By using finite-element method analysis, partial differential values of flux linkage are calculated directly and precisely in a short time. High-speed analysis of a motor voltage equation is realized by interpolating table data of calculated partial differential values. Analyzed results show good correlation with experimental results. The performance of sensorless control is greatly improved using analyzed results, and the influence of permanent-magnetic flux variation is predicted well. The proposed method is very useful for designing control algorithms, considering the influence of permanent-magnetic flux variation and magnetic saturation. [ABSTRACT FROM AUTHOR]