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Method for suppressing inrush current of variable frequency soft starter switching process

A soft starter, inrush current technology, applied in the starter of a single polyphase induction motor, AC motor control, motor generator/starter, etc., can solve the problem of shortened motor life, AC grid oscillation, large inrush current, etc. problem, to achieve the effect of reducing inrush current and reducing phase and amplitude differences

Active Publication Date: 2019-05-14
WUHAN MARINE ELECTRIC PROPULSION RES INST CHINA SHIPBUILDING IND CORP NO 712 INST
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  • Application Information

AI Technical Summary

Problems solved by technology

However, when the variable frequency soft starter is switched to the AC grid power supply process after the start process, because there is a phase and amplitude difference between the back EMF U2 of the asynchronous motor and the AC grid voltage U1, the inrush current at the moment of switching will be relatively large
If not suppressed, it may cause problems such as AC grid oscillation and shortened motor life

Method used

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  • Method for suppressing inrush current of variable frequency soft starter switching process
  • Method for suppressing inrush current of variable frequency soft starter switching process
  • Method for suppressing inrush current of variable frequency soft starter switching process

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Embodiment Construction

[0027] Through the following examples, combined with Figure 1 to Figure 3 , the technical solution of the present invention will be further specifically described.

[0028] When the asynchronous motor is started directly, there are excitation inrush current and torque inrush current, and the total instantaneous inrush current reaches 5 to 7 times the rated current, which may cause instability of the power grid, or even power loss (such as ship power grid), and may also cause mechanical damage to the motor. damage and shorten the service life.

[0029] The variable frequency soft starter (Soft Starter) is composed of three parts: the rectifier (Rectifier), the inverter (Inverter) and the controller (Controller). The frequency and amplitude controllable three-phase alternating current drives the motor (Machine) to run.

[0030] Aiming at the inrush current problem in the switching process of the variable frequency soft starter, the present invention adopts the control output ...

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Abstract

The invention discloses a method for suppressing inrush current of a frequency conversion soft starter switching process. The method comprises a phase difference and amplitude difference compensationalgorithm for the motor back EMF and the AC grid voltage and the main switch closing delay prediction compensation processing. The method comprises the steps of performing phase locking on the AC gridvoltage by using a phase-locked loop after the soft startup of the frequency conversion soft starter is completed to obtain the phase and amplitude, after compensation such as filter phase and amplitude are performed on the sampling voltage of the AC grid, using the phase difference between the back EMF and the AC grid voltage as an additional control value of the speed set value, and using the amplitude difference between the back EMF and the AC grid voltage as an additional control value of the flux linkage set value, so as to adjust the phase and amplitude of the output voltage to reduce the phase difference and amplitude difference to an acceptable dynamic interval.

Description

technical field [0001] The invention belongs to the technical field of frequency conversion and speed regulation of asynchronous motors, and in particular relates to a control method for suppressing the impact current in the switching process of a variable frequency soft starter, which can be used in the fields of high-power industrial electric transmission, rail transportation, and ship electric propulsion. Background technique [0002] Asynchronous motors are widely used in various industries due to their simple structure, convenient manufacture, reliable operation, low price, durability, and high efficiency, such as industrial electric transmission, rail transit, and ship electric propulsion. [0003] When the asynchronous motor is started directly, there are excitation inrush current and torque inrush current, and the total instantaneous inrush current reaches 5 to 7 times the rated current, which may cause instability of the power grid, or even power loss (such as ship p...

Claims

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Application Information

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IPC IPC(8): H02P1/30H02P27/06
Inventor 胡传西陈坤李争光
Owner WUHAN MARINE ELECTRIC PROPULSION RES INST CHINA SHIPBUILDING IND CORP NO 712 INST