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This paper deals with stator-flux-oriented control of permanent-magnet (PM) synchronous motors and synchronous reluctance motors (SyRMs). The variables to be controlled are the stator-flux magnitude and the torque-producing current component, whose references are easy to calculate. However, the dynamics of these variables are nonlinear and coupled, potentially compromising the control performance. We propose an exact input–output feedback linearization structure and a systematic design procedure for the stator-flux-oriented control method in order to improve the control performance. The proposed controller is evaluated by means of experiments using a 6.7-kW SyRM drive and a 2.2-kW interior PM synchronous motor drive. [ABSTRACT FROM AUTHOR]

In this study, the authors presented a systematic design procedure of outer rotor bearingless synchronous reluctance motor (SynRM). The proposed motor is compared with an already prototyped inner rotor bearingless SynRM at different operation points. It has been shown that a properly designed outer rotor SynRM can produce higher levitation forces than the inner rotor counterpart. The inner rotor motor produces higher torque and eccentric forces than the outer rotor motor. [ABSTRACT FROM AUTHOR]

This paper deals with the optimal state reference calculation for synchronous motors having a magnetically salient rotor. A lookup table computation method for the maximum torque-per-ampere locus, maximum torque-per-volt limit, and field-weakening operation is presented. The proposed method can be used during the start up of a drive, after the magnetic model identification. It is computationally efficient enough to be implemented directly in the embedded processor of the drive. When combined with an identification method for the magnetic model, the proposed method enables the plug-and-play startup of an unknown motor. Furthermore, a conventional reference calculation scheme is improved by removing the need for one two-dimensional lookup table. A 6.7-kW synchronous reluctance motor drive is used for experimental validation. [ABSTRACT FROM AUTHOR]

This paper deals with methods for parameter estimation of two-mass mechanical systems in electric drives. Estimates of mechanical parameters are needed in the start-up of a drive for automatic tuning of model-based speed and position controllers. A discrete-time output error (OE) model is applied to parameter estimation. The resulting pulse-transfer function is transformed into a continuous-time transfer function, and parameters of the two-mass system model are analytically solved from the coefficients of this transfer function. An open-loop identification setup and two closed-speed-loop identification setups (direct and indirect) are designed and experimentally compared. The experiments are carried out at nonzero speed to reduce the effect of nonlinear friction phenomena on the parameter estimates. According to results, all three identification setups are applicable for the parameter estimation of two-mass mechanical systems. [ABSTRACT FROM PUBLISHER]

This paper proposes a model-based two-degree-of-freedom (2DOF) state-space speed controller design for a two-mass mechanical system. Analytical tuning rules for a feedback gain, the reduced-order state observer, full-order state observer, and prefilter are derived. The proposed design rules enable the automatic tuning of the controller if the mechanical parameters are known. The prefilter is designed for step, ramp, and parabolic command tracking. The effects of the time delay, measurement noise, and parameter variations on controller tuning and control performance are studied by means of Nyquist diagrams, noise transfer functions, and time-domain simulations. It is shown that the full-order-observer-based controller is a preferable choice, particularly if the feedback loop is delayed and noisy. The proposed controller design is experimentally evaluated using two 4-kW servo motors coupled with a toothed belt; good reference tracking for step and dynamic commands, as well as robust and fast load-torque rejection, is demonstrated. [ABSTRACT FROM PUBLISHER]

An interior permanent-magnet (PM) motor is modeled by a combined analytical–numerical approach, in which the relationships between the stator currents and flux linkages are identified with static finite-element (FE) analysis. In addition to the previous approaches using the current space vector as the state variable, new models are also developed using the flux-linkage space vector, which leads to more convenient time-integration of the voltage equations. In order to account for the zero-sequence effects in delta connection, the models also include either the zero-sequence flux or current as an additional state variable. Finally, the possibilities of deriving the required quantities as partial derivatives of the magnetic field energy are discussed. The energy-based approaches avoid inaccuracies related to torque computation and thus allow better satisfying the power balance in the state-space model. We show the ability of the developed state-space models to predict the currents and torque equally to a nonlinear time-stepping FE model with much less computational burden. The results are validated by means of measurements for a prototype machine in both star and delta connections. In addition, we also demonstrate the effect of the zero-sequence current on the torque ripple in case of a delta-connected stator winding. [ABSTRACT FROM PUBLISHER]

A classical control approach to the design and analysis of proportional–integral (PI) speed controllers for electrical drives is presented. After vindicating the fact that traditional one-degree-of-freedom PI control generally gives unsatisfactory performance, a well-performing two-degree-of-freedom PI controller is designed, with analytical parameter selection. The robustness of the obtained closed-loop system is analyzed and is found to be satisfactory. All the proposed control designs are validated by means of experiments. [ABSTRACT FROM AUTHOR]

This paper applies a dynamic space-vector model to loss-minimizing control in induction motor drives. The induction motor model, which takes hysteresis losses and eddy-current losses as well as the magnetic saturation into account, improves the flux estimation and rotor-flux-oriented control. Based on the corresponding steady-state loss function, a method is proposed for solving the loss-minimizing flux reference at each sampling period. A flux controller augmented with a voltage feedback algorithm is applied for improving the dynamic operation and field weakening. Both the steady-state and dynamic performance of the proposed method is investigated using laboratory experiments with a 2.2-kW induction motor drive. The method improves the accuracy of the loss minimization and torque production, it does not require excessive computational resources, and it shows fast convergence to the optimum flux level. [ABSTRACT FROM PUBLISHER]

This paper deals with a speed and position estimation method for the sensorless control of permanent magnet synchronous motors. The method is based on a speed-adaptive observer. The dynamics of the system are analyzed by linearizing both the motor model and the observer, and the observer gain is selected to give improved damping and noise suppression. At low speeds, the observer is augmented with a signal injection technique, providing stable operation down to zero speed. The experimental results, obtained using a 2.2-kW interior magnet motor, are in agreement with the results of the analysis. [ABSTRACT FROM AUTHOR]

This paper deals with the maximum torque and speed of permanent-magnet synchronous motor (PMSM) drives when the inverter output voltage is filtered by an LC filter with a cutoff frequency well below the switching frequency. According to steady-state analysis, the filter affects the performance of the motor drive, especially at high speeds. The stator current is not equal to the inverter current, and due to the inverter current and inverter voltage limits, the torque-maximizing stator current locus differs from that of a drive without the filter. A field-weakening method is proposed for PMSM drives with an inverter output filter. The method is implemented and tested in a 2.2-kW PMSM drive. The experimental results agree well with the analysis, and validate the high- speed performance of the proposed field-weakening method. [ABSTRACT FROM AUTHOR]