Abstract
The wide applications of vector control improve the high-accuracy performance of alternating current (AC) adjustable speed system. In order to obverse the full-order flux and calculate the real-time speed, this article introduces the motor T equivalent circuit to build a full-order flux observer model, where the current and flux variables of stator and rotor are adopted. Model reference adaptive control is introduced to build the AC motor flux observer. The current output is used as feedback to build the feedback matrix. The calculation method of motor speed, which is part of the inputs of flux observation, is applied to realize the adaptive control. The concept of characteristic function is introduced to calculate the flux, of which the foundation is the variables of composite form of voltage and current models. The characteristic function is deduced as a relative-state variable function. The feedback matrix is improved and designed to ensure the motor flux observer is a smooth switch between current and voltage model in low and high speeds, respectively. Experimental results show that the feedback and characteristic model are feasible, and the vector control with speed sensorless based on the full-order flux observer has better performance and anti-disturbance.
Highlights
Magnetic field orientation is vital in vector control (VC) method for induction motor’s speed regulation
According to the research of virtual-oriented VC and estimation of instantaneous power, this study proposes a direct power strategy without grid voltage sensors
The full-order flux observer is improved for observation on flux
Summary
Magnetic field orientation is vital in vector control (VC) method for induction motor’s speed regulation. SSVC has many merits such as saving the speed sensor and reducing the construction and maintenance cost It achieves a similar dynamic performance as the conventional VC with speed-loop method. Unlike the conventional VC method with speed sensor, SSVC must build a flux observer and a speed observer so as to detect the real-time magnetic field orientation. The scholars are devoted to the study on speed sensorless control system because of the advantage of VC method to perform with high accuracy, which is simple construction scheme and has gradually become a hot topic in motor control field. According to the research of virtual-oriented VC and estimation of instantaneous power, this study proposes a direct power strategy without grid voltage sensors This strategy combines the virtual flux direct power control method to the space vector modulation. The rotor flux components on ab stationary coordinates are shown in equation (2)
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