A control method and device for a DC contactor for rail transit

Abstract

The invention discloses a control method for a DC contactor for rail transit, and the method specifically comprises the steps: outputting a broad pulse voltage to a coil of the DC contactor at the attraction stage of the DC contactor, so as to enable a coil current to reach an attracting current; and outputting a narrow pulse voltage to the coil at the closing maintaining stage of the DC contactor, so as to enable the coil current to be reduced to a holding current from the attracting current. The method provided by the invention is characterized in that the method comprises the steps: outputting a broad pulse voltage to a coil of the DC contactor at the attraction stage of the DC contactor, so as to enable a coil current to reach an attracting current; and outputting a narrow pulse voltage to the coil at the closing maintaining stage of the DC contactor, so as to enable the coil current to be reduced to a holding current from the attracting current. The method and device are simple in operation, and are safe and reliable.

Description

technical field [0001] The invention mainly relates to the technical field of switching devices, in particular to a control method and device for a DC contactor for rail transit. Background technique [0002] In the field of rail transit applications, the environmental conditions and electrical conditions of rolling stock are relatively harsh. The following problems exist in the actual use of DC contactors: [0003] (1) According to the national standard (GB / T 21413.1-2008), the long-term continuous working voltage range of the floating charge battery control power supply in the rolling stock control system of rail transit is 0.7Us ~ 1.25Us (Us is the nominal voltage); and the contactor It may be installed in different places inside the car body, such as the engine room, screen cabinet, box body, etc., and its working environment temperature can reach up to 70°C. When the contactor is working, the temperature rise of its coil is strongly related to the control voltage. Acco...

AI Technical Summary

Problems solved by technology

Such a wide range of operating voltage and ambient temperature range makes it extremely difficult to design the control coil of the contactor; if the designed coil power is too small, it cannot meet the minimum pull-in voltage requirements, and it is even more difficult to pull-in in a high-temperature environment; the designed coil If the power is too large, the heat will be more serious, causing the coil to burn out, and the strong closing shock and vibration caused by too large electric power will easily damage the mechanical parts, and may cause the main contacts to bounce and weld

[0004] Moreover, the test conducted according to the standard requirements found that the temperature rise of the hot spots in the coils of each short-circuited DC contactor is between 80°C and 120°C. Based on this calculation, the heat resistance level of the selected insulating material should be at least H (180°C ), which increases the material cost accordingly

[0005] (2) In the rolling stock converter (or other electrical panel cabinets), the action of the DC contactor is controlled by the DO (digital output) port of the panel cabinet control unit. Since the maximum output current of the DO circuit has been set, For high-power DC contactors, several DO channels need to be connected in parallel to drive, thus occupying the limited DO channel resources of the panel cabinet control unit;

[0006] (3) The vibration and shock during the operation of the rolling stock are transmitted to the contactor, which gradually causes the internal structure of the contactor to become loose. After a period of use, the contactor may be stuck. If the contactor continues to develop, it will not be able to operate, and online monitoring and early warning are required. ;

[0007] (4) Pollution dust and corrosive gas exist in the operating environment of rolling stock, which may easily cause surface contamination and vulcanization of the auxiliary contacts of the contactor, resulting in increased contact resistance or even failure to connect. To judge the state of the contactor, it will cause the system to misjudgment and protect the shutdown

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