Vector control system without sensor for inductive motor and method

Abstract

A sensorless vector control system of an induction motor includes: a magnetic flux and speed controlling unit for receiving a predetermined command value and generating two phase voltages of DC component; a first reference frame converting unit for converting the two phase voltages of DC component into three phase voltages of AC component; an inverter for receiving the three phase voltages of AC component and driving an induction motor; a current detecting unit for receiving the three phase power of AC component flowing between the inverter and the induction motor, and detecting and outputting three phase currents of AC component; a second reference frame converting unit for receiving the three phase currents of AC component, and converting and outputting two phase currents of DC component; a magnetic flux and speed estimating unit for receiving the two phase voltage of DC component and the two phase currents of DC component, estimating a magnetic flux and speed required for a vector control; and a primary resistance estimating unit for receiving the two phase voltages of DC component, the two phase currents of DC component and the magnetic flux and speed estimated values, estimating a primary resistance.

Description

technical field [0001] The present invention relates to a vector control system of an induction motor, in particular to a sensorless vector control system of an induction motor which can estimate the magnetic flux and speed of the induction motor without using a speed measuring device. Background technique [0002] In general, DC motors have been used for a long time as both fixed and variable speed controls due to their ease of control. But the DC current has the disadvantage that the brushes are consumed after a predetermined time of use, thereby requiring maintenance and repair. [0003] In the case of induction electric motors, they are excellent in maintenance and repair due to their robust construction. Especially its low price, so it is widely used in the industrial field. However, since induction motors are difficult to control compared to DC motors, they are mainly used for constant speed operation. [0004] However, recently, with the introduct...

AI Technical Summary

Problems solved by technology

But DC current has the disadvantage that the brushes are consumed after a predetermined period of use, thereby requiring maintenance and repair

[0022] For example, first, it is impossible to achieve instantaneous torque control in the transient state since the current / voltage command unit does not include the differential term of the magnetic flux and only considers the normal state

[0023] Second, to obtain estimated speed The values ​​of the proportional constant and the integral constant to be used by the integral and proportional constant calculation unit 20 should be accurately calculated. Since the values ​​of the proportional constant and the integral constant are different for each motor, and it is difficult to obtain these constants in practice, it is very difficult to perform accurate calculations.

This method is effective at low speeds, but not at high speeds

Also, in the case of high-speed algorithms, when controlling the motor speed, the algorithms are effective at high speeds but very difficult to implement at low speeds

Therefore, the method cannot cover the entire speed range

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