Switching circuits for frequency converters, frequency converter equipment, and cranes

Abstract

Embodiments of the present invention provide a switching circuit for a frequency converter, frequency conversion equipment, and a crane. The switching circuit includes: a switch comprising a movable terminal, a first static contact, and a second static contact, the movable terminal being connected to a first power source; a first contactor comprising a first coil and a first normally closed auxiliary contact; and a second contactor comprising a second coil and a second normally closed auxiliary contact; the first end of the second normally closed auxiliary contact being electrically connected to the first static contact, the second end of the second normally closed auxiliary contact being electrically connected to the first end of the first coil, and the second end of the first coil being electrically connected to a first common reference potential terminal; the first end of the first normally closed auxiliary contact being electrically connected to the second static contact, the second end of the first normally closed auxiliary contact being electrically connected to the first end of the second coil, and the second end of the second coil being electrically connected to the first common reference potential terminal. Embodiments of the present invention can improve the reliability, intelligence, and operational safety of an electronic control system.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical control, and in particular to a switching circuit for a frequency converter, a frequency conversion device and a crane. Background Art

[0002] Currently, tower crane motors are all driven by corresponding inverters. For example, the hoisting motor, slewing motor, and luffing motor are controlled by a hoisting inverter, a slewing inverter, and a luffing inverter, respectively. Under normal operating conditions, each motor type can be controlled by a corresponding inverter. If a major inverter failure occurs, it can simply be replaced. However, inverter replacement is subject to uncertainties such as supply availability and lead times. For critical and urgent engineering projects, replacing components inevitably impacts their progress. Therefore, a technical solution is urgently needed to improve the reliability, intelligence, and operational safety of the electronic control system to address these technical issues in the existing technology. Summary of the Invention

[0003] The purpose of the embodiments of the present invention is to provide a switching circuit for a frequency converter, a frequency conversion device, and a crane, so as to improve the reliability, intelligence, and operational safety of an electric control system.

[0004] In order to achieve the above-mentioned objectives, the first aspect of the present invention provides a switching circuit for a frequency converter, comprising: a switching switch, comprising a moving end, a first static contact and a second static contact, the moving end being used to connect to a first power supply, and when the switching switch is in a first switching state, the moving end is connected to the first static contact, and when the switching switch is in a second switching state, the moving end is connected to the second static contact; a first contactor, comprising a first coil and a first normally closed auxiliary contact, and when the first coil is energized, the first normally closed auxiliary contact is disconnected; and a second contactor, comprising a second coil and a second normally closed auxiliary contact, and when the second coil is energized, the second normally closed auxiliary contact is disconnected; wherein, the first end of the second normally closed auxiliary contact is electrically connected to the first static contact, the second end of the second normally closed auxiliary contact is electrically connected to the first end of the first coil, and the second end of the first coil is electrically connected to the first common reference potential terminal; the first end of the first normally closed auxiliary contact is electrically connected to the second static contact, the second end of the first normally closed auxiliary contact is electrically connected to the first end of the second coil, and the second end of the second coil is electrically connected to the first common reference potential terminal.

[0005] In an embodiment of the present invention, the switching circuit for the frequency converter also includes: a third contactor, including a third coil, a third normally open auxiliary contact and a third normally closed auxiliary contact, when the third coil is energized, the third normally open auxiliary contact is closed and the third normally closed auxiliary contact is opened; wherein, the first contactor also includes a first normally open auxiliary contact, when the first coil is energized, the first normally open auxiliary contact is closed; the first end of the first normally open auxiliary contact is electrically connected to the first end of the second normally closed auxiliary contact, the second end of the first normally open auxiliary contact is electrically connected to the first end of the third coil, and the second end of the third coil is electrically connected to the first common reference potential end; the first end of the third normally open auxiliary contact is electrically connected to the moving end, and the second end of the third normally open auxiliary contact is electrically connected to the first static contact; the third normally closed auxiliary contact is connected in series between the second static contact and the first end of the first normally closed auxiliary contact.

[0006] In an embodiment of the present invention, the switching circuit for the frequency converter also includes: a fourth contactor, including a fourth coil, a fourth normally open auxiliary contact and a fourth normally closed auxiliary contact, when the fourth coil is energized, the fourth normally open auxiliary contact is closed and the fourth normally closed auxiliary contact is opened; wherein, the second contactor also includes a second normally open auxiliary contact, when the second coil is energized, the second normally open auxiliary contact is closed; the first end of the second normally open auxiliary contact is electrically connected to the first end of the first normally closed auxiliary contact, the second end of the second normally open auxiliary contact is electrically connected to the first end of the fourth coil, and the second end of the fourth coil is electrically connected to the first common reference potential end; the first end of the fourth normally open auxiliary contact is electrically connected to the moving end, and the second end of the fourth normally open auxiliary contact is electrically connected to the second static contact; the fourth normally closed auxiliary contact is connected in series between the first static contact and the first end of the second normally closed auxiliary contact.

[0007] In an embodiment of the present invention, the switch circuit for the frequency converter further includes: an emergency stop switch connected in series between the driving end and the first power supply.

[0008] In an embodiment of the present invention, the switching circuit for the frequency converter further includes: a first relay, including a first relay coil; a second relay, including a second relay coil; wherein the third contactor further includes a fifth normally open auxiliary contact, and when the third coil is energized, the fifth normally open auxiliary contact is closed; the fourth contactor further includes a sixth normally open auxiliary contact, and when the fourth coil is energized, the sixth normally open auxiliary contact is closed; the first end of the fifth normally open auxiliary contact is used to access the second power supply, the second end of the fifth normally open auxiliary contact is electrically connected to the first end of the first relay coil, and the second end of the first relay coil is electrically connected to the second common reference potential terminal; the first end of the sixth normally open auxiliary contact is used to access the second power supply, the second end of the sixth normally open auxiliary contact is connected to the first end of the second relay coil, and the second end of the second relay coil is electrically connected to the second common reference potential terminal.

[0009] In an embodiment of the present invention, the first relay includes a plurality of first relays, and the second relay includes a plurality of second relays.

[0010] A second aspect of the present invention provides a frequency conversion device, comprising: a first frequency converter, comprising a first power input terminal and a first power output terminal; a second frequency converter, comprising a second power input terminal and a second power output terminal; and the switching circuit for the frequency converter of the aforementioned embodiment; wherein, the first contactor also comprises a first normally open main contact group, and when the first coil is energized, the first normally open main contact group is closed; the second contactor also comprises a second normally open main contact group, and when the second coil is energized, the second normally open main contact group is closed; the first normally open main contact group is electrically connected to the first power output terminal or the first power output terminal; the second normally open main contact group is electrically connected to the second power output terminal or the first power output terminal.

[0011] In an embodiment of the present invention, the third contactor of the switching circuit also includes a third normally open main contact group, and when the third coil is energized, the third normally open main contact group is closed; the fourth contactor of the switching circuit also includes a fourth normally open main contact group, and when the fourth coil is energized, the fourth normally open main contact group is closed; wherein, the first normally open main contact group is electrically connected to the first power output terminal; the second normally open main contact group is electrically connected to the second power output terminal; the third normally open main contact group is connected to the first power input terminal; and the fourth normally open main contact group is electrically connected to the second power input terminal.

[0012] In an embodiment of the present invention, the first frequency converter further includes a first external control connection terminal; the second frequency converter further includes a second external control connection terminal; wherein, the first relay further includes a first relay normally open auxiliary contact, and when the first relay coil is energized, the first relay normally open auxiliary contact is closed; the second relay further includes a second relay normally open auxiliary contact, and when the second relay coil is energized, the second relay normally open auxiliary contact is closed; the first relay normally open auxiliary contact is connected to the first external control connection terminal; the second relay normally open auxiliary contact is connected to the second external control connection terminal.

[0013] A third aspect of the present invention provides a crane, comprising: a motor; and the frequency conversion device of the aforementioned embodiment.

[0014] The aforementioned embodiments of the present invention can achieve safe, reliable and convenient switching to the second inverter through their technical solutions when the first inverter fails, thereby improving the reliability, intelligence and operational safety of the electric control system.

[0015] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following detailed description, they are used to explain the embodiments of the present invention, but do not constitute a limitation of the embodiments of the present invention. In the accompanying drawings:

[0017] Figures 1A to 1F FIG. 1 is a schematic diagram of a partial circuit structure of a switching circuit for a frequency converter according to an embodiment of the present invention; and

[0018] Figure 2 It is a schematic diagram of a partial circuit structure of a frequency conversion device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0019] The following describes the specific implementation of the embodiment of the present invention in detail with reference to the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the embodiment of the present invention and is not used to limit the embodiment of the present invention.

[0020] It should be noted that if the implementation methods of this application involve directional indications (such as up, down, left, right, front, back, etc.), such directional indications are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0021] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of this application, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features specified as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0022] The following combination Figures 1A to 1F and Figure 2 The circuit structure example shown is used to illustrate the technical solution of the embodiment of the present invention, but the embodiment of the present invention is not limited to the circuit structure in this example. Figures 1A to 1F and Figure 2 The circuit structure shown is only a partial example of the technical solution of the embodiment of the present invention, and is only used to illustrate the technical solution of the embodiment of the present invention.

[0023] like Figure 1A As shown, in an embodiment of the present invention, a switching circuit for a frequency converter is provided. The switching circuit for the frequency converter includes: a switch, a first contactor KMM1 and a second contactor KMM2.

[0024] Specifically, the switching switch includes, for example, a moving end, a first static contact KH:1 and a second static contact KH:2. The moving end is used to connect to a first power supply (not shown in the figure). When the switching switch is in the first switching state, the moving end is connected to the first static contact KH:1, and when the switching switch is in the second switching state, the moving end is connected to the second static contact KH:2. The switching switch can be implemented by, for example, a rotary switch or a key switch with two or more positions, that is, it must include at least two effective static contacts, and can only be in one switching state at the same time, that is, the moving end can only be connected to one of the effective static contacts at the same time. The first power supply is, for example, a +220V AC power supply, which can be obtained from an external power grid through a transformer for step-down. Of course, the embodiments of the present invention are not limited to this, and the first power supply can also be other suitable power supplies.

[0025] The first contactor KMM1 includes, for example, a first coil and a first normally closed auxiliary contact. When the first coil is energized, the first normally closed auxiliary contact is opened.

[0026] The second contactor KMM2 includes, for example, a second coil and a second normally closed auxiliary contact. When the second coil is energized, the second normally closed auxiliary contact is opened.

[0027] The first end of the second normally closed auxiliary contact is, for example, electrically connected to the first static contact KH:1, the second end of the second normally closed auxiliary contact is, for example, electrically connected to the first end of the first coil, and the second end of the first coil is, for example, electrically connected to a first common reference potential terminal (not shown). The voltage of the first common reference potential terminal is, for example, -220V, although embodiments of the present invention are not limited thereto and may alternatively be other suitable voltages.

[0028] The first end of the first normally closed auxiliary contact is electrically connected to the second static contact KH:2, for example, the second end of the first normally closed auxiliary contact is electrically connected to the first end of the second coil, for example, the second end of the second coil is electrically connected to the first common reference potential end.

[0029] In this way, the above-mentioned technical solution can realize the switching of two control circuits by switching the switch. When the control object of one control circuit fails, it can be switched to the other control circuit by switching the switch, and then the control object of the other control circuit is started to replace the failed control object, thereby ensuring the reliable operation of the entire electric control system. By connecting the second normally closed auxiliary contact and the first coil in series in the first control circuit controlled by the first static contact, and the first normally closed auxiliary contact and the second coil in series in the second control circuit controlled by the second static contact, the electrical interlocking of the first contactor and the second contactor can be realized, and the interlocking of the two control circuits can be further realized, that is, when one control circuit is working, the other control circuit is guaranteed not to work. Further, the switching and interlocking control of their control objects can be realized by other contacts associated with the first coil of the first contactor KMM1 and other contacts associated with the second coil of the second contactor KMM2.

[0030] Further, if Figure 1B As shown, based on the above technical solution, the switch circuit for the frequency converter may further include: a third contactor KM1.

[0031] Specifically, the third contactor KM1 includes, for example, a third coil, a third normally open auxiliary contact, and a third normally closed auxiliary contact. When the third coil is energized, the third normally open auxiliary contact is closed, and the third normally closed auxiliary contact is opened.

[0032] Correspondingly, the first contactor KMM1 may further include, for example, a first normally open auxiliary contact. When the first coil is energized, the first normally open auxiliary contact is closed.

[0033] Specifically, the first end of the first normally open auxiliary contact is electrically connected to the first end of the second normally closed auxiliary contact, the second end of the first normally open auxiliary contact is electrically connected to the first end of the third coil, and the second end of the third coil is electrically connected to the first common reference potential end.

[0034] The first end of the third normally open auxiliary contact is, for example, electrically connected to the moving end, and the second end of the third normally open auxiliary contact is, for example, electrically connected to the first static contact KH:1.

[0035] The third normally closed auxiliary contact is, for example, connected in series between the second stationary contact KH:2 and the first end of the first normally closed auxiliary contact.

[0036] In this way, the self-locking function of the first static contact KH:1 of the transfer switch can be further realized. That is, when the transfer switch is in the first switching state, after the moving end and the first static contact KH:1 are connected, the third coil will also be energized after a series of electrical actions of other components in the first control circuit, and then the third normally open auxiliary contact connected in parallel with the first static contact KH:1 will be closed, thereby realizing the self-locking function of the first static contact KH:1 after the moving end is connected, preventing accidental contact and further improving the reliability of the electronic control system. The mechanical interlocking function of the third normally closed auxiliary contact and the third normally open auxiliary contact can also further enhance the interlocking function between the first control circuit controlled by the first static contact KH:1 and the second control circuit controlled by the second static contact KH:2, thereby further improving the reliability of the electronic control system.

[0037] Further, if Figure 1C As shown, based on the above technical solution, the switch circuit for the frequency converter may further include: a fourth contactor KM2.

[0038] Specifically, the fourth contactor KM2 includes, for example, a fourth coil, a fourth normally open auxiliary contact, and a fourth normally closed auxiliary contact. When the fourth coil is energized, the fourth normally open auxiliary contact is closed, and the fourth normally closed auxiliary contact is opened.

[0039] Correspondingly, the second contactor KMM2 may further include, for example, a second normally open auxiliary contact. When the second coil is energized, the second normally open auxiliary contact is closed.

[0040] Specifically, the first end of the second normally open auxiliary contact is electrically connected to the first end of the first normally closed auxiliary contact, the second end of the second normally open auxiliary contact is electrically connected to the first end of the fourth coil, and the second end of the fourth coil is electrically connected to the first common reference potential end.

[0041] The first end of the fourth normally open auxiliary contact is, for example, electrically connected to the moving end, and the second end of the fourth normally open auxiliary contact is, for example, electrically connected to the second static contact KH:2.

[0042] The fourth normally closed auxiliary contact is, for example, connected in series between the first stationary contact KH:1 and the first end of the second normally closed auxiliary contact.

[0043] In this way, the self-locking function of the second static contact KH:2 of the switching switch can be further realized. That is, when the switching switch is in the second switching state, after the moving end is connected to the second static contact KH:2, the fourth coil will also be energized after a series of electrical actions of other components in the second control circuit, and then the fourth normally open auxiliary contact connected in parallel with the second static contact KH:2 will be closed, thereby realizing the self-locking function of the second static contact KH:2 after being connected to the moving end, preventing accidental touch and further improving the reliability of the electronic control system. The mechanical interlocking function of the fourth normally closed auxiliary contact and the fourth normally open auxiliary contact can also be further enhanced. The interlocking function of the first control circuit controlled by the first static contact KH:1 and the second control circuit controlled by the second static contact KH:2 can also be further enhanced, thereby further improving the reliability of the electronic control system. The switching circuit of the aforementioned technical solution can also realize the electrical interlocking of the third contactor KM1 and the fourth contactor KM2, further realizing the interlocking of the two control circuits. That is, when one control circuit is working, the other control circuit is guaranteed to be inoperative.

[0044] Further, if Figure 1D As shown, based on the above technical solution, the switch circuit for the frequency converter may further include, for example: an emergency stop switch K1.

[0045] Specifically, the emergency stop switch K1 is, for example, connected in series between the dynamic end and the first power supply.

[0046] In this way, before switching the two control circuits, there is no need to turn off the power supply to stop the control objects of the two control circuits. Therefore, the two control circuits can be switched while ensuring that the control objects are not working, which can further improve the operational safety of the electronic control system.

[0047] It is also worth mentioning that the switching circuit for the frequency converter in the embodiment of the present invention can further add corresponding delay devices such as delay relays on the basis of the aforementioned technical solution to delay the conduction between the moving end of the switching switch and the two static contacts, thereby further ensuring that the two control circuits are switched when the controlled object is not working, thereby further improving the operational safety of the electronic control system.

[0048] Further, if Figure 1E and Figure 1F As shown, based on the above technical solution, the switching circuit for the frequency converter may further include: a first relay and a second relay.

[0049] Specifically, the first relay includes, for example, a first relay coil.

[0050] The second relay includes, for example, a second relay coil.

[0051] Correspondingly, the third contactor KM1 may further include, for example, a fifth normally open auxiliary contact. When the third coil is energized, the fifth normally open auxiliary contact is closed.

[0052] The fourth contactor KM2 may further include, for example, a sixth normally-open auxiliary contact. When the fourth coil is energized, the sixth normally-open auxiliary contact is closed.

[0053] Specifically, the first end of the fifth normally open auxiliary contact is, for example, configured to connect to a second power source (not shown in the figure), the second end of the fifth normally open auxiliary contact is, for example, electrically connected to the first end of the first relay coil, and the second end of the first relay coil is, for example, electrically connected to a second common reference potential terminal (not shown in the figure). The second power source is, for example, a +24V DC power source, which may be derived from an external power grid via a transformer, a switching power supply, or other suitable power source. The embodiments of the present invention are not limited to this, and the second power source may alternatively be other suitable power sources. The voltage at the second common reference potential terminal is, for example, -24V, but the embodiments of the present invention are not limited to this, and may alternatively be other suitable voltages.

[0054] The first end of the sixth normally open auxiliary contact is for example used to access the second power supply, the second end of the sixth normally open auxiliary contact is for example connected to the first end of the second relay coil, and the second end of the second relay coil is for example electrically connected to the second common reference potential end.

[0055] More specifically, the first relay may include, for example, a plurality of first relays, such as Figure 1E KAA-1, KAB-1, ..., KAF-1, but the embodiment of the present invention is not limited thereto. Figure 1E The number of relays shown in is only an example. The second relay may include, for example, a plurality of second relays, such as Figure 1F KAA-2, KAB-2, ..., KAF-2, but the embodiment of the present invention is not limited thereto. Figure 1FThe number of relays shown is for illustrative purposes only. Furthermore, the plurality of first relays is not limited to being a plurality of identical relays, and the term "first" here merely distinguishes the relays in the first path. Similarly, the plurality of second relays is not limited to being a plurality of identical relays, and the term "first" here merely distinguishes the relays in the second path. The same applies to the first and second contacts of other contacts associated with the first and second relays mentioned later. In this case, those skilled in the art should understand that the first relay coil and the second relay coil involved in the aforementioned embodiments of the present invention also include a plurality of first relay coils and a plurality of second relay coils, respectively, and that the descriptions of "first relay coil" and "second relay coil" also refer to a plurality of first relay coils and a plurality of second relay coils. For example, the second end of the fifth normally open auxiliary contact is electrically connected to the first ends of the plurality of first relay coils, and the second ends of the plurality of first relay coils are electrically connected to the second common reference potential end. In this way, on the basis of the aforementioned technical solution, further, through the relationship between the fifth normally open auxiliary contact of the third contactor and the aforementioned other contacts and coil of the third contactor, and the relationship between the sixth normally open auxiliary contact of the fourth contactor and the aforementioned other contacts and coil of the fourth contactor, the switching and interlocking between the two relay coils, namely the first relay coil and the second relay coil, can be further realized, and the switching and interlocking control of the control object can be further realized through the other contacts of the first relay associated with the first relay coil and the other contacts of the second relay associated with the second relay coil.

[0056] In an embodiment of the present invention, a frequency conversion device is provided. As shown in FIG2 , the frequency conversion device includes, for example: a first frequency converter P1 , a second frequency converter P2 , and a switch circuit.

[0057] Specifically, the first frequency converter P1 includes, for example, a first power input terminal and a first power output terminal. The first power input terminal includes, for example, Figure 2 The first power supply output terminal includes, for example, L1, L2 and L3 connection terminals of the first frequency converter P1. Figure 2 The T1 / U, T2 / V and T3 / W connection terminals of the first frequency converter P1 are shown in FIG.

[0058] The second frequency converter includes, for example, a second power input terminal and a second power output terminal. The second power input terminal includes, for example, Figure 2 The second power supply output terminal includes, for example, L1, L2 and L3 connection terminals of the second frequency converter P2. Figure 2 The T1 / U, T2 / V and T3 / W connection terminals of the second frequency converter P2 are shown in FIG.

[0059] The switch circuit is, for example, the switch circuit for the frequency converter of any of the aforementioned embodiments. The specific functions and details of the switch circuit can be referred to the relevant description of the aforementioned embodiments and will not be repeated here.

[0060] Correspondingly, the first contactor KMM1 may further include, for example, a first normally open main contact group. When the first coil is energized, the first normally open main contact group is closed.

[0061] The second contactor KMM2 may further include, for example, a second normally open main contact group. When the second coil is energized, the second normally open main contact group is closed.

[0062] Specifically, the first normally open main contact group is, for example, electrically connected to the first power output terminal or the first power output terminal; the second normally open main contact group is, for example, electrically connected to the second power output terminal or the first power output terminal.

[0063] In this way, based on the functions realized by the technical solution of the aforementioned switching circuit, through the association relationship between the first coil and the first normally open main contact group and the association relationship between the second coil and the second normally open main contact group, it is possible to safely and reliably realize switching control and interlocking control of the input power supply of the first inverter P1 and the input power supply of the second inverter P2, or realize switching control and interlocking control of the output power supply of the first inverter P1 and the output power supply of the second inverter P2.

[0064] Furthermore, based on the above technical solution, the third contactor KM1 of the switch circuit may further include, for example, a third normally open main contact group. When the third coil is energized, the third normally open main contact group is closed.

[0065] The fourth contactor KM2 of the switch circuit may further include, for example, a fourth normally open main contact group. When the fourth coil is energized, the fourth normally open main contact group is closed.

[0066] Specifically, when the first normally open main contact group is electrically connected to the first power output terminal and the second normally open main contact group is electrically connected to the second power output terminal, the third normally open main contact group is, for example, connected to the first power input terminal, and the fourth normally open main contact group is, for example, electrically connected to the second power input terminal.

[0067] Similarly, when the first normally open main contact group is electrically connected to the first power input terminal and the second normally open main contact group is electrically connected to the second power input terminal, the third normally open main contact group is, for example, connected to the first power output terminal, and the fourth normally open main contact group is, for example, electrically connected to the second power output terminal.

[0068] In this way, based on the functions realized by the technical solution of the aforementioned switching circuit, through the association relationship between the first coil and the first normally open main contact group, the association relationship between the second coil and the second normally open main contact group, the association relationship between the third coil and the third normally open main contact group, and the association relationship between the fourth coil and the fourth normally open main contact group, it is possible to safely and reliably realize the switching control and interlocking control of the input power supply of the first inverter P1 and the input power supply of the second inverter P2, as well as the switching control and interlocking control of the output power supply of the first inverter P1 and the output power supply of the second inverter P2.

[0069] Furthermore, based on the above technical solution, the first frequency converter P1 may further include a first external control connection terminal. The first external control connection terminal may include Figure 2 The first frequency converter P1 is shown with multiple connection terminals 1, 2, ..., n.

[0070] The second frequency converter P2 may further include a second external control connection terminal. Figure 2 The second frequency converter P2 shown has multiple connection terminals 1, 2, ..., n.

[0071] Correspondingly, the first relay may further include, for example, a first relay normally-open auxiliary contact. When the first relay coil is energized, the first relay normally-open auxiliary contact is closed.

[0072] The second relay may further include, for example, a second relay normally-open auxiliary contact. When the second relay coil is energized, the second relay normally-open auxiliary contact is closed.

[0073] The first normally-open auxiliary contact of the relay is connected to the first external control connection, for example.

[0074] The second normally-open auxiliary contact of the relay is connected to the second external control connection, for example.

[0075] The first frequency converter P1 may further include, for example, a first braking resistor R1 , which is connected in series between R+ and R− connection terminals of the first frequency converter P1 .

[0076] The second frequency converter P2 may further include, for example, a second braking resistor R2. The second braking resistor R2 is, for example, connected in series between the R+ and R- connection terminals of the second frequency converter P2.

[0077] Similarly, in the case where the first relay includes a plurality of first relays and the second relay includes a plurality of second relays, the first relay normally open auxiliary contacts and the second relay normally open auxiliary contacts involved in the aforementioned solutions of the embodiments of the present invention also include a plurality of first relay normally open auxiliary contacts and a plurality of second relay normally open auxiliary contacts, respectively. The relevant descriptions of "first relay normally open auxiliary contacts" and "second relay normally open auxiliary contacts" also refer to a plurality of first relay normally open auxiliary contacts and a plurality of second relay normally open auxiliary contacts. For example, the plurality of first relay normally open auxiliary contacts are connected to the plurality of connection terminals of the first external control connection end in a one-to-one correspondence. For example, the plurality of second relay normally open auxiliary contacts are connected to the plurality of connection terminals of the second external control connection end in a one-to-one correspondence.

[0078] Thus, building on the functionality achieved by the aforementioned technical solution, the association between the first relay coil and the normally open auxiliary contact of the first relay, and the association between the second relay coil and the normally open auxiliary contact of the second relay, further safely and reliably implements switching control and interlocking control of the control signals of the first inverter and the second inverter. The inverter control signals may include, for example, digital input / output and encoder control signals.

[0079] A third aspect of the present invention provides a crane, comprising: a motor M1 (such as Figure 2 Specifically, the frequency conversion device is, for example, the frequency conversion device of any of the aforementioned embodiments. The specific functions and details of the frequency conversion device can be referred to the relevant description of the aforementioned embodiments and will not be repeated here.

[0080] Specifically, the number of motors M1 is, for example, one, and the power terminals of motor M1 are connected to the first power output terminal of the first frequency converter P1 and the second power output terminal of the second frequency converter P2, respectively. Of course, when the first power output terminal is electrically connected to the first normally open main contact group or the third normally open main contact group, the power terminals of motor M1 are connected to the first power output terminal via the first normally open main contact group or the third normally open main contact group. And when the second power output terminal is electrically connected to the second normally open main contact group or the fourth normally open main contact group, the power terminals of motor M1 are connected to the second power output terminal via the second normally open main contact group or the fourth normally open main contact group. Motor M1 is also, for example, connected to ground PE.

[0081] The crane may be, for example, a tower crane, but the embodiments of the present invention are not limited to the field of tower cranes, and all such drive-type electronic control systems are applicable.

[0082] Furthermore, in some other embodiments, the number of motors M1 can also be two, for example, a first power supply and a second power supply. In this case, the power supply terminal of the first motor is connected to the first power output terminal of the first frequency converter P1, for example, and the power supply terminal of the second motor is connected to the second power output terminal of the second frequency converter P2, for example. Similarly, when the first power output terminal is electrically connected to the first normally open main contact group or the third normally open main contact group, the power supply terminal of the first motor is connected to the first power output terminal via the first normally open main contact group or the third normally open main contact group, and when the second power output terminal is electrically connected to the second normally open main contact group or the fourth normally open main contact group, the power supply terminal of the second motor is connected to the second power output terminal via the second normally open main contact group or the fourth normally open main contact group.

[0083] In such Figures 1A to 1C as well as Figure 2 Taking the circuit structure shown as an example, the following specific functions can also be implemented to further ensure the reliability, intelligence and operational safety of the electronic control system.

[0084] 1) When the first static contact KH:1 of the switch is connected, the first inverter P1 is powered on normally and drives the motor to work, while the second inverter P2 is not powered and the control signal is disconnected.

[0085] 2) When the second static contact KH:2 of the switch is connected, the second inverter P2 is powered on normally and drives the motor to work. At the same time, the first inverter P1 is not powered on and the control signal is disconnected.

[0086] 3) When the first frequency converter P1 is powered on, the first coil of the first contactor KMM1 is powered first, and the third coil of the third contactor KM1 is powered later; when the second frequency converter P2 is powered on, the second coil of the second contactor KMM2 is powered first, and the fourth coil of the fourth contactor KM2 is powered later; this ensures that the frequency converter P1 or P2 is connected to the motor M1 first, and then the power supply and control signal are connected to the frequency converter P1 or P2.

[0087] 4) When the first frequency converter P1 is powered off, the third coil of the third contactor KM1 loses power first, and the first coil of the first contactor KMM1 loses power later; when the second frequency converter P2 is powered off, the fourth coil of the fourth contactor KM2 loses power first, and the second coil of the second contactor KMM2 loses power later; thereby ensuring that the frequency converter P1 or P2 first cuts off the power supply and control signal of the frequency converter P1 or P2, and then cuts off the connection with the motor M1.

[0088] 5) When the first coil of the first contactor KMM1 is energized, the fourth coil of the fourth contactor KM2 and the second coil of the second contactor KMM2 are de-energized; when the second coil of the second contactor KMM2 is energized, the third coil of the third contactor KM1 and the first coil of the first contactor KMM1 are de-energized.

[0089] In summary, the embodiment of the present invention, through the aforementioned technical solution, can achieve safe and reliable one-click switching to the second inverter when a fault occurs in the first inverter, thereby improving the reliability, intelligence and operational safety of the electronic control system, ensuring the normal operation of the controlled object, ensuring the normal progress of the engineering project, and avoiding delays in the engineering project due to handling of the faulty inverter.

[0090] It is also worth mentioning that the embodiment of the present invention is not limited to realizing the switching between two inverters. The control strategy in the technical solution of the embodiment of the present invention can also be simply expanded and transformed to realize the switching between more than two inverters.

[0091] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0092] The above are merely embodiments of the present invention and are not intended to limit the present invention. It will be apparent to those skilled in the art that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are intended to be included within the scope of the claims of the present invention.

Claims

1. A switching circuit for a frequency converter, characterized in that: include: A switching switch, comprising a movable end, a first static contact, and a second static contact, wherein the movable end is used to connect to a first power source, and when the switching switch is in a first switching state, the movable end is connected to the first static contact, and when the switching switch is in a second switching state, the movable end is connected to the second static contact; A first contactor includes a first coil and a first normally closed auxiliary contact, wherein when the first coil is energized, the first normally closed auxiliary contact is opened; as well as a second contactor comprising a second coil and a second normally closed auxiliary contact, wherein when the second coil is energized, the second normally closed auxiliary contact is opened; Wherein, the first end of the second normally closed auxiliary contact is electrically connected to the first static contact, the second end of the second normally closed auxiliary contact is electrically connected to the first end of the first coil, and the second end of the first coil is electrically connected to the first common reference potential end; The first end of the first normally closed auxiliary contact is electrically connected to the second static contact, the second end of the first normally closed auxiliary contact is electrically connected to the first end of the second coil, and the second end of the second coil is electrically connected to the first common reference potential end; a third contactor, comprising a third coil, a third normally open auxiliary contact, and a third normally closed auxiliary contact, wherein when the third coil is energized, the third normally open auxiliary contact is closed, and the third normally closed auxiliary contact is opened; Wherein, the first contactor further includes a first normally open auxiliary contact, and when the first coil is energized, the first normally open auxiliary contact is closed; The first end of the first normally open auxiliary contact is electrically connected to the first end of the second normally closed auxiliary contact, the second end of the first normally open auxiliary contact is electrically connected to the first end of the third coil, and the second end of the third coil is electrically connected to the first common reference potential end; The first end of the third normally open auxiliary contact is electrically connected to the moving end, and the second end of the third normally open auxiliary contact is electrically connected to the first static contact; The third normally closed auxiliary contact is connected in series between the second static contact and the first end of the first normally closed auxiliary contact; a fourth contactor, comprising a fourth coil, a fourth normally open auxiliary contact, and a fourth normally closed auxiliary contact, wherein when the fourth coil is energized, the fourth normally open auxiliary contact is closed and the fourth normally closed auxiliary contact is opened; Wherein, the second contactor further includes a second normally open auxiliary contact, and when the second coil is energized, the second normally open auxiliary contact is closed; The first end of the second normally open auxiliary contact is electrically connected to the first end of the first normally closed auxiliary contact, the second end of the second normally open auxiliary contact is electrically connected to the first end of the fourth coil, and the second end of the fourth coil is electrically connected to the first common reference potential end; The first end of the fourth normally open auxiliary contact is electrically connected to the moving end, and the second end of the fourth normally open auxiliary contact is electrically connected to the second static contact; The fourth normally closed auxiliary contact is connected in series between the first static contact and the first end of the second normally closed auxiliary contact.

2. The switching circuit according to claim 1, wherein: Also includes: An emergency stop switch is connected in series between the moving end and the first power supply.

3. The switching circuit according to claim 1, wherein: Also includes: a first relay comprising a first relay coil; a second relay comprising a second relay coil; Wherein, the third contactor further includes a fifth normally open auxiliary contact, and when the third coil is energized, the fifth normally open auxiliary contact is closed; The fourth contactor further includes a sixth normally open auxiliary contact, and when the fourth coil is energized, the sixth normally open auxiliary contact is closed; The first end of the fifth normally open auxiliary contact is used to connect to the second power supply, the second end of the fifth normally open auxiliary contact is electrically connected to the first end of the first relay coil, and the second end of the first relay coil is electrically connected to the second common reference potential end; The first end of the sixth normally open auxiliary contact is used to connect to the second power supply, the second end of the sixth normally open auxiliary contact is connected to the first end of the second relay coil, and the second end of the second relay coil is electrically connected to the second common reference potential end.

4. The switching circuit according to claim 3, wherein: The first relay includes a plurality of first relays, and the second relay includes a plurality of second relays.

5. A frequency conversion device, characterized in that: include: A first frequency converter, comprising a first power input terminal and a first power output terminal; A second frequency converter, comprising a second power input terminal and a second power output terminal; as well as The switching circuit for a frequency converter according to any one of claims 3 to 4; Wherein, the first contactor further comprises a first normally open main contact group, and when the first coil is energized, the first normally open main contact group is closed; The second contactor further comprises a second normally open main contact group, and when the second coil is energized, the second normally open main contact group is closed; The first normally open main contact group is electrically connected to the first power output terminal or the first power input terminal; The second normally open main contact group is electrically connected to the second power output terminal or the second power input terminal.

6. The frequency conversion device according to claim 5, characterized in that: The third contactor of the switch circuit further comprises a third normally open main contact group, and when the third coil is energized, the third normally open main contact group is closed; The fourth contactor of the switch circuit further comprises a fourth normally open main contact group, and when the fourth coil is energized, the fourth normally open main contact group is closed; Wherein, the first normally open main contact group is electrically connected to the first power output terminal; The second normally open main contact group is electrically connected to the second power output terminal; The third normally open main contact group is connected to the first power input terminal; The fourth normally open main contact group is electrically connected to the second power input terminal.

7. The frequency conversion device according to claim 6, characterized in that: The first frequency converter further includes a first external control connection terminal; The second frequency converter further includes a second external control connection terminal; Wherein, the first relay further includes a first relay normally open auxiliary contact, and when the first relay coil is energized, the first relay normally open auxiliary contact is closed; The second relay further includes a second relay normally open auxiliary contact, and when the second relay coil is energized, the second relay normally open auxiliary contact is closed; The normally open auxiliary contact of the first relay is connected to the first external control connection terminal; The normally-open auxiliary contact of the second relay is connected to the second external control connection terminal.

8. A crane, characterized in that: include: Motor; as well as The frequency conversion device according to any one of claims 5 to 7.

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