Multi-fan variable frequency control circuit with backup variable frequency converter

Abstract

This utility model relates to a multi-fan frequency converter control circuit with a backup frequency converter, comprising: a three-phase power supply, a fan circuit, a control circuit, and a switching power supply; wherein, the fan circuit includes a first frequency converter, a second frequency converter, a backup frequency converter, a first contactor, a second contactor, a third contactor, a fourth contactor, a first fan, and a second fan. The first and third contactors are interlocked, the second and fourth contactors are interlocked, and the backup frequency converter is used to start the first fan when the first frequency converter stops, and to start the second fan when the second frequency converter stops. The multi-fan frequency converter control circuit with a backup frequency converter described in this utility model can automatically and promptly start the backup frequency converter when any frequency converter fails, enabling maintenance and replacement of the faulty frequency converter without interrupting the main power supply and without affecting the operation of other normal fans.

Description

Technical Field

[0001] This utility model relates to the field of electrical control technology, and in particular to a multi-fan frequency conversion control circuit with a backup frequency converter. Background Technology

[0002] In fan control systems requiring speed regulation, asynchronous motors combined with frequency converters are commonly used to achieve speed control. Currently, independent multi-fan frequency converter speed control systems typically employ a one-to-one independent design, where one frequency converter drives one corresponding fan. This allows for speed regulation of each fan.

[0003] In the current control method, if the frequency converter of the corresponding fan fails, the corresponding equipment cannot start, affecting production. Adding a frequency converter to each fan to achieve a one-in-one-backup configuration would be too costly. Utility Model Content

[0004] Therefore, the technical problem to be solved by this utility model is to overcome the problem in the existing wind turbine control system that it is impossible to simultaneously address both the failure of a single frequency converter and the cost control of multiple frequency converters.

[0005] To solve the above technical problems, this utility model provides a multi-fan frequency conversion control circuit with a backup frequency converter, including: a three-phase power supply, a fan circuit, a control circuit, and a switching power supply. The three-phase power supply powers the fan circuit and the switching power supply, and the switching power supply powers the control circuit. The fan circuit includes a first frequency converter, a second frequency converter, a backup frequency converter, a first contactor, a second contactor, a third contactor, a fourth contactor, a first fan, and a second fan. The first frequency converter is connected to the first fan after being connected to the normally open contact of the first contactor. The second frequency converter is connected to the second fan via the normally open contact of the second contactor. The standby frequency converter is connected to the first fan via the normally open contact of the third contactor, and to the second fan via the normally open contact of the fourth contactor. The first and third contactors are interlocked, as are the second and fourth contactors. The standby frequency converter is used to start the first fan when the first frequency converter stops, and to start the second fan when the second frequency converter stops.

[0006] In one embodiment of this utility model, the switching power supply is a 24V switching power supply, the power input terminal of the switching power supply is connected to a three-phase power supply, and the power output terminal of the switching power supply outputs a 24V voltage.

[0007] In one embodiment of this utility model, the control circuit includes a PLC controller, a first relay, a second relay, a third relay, and a fourth relay. One end of the coils of the first relay, the second relay, the third relay, and the fourth relay are respectively connected to different output terminals of the PLC controller, and the other end of the coils of the first relay, the second relay, the third relay, and the fourth relay are connected to the 24-pin terminal of the switching power supply.

[0008] In one embodiment of this utility model, one end of the normally open contact of the first contactor, the normally open contact of the second contactor, the normally open contact of the third contactor, and the normally open contact of the fourth contactor are connected to the 24+ of the switching power supply, and the other end of the normally open contact of the first contactor, the normally open contact of the second contactor, the normally open contact of the third contactor, and the normally open contact of the fourth contactor are connected to different input terminals of the PLC controller.

[0009] In one embodiment of this utility model, the normally open contact of the first relay, the normally closed contact of the third contactor, and the two ends of the branch circuit connected in series with the coil of the first contactor are connected to the L line and N line of the three-phase power supply.

[0010] In one embodiment of this utility model, the normally open contact of the second relay, the normally closed contact of the fourth contactor, and the two ends of the branch circuit connected in series with the coil of the second contactor are connected to the L line and N line of the three-phase power supply.

[0011] In one embodiment of this utility model, the normally open contact of the third relay, the normally closed contact of the first contactor, the normally closed contact of the fourth contactor, and the two ends of the branch circuit connected in series with the coil of the third contactor are connected to the L line and N line of the three-phase power supply.

[0012] In one embodiment of this utility model, the two ends of the branch circuit formed by the normally open contact of the fourth relay, the normally closed contact of the second contactor, the normally closed contact of the third contactor, and the coil of the fourth contactor are connected in series to the L line and N line of a three-phase power supply.

[0013] In one embodiment of this utility model, the control circuit also includes four buttons, one end of which is connected to the 24+ of the switching power supply, and the other end of which is electrically connected to different input terminals of the PLC controller.

[0014] In one embodiment of this utility model, the multi-fan frequency converter control circuit further includes a first circuit breaker, a second circuit breaker, a third circuit breaker, a fourth circuit breaker, and a fuse. The three-phase power supply is a 380VAC three-phase power supply. The three-phase power supply is connected to the first circuit breaker. The first circuit breaker divides the 380VAC three-phase power supply into three circuits, which are respectively connected to the second circuit breaker, the third circuit breaker, and the fourth circuit breaker. The second circuit breaker is connected to the power supply circuit of the first frequency converter. The third circuit breaker is connected to the power supply circuit of the standby frequency converter. The fourth circuit breaker is connected to the power supply circuit of the second frequency converter. A live wire is connected to the L1 phase of the first circuit breaker to terminal one of the fuse, and terminal two of the fuse is connected to the L input terminal of the switching power supply. A neutral wire is connected to the N terminal of the switching power supply.

[0015] Compared with the prior art, the above-mentioned technical solution of this utility model has the following beneficial effects:

[0016] This utility model describes a multi-fan frequency converter control circuit with a backup frequency converter. In a frequency converter speed control cabinet with multiple fans of the same power, when any frequency converter fails, the backup frequency converter can be automatically and promptly activated to prevent equipment downtime. The main circuits of the frequency converters in this utility model are interlocked through software and hardware. Control is achieved via network cable communication, making wiring simple and reliable. It allows for the maintenance and replacement of faulty frequency converters without interrupting the main power supply or affecting the operation of other normal fans, without impacting on-site production. In practical applications, the probability of two or more frequency converters failing simultaneously is relatively low, so only one backup frequency converter is needed in the entire control cabinet. This utility model provides a control scheme for two fans, and can also be extended to control schemes for more than two fans. Attached Figure Description

[0017] To make the content of this utility model easier to understand, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein:

[0018] Figure 1 The preferred embodiment of this utility model is a multi-fan frequency converter control circuit with a backup frequency converter. Figure 1 ;

[0019] Figure 2 The preferred embodiment of this utility model is a multi-fan frequency converter control circuit with a backup frequency converter. Figure 2 ;

[0020] Figure 3 The preferred embodiment of this utility model is a multi-fan frequency converter control circuit with a backup frequency converter. Figure 3 .

[0021] Explanation of reference numerals in the accompanying drawings: Three-phase power supply 1, Switching power supply 2, First frequency converter 3, Second frequency converter 4, Standby frequency converter 5, First contactor 6, Second contactor 7, Third contactor 8, Fourth contactor 9, First fan 10, Second fan 11, PLC controller 12, First relay 13, Second relay 14, Third relay 15, Fourth relay 16, Button 17, First circuit breaker 18, Second circuit breaker 19, Third circuit breaker 20, Fourth circuit breaker 21, Fuse 22. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments are not intended to limit the present invention.

[0023] Reference Figure 1-3 As shown, the multi-fan frequency conversion control circuit with backup frequency converter of this utility model includes: a three-phase power supply 1, a fan circuit, a control circuit and a switching power supply 2. The three-phase power supply 1 is used to supply power to the fan circuit and the switching power supply 2, and the switching power supply 2 is used to supply power to the control circuit.

[0024] The fan circuit includes a first frequency converter 3, a second frequency converter 4, a standby frequency converter 5, a first contactor 6, a second contactor 7, a third contactor 8, a fourth contactor 9, a first fan 10, and a second fan 11. The first frequency converter 3 is connected to the first fan 10 via the normally open contact of the first contactor 6. The second frequency converter 4 is connected to the second fan 11 via the normally open contact of the second contactor 7. The standby frequency converter 5 is connected to the first fan 10 via the normally open contact of the third contactor 8 and to the second fan 11 via the normally open contact of the fourth contactor 9. The first contactor 6 and the third contactor 8 are interlocked, as are the second contactor 7 and the fourth contactor 9. The standby frequency converter 5 is used to start the first fan 10 when the first frequency converter 3 is stopped, and it is used to start the second fan 11 when the second frequency converter 4 is stopped. The first frequency converter 3, the second frequency converter 4, the standby frequency converter 5, the first contactor 6, the second contactor 7, the third contactor 8, and the fourth contactor 9 are all powered by a three-phase power supply 1.

[0025] In the circuit described above, under normal conditions, the first frequency converter 3 and the second frequency converter 4 control the starting of their respective fans. When the first fan 10 is started, the first contactor 6 engages, then the first frequency converter 3 starts, and the first fan 10 runs. When the second fan 11 is started, the second contactor 7 engages, then the second frequency converter 4 starts, and the second fan 11 runs. If the first frequency converter 3 fails during normal operation, it stops, the first contactor 6 disconnects, then the third contactor 8 engages, and finally the standby frequency converter 5 starts, allowing the first fan 10 to resume operation. Similarly, if the second frequency converter 4 fails during normal operation, it stops, the second contactor 7 disconnects, then the fourth contactor 9 engages, and finally the standby frequency converter 5 starts, allowing the second fan 11 to resume operation.

[0026] During system operation, the first contactor 6 and the third contactor 8 are interlocked by hardware and software, preventing them from engaging simultaneously; the second contactor 7 and the fourth contactor 9 are also interlocked by hardware and software, preventing them from engaging simultaneously; similarly, the third contactor 8 and the fourth contactor 9 are interlocked by hardware and software, preventing them from engaging simultaneously. Specifically, the interlocking circuit formed by the first contactor 6, the second contactor 7, the third contactor 8, and the fourth contactor 9 is as follows: the two ends of the branch formed by the normally open contact of the first relay 13, the normally closed contact of the third contactor 8, and the coil of the first contactor 6 connected in series are connected to the L and N lines of the three-phase power supply 1. The two ends of the branch formed by the normally open contact of the second relay 14, the normally closed contact of the fourth contactor 9, and the coil of the second contactor 7 connected in series are also connected to the L and N lines of the three-phase power supply 1. The two ends of the branch formed by the normally open contact of the third relay 15, the normally closed contact of the first contactor 6, the normally closed contact of the fourth contactor 9, and the coil of the third contactor 8 connected in series are also connected to the L and N lines of the three-phase power supply 1. The two ends of the branch circuit formed by the normally open contact of the fourth relay 16, the normally closed contact of the second contactor 7, the normally closed contact of the third contactor 8, and the coil of the fourth contactor 9 connected in series are connected to the L line and N line of the three-phase power supply 1.

[0027] In the above circuit, the switching power supply 2 is a 24V switching power supply. The power input terminal of the switching power supply 2 is connected to the three-phase power supply 1, and the power output terminal of the switching power supply 2 outputs a 24V voltage.

[0028] In the above circuit, the control loop includes a PLC controller 12, a first relay 13, a second relay 14, a third relay 15, and a fourth relay 16. One end of the coils of the first relay 13, the second relay 14, the third relay 15, and the fourth relay 16 are respectively connected to different output terminals of the PLC controller 12, and the other end of the coils of the first relay 13, the second relay 14, the third relay 15, and the fourth relay 16 are connected to terminal 24 of the switching power supply 2. Specifically, the PLC controller 12 is an S7-200SMART.

[0029] In the circuit described above, one end of the normally open contact of the first contactor 6, the normally open contact of the second contactor 7, the normally open contact of the third contactor 8, and the normally open contact of the fourth contactor 9 are connected to the 24+ of the switching power supply 2, and the other end of the normally open contact of the first contactor 6, the normally open contact of the second contactor 7, the normally open contact of the third contactor 8, and the normally open contact of the fourth contactor 9 are connected to different input terminals of the PLC controller 12.

[0030] In the circuit described above, the control loop also includes four buttons 17 for controlling the switches of the two fans: a first fan start button, a first fan stop button, a second fan start button, and a second fan stop button. One end of each of the four buttons 17 is connected to the 24+ terminal of the switching power supply 2, and the other end of each button is electrically connected to different input terminals of the PLC controller 12.

[0031] In the above circuit, the multi-fan frequency converter control circuit also includes a first circuit breaker 18, a second circuit breaker 19, a third circuit breaker 20, a fourth circuit breaker 21, and a fuse 22. The three-phase power supply 1 is a 380VAC three-phase power supply. The three-phase power supply 1 is connected to the first circuit breaker 18. The first circuit breaker 18 divides the 380VAC three-phase power supply into three circuits, which are respectively connected to the second circuit breaker 19, the third circuit breaker 20, and the fourth circuit breaker 21. The second circuit breaker 19 is connected to the power supply circuit of the first frequency converter 3. The third circuit breaker 20 is connected to the power supply circuit of the standby frequency converter 5. The fourth circuit breaker 21 is connected to the power supply circuit of the second frequency converter 4. A live wire is connected from the L1 phase of the first circuit breaker 18 to terminal one of the fuse 22, and terminal two of the fuse 22 is connected to the L input terminal of the switching power supply 2. A neutral wire is connected from the three-phase power supply 1 to the N terminal of the switching power supply 2.

[0032] First, an external three-phase power supply 1 is connected to the first circuit breaker 18 of the control cabinet. Then, three 380VAC three-phase power supplies are split from the first circuit breaker 18 to power the second circuit breaker 19, the third circuit breaker 20, and the fourth circuit breaker 21. The second circuit breaker 19 is the power supply circuit for the first fan 10, the third circuit breaker 20 is the power supply circuit for the standby frequency converter, and the fourth circuit breaker 21 is the power supply circuit for the second fan 11. A live wire is connected from the L1 phase of the first circuit breaker 18 to terminal one of the fuse 22. Terminal two of the fuse 22 is connected to the L input terminal of the switching power supply 2. A neutral wire is connected from the neutral terminal to the N terminal of the switching power supply.

[0033] The second circuit breaker 19 is connected to the main input terminal of the first frequency converter 3, and then connected from the main output terminal of the first frequency converter 3 to the main input terminal of the first contactor 6. Finally, the main output terminal of the first contactor 6 is connected to the first fan 10.

[0034] The outgoing line of the fourth circuit breaker 21 is connected to the main incoming line of the second frequency converter 4. The main outgoing line of the second frequency converter 4 is then connected to the main incoming line of the second contactor 7. Finally, the main outgoing line of the second contactor 7 is connected to the second fan 11.

[0035] The outgoing line of the third circuit breaker 20 is connected to the main incoming line of the standby frequency converter 5. The main outgoing line of the standby frequency converter is then connected to the main incoming line of the third contactor 8 and the fourth contactor 9 respectively. The main outgoing line of the third contactor 8 is then connected to the first fan 10; and the main outgoing line of the fourth contactor 9 is connected to the second fan 11.

[0036] The specific connection of the multi-fan frequency converter control circuit with backup frequency converter of this utility model is as follows:

[0037] Connect a wire from the output terminal of fuse 22 to the input terminal of the first pair of normally open contacts of the first relay 13. Connect a wire from the output terminal of the first pair of normally open contacts of the first relay 13 to the input terminal of the first pair of normally closed auxiliary contacts of the third contactor 8. Connect a wire from the output terminal of the first pair of normally closed auxiliary contacts of the third contactor 8 to one end of the coil of the first contactor 6. Connect a wire from the other end of the coil of the first contactor 6 to the neutral terminal of the three-phase power supply 1.

[0038] Connect a wire from the output terminal of fuse 22 to the input terminal of the first pair of normally open contacts of the second relay 14. Connect a wire from the output terminal of the first pair of normally open contacts of the second relay 14 to the input terminal of the first pair of normally closed auxiliary contacts of the fourth contactor 9. Connect a wire from the output terminal of the first pair of normally closed auxiliary contacts of the fourth contactor 9 to one end of the coil of the second contactor 7. Connect a wire from the other end of the coil of the second contactor 7 to the neutral terminal of the three-phase power supply 1.

[0039] Connect a wire from the output terminal of fuse 22 to the input terminal of the first pair of normally open contacts of the third relay 15. Connect a wire from the output terminal of the first pair of normally open contacts of the second relay 14 to the input terminal of the first pair of normally closed auxiliary contacts of the first contactor 6. Connect a wire from the output terminal of the first pair of normally closed auxiliary contacts of the first contactor 6 to the input terminal of the second pair of normally closed auxiliary contacts of the fourth contactor 9. Connect a wire from the output terminal of the second pair of normally closed auxiliary contacts of the fourth contactor 9 to one end of the coil of the third contactor 8. Connect a wire from the other end of the coil of the third contactor 8 to the neutral terminal of the three-phase power supply 1.

[0040] Connect a wire from the output terminal of fuse 22 to the input terminal of the first pair of normally open contacts of the fourth relay 16. Connect the wire from the output terminal of the first pair of normally open contacts of the fourth relay 16 to the input terminal of the first pair of normally closed auxiliary contacts of the second contactor 7. Connect the wire from the output terminal of the first pair of normally closed auxiliary contacts of the second contactor 7 to the input terminal of the second pair of normally closed auxiliary contacts of the third contactor 8. Connect the wire from the output terminal of the second pair of normally closed auxiliary contacts of the third contactor 8 to one end of the coil of the fourth contactor 9. Connect the wire from the other end of the coil of the fourth contactor 9 to the neutral terminal of the three-phase power supply 1.

[0041] When both the first frequency converter 3 and the second frequency converter 4 are functioning correctly, the control flow is as follows:

[0042] Pressing the start button for the first fan 10 activates the first relay 13 via the PLC controller 12, which in turn activates the first contactor 6. When the PLC controller 12 receives the signal that the first contactor 6 is activated, it starts the first frequency converter 3, and the first fan 10 runs. Pressing the stop button for the first fan 10 first stops the first frequency converter 3, and then disconnects the first relay 13, thereby disconnecting the first contactor 6 and stopping the first fan 10.

[0043] Pressing the start button for the second fan 11 activates the second relay 14 via the PLC controller 12, which in turn activates the second contactor 7. When the PLC controller 12 receives the signal that the second contactor 7 is activated, it starts the second frequency converter 4, and the second fan 11 begins operation. Pressing the stop button for the second fan 11 first stops the second frequency converter 4, and then disconnects the second relay 14, thereby disconnecting the second contactor 7 and stopping the second fan 11.

[0044] When the first frequency converter 3 malfunctions, the control flow is as follows:

[0045] When the first fan 10 starts or the first frequency converter 3 malfunctions during operation, the PLC controller 12 first controls the first frequency converter 3 to stop working, and then controls the first relay 13 to open, thereby disconnecting the first contactor 6. After receiving the signal that the first contactor 6 has been disconnected, the PLC controller 12 controls the third relay 15 to close, thereby controlling the third contactor 8 to close. After receiving the signal that the third contactor 8 has been closed, the PLC controller 12 controls the backup frequency converter to start, thereby restoring the operation of the first fan 10.

[0046] When the second frequency converter 4 malfunctions, the control flow is as follows:

[0047] When the second fan 11 starts or the second frequency converter 4 malfunctions during operation, the PLC controller 12 first controls the second frequency converter 4 to stop working, then controls the second relay 141 to open, thereby disconnecting the second contactor 7. After receiving the signal that the second contactor 7 has opened, the PLC controller 12 controls the fourth relay 16 to close, thereby controlling the fourth contactor 9 to close. After receiving the signal that the fourth contactor 9 has closed, the PLC controller 12 controls the standby frequency converter to start, thereby restoring the operation of the second fan 11.

[0048] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the protection scope of this invention.

Claims

1. A multi-fan frequency converter control circuit with a backup frequency converter, characterized in that, include: The system includes a three-phase power supply, a fan circuit, a control circuit, and a switching power supply. The three-phase power supply is used to power the fan circuit and the switching power supply, and the switching power supply is used to power the control circuit. The fan circuit includes a first frequency converter, a second frequency converter, a standby frequency converter, a first contactor, a second contactor, a third contactor, a fourth contactor, a first fan, and a second fan. The first frequency converter is connected to the first fan via the normally open contact of the first contactor. The second frequency converter is connected to the second fan via the normally open contact of the second contactor. The standby frequency converter is connected to the first fan via the normally open contact of the third contactor and to the second fan via the normally open contact of the fourth contactor. The first and third contactors are interlocked, as are the second and fourth contactors. The standby frequency converter is used to start the first fan when the first frequency converter stops, and it is also used to start the second fan when the second frequency converter stops.

2. The multi-fan frequency converter control circuit with a backup frequency converter according to claim 1, characterized in that: The switching power supply is a 24V switching power supply. The power input terminal of the switching power supply is connected to a three-phase power supply, and the power output terminal of the switching power supply outputs a 24V voltage.

3. The multi-fan frequency converter control circuit with a backup frequency converter according to claim 2, characterized in that: The control circuit includes a PLC controller, a first relay, a second relay, a third relay, and a fourth relay. One end of the coils of the first relay, the second relay, the third relay, and the fourth relay are respectively connected to different output terminals of the PLC controller, and the other end of the coils of the first relay, the second relay, the third relay, and the fourth relay are connected to the 24-pin switch power supply.

4. The multi-fan frequency converter control circuit with a backup frequency converter according to claim 3, characterized in that: One end of the normally open contact of the first contactor, the normally open contact of the second contactor, the normally open contact of the third contactor, and the normally open contact of the fourth contactor are connected to the 24+ of the switching power supply, and the other end of the normally open contact of the first contactor, the normally open contact of the second contactor, the normally open contact of the third contactor, and the normally open contact of the fourth contactor are connected to different input terminals of the PLC controller.

5. The multi-fan frequency converter control circuit with a backup frequency converter according to claim 3, characterized in that: The normally open contact of the first relay, the normally closed contact of the third contactor, and the two ends of the branch circuit connected in series with the coil of the first contactor are connected to the L and N lines of the three-phase power supply.

6. The multi-fan frequency converter control circuit with a backup frequency converter according to claim 5, characterized in that: The normally open contact of the second relay, the normally closed contact of the fourth contactor, and the two ends of the branch circuit connected in series with the coil of the second contactor are connected to the L and N lines of the three-phase power supply.

7. The multi-fan frequency converter control circuit with a backup frequency converter according to claim 6, characterized in that: The normally open contact of the third relay, the normally closed contact of the first contactor, the normally closed contact of the fourth contactor, and the two ends of the branch circuit connected in series with the coil of the third contactor are connected to the L line and N line of the three-phase power supply.

8. The multi-fan frequency converter control circuit with a backup frequency converter according to claim 7, characterized in that: The normally open contact of the fourth relay, the normally closed contact of the second contactor, the normally closed contact of the third contactor, and the coil of the fourth contactor are connected in series at both ends of the branch to the L and N lines of the three-phase power supply.

9. The multi-fan frequency converter control circuit with a backup frequency converter according to claim 3, characterized in that: The control circuit also has four buttons, one end of which is connected to the 24+ of the switching power supply, and the other end of which is electrically connected to different input terminals of the PLC controller.

10. The multi-fan frequency converter control circuit with a backup frequency converter according to claim 1, characterized in that: The multi-fan frequency converter control circuit also includes a first circuit breaker, a second circuit breaker, a third circuit breaker, a fourth circuit breaker, and a fuse. The three-phase power supply is a 380VAC three-phase power supply. The three-phase power supply is connected to the first circuit breaker. The first circuit breaker divides the 380VAC three-phase power supply into three circuits, which are respectively connected to the second circuit breaker, the third circuit breaker, and the fourth circuit breaker. The second circuit breaker is connected to the power supply circuit of the first frequency converter. The third circuit breaker is connected to the power supply circuit of the standby frequency converter. The fourth circuit breaker is connected to the power supply circuit of the second frequency converter. A live wire from the L1 phase of the first circuit breaker is connected to terminal one of the fuse, and terminal two of the fuse is connected to the L input terminal of the switching power supply. A neutral wire from the three-phase power supply is connected to the N terminal of the switching power supply.

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