Switching circuit of direct current output end

Abstract

The utility model relates to the technical field of switching power supply circuits, and provides a switching circuit of a direct current output end, which comprises a relay K1 and a relay K2 which are connected in parallel, and a thermistor R1 which is connected with the K2 in series to form a pre-charging loop. The positive end of the battery is connected to the contacts 1 of the K1 and the K2, the contact 2 of the K2 is connected with the end 1 of the R1, the end 2 of the R1 is connected with the contact 2 of the K1 and the cathode of the fly-wheel diode D1, and the load takes electricity from the two ends of the D1. According to the design, through a specific actuation and disconnection logic sequence, i.e., the K1 is actuated after the K2 is actuated for 100 milliseconds, and the K2 is disconnected after the K1 is disconnected for 100 milliseconds during power failure, actuation surge current and breaking surge are effectively inhibited, and contact abrasion and damage are reduced. The circuit improves the adaptability to different loads including inductive and nonlinear loads, is low in control difficulty, is easy to modify a traditional circuit, and prolongs the service life of a product.

Description

Technical Field

[0001] The utility model relates to the technical field of switch power supply circuits, in particular to a switch circuit at a direct current output end. Background Art

[0002] In the low-voltage electrical appliance vehicle system, a relay or contactor switch is used as a load switch. When power is needed for the load, the switch is turned on and the battery power passes through the contacts to supply power to the load; when the power supply is stopped, the switch is turned off and the battery stops supplying power to the load.

[0003] Since the load end is not entirely resistive loads like lamps, there are also inductive loads (motors), or mixed nonlinear loads (motor speed controllers) and other loads. Therefore, when the switch is actuated, the equivalent capacitance will cause the two ends of the contacts to be in a short-circuit state, causing the current to surge and exceed the rated current of the contacts, resulting in electrical corrosion of the contacts. The equivalent inductance will cause a large voltage difference across the contacts when the switch is disconnected, causing the voltage between the contacts to exceed the contact tolerance, resulting in arcing between the contacts. Utility Model Content

[0004] In order to solve the problems existing in the background technology, the utility model provides a switch circuit of a DC output end, comprising a relay K1 and a relay K2 connected in parallel, and a thermistor R1 connected in series with the relay K2; the contact "2" end of the relay K2 is connected to the "1" end of the thermistor R1 to form a pre-charging circuit;

[0005] Battery, the "positive" end of the battery is connected to the contact "1" end of relay K2 and the "1" end of relay K1;

[0006] The freewheeling diode D1, whose "positive" terminal is connected to the "negative" terminal of the battery;

[0007] The "2" terminal of thermistor R1 is connected to the "2" terminal of relay K1 and the "cathode" of freewheeling diode D1;

[0008] The load is powered from both ends of the freewheeling diode D1.

[0009] The closing and opening of relays K1 and K2 have the following logical sequence:

[0010] When power is needed for the load, relay K2 is first energized for 100ms and then relay K1 is energized;

[0011] When the load needs to be de-energized, relay K1 is disconnected for 100 mS before relay K2 is disconnected.

[0012] The beneficial effects achieved by the utility model are:

[0013] The utility model improves the adaptability of the DC output switch circuit to different loads (including inductive loads and nonlinear loads) through the combined configuration of the dual switch and the freewheeling diode. The circuit design effectively avoids electrical corrosion and arcing between contacts, thereby reducing the wear and damage of the contacts. Compared with traditional relays or transistor switches, the control difficulty of the present invention is less increased on the basis of traditional control, and the traditional circuit can be simply modified to meet the control requirements.

[0014] When supplying power to the load, relay K2 is first closed for 100 milliseconds and then relay K1 is closed. The current first passes through K2 and the thermistor to charge the load for 100 milliseconds. As the voltage rises after the switch, K1 is closed to supply power to the load. This operation can effectively suppress the generation of the pull-in surge current. When the load is powered off, K1 is first disconnected for 100 milliseconds and then K2 is disconnected. Since K2 and the thermistor are still supplying power to the load, there is no large disconnection surge at the load end when K1 is turned off. K2 is disconnected after 100 milliseconds. Due to the impedance limitation of the thermistor, the generated disconnection surge is within a controllable range. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is the overall circuit diagram of the utility model;

[0016] Figure 2 This is a circuit diagram of a relay or contactor used as a load switch in a traditional low-voltage electrical appliance vehicle system. DETAILED DESCRIPTION

[0017] The technical solution of the utility model will be clearly and completely described below in conjunction with the drawings in the utility model. In addition, the forms of the various structures recorded in the following embodiments are merely illustrative, and the utility model is not limited to the various structures recorded in the following embodiments. All other implementations obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the utility model.

[0018] The circuit diagram of the relay or contactor used as the load switch in the traditional low-voltage electrical appliance vehicle system is shown in Figure 2. When power is needed for the load, the switch is turned on and the battery power passes through the contacts to supply power to the load; when the power supply is stopped, the switch is turned off and the battery stops supplying power to the load.

[0019] The utility model has been improved, referring to Figure 1 The utility model provides a switch circuit of a DC output terminal, comprising a relay K1 and a relay K2 connected in parallel, and a thermistor R1 connected in series with the relay K2; a contact "2" end of the relay K2 is connected to a "1" end of the thermistor R1 to form a pre-charging circuit;

[0020] Battery, the "positive" end of the battery is connected to the contact "1" end of relay K2 and the "1" end of relay K1;

[0021] The freewheeling diode D1, whose "positive" terminal is connected to the "negative" terminal of the battery;

[0022] The "2" terminal of thermistor R1 is connected to the "2" terminal of relay K1 and the "cathode" of freewheeling diode D1;

[0023] The load is powered from both ends of the freewheeling diode D1.

[0024] The closing and opening of relays K1 and K2 have the following logical sequence:

[0025] When power is needed for the load, relay K2 is first energized for 100ms and then relay K1 is energized;

[0026] When the load needs to be de-energized, relay K1 is disconnected for 100 mS before relay K2 is disconnected.

[0027] When supplying power to the load, the current first passes through K2 and thermistor R1 to pre-charge the load for 100 milliseconds, then the voltage rises and K1 is pulled in to provide a stable power supply to the load. This operation can effectively suppress the generation of pull-in surge current.

[0028] When the load is powered off, K1 is disconnected first, and K2 and thermistor R1 continue to supply power to the load, avoiding a large disconnection surge at the load end. After 100 milliseconds, K2 is disconnected, and due to the impedance limitation of the thermistor, the generated disconnection surge is within a controllable range.

[0029] The combined configuration of the dual switch and the freewheeling diode of the utility model improves the adaptability of the DC output switch circuit to different loads (including inductive loads and nonlinear loads). The circuit design effectively avoids electrical erosion and arcing between contacts, and reduces the wear and damage of contacts. The control difficulty is slightly increased on the basis of traditional control, and the traditional circuit can meet the control requirements by simple modification.

[0030] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A switching circuit at a DC output end, characterized in that: include: Relay K1, relay K2 and thermistor R1 connected in series with relay K2 are connected in parallel; the contact "2" end of relay K2 is connected with the "1" end of thermistor R1 to form a pre-charging circuit; Battery, the "positive" end of the battery is connected to the contact "1" end of relay K2 and the "1" end of relay K1; The freewheeling diode D1, whose "positive" pole is connected to the "negative" end of the battery; The "2" terminal of thermistor R1 is connected to the "2" terminal of relay K1 and the "cathode" of freewheeling diode D1; The load is powered from both ends of the freewheeling diode D1.

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