Abstract
This paper proposes using a frequency-locked loop-based detector to estimate rotational speed and angle position for an electric machine rotor shaft. The measurement system consists of arrays of permanent magnets fixed to the rotor shaft together with linear Hall-effect sensors attached to a fixed frame. Parametric uncertainties on the sensor assembly lead to significantly noisy signals, exhibiting unbalance and harmonic distortion. To accurately estimate rotational speed and angle, it is proposed to use a frequency-locked loop scheme based on a fourth-order harmonic oscillator (FOHO) to allow the processing of the symmetric components, thus dealing with the unbalance. The scheme also includes an adaptive law to reconstruct the fundamental frequency. Moreover, a harmonic compensation mechanism comprising parallel FOHOs is included; each FOHO is tuned at the spectral component under concern for its cancellation. The proposed algorithm delivers a clean estimate of the positive sequence fundamental component despite the disturbances at the signals provided by the Hall-effect sensor, which is used to reconstruct the rotation angle. The described approach could enhance low-cost sensing solutions in applications where position feedback is mandatory and sensorless control is impossible, not requiring special installation considerations.
Highlights
Rotating electrical machines benefit from the use of speed up coils in quadrature to measure the back-electromotive 3 and position signals to attain motion control
The demodulation of 4 fication of numerous applications in the industrial, aerospace, pickup-coil signals yields the angular position of the rotor. 5 and automotive fields, offered solutions must be precise, In contrast, encoders rely on optical readings of slits etched 6 robust, and cost-effective
Based on the fourth-order harmonic oscillator (FOHO) structure of the above-described model 284 in (11) and (12), we propose the following FOHO-based adaptive estimator (FOHO-AE) to approximate the fundaradially unbounded, the result is global
Summary
Rotating electrical machines benefit from the use of speed up coils in quadrature to measure the back-electromotive 3 and position signals to attain motion control. The demodulation of 4 fication of numerous applications in the industrial, aerospace, pickup-coil signals yields the angular position of the rotor. Position For this reason, numerous efforts have been devoted to feedback is relevant in synchronous machines to developing sensorless control solutions that estimate the rotor implement the so-called field-oriented control. Electric machines use resolvers or encoders 32 tion estimates could face challenges in situations like startup, to measure rotor position and speed. While these drawbacks can be accepted in some systems, The rotor of the resolver is mechanically coupled to the motor many applications still require a more robust sensing solushaft and has an excitation coil fed by a high-frequency tion. The authors in [12] proposed the use of a delayed position can be measured by magnetic means using linear 94 signal cancellation-based (CDSC) PLL over an array of two
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