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Review of Ontology and Metaontology: A Contemporary Guide by Francesco Berto & Matteo Plebani
No full textReview of Ontology and Metaontology: A Contemporary Guide by Francesco Berto & Matteo Plebani
Advanced Modeling of Anisotropic Synchronous Machine Drives for Sensorless Control
Full text linkSynchronous machines are extensively used for home appliances and industrial applications thanks to their fast dynamic response, good overload capability and high energy density. A precise knowledge of the rotor position is required to control efficiently this kind of motors. In most of the applications resolvers or absolute encoders are installed on the rotor shaft. The employment of position sensors leads to significant drawbacks such as the increased size and cost of the system and a lower reliability of the drive, caused by additional hardware and cabling.
In sensorless drives motor position is estimated and employed in the machine control. Thus, no position sensor is required by the drive and all the drawbacks entailed by the sensor are eliminated. Moreover, the position estimation could be useful for redundancy in case of system failures. Therefore, position estimation techniques are object of great interest in the electric drives field.
Position estimation techniques can be divided into two main categories: methods that are suitable for medium or high speed and techniques suitable for low speed or standstill operations. In the former group the motor position is estimated through a reconstruction of the permanent magnet flux or back electromotive force (back-EMF). In case of synchronous reluctance machines it is possible to reconstruct the extended active flux or back-EMF. Stator voltages and currents measurements are needed for these reconstruction methods. Since these signals amplitude is proportional to the rotor speed, position estimation can be successfully performed only for medium and high speed machine operations.
In the low speed range, sensorless schemes exploit the rotor magnetic anisotropy. Thus, position can be estimated only for anisotropic motors, i.e. synchronous reluctance motors (SynRM), permanent magnet assisted synchronous reluctance motors (PMA-SynRM) and interior permanent magnet synchronous motors (IPMSM). The rotor anisotropy is recognized thanks to an high frequency voltage injection in the stator windings. Several injection techniques have been proposed, differing from the signal typology. In particular, high frequency sinusoidal or square-wave carriers are often applied. The position information is usually extracted from the current response through a heterodyning demodulation that entails the use of low pass filters in the position estimator, limiting its dynamic.
The aim of the research was proposing a new algorithm to estimate the rotor position from the HF current response, getting rid of the demodulation and its weaknesses. Thus, the ellipse fitting technique has been proposed. Robustness against signal processing delay effects and a reduced number of required filters are the main advantages of this novel approach. The inverse problem related to the ellipse fitting is solved implementing a recursive least squares algorithm. The proposed ellipse fitting technique is not affected by signal processing delay effects, and it requires the tuning of only one parameter, called forgetting factor, making the studied method suitable for industrial application thanks to its minimal setup effort.
Besides the ellipse fitting technique for rotor position estimation, two other topics have been studied:
- Computation of self-sensing capabilities of synchronous machines.
- Online incremental inductances identification for SynRM.Synchronous machines are extensively used for home appliances and industrial applications thanks to their fast dynamic response, good overload capability and high energy density. A precise knowledge of the rotor position is required to control efficiently this kind of motors. In most of the applications resolvers or absolute encoders are installed on the rotor shaft. The employment of position sensors leads to significant drawbacks such as the increased size and cost of the system and a lower reliability of the drive, caused by additional hardware and cabling.
In sensorless drives motor position is estimated and employed in the machine control. Thus, no position sensor is required by the drive and all the drawbacks entailed by the sensor are eliminated. Moreover, the position estimation could be useful for redundancy in case of system failures. Therefore, position estimation techniques are object of great interest in the electric drives field.
Position estimation techniques can be divided into two main categories: methods that are suitable for medium or high speed and techniques suitable for low speed or standstill operations. In the former group the motor position is estimated through a reconstruction of the permanent magnet flux or back electromotive force (back-EMF). In case of synchronous reluctance machines it is possible to reconstruct the extended active flux or back-EMF. Stator voltages and currents measurements are needed for these reconstruction methods. Since these signals amplitude is proportional to the rotor speed, position estimation can be successfully performed only for medium and high speed machine operations.
In the low speed range, sensorless schemes exploit the rotor magnetic anisotropy. Thus, position can be estimated only for anisotropic motors, i.e. synchronous reluctance motors (SynRM), permanent magnet assisted synchronous reluctance motors (PMA-SynRM) and interior permanent magnet synchronous motors (IPMSM). The rotor anisotropy is recognized thanks to an high frequency voltage injection in the stator windings. Several injection techniques have been proposed, differing from the signal typology. In particular, high frequency sinusoidal or square-wave carriers are often applied. The position information is usually extracted from the current response through a heterodyning demodulation that entails the use of low pass filters in the position estimator, limiting its dynamic.
The aim of the research was proposing a new algorithm to estimate the rotor position from the HF current response, getting rid of the demodulation and its weaknesses. Thus, the ellipse fitting technique has been proposed. Robustness against signal processing delay effects and a reduced number of required filters are the main advantages of this novel approach. The inverse problem related to the ellipse fitting is solved implementing a recursive least squares algorithm. The proposed ellipse fitting technique is not affected by signal processing delay effects, and it requires the tuning of only one parameter, called forgetting factor, making the studied method suitable for industrial application thanks to its minimal setup effort.
Besides the ellipse fitting technique for rotor position estimation, two other topics have been studied:
- Computation of self-sensing capabilities of synchronous machines.
- Online incremental inductances identification for SynRM
Inductance and Self-Sensing Capabilities Computation for Synchronous Reluctance Motors Based on Coenergy Model
No full text
Investigation on the Self-Sensing Capability of a Dual Three-Phase Synchronous Reluctance Machine
No full textEfficient QR Updating Factorization for Sensorless Synchronous Motor Drive Based on High Frequency Voltage Injection
No full textThe conventional methods for estimating the rotor position of permanent magnet synchronous machines, at low speed range and characterized by rotor saliency, rely on high frequency voltage injection in the stator windings. Ordinarily, the rotor position estimation is achieved through the demodulation of the high frequency current response. In this paper, an alternative method is presented for detecting rotor position from the rotating high frequency injection current response. The proposed ellipse fitting technique is not affected by signal processing delay effects and it requires the tuning of only one parameter, called forgetting factor, making the studied method suitable for industrial application thanks to its minimal setup effort. The inverse problem related to the ellipse fitting is solved implementing a QR recursive least squares algorithm. Efficient updating QR factorization has been adopted because of its features in terms of numerical stability and required limited computational effort. The proposed sensorless control scheme is validated by means of many experiments
An effective ellipse fitting technique of the current response locus to rotating HF voltage injection in IPMSM for sensorless rotor position estimation
No full textSensorless control schemes are object of great interest in the synchronous motor drives field.
They permit to avoid the use of position sensors in the system, allowing several benefits.
In this paper a sensorless control scheme is proposed for low speed or standstill operation of a synchronous motor drive, characterized by a rotor anisotropy.
The method is based on a high frequency voltage injection in the stator motor windings.
High frequency current response to this injection is obtained from the measured currents thanks to a high pass filter.
These filtered currents describe an ellipse trajectory, that is deeply analysed considering all its components.
In particular, ellipse major semi-axis tilt is related to the rotor position.
A recursive least squares estimator is proposed for the ellipse equation coefficients identification.
After some manipulations, the rotor position is extrapolated from these information
Francesco Berto e Matteo Plebani, 2015, "Ontology and Metaontology: A contemporary Guide"
No full textRecensione di "Ontology and Metaontology: A Contemporary Guide" di Francesco Berto, Matteo Pleban
Measurement of the Self-Sensing Capability of Synchronous Machines for High Frequency Signal Injection Sensorless Drives
Full text linkSignal injection sensor-less control for synchronous
machines is known to be afflicted by an estimation error dependent
on the load current. The estimation error is related to the cross-
saturarion and the saliency of the adopted synchronous machine.
A motor can be more or less suitable for signal injection sensorless
control compared to other motors with different designs or sizes.
A sensorless drive can even be afflicted by the control divergence
when the machine is highly saturated, resulting in a useless drive.
Moreover, even when the control converges, the actual current
control trajectory is different from the given reference. In this
paper, a measurement procedure of the convergence region, i.e. the
operating points where the motor can be successfully controlled
without a position sensor is presented and validated. In particular,
two different synchronous motors are considered, a permanent
magnet assisted synchronous reluctance motor (PMA-SynRM) and
a synchronous reluctance motor (SynRM
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