Applying a control unit to an asynchronous machine which is operated without a rotary encoder

Abstract

The object of the invention is to connect or connect a frequency converter to an encoderless rotating asynchronous motor without high currents and torque pulses. Machine systems and control systems should not be overloaded. The method should be able to work independently of residual magnetism. A method is proposed as a control device using an inverter or a frequency converter to feed an asynchronous motor (5) rotating at a mechanical rotational speed. The asynchronous motor is regulated by a control device. The stator current vector (iS) is determined from the measured current of the stator winding of the asynchronous machine (5) and the rotating stator voltage vector (uS). The stator flux change vector is calculated from the stator current vector (iS), the stator voltage vector (uS) and the stator resistance (RS) according to the motor model (100). Calculate the angular difference (γ) between the stator current vector (iS) and the stator flux change vector. The angular difference (γ) is adjusted to a target value of +90° or −90°, wherein the output signal of the controller corresponds to the frequency of the rotating field (ω) to be applied of the stator voltage vector. The amplitude of the stator voltage vector is regulated by means of a current regulator ( 51 ), the difference between the current target value and the variable corresponding to the amplitude of the stator current being supplied to the current regulator as a control difference ( 51 a ) at the input.

Description

technical field [0001] The method according to the invention is used to connect or connect an inverter or a frequency converter (as a control unit) to a stationary or rotating asynchronous machine. Generally speaking, the control device is not synchronized with the machine. The method is used for asynchronous motors in which the rotational speed is not fed back to an inverter or frequency converter (encoderless operation), so that there is no current mechanical rotational speed for the asynchronous motor (as actual rotational speed ) for any information. Background technique [0002] The control unit must be connected to and synchronized with a rotating or stationary asynchronous motor (ASM or DSM). [0003] In the case of an asynchronous machine operated without an encoder, the identification process of the mechanical rotational speed or of the synchronous rotating field frequency is referred to in the literature as "catch operation", see eg Witt & Sohn, Regulation of fre...

AI Technical Summary

Problems solved by technology

Disadvantages of the search method described are the time requirement for the identification of the mechanical rotational speed and the applied torque due to magnetization

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