Looking for breakthrough ideas for innovation challenges? Try Patsnap Eureka!

AC motor over-load inverse time-lag protection method based on heat accumulation

A technology of inverse time protection and AC motors, applied in emergency protection circuit devices, electrical components, etc., can solve problems such as hard to find, low control accuracy, and inability to reflect motor thermal overload characteristics, and achieve the effect of improving control accuracy

Inactive Publication Date: 2008-02-27
XIAN UNIV OF TECH
View PDF0 Cites 21 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0002] At present, the heat accumulation method adopted for the overload protection of the motor, in this method, the heat accumulation adjustment coefficient T C The value is constant in the entire overload range of the motor (1 to 10 times), and it is difficult to find a T C value to ensure that the protection trip time at each specified overload point is within the allowable error range
Therefore, the current heat accumulation method cannot accurately reflect the thermal overload characteristics of the motor, and its control accuracy is not high

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • AC motor over-load inverse time-lag protection method based on heat accumulation
  • AC motor over-load inverse time-lag protection method based on heat accumulation
  • AC motor over-load inverse time-lag protection method based on heat accumulation

Examples

Experimental program
Comparison scheme
Effect test

Embodiment Construction

[0023] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0024] The AC motor overload inverse time protection method of the present invention, as shown in the accompanying drawing, is carried out according to the following steps:

[0025] (1) The overload protector of the AC motor collects the three-phase load current of the AC motor through AD conversion, and calculates the effective current I of each phase eq and load rate n,

[0026] Load rate n=I eq / I N , I N The rated operating current of the motor

[0027] (2) According to the load rate n obtained in the previous step, calculate the heat accumulation coefficient T of each point corresponding to the load rate n c ,

[0028] a. Corresponding to the load rate n, the heat accumulation coefficient value Tc(i) of the motor at each ideal operating point is calculated according to the following formula (1). The ideal operating point refers to ...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

PUM

No PUM Login to View More

Abstract

This invention discloses an inverse time-lag protective method for heat overload of AC electric motor based on heat accumulation. The steps are as below: obtaining three phase load current; calculating the active current and load factor of every phase; calculating all the ideal action points corresponding the load factors, and heat accumulation coefficients between the action points; calculating, respectively, the increments of heat accumulation of the motor within an established time interval, and the heat accumulation value at that time; comparing said value with the determined triggering action value to judge if the triggering of the trigger relay is needed or not. In this invention, sectional linearized TC value obtaining is used, so it can accurately simulate the heat overload of an electric motor.

Description

technical field [0001] The invention belongs to the technical field of motor overload control, and relates to an overload inverse time limit protection method of an AC motor. Background technique [0002] At present, the heat accumulation method adopted for the overload protection of the motor, in this method, the heat accumulation adjustment coefficient T C The value is constant in the entire overload range of the motor (1 to 10 times), and it is difficult to find a T C value to ensure that the protection trip time at each specified overload point is within the allowable error range. Therefore, the current heat accumulation method cannot accurately reflect the thermal overload characteristics of the motor, and its control accuracy is not high. Contents of the invention [0003] The object of the present invention is to provide a kind of AC motor overload inverse time protection method based on heat accumulation, this method adopts piecewise linearization T C The value ...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

Application Information

Patent Timeline
no application Login to View More
IPC IPC(8): H02H7/085
Inventor 李生民孙旭霞
Owner XIAN UNIV OF TECH
Who we serve
  • R&D Engineer
  • R&D Manager
  • IP Professional
Why Patsnap Eureka
  • Industry Leading Data Capabilities
  • Powerful AI technology
  • Patent DNA Extraction
Social media
Patsnap Eureka Blog
Learn More
PatSnap group products

Browse by: Latest US Patents, China's latest patents, Technical Efficacy Thesaurus, Application Domain, Technology Topic, Popular Technical Reports.

© 2024 PatSnap. All rights reserved.Legal|Privacy policy|Modern Slavery Act Transparency Statement|Sitemap|About US| Contact US: help@patsnap.com