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For interior permanent magnet synchronous motor (IPMSM) drives, high-frequency (HF) rotating voltage signal injection method is widely employed to estimate the initial rotor position. However, conventional demodulation method based on current phase is complex and susceptible to filters and digital control delays, an amplitude demodulation algorithm is proposed in this paper. With the proposed method,...
High frequency (HF) signal injection scheme is widely used to estimate the initial rotor position of Interior Permanent Magnet Synchronous Motors (IPMSM). The accuracy of the estimated rotor position, however, may be degraded by the phase delay caused by pulse width modulation (PWM), digital filters in signal demodulation process, non- ideality of inverter, and so on. To solve this problem, the main...
Rotor time constant is a key parameter in an induction motor drive with indirect field oriented control. In this paper, a modified Model Reference Adaptive Controller (MRAC) utilizing d-axis stator voltage is proposed for online updating of rotor time constant. Compared with the traditional d-axis voltage model, the information of torque current and stator frequency is incorporated into the adaptive...
Image splicing is a simple and common image tampering operation, where a selected region from an image is pasted into another image with the aim to change its content. In this paper, based on the fact that images from different origins tend to have different amount of noise introduced by the sensors or post-processing steps, we describe an effective method to expose image splicing by detecting inconsistencies...
One common form of tampering in digital audio signals is known as splicing, where sections from one audio is inserted to another audio. In this paper, we propose an effective splicing detection method for audios. Our method achieves this by detecting abnormal differences in the local noise levels in an audio signal. This estimation of local noise levels is based on an observed property of audio signals...
The Brushless Doubly-Fed Machine (BDFM), which removes the brush and slip ring, improves security and reliability. The BDFM is proposed to have a bright prospect as an AC drive system or variable-speed constant-frequency power generation system. Vector control is widely studied in the BDFM, but the information of rotor speed and position must be obtained. This paper presents speed sensorless vector...
On the research of the economic effects of national debt, the Ricardo equivalence proposition(REP) is definitely the core issue and has been brought far-reaching influences as well. The REP has a very important policy implication, that is, the government debt failed to bring any changes of the aggregate social demand, and hence no changes to the national income either. To say it more clearly, if the...
A novel control strategy is proposed in this paper since available sensorless speed control strategies of doubly fed induction generator (DFIG) usually fail around the synchronous speed or limited by the operation state (motor or generator). The new control strategy uses the stator voltage to estimate the rotor position and speed. This strategy works properly in the whole speed zone. The principle...
Decoupled control has been widely used in the DIFG (doubly fed induction generator) which needs the rotor position as well as the rotor speed for the control system. A lot of research has been done in the sensorless control field for the DFIG because of the disadvantages of the speed sensor. Three representative sensorless control strategies are considered in this paper and they are compared in terms...
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