A protection control device for a direct current contactor

Abstract

The application discloses a protection control device of a direct current contactor, which comprises a pre-charging circuit and a delay control circuit; wherein the pre-charging circuit comprises a first switch and a first resistor, and the first switch and the first resistor are connected in series and then connected in parallel with a second contact of the direct current contactor; the delay control circuit comprises a voltage stabilizer, a switch control circuit and a third switch; the voltage stabilizer is reversely connected in parallel across the second contact; the switch control circuit is connected in series with the voltage stabilizer, and the third switch is connected in series in a loop of a second coil of the direct current contactor; the third switch is disconnected after the switch control circuit is powered on, and the third switch is closed after the switch control circuit is powered off. After pre-charging through the first resistor by closing the first switch, the voltage stabilizer is used to control attraction when a voltage difference across the contact of the direct current contactor reaches a proper value, so that a delay control effect is achieved, the effect is not influenced by load change, a detection circuit and a single-chip microcomputer are not needed, the circuit is simpler, the cost is lower, and the service life of the direct current contactor is effectively guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic circuit, in particular to a protection control device of a direct current contactor. BACKGROUND

[0002] Direct current power supply system is widely used in various fields, common applications include electric vehicles, communications, energy, server room, lighting, etc. In the direct current power supply system, the switch control between the power supply circuit and the load is usually controlled by mechanical direct current contactor. The main failure reason of direct current contactor is that there is a large current passing through the contactor in the process of use, and the temperature rises in the moment of large current passing through, which causes the contact of the relay to stick, and finally leads to the uncontrolled contactor.

[0003] Figure 1 A circuit diagram of a pre-charge circuit of a direct current contactor in the prior art.

[0004] To solve the problem of contact burning and sticking in the closing process of the direct current contactor, a pre-charge method is usually used, as shown in FIG. 1, by controlling the on-off of the pre-charge circuit composed of the switch K and the resistance R in parallel with the AB of the contact of the direct current contactor KM, the current flowing through the contact of the direct current contactor KM is reduced, thereby prolonging the service life of the direct current contactor. The impact current flowing through the switch K is effectively limited by the resistance R. Figure 1

[0005] There are mainly two kinds of schemes for controlling the pre-charge circuit in the prior art:

[0006] I. Time delay method: the switch K is first attracted, and the time delay ΔT of the attraction of the two direct current contactors KM and K is controlled by the time delay circuit, and the load circuit is pre-charged.

[0007] II. Differential pressure method: the switch K is first attracted, and the voltage difference between the AB of the contact of the direct current contactor KM is sampled by the single-chip microcomputer, and when the voltage difference between the AB is less than a certain value, the contact of the direct current contactor KM is controlled to be attracted.

[0008] However, if the time delay method is used, the attraction time delay ΔT needs to be calculated by matching the load characteristics and the resistance R. When the capacitive load becomes larger, the attraction time delay ΔT needs to be recalculated, and then the time delay circuit is adjusted by hardware or software, but it is impossible to reasonably adjust the time delay circuit after the system is delivered, and when the load changes, because there is no reasonable adjustment of the time delay, there is still a large impact current when the contactor is attracted, which eventually leads to the uncontrolled sticking of the contact of the direct current contactor.

[0009] If the differential pressure method is used, the voltage between the AB of the contact of the direct current contactor KM needs to be measured at the same time, the differential pressure ΔV is calculated, and the control circuit needs to be completed by a complex digital chip and a detection circuit, which has high cost and low reliability.​

[0010] Providing a high-reliability, low-cost DC contactor protection device is a technical problem that those skilled in the art need to solve. SUMMARY

[0011] The purpose of the present application is to provide a DC contactor protection control device that is more reliable and lower in cost than existing DC contactor protection schemes.

[0012] To solve the above technical problems, the present application provides a DC contactor protection control device, comprising a pre-charging circuit and a delay control circuit.

[0013] The pre-charging circuit comprises a first switch and a first resistor, which are connected in series and then connected in parallel with the second contact of the DC contactor.

[0014] The delay control circuit comprises a voltage stabilizer, a switch control circuit and a third switch. The voltage stabilizer is connected in reverse parallel across the second contact. The switch control circuit is connected in series with the voltage stabilizer, and the third switch is connected in series in the loop where the second coil of the DC contactor is located. The third switch is opened after the switch control circuit is powered on, and the third switch is closed after the switch control circuit is powered off.

[0015] Optionally, the voltage stabilizer is specifically a voltage stabilizing diode.

[0016] Optionally, the switch control circuit specifically comprises a second resistor, a third resistor, an optocoupler, a fourth resistor and a fifth resistor. The third switch is specifically a triode.

[0017] The second resistor is connected in series in the loop where the voltage stabilizer is located. The third resistor and the input end of the optocoupler are connected in series and then connected in parallel with the second resistor. The positive electrode of the output end of the optocoupler is connected with the second end of the fourth resistor and the first end of the fifth resistor. The negative electrode of the output end of the optocoupler is grounded. The first end of the fourth resistor is connected with a DC power supply. The second end of the fifth resistor is connected with the base of the triode. The collector of the triode is connected with a DC power supply. The emitter of the triode is connected with the first end of the second coil. The second end of the second coil is grounded.

[0018] Optionally, the first switch is specifically a relay, and the pre-charging circuit further comprises a fourth switch.

[0019] The first end of the first coil of the first switch is connected with a DC power supply and the collector of the third switch. The second end of the first coil is grounded. The fourth switch is arranged between the DC power supply and the collector of the third switch, or the fourth switch is arranged between the emitter of the third switch and the ground.

[0020] Optionally, the fourth switch is a relay.

[0021] The fourth contact of the fourth switch is arranged between the DC power supply and the collector of the third switch or between the emitter of the third switch and the ground.

[0022] Optionally, the pre-charge circuit further comprises a sixth resistor connected in series between the negative side of the second contact and the negative pole of the DC power supply loop.

[0023] Optionally, the switch control circuit specifically comprises a seventh resistor and a fifth switch, and the fifth switch is a relay.

[0024] The fifth coil of the fifth switch and the sixth resistor are connected in series in the loop where the voltage stabilizer is arranged, the fifth contact of the fifth switch is connected in series in the loop where the second coil is arranged, and the fifth contact is disconnected after the fifth coil is energized, and the fifth contact is closed after the fifth coil is de-energized.

[0025] Optionally, the first LED indicator lamp connected in series in the loop where the first switch is arranged and the second LED indicator lamp connected in series in the loop where the third switch is arranged are further included.

[0026] The protection control device of the DC contactor provided by the application comprises a pre-charge circuit and a delay control circuit; wherein the pre-charge circuit comprises a first switch and a first resistor, and the first switch and the first resistor are connected in series and then connected in parallel with the second contact of the DC contactor; the delay control circuit comprises a voltage stabilizer, a switch control circuit and a third switch; the voltage stabilizer is connected reversely in parallel across the second contact; the switch control circuit is connected in series with the voltage stabilizer, and the third switch is connected in series in the loop where the second coil of the DC contactor is arranged, the third switch is disconnected after the switch control circuit is energized, and the third switch is closed after the switch control circuit is de-energized. After the first switch is closed to realize pre-charging through the first resistor, the voltage stabilizer connected reversely in parallel across the second contact of the DC contactor can realize that when the voltage difference across the second contact of the DC contactor is higher than a certain value, the third switch is disconnected by energizing the switch control circuit, at this time the second contact of the DC contactor is not attracted, and when the voltage difference across the second contact of the DC contactor is lower than the value, the switch control circuit is de-energized by de-energizing the voltage stabilizer, and then the third switch is turned on to control the second contact of the DC contactor to be attracted. The function realization of the protection control device of the DC contactor provided by the application is only related to the appropriate voltage difference across the second contact of the DC contactor, and is not affected by the load change, and a detection circuit and a single-chip microcomputer are not needed, the circuit is simpler, the cost is lower, the service life of the DC contactor is effectively guaranteed, and the operation and maintenance period of the entire electrical system is prolonged. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to make the technical solutions of the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or the prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only need to be some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort.

[0028] Figure 1 A circuit diagram of a pre-charge circuit of a direct current contactor in the prior art;

[0029] Figure 2 A circuit diagram of a protection control device of a direct current contactor provided by the embodiment of the present application;

[0030] Figure 3 A circuit diagram of another protection control device of a direct current contactor provided by the embodiment of the present application. DETAILED DESCRIPTION

[0031] The core of the present application is to provide a protection control device of a direct current contactor, which is more reliable and lower in cost than the existing protection scheme of a direct current contactor.

[0032] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without any creative effort fall within the protection scope of the present application.

[0033] Figure 2 A circuit diagram of a protection control device of a direct current contactor provided by the embodiment of the present application.

[0034] As shown in Figure 2 , an end of a second contact of a direct current contactor KM1 close to a positive input end HV+ of a direct current power supply system is denoted as point A, another end of the second contact of the direct current contactor KM1 is denoted as point B, and an interface of a loop where a second coil of the direct current contactor KM1 is located is denoted as D02.

[0035] As shown in Figure 2 , the protection control device of the direct current contactor provided by the embodiment of the present application includes a pre-charge circuit and a delay control circuit;

[0036] The pre-charge circuit includes a first switch K1 and a first resistor R1, and the first switch K1 and the first resistor R1 are connected in series and then connected in parallel with the second contact of the direct current contactor.

[0037] The delay control circuit comprises a stabilizer ZD1, a switch control circuit and a third switch. The stabilizer ZD1 is connected in reverse parallel to the second contact. The switch control circuit is connected in series with the stabilizer ZD1. The third switch is connected in series to the loop where the second coil of the DC contactor is located. The third switch is opened after the switch control circuit is powered on. The third switch is closed after the switch control circuit is powered off.

[0038] In a specific implementation, the stabilizer ZD1 can be a stabilizing diode or other types of stabilizers ZD1.

[0039] By connecting the stabilizer ZD1 in reverse to the second contact of the DC contactor KM1, i.e. connecting the anode of the stabilizer ZD1 to point B and the cathode of the stabilizer ZD1 to point A, the voltage V ZD1 across the stabilizer ZD1 is compared with the stabilized voltage V ZD1 of the stabilizer ZD1, so that the optimal closing timing of the second contact of the DC contactor KM1 can be obtained. Then, the switch control circuit is turned on by the stabilizer ZD1. The third switch is set to be in an open state corresponding to the on state of the switch control circuit. The third switch is located in the loop where the second coil is located, i.e. at D02.

[0040] When it is needed to control the closing of the second contact of the DC contactor KM1, the first switch K1 of the pre-charge circuit is first controlled to be closed to pre-charge the load loop. The first switch K1 can be a relay.

[0041] When the voltage V AB across points A and B is greater than the stabilized voltage V ZD1 of the stabilizer ZD1, the stabilizer ZD1 is turned on to turn on the switch control circuit, and then the third switch is in an open state. When the voltage V AB across points A and B gradually decreases, and the voltage V AB across points A and B is less than the stabilized voltage V ZD1 of the stabilizer ZD1, the stabilizer ZD1 is turned off to turn off the switch control circuit, and then the third switch is turned on to control the closing of the second contact of the DC contactor KM1.

[0042] Based on the above circuit design, according to the voltage V AB across points A and B at the optimal closing timing of the second contact of the DC contactor KM1 and the stabilized voltage V ZD1 of the stabilizer, a current-limiting resistor is matched, so that the second contact of the DC contactor KM1 can be closed at the optimal closing timing by a simple circuit structure without the need of setting a complex digital chip and detection circuit, thereby ensuring the service life of the DC contactor KM1 and prolonging the operation and maintenance period of the entire electrical system.

[0043] The protection control device of the DC contactor provided by the embodiment of the application comprises a pre-charging circuit and a delay control circuit; the pre-charging circuit comprises a first switch and a first resistor, and the first switch and the first resistor are connected in series and then connected in parallel with a second contact of the DC contactor; the delay control circuit comprises a voltage stabilizer, a switch control circuit and a third switch; the voltage stabilizer is connected reversely in parallel across the second contact; the switch control circuit is connected in series with the voltage stabilizer, and the third switch is connected in series in a loop where a second coil of the DC contactor is located; the third switch is disconnected after the switch control circuit is powered on, and the third switch is connected after the switch control circuit is powered off. After pre-charging through the first resistor by closing the first switch, the voltage stabilizer connected reversely in parallel across the second contact of the DC contactor can be used to disconnect the third switch by powering on the switch control circuit when the voltage difference across the second contact of the DC contactor is higher than a certain value, at this time, the second contact of the DC contactor is not attracted, and when the voltage difference across the second contact of the DC contactor is lower than the certain value, the switch control circuit is powered off by the voltage stabilizer to make the third switch conductive, thereby controlling the second contact of the DC contactor to be attracted. The function of the protection control device of the DC contactor provided by the application is only related to the appropriate voltage difference across the second contact of the DC contactor, and is not affected by the load change, and a detection circuit and a single-chip microcomputer are not needed, the circuit is simpler, the cost is lower, the service life of the DC contactor is effectively guaranteed, and the operation and maintenance period of the entire electrical system is prolonged.

[0044] On the basis of the above embodiment, in the protection control device of the DC contactor provided by the embodiment of the application, as shown in Figure 2 The switch control circuit specifically comprises a second resistor R2, a third resistor R3, an optical coupler OP1, a fourth resistor R4 and a fifth resistor R5; and the third switch is specifically a triode Q3.

[0045] The second resistor R2 is connected in series in a loop where the voltage stabilizer ZD1 is located, the third resistor R3 and the input end of the optical coupler OP1 are connected in series and then connected in parallel with the second resistor R2, the positive electrode of the output end of the optical coupler OP1 is connected with the second end of the fourth resistor R4 and the first end of the fifth resistor R5, the negative electrode of the output end of the optical coupler OP1 is grounded, the first end of the fourth resistor R4 is connected with a DC power supply VCC, the second end of the fifth resistor R5 is connected with the base of the triode Q3, the collector of the triode Q3 is connected with the DC power supply VCC, the emitter of the triode Q3 is connected with the first end of the second coil, and the second end of the second coil of the DC contactor KM1 is grounded.

[0046] The second resistor R2 is used to realize the current-limiting and sampling functions of the voltage stabilizer branch, the optical coupler OP1 is used to realize the safe isolation of the sampling circuit and the subsequent control circuit, and the switching of the triode Q3 is controlled.

[0047] When the voltage V AB of the two ends A and B is greater than the voltage stabilizing value V ZD1When the voltage VAB is less than the voltage VZD1 of the voltage stabilizer ZD1, the voltage stabilizer ZD1 is off, the light coupling OP1 is off, the base of the triode Q3 is pulled up by the DC power supply VCC, the second coil of the DC contactor KM1 is electrified through the D02 end, and the second contact of the DC contactor KM1 is attracted. AB When the voltage VAB is less than the voltage VZD1 of the voltage stabilizer ZD1, the voltage stabilizer ZD1 is off, the light coupling OP1 is off, the base of the triode Q3 is pulled up by the DC power supply VCC, the second coil of the DC contactor KM1 is electrified through the D02 end, and the second contact of the DC contactor KM1 is attracted. ZD1 When the voltage VAB is less than the voltage VZD1 of the voltage stabilizer ZD1, the voltage stabilizer ZD1 is off, the light coupling OP1 is off, the base of the triode Q3 is pulled up by the DC power supply VCC, the second coil of the DC contactor KM1 is electrified through the D02 end, and the second contact of the DC contactor KM1 is attracted.

[0048] In order to cooperate with the sampling of the second resistor R2, the switch control circuit can further include a sixth resistor R6 connected in series between the negative side (i.e. point B) of the second contact of the DC contactor KM1 and the negative pole (i.e. HV-) of the DC power supply loop. In actual application, the sixth resistor R6 is not limited to be implemented by one resistor, and a plurality of resistors can be set according to needs.

[0049] The control circuit of the first switch K1 in the precharge circuit can be separately set. In order to facilitate unified control and save circuit components, the first switch K1 can be a relay, and the precharge circuit further includes a fourth switch K4. Figure 2 As shown in the figure, the first switch K1 can be a relay, and the precharge circuit further includes a fourth switch K4.

[0050] The first end of the first coil of the first switch K1 is connected with the DC power supply VCC and the collector of the third switch, the second end of the first coil is grounded, and the fourth switch K4 is arranged between the DC power supply VCC and the collector of the third switch or arranged between the emitter of the third switch and the ground.

[0051] The control end of the loop in which the first coil of the first switch K1 is located is denoted as D01. When the fourth switch K4 is closed, the first coil is electrified to make the first contact of the first switch K1 closed, and at the same time, the triode Q3 is provided with a power supply.

[0052] Further, the fourth switch K4 can also be a relay.

[0053] The fourth contact of the fourth switch K4 is arranged between the DC power supply VCC and the collector of the third switch or arranged between the emitter of the third switch and the ground.

[0054] The fourth coil of the fourth switch K4 is connected to the loop switch control unit to realize unified control of the attraction of the DC contactor KM1. After the fourth contact is closed by electrifying the fourth coil through the loop switch control unit, the first coil is turned on, the first contact is attracted, and the precharge to the load starts, until the voltage VAB is less than the voltage VZD1 of the voltage stabilizer ZD1. AB When the voltage VAB is less than the voltage VZD1 of the voltage stabilizer ZD1, the voltage stabilizer ZD1 is off, the light coupling OP1 is off, the base of the triode Q3 is pulled up by the DC power supply VCC, the second coil of the DC contactor KM1 is electrified through the D02 end, and the second contact of the DC contactor KM1 is attracted. ZD1 When the voltage VAB is less than the voltage VZD1 of the voltage stabilizer ZD1, the voltage stabilizer ZD1 is off, the light coupling OP1 is off, the base of the triode Q3 is pulled up by the DC power supply VCC, the second coil of the DC contactor KM1 is electrified through the D02 end, and the second contact of the DC contactor KM1 is attracted.

[0055] Figure 3 A circuit diagram of another protection and control device for a DC contactor provided in an embodiment of the present invention.

[0056] Based on the above embodiments, in the protection and control device for the DC contactor provided in the embodiments of the present invention, such as Figure 3 As shown, the switch control circuit specifically includes: a seventh resistor R7 and a fifth switch K5; the fifth switch K5 is a relay;

[0057] The fifth coil of the fifth switch K5 and the seventh resistor R7 are connected in series in the circuit where the voltage regulator ZD1 is located. The fifth contact of the fifth switch K5 is connected in series in the circuit where the second coil is located. The fifth contact opens when the fifth coil is energized and closes when the fifth coil is de-energized.

[0058] In the specific implementation, the seventh resistor R7 is set as a current-limiting resistor, and the voltage regulator ZD1, together with the seventh resistor R7 and the fifth coil, controls the voltage V across terminals A and B. AB Sampling is performed. When the voltage V across terminals A and B... AB The voltage regulation value V is greater than that of voltage regulator ZD1. ZD1 When the voltage regulator ZD1 is turned on, the fifth coil is energized, and the fifth contact remains open. When the voltage V across A and B... AB The voltage regulation value V is less than that of voltage regulator ZD1. ZD1 When the voltage regulator ZD1 is cut off, the fifth coil is disconnected, the fifth contact is energized, and the second contact of the DC contactor KM1 is energized.

[0059] Furthermore, the control of the pre-charging circuit can be referred to in the previous embodiment, and will not be repeated here.

[0060] Based on the above embodiments, the protection and control device for the DC contactor provided in this embodiment of the invention may further include a first LED indicator connected in series in the circuit where the first switch K1 is located, and a second LED indicator connected in series in the circuit where the third switch is located.

[0061] The first and second LED indicators show the on / off status of the pre-charging circuit and the DC contactor KM1, making it easy for staff to check the status of the DC contactor KM1 and promptly troubleshoot any abnormalities.

[0062] The protection control device of the direct current contactor is described in detail above. The embodiments in the specification are described in a progressive manner, and each embodiment mainly describes the difference from other embodiments. The same or similar parts of each embodiment can be understood by referring to each other. It should be pointed out that, for those skilled in the art, some improvements and modifications can be made to the present application without departing from the principles of the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

[0063] It should also be noted that in this specification, the relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitations, the element defined by the statement "including a" does not exclude the presence of other identical elements in the process, method, article or device including the element.

Claims

1. A protective control device for a direct current contactor, characterized by, The pre-charging circuit and the delay control circuit are included. The pre-charging circuit includes a first switch and a first resistor, and the first switch and the first resistor are connected in series and then connected in parallel with a second contact of a DC contactor. The delay control circuit includes a voltage stabilizer, a switch control circuit and a third switch; the voltage stabilizer is connected in series with a second resistor and then reversely connected in parallel across the second contact; the switch control circuit is connected in series with the voltage stabilizer; and the third switch is connected in series in a loop in which a second coil of the DC contactor is located, the third switch is opened after the switch control circuit is powered on, and the third switch is closed after the switch control circuit is powered off. The switch control circuit specifically includes a second resistor, a third resistor, a photo-coupler, a fourth resistor and a fifth resistor; the third switch is specifically a triode; the second resistor is connected in series in a loop in which the voltage stabilizer is located; the third resistor and an input end of the photo-coupler are connected in series and then connected in parallel with the second resistor; a positive pole of an output end of the photo-coupler is connected with a second end of the fourth resistor and a first end of the fifth resistor; a negative pole of the output end of the photo-coupler is grounded; a first end of the fourth resistor is connected with a DC power supply; a second end of the fifth resistor is connected with a base of the triode; a collector of the triode is connected with the DC power supply; an emitter of the triode is connected with a first end of the second coil; and a second end of the second coil is grounded. The second contact is closed at an optimal closing time according to a voltage across the second contact, a voltage stabilizing value of the voltage stabilizer and the second resistor, so that the first switch is closed and the second contact is closed at the optimal closing time. The voltage stabilizer is specifically a voltage stabilizing diode.

2. The protective control device according to claim 1, characterized in that The first switch is specifically a relay, and the pre-charging circuit further includes a fourth switch. A first end of a first coil of the first switch is connected with a DC power supply and a collector of the third switch; a second end of the first coil is grounded; and the fourth switch is arranged between the DC power supply and the collector of the third switch or arranged between an emitter of the third switch and the ground.

3. The protective control device according to claim 2, characterized in that The fourth switch is specifically a relay. A fourth contact of the fourth switch is arranged between the DC power supply and the collector of the third switch or arranged between the emitter of the third switch and the ground.

4. The protection control device of claim 1, wherein The pre-charging circuit further includes a sixth resistor connected in series between a negative pole side of the second contact and a negative pole of a DC power supply loop.

5. The protection control device of claim 1, wherein The pre-charging circuit further includes a first LED indicator connected in series in a loop in which the first switch is located and a second LED indicator connected in series in a loop in which the third switch is located.

6. A protection control device for a direct current contactor, characterized by The pre-charging circuit and the delay control circuit are included. The pre-charging circuit includes a first switch and a first resistor, and the first switch and the first resistor are connected in series and then connected in parallel with a second contact of a DC contactor. The delay control circuit includes a voltage stabilizer and a switch control circuit. The switch control circuit specifically includes a seventh resistor and a fifth switch; the fifth switch is a relay; The voltage stabilizer is connected in series with a fifth coil of the fifth switch and the seventh resistor and then reversely connected in parallel across the second contact; and the switch control circuit is connected in series with the voltage stabilizer. The fifth contact of the fifth switch is connected in series to a loop in which the second coil of the direct current contactor is located, and the fifth contact is opened after the fifth coil is energized, and the fifth contact is closed after the fifth coil is de-energized; The second contact is closed at the optimal closing time according to the voltage across the second contact, the voltage of the voltage stabilizer and the seventh resistor before the first switch is closed. The voltage stabilizer is specifically a voltage stabilizing diode.

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