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The sensorless position control of permanent magnet synchronous motors can be successfully implemented by superimposing a high-frequency voltage signal on the control voltage. In this paper the position estimation is obtained by means of a high-frequency sinusoidal voltage signal injected along the estimated d-axis. Several methods proposed in the literature obtain the position estimation by tracking the zero condition of the high-frequency q current component. We propose a new approach that also exploits the d-axis high-frequency current component, allows working with injected voltage signal of reduced amplitude thus reducing noise and additional losses. The main contribution of paper relies in the compensation of the motor end-effects, due to the finite length of the tubular motor armature. These effects must be taken into account in the motor modeling because cause an error in the position estimation that is variable with the motor position. The modeling of the phenomenon and a proper compensation technique are proposed in the paper. Last, a simplified I-type controller is used to estimate motor position instead of the commonly adopted PI controller plus integrator and this requires a low-effort design. Experiments on a linear tubular permanent-magnet synchronous motor prototype are presented to validate the theoretical analysis and evidence the feasibility of the proposed sensorless technique. I.

The sensorless position control of permanent-magnet motors is successfully implemented by superimposing a highfrequency voltage signal on the voltage reference or adding a high-frequency current signal to the current reference. The former approach is usually preferred because of its simplicity, although the latter one may allow better performance. This paper presents a new algorithm for the sensorless control of low-saliency permanent-magnet synchronous motors based on high-frequency sinusoidal current signal injection into the d-axis. Different from the related literature, the position information is derived by analyzing the measured high-frequency currents. The amplitude of the d-axis voltage reference is also exploited to improve performance. A proportional-integral (PI) controller plus a resonant term (PI-RES) is adopted to ensure the accurate tracking of both the dc and high-frequency components of the d-axis current reference. The main advantages of the proposed approach are the increased accuracy and sensitivity with respect to the approach based on voltage injection, the insensitiveness to inverter nonlinearities that are compensated by the current regulation loop, the actual control on the injected current value, and the practical absence of acoustic noise. Experiments on a linear tubular permanent-magnet synchronous motor prototype have been carried out to verify the aforementioned advantages. This paper also presents a discussion of the parameters of the PI-RES.

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The sensorless control schemes based on machine saliency detection by signal injection commonly adopt a position observer to estimate the motor position. The position observer usually employs proportional-integral-derivative-(PID-) type controllers and low-pass-filters (LPFs) whose parameters need to be properly tuned to achieve satisfactory, or at least stable, performances. Generally, the position observers are tuned with trial and error procedures that require commissioning time and control design experience. This paper deals with the observer modelling and tuning. In particular, the observer model is used for a model-based position control tuning and the effectiveness of the proposed procedure is confirmed by the good agreement of theoretical and experimental results. The experimental test have been realized using both a linear tubular permanent magnet motor (LTPM) and a rotating internal permanent magnet motor (IPM) to demonstrate that the motor control performances can be predicted only if the observer behaviour is considered.Index Terms--High frequency signal injection, linear tubular permanent magnet motors, internal permanent magnet motors, position observer tuning, sensorless position control.

This paper presents a performance comparison among some of the most effective spectral estimation techniques applied to the fault diagnosis o f induction machines. The diagnostic test is based on the analysis ofthe current space vector during motor starling via short-time analysis, using a sliding window and different spectral estimation algorithms. Differently from most o f the diagnostic techniques already proposed in the technical literature, the approach, presented in this work, i s effective regardless the load condition of the machine. Algorithms based on the FFT o r optimal band-pass filters (nonparametric methods), on the estimation o f a linear time-invariant model of the signal (parametric mefhods), and on the eigenanalysis of the autocorrelation matrix (high-resolution methods) have been used to process the motor current spare-vector. Experiments prove that both parametric and high-resolution methods overcame the FFT-based approaches, keep only the principal frequency components o f the signal and decrease the noise influence, thus permitting a better interpretation of the current vector spectrum and an automatic fault detection procedure.

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