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Three-phase AC power supply detection and protection device and its detection and protection method

A three-phase alternating current, detection and protection technology, applied in the direction of multi-phase network asymmetry measurement, etc., can solve the problems that the abnormal state of the external power cannot be detected, and the electrical equipment cannot be protected in time

Active Publication Date: 2017-12-22
PANASONIC WELDING SYST TANGSHAN
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In addition, when electrical equipment is used to share external power, it is often connected in parallel or with other electrical equipment with large phase-to-phase capacitance, so even if the electrical equipment is equipped with the above-mentioned phase loss detection circuit, due to the existence of phase-to-phase capacitance, it cannot Detect the abnormal state of the external power supply when there is a lack of phase
Therefore, in the event of external power phase loss, the problem that electrical equipment cannot be protected in time occurs from time to time

Method used

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  • Three-phase AC power supply detection and protection device and its detection and protection method
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  • Three-phase AC power supply detection and protection device and its detection and protection method

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no. 1 example

[0028] Refer below figure 1 with Figure 8 , Describe the first embodiment of the present invention. Such as figure 1 with Figure 8 As shown, the three-phase AC power supply detection and protection device of the present invention includes: a first transformer TR1, both ends of the primary winding of which are respectively connected to the U-phase input terminal and the V-phase input terminal of the three-phase AC power; the second transformer TR2, the primary The two ends of the winding are respectively connected to the V-phase input terminal and the W-phase input terminal of the three-phase alternating current. The three-phase AC power supply detection and protection device further includes: a first rectifying and filtering circuit, the input end of which is connected to both ends of the secondary winding of the first transformer, and is used to correct the second winding of the secondary winding of the first transformer. An AC voltage Vac1 is rectified and filtered to becom...

no. 2 example

[0044] Refer below Figure 5 The second embodiment of the present invention is described. The hardware structure of the second embodiment is the same as that of the first embodiment, and the description will not be repeated here. In addition, the flowchart of the detection method of the second embodiment is basically the same as that of the first embodiment, and therefore, the same reference numerals are used for the same parts as the first embodiment. Below, only the differences between the two are described. The second embodiment is different from the first embodiment only in that the detection and judgment of the V phase missing phase are added.

[0045] Such as Figure 5 As shown, in the second embodiment, when it is determined that |VP1-VP2| is less than or equal to 50 (step S403: No), the process proceeds to step S501. In step S501, it is determined whether |VP1-VP2| is equal to 0, and when |VP1-VP2| is not equal to 0 (step S501: No), it is determined that the current pow...

no. 3 example

[0049] Refer below Image 6 with Figure 7 The third embodiment of the present invention is described. The hardware structure of the third embodiment is the same as that of the first embodiment, and the description will not be repeated here. In addition, the flow chart of the detection method of the third embodiment is basically the same as that of the first embodiment and the second embodiment, and therefore, the same reference numerals are used for the same parts as the first embodiment and the second embodiment. Below, only the differences are described. The third embodiment is different from the first embodiment only in the software structure, that is, before performing the difference calculation, the detection and judgment of the V phase missing phase are performed first.

[0050] Image 6 The software structure of the third embodiment is shown. Such as Image 6 As shown, in addition to the same software structure as the first embodiment, the controller also includes a se...

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Abstract

The invention provides a three-phase AC power supply detection and protection device. It includes a first transformer connected to the input end of the three-phase alternating current, and a second transformer, and the first transformer and the second transformer are respectively connected to the controller through a rectification filter circuit and a potential correction circuit. The controller includes: a difference calculation unit, which is used to calculate the absolute value of the difference between the output voltage of the first potential correction circuit and the output voltage of the second potential correction circuit; a first comparison and judgment unit, which It is used to compare the absolute value of the difference with a predetermined threshold to judge the power supply state of the three-phase alternating current; and a protection control unit is used to perform corresponding actions according to the judgment result of the first comparison judgment unit protection control. It can timely and accurately detect the abnormal state of lack of phase in the power supply of three-phase alternating current, so as to effectively protect the electrical equipment.

Description

[Technical Field] [0001] The invention relates to the field of three-phase AC power supply detection and protection, and in particular to a device and method for detecting abnormal states that occur when electrical equipment is supplied with three-phase AC power supply, and providing corresponding protection. [Background technique] [0002] At present, with the popularity of inverter welding machines and frequency converters (collectively referred to as electrical equipment) that use three-phase AC power supply, electrical equipment often runs due to abnormal external power (including external three-phase power imbalance, lack of equality). The phenomenon of instability and even burnout. [0003] In order to achieve reliable and safe use, it is usually equipped with a detection circuit to detect abnormal conditions of external power. Figure 8 It is a schematic diagram of the general power supply structure of the existing inverter welding machine. Picture 9 It is a common lack phas...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R29/16
Inventor 刘树雨何双旺何艳红石增光
Owner PANASONIC WELDING SYST TANGSHAN