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A novel structure for sensorless induction motor drive is proposed based on flux vector acceleration torque control. The proposed structure combines direct torque control with speed estimation based on slip frequency evaluation. A stable drive operation is enabled in a wide range of operating speeds, including at standstill. Index Terms--Direct torque control (DTC), induction motor (IM), sensorless drive, speed estimation.

A novel control strategy for the induction motor drive, based on the field acceleration method, is presented. The torque is controlled through variations of the stator flux angular velocity. The stator flux is controlled by using a feedforward control scheme, with the stator flux reference vector adjusted so as to obtain the fixed rotor flux amplitude. The applied controller assures a fast torque response, low torque ripple in the steady state, and drive operation with a constant switching frequency. The algorithm includes the improved stator and rotor flux estimation that guarantees the stable drive operation in all operating conditions, even at low speeds. The experimental tests verify the performance of the proposed algorithm, proving that good behavior of the drive is achieved in the transient and steady-state operating conditions. Index Terms--AC motor drives, flux vector estimation, sensorless torque control.

In this paper a second order generalized integrator (SOGI) based quadrature signal generator (QSG) is proposed with the improved DC offset compensation parameter tuning procedure. Namely, for the conventional DC rejection technique, which comprises an integrator (I) included in the SOGI, the modified parameter tuning procedure is proposed based on the set QSG response damping factor value. In this way, when compared to existing QSG tuning techniques based on empirical trial-and-error approach, simplified parameter tuning procedure is proposed based on proposed parametric equations, which enable improved QSG performance verified by simulation and experimental runs by a single-phase phase-locked loop PLL. In this way the increased SOGI based QSG DC offset compensation speed can be achieved, which is critical in various types of single phase PLL applications. [ABSTRACT FROM AUTHOR]

In this paper, a novel closed-loop synchronization algorithm is proposed based on the linear phase angle detection. The linear phase detection is performed by the inverse tangent (atan2) trigonometric function, while the frequency tracking is performed by a proportional-integral (PI) loop filter and phase integrator. By using the linear phase detection, the linear phase-locked loop (PLL) is employed, which is simpler to implement and to tune, and which also performs better for large frequency and phase variations when compared to conventional PLL algorithms. Also, the novel technique operates consistently for a whole range of designated PLL crossover frequencies when compared to existing PLL techniques, which makes it a better candidate when higher filtering is required of higher harmonics and measurement noise. When compared with existing algorithms that use atan function for phase angle estimation, the novel algorithm enables the frequency estimation that does not include differentiation, which improves the resulting algorithm immunity to measurement noise and higher harmonics. The novel PLL is tested by simulation and experimental runs. [ABSTRACT FROM AUTHOR]

In this paper an improved stationary-frame AC current controller based on the proportional-integral-resonant control action (PIR) is proposed. Namely, the novel twoparameter PIR controller is applied in the stationary-frame AC current control, accompanied by the corresponding parameter-tuning procedure. In this way, the proportionalresonant (PR) controller, common in the stationary-frame AC current control, is extended by the integral (I) action in order to enable the AC current DC component tracking, and, also, to enable the DC disturbance compensation, caused by the voltage source inverter (VSI) nonidealities and by nonlinear loads. The proposed controller parameter-tuning procedure is based on the three-phase back-EMF-type load, which corresponds to a wide range of AC power converter applications, such as AC motor drives, uninterruptible power supplies, and active filters. While the PIR controllers commonly have three parameters, the novel controller has two. Also, the provided parameter-tuning procedure needs only one parameter to be tuned in relation to the load and power converter model parameters, since the second controller parameter is directly derived from the required controller bandwidth value. The dynamic performance of the proposed controller is verified by means of simulation and experimental runs. [ABSTRACT FROM AUTHOR]

Summary: This paper presents a new method for the fast detection of series electrical arc (SEA) fault in a photovoltaic (PV) system, which relies on a power converter output switching waveforms as the excitation signal used to identify PV small‐signal impedance at switching frequency. In addition to the small‐signal impedance value, the proposed method extracts the high frequency noise power value caused by SEA from the PV current and uses it to indicate the presence of SEA. Both theoretical analysis and measurements performed on a commercial PV system show that SEA causes a step‐like increase in small‐signal reactance. SEA was detected in less than 10 ms during tests of the proposed algorithm. Moreover, various tests showed that there was no false tripping during transients in normal operation. Finally, the proposed algorithm was implemented and tested with a commercially available digital signal processor. [ABSTRACT FROM AUTHOR]