A dual-power switching circuit, control method and control system

Abstract

The present invention provides a dual-power switching circuit, a control method and a control system, including: a first contactor, a second contactor, a first power supply detection board and a second power supply detection board. The 485 communication function is integrated in the first power supply detection board and the second power supply detection board. The A power supply is electrically connected to the first contactor and the first power supply detection board respectively, and the B power supply is electrically connected to the second contactor and the second power supply detection board respectively; the A power supply and the B power supply are respectively connected to the COM ports of the first power supply detection board and the second power supply detection board; the normally open contact of the first power supply detection board is electrically connected to the normally closed contact of the second contactor through the control coil of the first contactor, and the normally open contact of the second power supply detection board is electrically connected to the normally closed contact of the first contactor through the control coil of the second contactor. The present invention has low cost, small volume, low cost and difficulty in later maintenance, and can also effectively realize power failure feedback.

Description

Technical Field

[0001] The present invention relates to a switching circuit, in particular to a dual-power switching circuit, and also relates to a control method and a control system for the dual-power switching circuit. Background Art

[0002] A dual-power switching device is an automatic switching device that selects one of two power supplies. In the normal working state, when the main power supply is within the normal voltage range, the load is always connected to the main power supply. When the main power supply fails, the load automatically switches to the backup power supply, and when the main power supply returns to normal, the load automatically switches back to the main power supply.

[0003] Currently, the dual-power switching technical solutions for distribution cabinets in the industry are mainly divided into two categories: The first category is an automatic transfer switch, such as ATS. ATS is mainly used in emergency power supply systems and is a switching electrical appliance that automatically switches the load power from one power supply to another backup power supply. The disadvantages of this method are high cost, expensive price, large volume, and difficult later maintenance. The second category is an automatic switching circuit composed of devices such as AC contactors, power monitors, intermediate relays, and transfer switches. The transfer switch is used to set the working mode, the power monitor detects the power supply, its contacts control the coil of the intermediate relay, and then control the coil of the AC contactor to achieve the purpose of switching the power supply. The disadvantage of this method is that there is no power failure feedback function, and 2 intermediate relays are required to control the AC contactor, resulting in increased costs. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a dual-power switching circuit with low cost, small volume, convenient later maintenance, and capable of realizing power failure feedback. On this basis, a control method and a control system for the dual-power switching circuit are further provided.

[0005] To this end, the present invention provides a dual-power switching circuit, including: a first contactor, a second contactor, a first power detection board, and a second power detection board. The 485 communication function is integrated in the first power detection board and the second power detection board. The A power supply is electrically connected to the first contactor and the first power detection board respectively, and the B power supply is electrically connected to the second contactor and the second power detection board respectively; the A power supply and the B power supply are respectively connected to the COM ports of the first power detection board and the second power detection board; the normally open contact of the first power detection board is electrically connected to the normally closed contact of the second contactor through the control coil of the first contactor, and the normally open contact of the second power detection board is electrically connected to the normally closed contact of the first contactor through the control coil of the second contactor.

[0006] A further improvement of the present invention lies in that after the control coil of the first contactor is energized, the second contactor is locked through the normally closed contact of the second contactor connected electrically; after the control coil of the second contactor is energized, the first contactor is locked through the normally closed contact of the first contactor connected electrically, so as to realize the interlock between the first contactor and the second contactor.

[0007] A further improvement of the present invention lies in that in the first power supply detection board and the second power supply detection board, the normally open contact is closed when the detected power supply is normal, and the normally open contact is disconnected when the detected power supply fails or is powered off.

[0008] A further improvement of the present invention lies in that the power supply of path A and the power supply of path B are the two input power supplies of A and B after passing through the air switch.

[0009] The present invention also provides a control method for a dual-power switching circuit, which is used to control the dual-power switching circuit as described above. The working mode of the dual-power switching circuit is controlled through the power supply detection state. The working modes include the self-switching and self-restoring mode and the self-switching and non-self-restoring mode. In the self-switching and self-restoring mode, when the current power supply fails, it automatically switches to the standby power supply, and after the original power supply returns to normal, it automatically switches back to the original power supply again; in the self-switching and non-self-restoring mode, when the current power supply fails, it automatically switches to the standby power supply, and after the original power supply returns to normal, it does not automatically switch back to the original power supply.

[0010] A further improvement of the present invention lies in that in the self-switching and self-restoring mode, the power supply of path A is set as the main power supply to supply power, and the power supply control is realized according to the power supply detection state of the power supply of path A:

[0011] When the power supply of path A is normal and the power supply of path B is normal or abnormal, the COM port and / or the normally open contact of the first power supply detection board are closed, the COM port and the normally open contact of the second power supply detection board do not act and remain in the open state, the normally closed contact of the second contactor does not act and remains in the closed state, the coil of the first contactor is energized and attracted, the main contact of the first contactor acts and conducts, and the power supply of path A supplies power;

[0012] When the power supply of path A is abnormal and the power supply of path B is normal, the COM port and the normally open contact of the first power supply detection board do not act and remain in the open state, the COM port and the normally open contact of the second power supply detection board are closed, the normally closed contact of the first contactor is closed, the coil of the second contactor is energized and attracted, the main contact of the second contactor acts and conducts, and the power supply of path B supplies power; until the power supply of path A returns to normal, the COM port and the normally open contact port of the second power supply detection board are disconnected to control the power supply of path A.

[0013] A further improvement of the present invention lies in that, in the self-switching and self-restoring mode, the B power supply is set as the main power supply for power supply, and power supply control is realized according to the power detection status of the B power supply:

[0014] When the B power supply is normal and the A power supply is normal or abnormal, the COM port and normally open contact of the second power detection board are closed, the COM port and normally open contact of the first power detection board do not act and remain in the open state, the normally closed contact of the first contactor does not act and remains closed, the coil of the second contactor is energized and attracted, and the main contact of the second contactor acts to conduct, and the B power supply supplies power;

[0015] When the B power supply is abnormal and the A power supply is normal, the COM port and normally open contact of the second power detection board do not act and remain in the open state, the COM port and normally open contact of the first power detection board are closed, the normally closed contact of the second contactor is closed, the coil of the first contactor is energized and attracted, and the main contact of the first contactor acts to conduct, and the A power supply supplies power; until the B power supply returns to normal, the COM port and normally open contact port of the first power detection board are disconnected to control the B power supply to supply power.

[0016] A further improvement of the present invention lies in that, in the self-switching but non-self-restoring mode, power supply control is realized according to the power detection status of the A power supply:

[0017] When the A power supply is normal and the B power supply is normal or abnormal, the COM port and normally open contact of the first power detection board are closed, the COM port and normally open contact of the second power detection board do not act and remain in the open state, the normally closed contact of the second contactor does not act and remains closed, the coil of the first contactor is energized and attracted, and the main contact of the first contactor acts to conduct, and the A power supply supplies power;

[0018] When the A power supply is abnormal and the B power supply is normal, the COM port and normally open contact of the first power detection board do not act and remain in the open state, the COM port and normally open contact of the second power detection board are closed, the normally closed contact of the first contactor is closed, the coil of the second contactor is energized and attracted, and the main contact of the second contactor acts to conduct, and the B power supply supplies power; when the A power supply returns to normal, the B power supply continues to supply power.

[0019] A further improvement of the present invention lies in outputting and feedbacking power supply faults through the power detection status:

[0020] When the input power supply voltage of the A power supply and / or the B power supply exceeds the set overvoltage range, the corresponding first power detection board and / or second power detection board issues an overvoltage fault status signal;

[0021] When the input power supply voltage of the power supply of circuit A and / or circuit B is lower than the set undervoltage range, the corresponding first power supply detection board and / or second power supply detection board sends out an undervoltage fault status signal;

[0022] When the input power supply of the power supply of circuit A and / or circuit B is single-phased, the corresponding first power supply detection board and / or second power supply detection board sends out a single-phase fault status signal;

[0023] When the phase sequence of the input power supply of the power supply of circuit A and / or circuit B is reversed, the corresponding first power supply detection board and / or second power supply detection board sends out a phase sequence fault status signal.

[0024] The present invention also provides a control system for a dual power supply switching circuit, which is characterized by including the dual power supply switching circuit as described above, and realizing the power supply switching control between the power supply of circuit A and the power supply of circuit B through the dual power supply switching circuit.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: By optimizing the circuit structure and control method of the dual power supply switching circuit, the function of switching the input power supply is realized, and the feedback signal and input working mode can be output through the corresponding power supply detection board; the present invention has low cost, small volume, and few components included, effectively reducing the cost and difficulty of later maintenance. On this basis, the power supply fault feedback can be effectively realized, so that the control system of the dual power supply switching circuit can feedback the power supply status without configuring a power monitor, and there is no need to set devices such as a transfer switch or an intermediate relay, reducing the cost and volume, and effectively reducing the maintenance difficulty of the product and improving the stability performance of the product. Description of the Drawings

[0026] Figure 1 is a schematic circuit principle diagram of a three-phase dual power supply switching circuit in an embodiment of the present invention;

[0027] Figure 2 is a schematic circuit principle diagram of a single-phase dual power supply switching circuit in an embodiment of the present invention;

[0028] Figure 3 is a schematic circuit principle diagram of a DC dual power supply switching circuit in an embodiment of the present invention. Detailed Embodiments

[0029] The following further describes in detail the preferred embodiments of the present invention with reference to the drawings.

[0030] As Figures 1 to 3As shown, this example provides a dual-power switching circuit, including: a first contactor KM1, a second contactor KM2, a first power detection board FV1, and a second power detection board FV2. The 485 communication function is integrated in the first power detection board FV1 and the second power detection board FV2. In a three-phase dual-power switching circuit, the L1, L2, L3, and N lines of the A-phase power supply are respectively electrically connected to the first contactor KM1 and the first power detection board FV1, and the L1, L2, L3, and N lines of the B-phase power supply are respectively electrically connected to the second contactor KM2 and the second power detection board FV2, as Figure 1 shown. As Figure 2 shown, if it is a single-phase dual-power switching circuit, the L and N lines of the A-phase power supply are respectively electrically connected to the first contactor KM1 and the first power detection board FV1, and the L and N lines of the B-phase power supply are respectively electrically connected to the second contactor KM2 and the second power detection board FV2. As Figure 3 shown, if it is in a DC dual-power switching circuit, the positive and negative poles of the A-phase power supply are respectively electrically connected to the first contactor KM1 and the first power detection board FV1, and the positive and negative poles of the B-phase power supply are respectively electrically connected to the second contactor KM2 and the second power detection board FV2.

[0031] As Figure 1 shown, the L1 of the A-phase power supply and the L1 of the B-phase power supply in this example are respectively connected to the COM ports of the first power detection board FV1 and the second power detection board FV2. Figure 1 In this connection method, the control coil is powered by L1. In actual applications, it is not limited to only powering the control coil by L1. It can be adaptively replaced by connecting the live wire of other phases to the COM port. The normally open contact NO of the first power detection board FV1 is electrically connected to the normally closed contact NC of the second contactor KM2 through the control coil of the first contactor KM1, and the normally open contact NO of the second power detection board FV2 is electrically connected to the normally closed contact NC of the first contactor KM1 through the control coil of the second contactor KM2.

[0032] In this example, the first contactor KM1 and the second contactor KM2 are equipped with normally closed contacts NC. After the control coil is energized, the normally closed contact NC is disconnected. The control coil of the first contactor KM1 is connected in series with the normally closed contact NC of the second contactor KM2, and the control coil of the second contactor KM2 is connected in series with the normally closed contact NC of the first contactor KM1. That is, after the control coil of the first contactor KM1 is powered on, the second contactor KM2 is locked through the electrically connected normally closed contact NC of the first contactor KM1. After the control coil of the second contactor KM2 is powered on, the first contactor KM1 is locked through the electrically connected normally closed contact NC of the second contactor KM2, so as to realize the interlock between the first contactor KM1 and the second contactor KM2. That is, the control coil of one relay is connected in series with the normally closed contact of the other relay, thus realizing the interlock principle of the two relays.

[0033] In the normally open contact NO / COM ports of the first power detection board FV1 and the second power detection board FV2 described in this example, the normally open contact NO is closed when the detected power supply is normal, and the normally open contact NO is disconnected when the detected power supply fails or is powered off. The A-phase power supply and the B-phase power supply described in this example are the A and B two-way input power supplies after passing through the air switch. The communication ports A / B of the first power detection board FV1 and the second power detection board FV2 output the power detection status signal through 485 communication, and set and control the working mode of the dual-power switching circuit.

[0034] This example also provides a control method for a dual-power switching circuit, which is used to control the dual-power switching circuit as described above, and controls the working mode of the dual-power switching circuit through the power detection status. The working modes include the self-switching and self-restoring mode and the self-switching and non-self-restoring mode. In the self-switching and self-restoring mode, when the current power supply fails, it automatically switches to the standby power supply, and after the original power supply returns to normal, it automatically switches back to the original power supply again. In the self-switching and non-self-restoring mode, when the current power supply fails, it automatically switches to the standby power supply, and after the original power supply returns to normal, it does not automatically switch back to the original power supply.

[0035] In this example, in the self-switching and self-restoring mode, it is preferably set through 485 communication that the A-phase power supply is the main power supply for power supply, and the power supply control is realized according to the power detection status of the A-phase power supply:

[0036] When the A-phase power supply is normal and the B-phase power supply is normal, the COM port and the normally open contact NO of the first power detection board FV1 are closed, the COM port and the normally open contact NO of the second power detection board FV2 do not act (remain in the open state), the normally closed contact NC of the second contactor KM2 does not act (remains closed), the coil of the first contactor KM1 is energized and attracted, and the main contact of the first contactor KM1 acts to conduct, and the A-phase power supply supplies power;

[0037] When the power supply of circuit A is normal and the power supply of circuit B is abnormal, the COM port and the normally open contact NO of the first power supply detection board FV1 are closed, the COM port and the normally open contact NO of the second power supply detection board FV2 do not act (remain open), the normally closed contact NC of the second contactor KM2 does not act (remain closed), the coil of the first contactor KM1 is energized and attracted, the main contacts of the first contactor KM1 act and conduct, and the power supply of circuit A is supplied;

[0038] When the power supply of circuit A is abnormal and the power supply of circuit B is normal, the COM port and the normally open contact NO of the first power supply detection board FV1 do not act (remain open), the COM and the normally open contact NO ports of the second power supply detection board FV2 are closed, the normally closed contact NC of the first contactor KM1 is closed, the coil of the second contactor KM2 is energized and attracted, the main contacts of the second contactor KM2 act and conduct, and the power supply of circuit B is supplied; until the power supply of circuit A returns to normal, control the power supply of circuit A, that is, the COM port and the normally open contact NO of the first power supply detection board FV1 are closed, the COM port and the normally open contact NO of the second power supply detection board FV2 are opened, the normally closed contact NC of the first contactor KM1 is opened, the normally closed contact NC of the second contactor KM2 is closed, the coil of the first contactor KM1 is energized and attracted, and the main contacts of the first contactor KM1 act and conduct to realize the power supply of circuit A.

[0039] In this example, in the self-switching and self-restoring mode, the power supply of circuit B can also be set as the main power supply through 485 communication to realize power supply, and power supply control is realized according to the power supply detection state of the power supply of circuit B:

[0040] When the power supply of circuit B is normal and the power supply of circuit A is normal, the COM port and the normally open contact NO of the second power supply detection board FV2 are closed, the COM port and the normally open contact NO of the first power supply detection board FV1 do not act (remain open), the normally closed contact NC of the first contactor KM1 does not act (remain closed), the coil of the second contactor KM2 is energized and attracted, the main contacts of the second contactor KM2 act and conduct, and the power supply of circuit B is supplied;

[0041] When the power supply of circuit B is normal and the power supply of circuit A is abnormal, the COM port and / or the normally open contact NO of the second power supply detection board FV2 are closed, the COM port and the normally open contact NO of the first power supply detection board FV1 do not act (remain open), the normally closed contact NC of the first contactor KM1 does not act (remain closed), the coil of the second contactor KM2 is energized and attracted, the main contacts of the second contactor KM2 act and conduct, and the power supply of circuit B is supplied;

[0042] When the power supply of circuit B is abnormal and the power supply of circuit A is normal, the COM port and normally open contact NO of the second power supply detection board FV2 do not act (remain disconnected), the COM port and normally open contact NO of the first power supply detection board FV1 close, the normally closed contact NC of the second contactor KM2 closes, the coil of the first contactor KM1 is energized and attracted, the main contacts of the first contactor KM1 act and conduct, and the power supply of circuit A is supplied; until the power supply of circuit B returns to normal, the power supply of circuit B is controlled to be supplied, that is, the COM port and normally open contact NO of the first power supply detection board FV1 are disconnected, the COM port and normally open contact NO of the second power supply detection board FV2 close, the normally closed contact NC of the first contactor KM1 closes, the coil of the second contactor KM2 is energized and attracted, the normally closed contact NC of the second contactor KM2 is disconnected, and the main contacts of the second contactor KM2 act and conduct to realize the power supply of circuit B.

[0043] In this example, in the self-switching and non-self-restoring mode, the power supply control is realized according to the power supply detection state of the power supply of circuit A:

[0044] When the power supply of circuit A is normal and the power supply of circuit B is normal, the COM port and normally open contact NO of the first power supply detection board FV1 close, the COM port and normally open contact NO of the second power supply detection board FV2 do not act (remain disconnected), the normally closed contact NC of the second contactor KM2 does not act (remain closed), the coil of the first contactor KM1 is energized and attracted, the main contacts of the first contactor KM1 act and conduct, and the power supply of circuit A is supplied;

[0045] When the power supply of circuit A is normal and the power supply of circuit B is abnormal, the COM port and normally open contact NO of the first power supply detection board FV1 close, the COM port and normally open contact NO of the second power supply detection board FV2 do not act (remain disconnected), the normally closed contact NC of the second contactor KM2 does not act (remain closed), the coil of the first contactor KM1 is energized and attracted, the main contacts of the first contactor KM1 act and conduct, and the power supply of circuit A is supplied;

[0046] When the power supply of circuit A is abnormal and the power supply of circuit B is normal, the COM port and normally open contact NO of the first power supply detection board FV1 do not act (remain disconnected), the COM port and normally open contact NO of the second power supply detection board FV2 close, the normally closed contact NC of the first contactor KM1 closes, the coil of the second contactor KM2 is energized and attracted, the main contacts of the second contactor KM2 act and conduct, and the power supply of circuit B is supplied; when the power supply of circuit A returns to normal, it will not automatically switch to the power supply of circuit A, and the power supply of circuit B will continue to be used.

[0047] When there is input from Power Supply A and Power Supply B, after being detected by the corresponding power supply detection board, the first power supply detection board FV1 and the second power supply detection board FV2 communicate via 485 and output the status signals of Power Supply A and Power Supply B being detected. Therefore, in this example, the power supply fault is output and fed back through the power supply detection status, and the power supply faults include over-voltage and under-voltage of the power supply, incorrect power supply phase sequence, and power supply phase loss.

[0048] When the input power supply voltage of Power Supply A and / or Power Supply B exceeds the set over-voltage range, the corresponding first power supply detection board FV1 and / or the second power supply detection board FV2 send out over-voltage fault status signals; the set over-voltage range is the pre-set over-voltage threshold value, which can be customized and adjusted according to actual needs;

[0049] When the input power supply voltage of Power Supply A and / or Power Supply B is lower than the set under-voltage range, the corresponding first power supply detection board FV1 and / or the second power supply detection board FV2 send out under-voltage fault status signals; the set under-voltage range is the pre-set under-voltage threshold value, which can be customized and adjusted according to actual needs;

[0050] When there is a phase loss in the input power supply of Power Supply A and / or Power Supply B, the corresponding first power supply detection board FV1 and / or the second power supply detection board FV2 send out phase-loss fault status signals;

[0051] When the phase sequence of the input power supply of Power Supply A and / or Power Supply B is reversed, the corresponding first power supply detection board FV1 and / or the second power supply detection board FV2 send out phase-sequence fault status signals.

[0052] This example also provides a control system for a dual-power supply switching circuit, which is characterized by including the above-mentioned dual-power supply switching circuit, and realizing the power supply switching control between Power Supply A and Power Supply B through the dual-power supply switching circuit.

[0053] To sum up, in this example, through the optimized design of the circuit structure and control method of the dual-power supply switching circuit, the function of switching the input power supply is realized, and the feedback signal and input working mode can be output through the corresponding power supply detection board; this example has low cost, small volume, and few components included, effectively reducing the cost and difficulty of later maintenance. On this basis, it can also effectively realize the power supply fault feedback, so that the control system of the dual-power supply switching circuit can feedback the power supply status without configuring a power supply monitor, and there is no need to set devices such as transfer switches or intermediate relays. While reducing the cost and volume, it can also effectively reduce the maintenance difficulty of the product and improve the stability performance of the product.

[0054] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention pertains, without departing from the concept of the present invention, several simple deductions or substitutions can still be made, and all should be regarded as falling within the protection scope of the present invention.

Claims

1. A dual - power switching circuit, characterized in that, it includes: a first contactor, a second contactor, a first power - supply detection board and a second power - supply detection board. The 485 communication function is integrated in the first power - supply detection board and the second power - supply detection board. The A - path power supply is electrically connected to the first contactor and the first power - supply detection board respectively, and the B - path power supply is electrically connected to the second contactor and the second power - supply detection board respectively; The A - path power supply and the B - path power supply are respectively connected to the COM ports of the first power - supply detection board and the second power - supply detection board. By outputting a power - supply detection status signal, the working mode of the dual - power switching circuit is set and controlled. The normally - open contact of the first power - supply detection board is electrically connected to the control coil of the first contactor through the normally - closed contact of the second contactor, and the normally - open contact of the second power - supply detection board is electrically connected to the control coil of the second contactor through the normally - closed contact of the first contactor; In a single - phase dual - power switching circuit, the L wire and N wire of the A - path power supply are respectively electrically connected to the first contactor and the first power - supply detection board, and the L wire and N wire of the B - path power supply are respectively electrically connected to the second contactor and the second power - supply detection board; In a DC dual - power switching circuit, the positive and negative poles of the A - path power supply are respectively electrically connected to the first contactor and the first power - supply detection board, and the positive and negative poles of the B - path power supply are respectively electrically connected to the second contactor and the second power - supply detection board; After the control coil of the first contactor is energized, the second contactor is locked through the electrically - connected normally - closed contact of the second contactor; After the control coil of the second contactor is energized, the first contactor is locked through the electrically - connected normally - closed contact of the first contactor, so as to realize the interlock between the first contactor and the second contactor.

2. The dual - power switching circuit according to claim 1, characterized in that, in the first power - supply detection board and the second power - supply detection board, the normally - open contact closes when the detected power supply is normal, and the normally - open contact disconnects when the detected power supply fails or loses power.

3. The dual - power switching circuit according to claim 1, characterized in that, the A - path power supply and the B - path power supply are two input power supplies A and B after passing through air switches.

4. A control method for a dual - power switching circuit, characterized in that, it is used to control the dual - power switching circuit according to any one of claims 1 to 3. The working mode of the dual - power switching circuit is controlled through the power - supply detection status. The working modes include the self - switching and self - restoring mode and the self - switching and non - self - restoring mode. In the self - switching and self - restoring mode, when the current power supply fails, it automatically switches to the standby power supply, and after the original power supply returns to normal, it automatically switches back to the original power supply again. In the self - switching and non - self - restoring mode, when the current power supply fails, it automatically switches to the standby power supply, and after the original power supply returns to normal, it does not automatically switch back to the original power supply.

5. The control method for a dual - power switching circuit according to claim 4, characterized in that, in the self - switching and self - restoring mode, the A - path power supply is set as the main power supply for power supply, and the power - supply control is realized according to the power - supply detection status of the A - path power supply: When the power supply of Circuit A is normal and the power supply of Circuit B is normal or abnormal, the COM port and / or normally open contact of the first power supply detection board is closed, the COM port and normally open contact of the second power supply detection board do not act and remain in the open state, the normally closed contact of the second contactor does not act and remains closed, the coil of the first contactor is energized and attracted, and the main contact of the first contactor acts to conduct, and the power supply of Circuit A supplies power; When the power supply of Circuit A is abnormal and the power supply of Circuit B is normal, the COM port and normally open contact of the first power supply detection board do not act and remain in the open state, the COM port and normally open contact of the second power supply detection board are closed, the normally closed contact of the first contactor is closed, the coil of the second contactor is energized and attracted, and the main contact of the second contactor acts to conduct, and the power supply of Circuit B supplies power; Until the power supply of Circuit A returns to normal, the COM port and normally open contact port of the second power supply detection board are disconnected to control the power supply of Circuit A.

6. The control method of the dual-power switching circuit according to claim 4, characterized in that, In the self-switching and self-restoring mode, the power supply of Circuit B is set as the main power supply to supply power, and the power supply control is realized according to the power supply detection state of the power supply of Circuit B: When the power supply of Circuit B is normal and the power supply of Circuit A is normal or abnormal, the COM port and normally open contact of the second power supply detection board are closed, the COM port and normally open contact of the first power supply detection board do not act and remain in the open state, the normally closed contact of the first contactor does not act and remains closed, the coil of the second contactor is energized and attracted, and the main contact of the second contactor acts to conduct, and the power supply of Circuit B supplies power; When the power supply of Circuit B is abnormal and the power supply of Circuit A is normal, the COM port and normally open contact of the second power supply detection board do not act and remain in the open state, the COM port and normally open contact of the first power supply detection board are closed, the normally closed contact of the second contactor is closed, the coil of the first contactor is energized and attracted, and the main contact of the first contactor acts to conduct, and the power supply of Circuit A supplies power; Until the power supply of Circuit B returns to normal, the COM port and normally open contact port of the first power supply detection board are disconnected to control the power supply of Circuit B.

7. The control method of the dual-power switching circuit according to claim 4, characterized in that, In the self-switching and non-self-restoring mode, the power supply control is realized according to the power supply detection state of the power supply of Circuit A: When the power supply of Circuit A is normal and the power supply of Circuit B is normal or abnormal, the COM port and normally open contact of the first power supply detection board are closed, the COM port and normally open contact of the second power supply detection board do not act and remain in the open state, the normally closed contact of the second contactor does not act and remains closed, the coil of the first contactor is energized and attracted, and the main contact of the first contactor acts to conduct, and the power supply of Circuit A supplies power; When the power supply of Circuit A is abnormal and the power supply of Circuit B is normal, the COM port and normally open contact of the first power supply detection board do not act and remain in the open state, the COM port and normally open contact of the second power supply detection board are closed, the normally closed contact of the first contactor is closed, the coil of the second contactor is energized and attracted, and the main contact of the second contactor acts to conduct, and the power supply of Circuit B supplies power; When the power supply of Circuit A resumes normal, continue to use the power supply of Circuit B.

8. The control method of the dual-power switching circuit according to claim 4, characterized in that the power supply failure is output and fed back through the power supply detection status: when the input power supply voltage of Circuit A and / or Circuit B exceeds the set overvoltage range, the corresponding first power supply detection board and / or second power supply detection board issue an overvoltage fault status signal; when the input power supply voltage of Circuit A and / or Circuit B is lower than the set undervoltage range, the corresponding first power supply detection board and / or second power supply detection board issue an undervoltage fault status signal; when the input power supply of Circuit A and / or Circuit B is out of phase, the corresponding first power supply detection board and / or second power supply detection board issue an out-of-phase fault status signal; when the input power supply phase sequence of Circuit A and / or Circuit B is reversed, the corresponding first power supply detection board and / or second power supply detection board issue a phase-sequence fault status signal.

9. A control system of a dual-power switching circuit, characterized in that it includes the dual-power switching circuit according to any one of claims 1 to 3, and realizes the power supply switching control between Circuit A and Circuit B through the dual-power switching circuit.

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