Observing method for rotor flux linkage in vector control system of induction motor

Abstract

The invention relates to an observing method of a rotor flux linkage in a vector control system of an induction motor. The observing method comprises the steps of conducting digital filter processing on acquired current signals and voltage signals by an FPGA (Field Programmable Gate Array), and removing noise interference, obtaining a three-phase current value, establishing a induction motor vector type dynamic mathematical model, constructing an observer in a full-order flux linkage state, conducting discretization on the observer in the full-order flux linkage state by adopting a high-precision four-order Runge-Kutta method, conducting real-time processing on the discretized data by utilizing a DSP (Digital Signal Processor) to realize the rotor flux linkage observation, calculating rotor flux linkage components psi r alpha and psi r beta under an alpha-beta coordinate system to complete the magnetic field orientation subjected to vector control, and determining the magnetic field orientation subjected to vector control through a formula. According to the observing method provided by the invention, the rotor flux linkage can be accurately observed under the alpha-beta coordinate system in the full revolving range without any switching mechanism; and the effectiveness and the stability of the vector control are ensured, the inhibition capability to the parameter change of the induction motor and the noise interference of the current detection is strong, and the robustness of the whole control system is promoted effectively.

Description

technical field [0001] The invention relates to a method for observing the flux linkage in an induction motor vector control system in an AC speed regulating system, in particular to a method for observing the rotor flux linkage in a vector control system of an asynchronous motor based on the Romberg observer theory. Background technique [0002] High-performance AC speed control has been widely used in transportation and other fields. Among them, vector control is considered to be the most widely used control method for high-performance control of induction motors. In the vector control, the vector control based on the rotor field orientation can realize the decoupling control of the induction motor, and its control performance is comparable to that of the DC motor. In the vector control system of induction motor, the observation of flux linkage is the key link to realize the accurate orientation of the magnetic field, which directly affects the performance of the control s...

AI Technical Summary

Problems solved by technology

[0012] The current model method is suitable for analog control. When computer digital control is widely used now, because ψ rα and ψ rβ There is a cross-feedback relationship between them, and the discrete calculation may not converge, which eventually leads to the failure of the magnetic field orientation

In addition, the current model method is greatly affected by the parameters of the induction motor at low speeds, and it will also have a greater impact on the flux calculation when the parameters of the induction motor change, and the performance of this method is not as good as that of the voltage model method at high speeds.

[0013] The voltage model method is less affected by changes in motor parameters, but it still has two limitations

First of all, the voltage model is actually a pure integrator, and the cumulative error and drift of the calculation will lead to system instability; secondly, at low speed, the effect of the change of the voltage drop of the stator resistance is enhanced, which makes the observation accuracy much lower, which is not suitable for use at low speed

[0014] The hybrid model is to switch between the two modes, but there is an important problem in this way, that is, a complex switching mechanism needs to be established, and it is difficult to achieve smooth switching

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