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This paper proposes a d–q cross-coupling current controller for permanent magnet synchronous motor (PMSM) drives. Slotting and cross-coupling effects in PMSMs cause the effective air-gap length to vary with the rotor angle and distort the distribution of the air-gap flux. Such distortions have a significant influence on the current control by changing the relationship between the stator currents and voltages. To investigate their effects, a d–q model is established in this paper, which is suitable for describing the voltage characteristics of the actual PMSMs. The model contains the angle-dependent parameters, the cross-coupling inductance between d–q axes, and the q-axis permanent magnet flux linkage, unlike the ideal d–q model. The transfer function matrix from the d–q currents to d–q voltages of PMSM is newly derived from the model. Based on that, the current controller with the feedback and feedforward terms of 2-by-2 matrix is proposed. It is designed so that the independent gains are in low-pass filter forms and the coupling control gains are zero with eliminating interference between d–q axes. The proposed controller contributes to providing the stable control performance by canceling the slotting and cross-coupling effects. The performance of the proposed current controller is verified by experimental results. [ABSTRACT FROM AUTHOR]

The linear vernier permanent magnet (LVPM) motor incorporates the merits of high efficiency, simple mechanism, and low cost, which have a bright future in urban rail transportation. This paper proposes a new sensorless direct thrust force control (DTFC) for the LVPM motor. The novelty is the introduction of a modified flux linkage observer, which has strong robustness against the interferences, no phase lag, and no attenuation. Compared with conventional flux linkage calculation methods, the proposed observer can provide desirable flux linkages, which increases the robustness of the sensorless DTFC system. Simulation and experimental results based on an LVPM motor drive demonstrate the accuracy and robustness. The validations in the aspect of the robustness to parameter errors, measurement errors, and noise show the superiorities of the modified flux linkage observer. [ABSTRACT FROM AUTHOR]

This paper proposes a dc-flux-injection method for fault diagnosis of high-resistance connection (HRC) in a direct-torque-controlled permanent magnet synchronous machine (PMSM) drive system. In this method, the flux linkage bias is superimposed in the flux control loop of the direct torque control system, and then the dc current offset is excited in the stator windings. By superimposing two different pairs of flux linkage biases, a binary linear equation group about the resistance deviations can be established based on the stator currents and zero-sequence voltage component. By solving the equation group, the resistance deviations can be calculated for the HRC fault detection, faulty phase location, and fault severity estimation. Both the simulation and experimental results validate the effectiveness of the proposed method. In addition, the proposed method is immune to the symmetrical variations of stator resistance and interturn fault of the PMSM. [ABSTRACT FROM AUTHOR]

This paper explores the use of speed harmonic for accurate and fast maximum-torque-per-ampere (MTPA) control of interior permanent magnet synchronous machines (IPMSMs). A novel MTPA angle calculation approach is proposed, in which the MTPA angle is directly calculated from the phase angle of the speed harmonic that is induced by an injected harmonic current. At first, the relation between the speed harmonic and machine parameters is derived from the IPMSM model, which shows that the phase angle of the induced speed harmonic can be utilized to cancel the machine parameters in existing MTPA equation. Thus, a new MTPA equation is derived, which does not involve machine parameters for MTPA angle calculation. Compared with existing methods, the proposed approach is independent from the machine and drive nonlinearities. Moreover, the MTPA angle is directly calculated from the derived MTPA equation, so the proposed approach is fast and computationally efficient. Thus, the proposed approach is suitable for both on-line applications and building off-line lookup tables of MTPA angles for IPMSMs. The proposed approach is experimentally evaluated on a laboratory IPMSM drive system. [ABSTRACT FROM AUTHOR]

The aim of this study is to introduce the maximum torque per total ampere (MTPTA) control strategy for brushless doubly fed induction machine drives taking iron loss into account. In this regard, the condition for realizing the MTPTA is investigated in the presence of iron loss by a theoretical approach. It is shown the proposed strategy is realized when the MTPTA criterion tracks zero as reference signal. As a result, the current is not only shared between the stator windings fairly but also total stator currents are minimized for a given torque. The experimental results confirm the performance of the proposed control strategy. [ABSTRACT FROM AUTHOR]

When multiphase drives are used for specific applications, the modular solutions are preferred as they use consolidated power electronics technologies. The literature reports two modeling approaches for multiphase machines having a modular configuration of the stator winding. The first approach is the vector space decomposition (VSD) that models the energy conversion as for an equivalent three-phase machine. The main alternative to the VSD is the multistator (MS) modeling that emphasizes machine modularity in terms of torque production. Both approaches have advantages and disadvantages for multiphase machines with a modular structure. Therefore, this article aims to combine the VSD and MS approaches, defining a new matrix transformation and, hence, developing a new modeling approach for multiphase machines with a modular structure. The proposed transformation allows a decoupled and independent torque control of the sets composing the machine, preserving the torque regulation's modularity. Together with a new vector control scheme, it has been applied to a modular permanent magnet synchronous machine (PMSM) with a nonstandard spatial shift between windings. Experimental results are presented for a nine-phase PMSM prototype with a triple-three-phase stator winding configuration. [ABSTRACT FROM AUTHOR]

In this article, a method to estimate the temperature of an NdFeB magnet in an interior permanent magnet synchronous motor (IPMSM) has been developed in medium and high speed operating conditions. Fundamental reactive energy is newly brought out and directly used in the developed method to estimate the magnet temperature accurately, which results in higher sensitivity with respect to the magnet temperature variation compared to the conventional methods. It is because the variation of the reactive energy caused by the magnet temperature includes variations of inductances in addition to that of the magnet flux linkage. In the proposed method, a stator resistance error effect caused by a stator temperature is inherently removed without any additional temperature sensor on stator winding. Moreover, the proposed method is robust to an inverter nonlinearity effect and ac resistance effect. As a result, the proposed method can estimate the magnet temperature accurately in real time, even in load variation, regardless of the stator temperature variation. The magnet temperature estimation error has been less than 3.7 °C in the online estimation for 10 000 s under wide speed and torque variations. [ABSTRACT FROM AUTHOR]

A sensorless algorithm is developed on the basis of a rotor flux observer in the stationary frame. In particular, it involves a parameter adaptive algorithm for an initial rotor flux like the observer, which was recently proposed by Bobtsov et al. (Automatica, vol. 61, Nov. 2015). In the proposed method, the flux observer is linked to the parameter estimator via a compensating term that results from parameter error. This method has a robust property against dc bias errors, i.e., it cures the inherent weakness of the pure integrator (flux observer) to dc offsets that frequently occur in current measurements and voltage estimates. The robust performance is demonstrated through simulations and experimental results. [ABSTRACT FROM AUTHOR]