This paper presents a new sensorless method, the so-called harmonic impedance / admittance, for detecting speed of induction motors, which is based on the impedance measurement, harmonic analysis and digital signal p...This paper presents a new sensorless method, the so-called harmonic impedance / admittance, for detecting speed of induction motors, which is based on the impedance measurement, harmonic analysis and digital signal processing. The method improves theperformance of conventional voltage-based and current-based techniques, because the impedance or admittance harmonics is independent of input or output of motor system due to the system-inherent nature of impedance. It has been used successfully in detecting the rotor speed of three-phase induction motors. A comparison between the proposed method and the conventionalcurrent-based method is also demonstrated.展开更多
Precise extraction of coupling-of-mode (COM) parameters plays a key role in the design for modern high performance surface acoustic wave (SAW) filters. An accurate and efficient analysis of char- acteristics for SAW p...Precise extraction of coupling-of-mode (COM) parameters plays a key role in the design for modern high performance surface acoustic wave (SAW) filters. An accurate and efficient analysis of char- acteristics for SAW propagating under periodic metal gratings has been developed based on the concept of harmonic admittance and periodic Green抯 function. Some further improvement is made on the nu- merical algorithm, such as isolation of the logarithmic singularity, asymptotic simplification of periodic Green抯 function, and utilization of Chebyshev polynomials as basis functions of the charge distribution. The most important point is extraction of the phase of coupling reflection coefficient by the characteris- tics of standing wave on the edges of stopband. This approach leads to a fast, precise and full extraction of COM parameters. The results and discussions for several materials have been presented.展开更多
文摘This paper presents a new sensorless method, the so-called harmonic impedance / admittance, for detecting speed of induction motors, which is based on the impedance measurement, harmonic analysis and digital signal processing. The method improves theperformance of conventional voltage-based and current-based techniques, because the impedance or admittance harmonics is independent of input or output of motor system due to the system-inherent nature of impedance. It has been used successfully in detecting the rotor speed of three-phase induction motors. A comparison between the proposed method and the conventionalcurrent-based method is also demonstrated.
基金supported by National Natural Science Foundation of China(Grant Nos.10074034 and 60261003).
文摘Precise extraction of coupling-of-mode (COM) parameters plays a key role in the design for modern high performance surface acoustic wave (SAW) filters. An accurate and efficient analysis of char- acteristics for SAW propagating under periodic metal gratings has been developed based on the concept of harmonic admittance and periodic Green抯 function. Some further improvement is made on the nu- merical algorithm, such as isolation of the logarithmic singularity, asymptotic simplification of periodic Green抯 function, and utilization of Chebyshev polynomials as basis functions of the charge distribution. The most important point is extraction of the phase of coupling reflection coefficient by the characteris- tics of standing wave on the edges of stopband. This approach leads to a fast, precise and full extraction of COM parameters. The results and discussions for several materials have been presented.
