Flux Oriented Control Of Induction Motor Research Articles

Stabilization of Rotor Flux-Oriented Control of Induction Motor With Filter by Active Damping

Sinusoidal LC filters are generally placed between the voltage source inverter (VSI) and squirrel cage induction motor (SQIM) to reduce the distortion in the output voltage of the VSI, voltage surges at the motor-terminals, core losses in the SQIM, bearing-current, and electromagnetic interferences. Rotor-flux oriented control (RFOC) of the SQIM is widely used in adjustable speed drives. However, the introduction of filter network may make the operating point of RFOC of SQIM drive unstable and may create sustained resonance frequency oscillations in the stator-current, stator-voltage of SQIM. This paper proposes a simple inverter-current-based active damping (AD) technique, which damps out the resonance frequency oscillation by emulating the virtual resistance connected in series with the filter inductor in its control structure. It also effectively stabilizes the unstable operating point of the closed-loop system without changing the parameters of the controllers used in RFOC. The idea of the proposed AD technique has been illustrated with mathematical expressions and justified through stability analysis. The instability of operating point and the impact of the AD technique are experimentally demonstrated on RFOC of VSI-fed SQIM with filters at different test conditions.

유도전동기 고정자자속 기준제어의 최대효율제어에서 부하증가로 인한 문제 해결방법

유도전동기 고정자자속 기준제어의 최대효율제어에서 경부하시 자속은 작은 값이 된다. 이러한 상태에서 갑자기 부하가 증가하였을 경우 전동기는 부하토크에 대응하는 토크를 발생시켜야 하지만, 낮은 자속 때문에 토크제한조건에 의한 토크성분전류는 작은 값으로 제한되며, 부하토크에 대응하는 토크를 발생시키지 못해서 속도제어가 안 되는 문제가 발생한다. 본 논문에서는 이러한 문제를 해결하기 위한 방법을 제안한다.

Speed Sensorless Stator Flux-Oriented Control of Induction Motor in the Field Weakening Region Using Luenberger Observer

In a conventional speed sensorless stator flux-oriented (SFO) induction motor drive, when the estimated speed is transformed into the sampled-data model using the first-forward difference approximation, the sampled-data model has a modeling error which, in turn, produces an error in the rotor speed estimation. The error included in the estimated speed is removed by the use of a low pass filter (LPF). As the result, the delay of the estimated speed occurs in transients by the use of the LPF. This paper investigates the problem of a conventional speed sensorless SFO system due to the delay of the estimated speed in the field weakening region. In addition, this paper proposes a method to estimate exactly speed by using Luenberger observer. The proposed method is verified by the simulation and experiment with a 5-hp induction motor drive.

Speed-Sensorless Stator Flux-Oriented Control of Induction Motor Drives in Traction

Indirect Stator-Quantities Control (ISC) combines the principle of stator flux-orientation proven successful in Direct Self Control (DSC) with Pulse Width Modulation (PWM). High torque dynamics and robust behavior against input voltage disturbance are achieved in the whole operation range including field-weakening. After careful correction of inverter voltage errors the difference of the stator current space vectors in the machine and in the control model is employed for speed estimation, allowing dispensing with speed sensors. A special flux management allows an infinitely slow change between driving and braking.