Vector controller without speed sensor

Abstract

A control apparatus for estimating the flux, the current, and the speed of an AC motor using the current and the voltage, and controlling the vector of an AC motor using the estimated speed, a flux command, and a torque current command. The speed is estimated by adding a product of the deviation between the actual value and the estimated value of a magnetization current, the level of a torque current correspondence value, the sign correspondence value of a primary frequency command value, and a gain to an outer product of an estimated current deviation and an estimated flux. Thus, a stable speed estimating operation can be performed to successfully operate the motor in a low speed area in which a voltage frequency applied to the motor is extremely low.

Description

technical field [0001] Generally, the present invention relates to a speed sensorless vector control apparatus capable of controlling the vector of an AC motor such as an induction motor or the like but having no speed sensor. Background technique [0002] In known vector control of high-performance and high-precision systems for controlling induction motors, information about the speed of the motor is required, and such information is usually obtained by a pulse generator (PG) or the like. However, it is desirable to implement speed sensor vector control with a variable speed drive system that can perform torque control and obtain maximum torque over a wide operating range without requiring high performance conventional speed sensor vector control Restrictions on installing the speed sensor are controlled, and it is also possible to simplify wiring, reduce costs, etc. [0003] Accompanying drawing 1 is shown as the functional block diagram of the conventional speed sensorl...

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Problems solved by technology

Therefore the secondary flux cannot be calculated from the primary voltage, neither the estimated flux nor the estimated speed

That is to say, the deviation between the estimated flux and its actual value and the deviation between the estimated velocity and its estimated value are not equal to zero, and cannot effectively converge

[0049] Generally, since it is difficult to estimate the speed stably in the range where the frequency of the voltage applied to the motor is very low, there is a problem in applying the conventional technique that the motor cannot be operated by the speed sensorless vector controller

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