Method and device for frequency converter to track motor speed and frequency converter

Abstract

A method, device, and frequency converter for tracking the speed of a motor by a frequency converter. The method includes step 1, obtaining an initial tracking frequency f0 and a tracking direction of speed tracking; step 2, performing degaussing processing on the motor, and blocking PWM output during the degaussing period of the frequency converter; Step 3, apply a rotating voltage to the motor and keep it for a period of time; Step 4, the speed tracking phase, use the initial tracking frequency f0 as the tracking frequency, calculate the output voltage based on the tracking frequency and the preset speed tracking V / F curve, and continuously Change the tracking frequency and output voltage of the inverter, and then detect the stator current of the inverter, and judge whether the direction of the active component of the stator current changes. If there is a change, the actual running speed and output voltage of the motor can be obtained according to the tracking frequency of the changed switching point. Raise to the output voltage value of normal control, this method has high detection efficiency, more accurate and stable, and the device and frequency converter include the above method.

Description

technical field [0001] The invention relates to the field of frequency converters, in particular to a method and device for a frequency converter to track the rotational speed of a motor and a frequency converter. Background technique [0002] Inverter is a device that converts fixed frequency AC mains into continuously adjustable frequency AC. Inverter speed regulation has been recognized as one of the most ideal and promising speed regulation methods. It is used in energy saving, automation systems and Improving the level of technology and quality has a wide range of applications. It can not only improve the level of my country's equipment manufacturing industry, but also achieve obvious energy-saving effects in certain industries. [0003] Before the inverter drives the motor to run, the initial state of the motor may not be in a static state, but in a rotating state. For example, a fan may rotate at a lower speed under the action of ambient wind; Falling (or power failur...

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Problems solved by technology

[0011] The disadvantages of this method are firstly that the bus current detection device is added, which increases the cost. The larger the model, the higher the cost and reduces the reliability of the system; secondly, the bus voltage has a waveform, which causes the bus current to fluctuate accordingly, so it is difficult to Determine whether the bus current is 0

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