Search

In traditional maximum torque per ampere (MTPA) method based on signal injection, fixed wave amplitude and constant integral coefficient are employed, which actually degrade the optimal current angle tracking performance in variable conditions, especially under heavy loads. In order to solve this problem, an improved MTPA method based on amplitude-adjustable square wave injection is proposed. First, the relationships among optimal current angle, square wave amplitude and electromagnetic torque are analyzed. The analysis results indicate that if fixed wave amplitude is adopted, the fluctuations in the obtained current angle increases when load torque rises. Based on this relationship, an amplitude-adjustable square wave virtual signal injection MTPA method is proposed. By adjusting square wave amplitude according to the load torque, steady-state fluctuations of the obtained current angle can be reduced compared to conventional method under heavy loads. Meanwhile, to improve the MTPA dynamic response under load change conditions, an adaptive fuzzy control method is proposed for adjusting integral coefficient. Finally, the validity of the improved MTPA method is verified through experimental results. [ABSTRACT FROM AUTHOR]

This paper proposes the design method using a numerical formula known as the Advanced Inverse Cosine Function (AICF) to reduce vibration of the Interior Permanent Magnet Synchronous Motor (IPMSM). The proposed method reduces the vibration by modifying the rotor shape based on the numerical formula that makes the air-gap flux density sinusoidal under certain load condition. The radial electromagnetic force that is the source causing the vibration of the motor is related to the air-gap flux density under load condition. Therefore, the AICF which reduces the magnitude of the harmonic of the air-gap flux density is derived in this paper and the radial electromagnetic force due to the harmonic of the air-gap flux density decreases applying the AICF. To verify the validity of the proposed method, an 8 pole 12 slot prototype applied with the AICF is proposed. Using the Finite Element Analysis (FEA), the radial electromagnetic force and the displacement of the prototype with the AICF are compared with those of the normal model without the AICF. Finally, the results of the vibration test of the normal and AICF models are compared. [ABSTRACT FROM AUTHOR]

As for the sensorless control of interior permanent magnet synchronous motor (IPMSM), conventional high frequency (HF) pulsating signal injection method is widely used, which uses band-pass filter (BPF) and low-pass-filter (LPF) based phase-locked-loop (PLL), however it may face the problems of poor stability and long convergence time. Therefore, an improved signal demodulation algorithm based on moving-average-filter (MAF)-PLL is proposed. MAF, which makes full use of the HF signal periodicity and half-wave symmetry, has higher bandwidth and better harmonics suppression ability than BPF or LPF. Furthermore, a proportional-integral (PI) regulator is used to gain the rotor speed and an integrator is applied to estimate rotor position. Compared with the conventional method, the proposed method gets rid of BPF and LPF, contributing to improving the stability and dynamic performance. Besides, undetermined parameters are reduced to one, i.e., window length of MAF, avoiding complex parameters design and selection. The proposed HF pulsating injection method has simpler signal demodulation process and is easy to implement. Finally, the experimental results have verified the feasibility and effectiveness of proposed method. [ABSTRACT FROM AUTHOR]

This paper proposes a new numerical formula and a design method to reduce the torque ripple while improving efficiency and the control performance of an interior permanent magnet synchronous motor. In previous studies, the inverse cosine function (ICF) has been used for torque ripple reduction by making the air gap flux density distribution sinusoidal under a no-load condition. However, in this paper, the advanced inverse cosine function (AICF) based on the ICF is proposed. It determines an asymmetric rotor shape for rendering the air gap flux density distribution sinusoidal, considering a certain load condition. In addition to the torque ripple reduction, lower peak values, the total harmonic distortion (THD) of the induced voltage, and a lower iron loss can be achieved by applying the AICF, compared to the other conventional methods. The lower peak value and THD of the induced voltage are important because they affect the control performance of the motor. The lower iron loss can also lead to a higher efficiency, particularly, in the high-speed region. To verify the validity of the proposed design method, the characteristics of 8-pole, 12-slot motors that have different rotor shapes are analyzed using finite element analysis and experiments. [ABSTRACT FROM AUTHOR]

At nonlinear field-weakening control of interior permanent magnet synchronous motor (IPMSM), the working point is difficult to calculate and the saturation of current regulators may lead to losing control. Linear field-weakening control (LFC) of IPMSM is proposed to control both torque and current in wide speed range applications and LFC can prevent loosing current control in IPMSM. IPMSM operation range is divided into three areas, namely constant torque linear area, constant power transition linear area, and constant direct axis current area. Current, speed, and torque of the three areas are obtained while maintaining the current and voltage constraints. Currents are controllable and the system can operate in deep field-weakening. Results are used to calculate the IPMSM working points. The validity of this study is verified by experiments. [ABSTRACT FROM PUBLISHER]

For the purpose of improving the performance of sensorless interior permanent magnet synchronous motor (IPMSM) drives, an enhanced electromotive-force (EMF)-based position observer adopting second-order generalized integrator (SOGI) to eliminate the harmonic error is proposed. The inverter nonlinearities and flux spatial harmonics that give rise to the harmonic error of position estimation are analyzed. A harmonic decoupling network consisting of multiple SOGIs based adaptive filters is adopted to achieve the multiple selective EMF harmonic elimination (MSEHE). The application of the frequency-locked loop ensures the SOGI resonance frequency adaptive, which is critical for the variable-speed operation in IPMSM drive applications. Using the SOGI-MSEHE in the position tracking estimator, the low-order harmonics in the estimated EMF can be effectively eliminated, contributing to cancelling the position estimation harmonic error. The effectiveness of the proposed enhanced position observer is verified by the experimental results at a 2.2-kW IPMSM sensorless drive. [ABSTRACT FROM PUBLISHER]