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Objective
To assess the correlation between Z‐scores of positive noninvasive prenatal testing (NIPT) results and the positive predictive value (PPV) of NIPT.
Methods
Pregnancies with positive NIPT results at Guangzhou Women and Children's Medical Centre between July 2017 and May 2020 were included in this study. Fetal karyotyping or microarray analysis was provided to patients with abnormal NIPT...
This paper proposes a new software strategy using rate limiter for torque command to reduce the surge voltage of DC bus bar in AC drives fed by voltage source inverter (VSI). Experimental results show that a remarkable reduction of surge voltage is achieved. The proposed software strategy is special useful to the AC drives with the frequent operation of start, stop and reversal.
In this paper, a new adaptive scheme for simultaneous on-line stator and rotor resistance estimation of induction motors is proposed. This method is based on the adaptive control theory of model reference adaptive system (MRAS) approach with Luenberger observer. And the stability of the observer with stator and rotor resistance estimation from the proposed adaptive scheme is proved by the Lyapunov's...
This paper presents a new adaptive scheme for online estimation of stator resistance in speed-sensorless induction motor drives. The method is based on the adaptive control theory of model reference adaptive system (MRAS) approach with Luenberger observer. And the stability of the observer with stator resistance estimation in sensorless vector control of induction motors is proved by the Lyapunov's...
In sensorless vector control of induction motor using voltage-fed inverter, the flux estimation error caused by stator voltage error due to the dead time and switch voltage drop and so on can deteriorate the performance of vector control. This paper proposes a method to compensate the stator voltage error by utilizing the error value between the measured current and estimated current. The DC component...
In sensorless vector control of induction motor using voltage-fed inverter, the flux estimation error caused by stator voltage error due to the dead time and switch voltage drop and so on can deteriorate the performance of vector control .This paper proposes a method to compensate the stator voltage error by utilizing the error value between the measured current and estimated current. The DC component...
In sensorless vector control of induction motor using voltage-fed inverter, the flux estimation error caused by stator voltage error due to the dead time and switch voltage drop and so on can deteriorate the performance of vector control. This paper proposes a method to compensate the stator voltage error by utilizing the error value between the measured current and estimated current. The DC component...
This paper presents a new adaptive scheme for online estimation of stator resistance in speed-sensorless induction motor drives. The method is based on the adaptive control theory of model reference adaptive system (MRAS) approach with Luenberger observer. And the stability of the observer with stator resistance estimation in sensorless vector control of induction motors is proved by the Lyapunov's...
In sensorless vector control of induction motor using voltage-fed inverter, the flux estimation error caused by stator voltage error due to the dead time and switch voltage drop and so on can deteriorate the performance of vector control. This paper proposes a method to compensate the stator voltage error by utilizing the error value between the measured current and estimated current. The dc component...
This paper presents two new adaptive estimation schemes in induction motor drives. The first adaptive scheme is to simultaneously estimate on-line stator and rotor resistance of induction motor with speed-sensor. The second adaptive scheme is to simultaneously estimate stator resistance and rotor speed in sensorless induction motor drives. These two methods are based on adaptive control theory of...
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