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|Title:||Position Sensorless Control of Interior Permanent Magnet Synchronous Machines with a Single DC-Link Current Sensor|
|Department:||Electrical and Computer Engineering|
|Abstract:||Interior Permanent magnet synchronous machines (IPM) have the capability of improving its flux weakening operation and satisfying higher torque requirement due to the rotor saliency structure. However, to reduce the cost and volume, sensorless control and single current control are under investigation in decades. The thesis develops a sensorless control method with a single dc-link current sensor for IPMs without shifting PWM waveform. The main challenge is the immeasurable region, which is divided into sector boundary region and low modulation region. An observer-assisted current reconstruction method is proposed to deal with the sector boundary region. This assistive model-based observer is a Luenberger type observer that estimates the back electromotive force (EMF) based on the error between the reconstructed and estimated currents. An adaptive band-pass filter is applied to eliminate the unexpected harmonics due to the lack of current samples in the sector boundary region. The algorithm is implemented and verified by simulation. However, the observer-assisted method is unfeasible in the low modulation region, where even one phase current is hardly acquired. A six-direction injection method with a modified reconstruction scheme is proposed when the system operates at low speed. The injected signal forces the reference voltage vector outside the low modulation region. But the unaligned measurement of the phase current increases the position estimation error and causes a third-order harmonic. The modified reconstruction scheme takes advantage of the symmetrical switching state to average the phase current measured in the different intervals, which improves the position estimation accuracy. The saliency-based sensorless control with the modified current reconstruction method is verified by simulation. At last, the experimental tests are conducted to verify the proposed methods of medium to high-speed operation and low-speed operation, respectively.|
|Appears in Collections:||Open Access Dissertations and Theses|
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|Zhao_Jing_2019Aug_Master.pdf||15.81 MB||Adobe PDF||View/Open|
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