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In this article, a phase-locked loop (PLL) rotor position and speed observer, including an integrated decoupled stator current observer, is proposed for wide-speed-range sensorless control of permanent magnet synchronous motor (PMSM) drives. This new PLL scheme consists of two interconnected observers: 1) a second-order PLL position observer using the direct current error as correction term and 2) a third-order extended Luenberger speed observer, based on the mechanical model of the drive, using the quadrature current error as the correction term. The estimated speed is just an unrefined reference for the position integrator, and it is further corrected by the PLL. The current observer is a subsystem integrated as a PLL phase detector. Key relations between the current errors and the position and speed errors are proven, and a practical two-step observer design method is presented. A method for real-time identification of the stator resistance at low speeds and of the permanent magnet flux at high speeds is proposed, using the current errors in the current reference frame. Experimental results for a 0.5-kW surface-mounted PMSM drive confirm the effectiveness, excellent dynamic performance, and robustness of the new PLL observer. Stable motor and generator operation at 15 r/min (0.01 p.u.) with ramp and step speed reversals, high-speed operation, and stator resistance adaptation is shown. [ABSTRACT FROM AUTHOR]

This article proposes a speed observer algorithm for the sensorless control of a doubly fed induction generator based on classical adaptive backstepping technique. The sensorless control is shown using classic stator field oriented control, which is use to active and reactive power control. Performance of the proposed algorithm of a speed observer is validated by simulation and experimental results obtained using a small-rating generator and bidirectional voltage source converter. The stability analysis of the presented solution with regard to observer gains changes is also considered. [ABSTRACT FROM AUTHOR]

Alternating current (ac) active electronic loads (AELs) based on pulsewidth modulation (PWM) converters, capable of emulating nonlinear loads, require effective current control techniques and power stages. These two aspects of an AEL are interdependent mainly due to the presence of electromagnetic compatibility filters to reduce electromagnetic emissions. However, the filter components affect the dynamics of the system. In this context, this paper proposes a digitally implemented control strategy comprising the state feedback, robust observer, phase-locked loop, and linear current controller to cope with ac AEL applications. The control-oriented modeling and the control system design are presented. Experimental results obtained from a 10-kW three-phase three-level PWM converter prototype illustrate and demonstrate the feasibility of the proposed AEL control strategy. [ABSTRACT FROM PUBLISHER]

A new family of speed-sensorless sliding-mode observers for induction motor drives has been developed. Three topologies are investigated in order to determine their feasibility, parameter sensitivity, and practical applicability. The most significant feature of all schemes is that they do not require the rotor speed adaptation, i.e., they are inherently sensorless observers. The most versatile and robust is a dual-reference-frame full-order flux observer. The other two schemes are flux observers implemented in stator frame and rotor frame, respectively. These are simpler than the first one and make use of the sliding-mode invariance over a specified range of modeling uncertainties and disturbances. Main theoretical aspects, results of parameter sensitivity analysis, and implementation details are given for each observer in order to allow the comparison. Experimental results with the dual-reference-frame observer, considered the most adequate for practical applications, are presented and discussed. Sensorless operation with a sliding-mode direct-torque-controlled drive at very low speeds is demonstrated. It is concluded that the new proposed observers represent a feasible alternative to the classical speed-adaptive flux observers. [ABSTRACT FROM AUTHOR]