Indirect speed sensor for asynchronous machine
ABSTRACT This paper presents a new and simple approach for sensorless speed control of asynchronous machine. It shows a self-contained electronic module which determines the speed of the machine with only two phase current measurements. Thus, the speed calculation is independent on the machine parameters and on control laws; this allows to design the control by considering the speed as an input. The principle of the method is based on rotor slot harmonics without high frequency injection. In fact, the rotor slot harmonics depend on rotor speed. These signals appear in the stator's spectrum with very low amplitude, in particular for a motor with skewed rotor slots. Moreover, the harmonics move with stator frequency. An analog adaptive band pass filter follows and amplifies this harmonics. As the response time is high at low speed, a digital algorithm is included in the microcontroller in order to decrease the response time. The proposed indirect speed sensor requires only some classical analog components and a low cost microcontroller. A short time calibration is necessary for the first start time of the inverter and the motor. Experimental results on a testing bench with different speed benchmarks are presented.
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ABSTRACT: A novel sensorless speed identifier for real-time application in induction motor drives under steady-state and transient conditions is proposed. It is based on the calculation of rotor slot harmonic (RSH) frequencies using an adaptive digital filter. It outperforms other analog or spectrum-based RSH speed identifiers in terms of accuracy and speed of response. The new identifier measures the speed with less than 0.1% error by processing the stator current on a sample-by-sample basis. It is also capable of tracking speed transients of high slew rates with high accuracy. The authors believe this to be the first effective tracking of RSHs during transients ever reported. The proposed algorithm is computationally very efficient and requires only a single processor for its real-time implementation. Simulated and experimental data were used to validate the algorithmIEEE Transactions on Industry Applications 02/1998; · 1.67 Impact Factor
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ABSTRACT: This paper presents a viable transducerless rotor position and velocity estimation scheme for PWM inverter driven induction, synchronous, and reluctance machines with the capability of providing robust and accurate dynamic estimation independent of operating point, including zero and very high speeds, light and heavy loading. The injection of a balanced three-phase high frequency signal (500 to 2 kHz) generated by the inverter, followed by appropriate signal demodulation and processing combined with a closed-loop observer, enable the tracking of rotor magnetic saliencies from the machine terminals. Although rotor magnetic saliency is inherent within reluctance machines, and most synchronous machines, saliency in the induction machine is introduced via a modulation of the rotor slot leakage with minimal detrimental effects on the machine performance. Experimental verification for the induction machine is includedIEEE Transactions on Industry Applications 04/1995; · 1.67 Impact Factor