電力電子變頻傳動(dòng)技術(shù)第9章-資料下載頁(yè)
2025-05-14 22:16本頁(yè)面
【正文】 ????? ? ? ?M K i d t??? ? ? ?? ()cM K i dt????? ? ??the current modelbased sensorless drive ?The current model is ?the current difference is M??26 ? torquespeed characteristics under a current modelbased algorithm. ?The motor rating is (kW), 6poles, 1200 (rpm), 98 (kgf cm). The maximum speed is 1500 (rpm), the minimum speed is 60 (rpm), and a steadystate maximum speed error is within %. 27 Sensorless Drives of Vector Controlled Induction Motors ? the basic idea is estimation of speed by using applied voltage, line current, and frequency – Slip frequency control approach – field orientation control approach 28 Slip frequency control approach sdsqrrs iiLR???sr ??? ?? ??29 field orientation control approach ?not only the speed but also the rotor flux are simultaneously estimated for the sensorless drive in a wide speed range. ?The stator equation is used for correction of adjustable current reference model. ?The speed is estimated by a kind of error of flux ponents which is derived from Popov39。s stability criteria. 30 ? The rotor flux observer based on the motor voltage model estimates the rotor flux by using the stator current transformed to the stationary coordinates ( ?? axis) system ? the vector control is carried out on the basis of the estimated rotor flux ? the motor speed is directly estimated through MRAS by using the flux and the stator current ? the estimated speed is used to adjust the motor model 31 Figure 916 ? an example of the sensorless control characteristics of (kW), 4poles induction motor. ? The maximum speed is 2400 (rpm) under the fieldweakening control and the minimum speed is 15 (rpm). ? It is noted here that the speed control accuracy is % under the tuned condition。 however, it is % under the detuned condition. ? Like the conventional vector control with sensors, the identification of the rotor resistance is important and difficult. 32 ? End of Chap9
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