Integrated pre-charge contactor

Abstract

Embodiments in accordance with the present disclosure relate to apparatuses, systems, and methods for integrating pre-charge contactors. Particular embodiments relate to an integrated pre-charge contactor assembly comprising a plurality of fixed main contacts, a plurality of fixed auxiliary contacts, and a movable contact assembly comprising a movable main contact and a movable auxiliary contact. The integrated pre-charge contactor assembly also includes an actuation shaft coupled to the movable contact assembly and configured to move the movable contact assembly between an open position, a pre-charge position, and a closed position relative to the plurality of fixed main contacts and the plurality of fixed auxiliary contacts.

Description

Background Technology

[0001] Electromechanical switching devices, such as contactors and relays, are designed to carry a certain amount of current for a given period of time. Such devices are particularly important in electric vehicles. Typically, an electric vehicle includes one or more high-voltage batteries connected to the vehicle's electrical distribution system via main contactors to power the electric motor. The main contactor is usually an electromechanical switch that opens or closes the high-current path between the battery pack and the vehicle's electrical distribution system. To facilitate switching in the high-voltage system, a pre-charging circuit charges the output capacitor to the battery voltage before connecting the high-voltage system to the high-voltage battery pack. Summary of the Invention

[0002] Embodiments of this disclosure relate to apparatus, systems, and methods for operating an integrated pre-charge contactor. In some examples, the integrated pre-charge contactor integrates the pre-charge relay function into the main contactor by combining the pre-charge contactor and the main contactor with an intermittent auxiliary switch. This eliminates the need for separate switching components for the pre-charge and main contactors and also reduces the number of components and complexity. The integrated pre-charge contactor reduces the space occupied by the main contactor and the pre-charge contactor by integrating them into the same component, and further reduces the connection and control logic by using the same coil to connect both the main contactor and the pre-charge contactor.

[0003] Specific embodiments relate to an integrated precharge contactor assembly comprising: a plurality of fixed main contacts, a plurality of fixed auxiliary contacts, and a movable contact assembly including movable main contacts and movable auxiliary contacts. The integrated precharge contactor assembly further includes an actuation shaft coupled to the movable contact assembly and configured to move the movable contact assembly relative to the plurality of fixed main contacts and the plurality of fixed auxiliary contacts between an open position, a precharge position, and a closed position.

[0004] Another embodiment relates to an integrated precharge contactor system, comprising: a high-voltage battery, a capacitor circuit, a precharge circuit configured to charge the capacitor circuit, a main circuit coupled in parallel with the precharge circuit to the high-voltage battery and the capacitor circuit, and an integrated precharge contactor coupled to the precharge circuit and the main circuit, wherein the integrated precharge contactor implements a first switch for the precharge circuit and a second switch for the main circuit.

[0005] Another embodiment relates to a method of operating an integrated pre-charge contactor, comprising: coupling the integrated pre-charge contactor to a pre-charge circuit and a main circuit. The method further comprises: applying a first voltage to the magnetic coil of the integrated pre-charge contactor, wherein the integrated pre-charge contactor closes the pre-charge circuit in response to the first voltage. The method further comprises: applying a second voltage to the magnetic coil of the integrated pre-charge contactor, wherein the integrated pre-charge contactor closes the main circuit in response to the second voltage.

[0006] These and other features, aspects and advantages of this disclosure can be better understood when the following detailed description is read with reference to the accompanying drawings, in which the same characters represent the same parts. Attached Figure Description

[0007] Figure 1 A side view of an example integrated precharge contactor assembly according to at least one embodiment of the present disclosure is shown.

[0008] Figure 2 Showing Figure 1 An example is an isometric top view of an integrated precharge contactor assembly.

[0009] Figure 3 Showing Figure 1 An example is an isometric top view of an integrated precharge contactor assembly.

[0010] Figure 4 A block diagram of an example integrated precharge contactor system according to at least one embodiment of the present disclosure.

[0011] Figure 5 A flowchart illustrating an example method for operating an integrated precharge contactor assembly according to at least one embodiment of the present disclosure is shown. Detailed Implementation

[0012] The terminology used to describe particular examples in this document is not intended to limit other examples. Whenever the singular forms such as “a,” “an,” and “the” are used, and the use of only a single element is neither explicitly nor implicitly defined as mandatory, further examples may use multiple elements to achieve the same functionality. Similarly, when a function is subsequently described as being implemented using multiple elements, further examples may use a single element or processing entity to achieve the same functionality. It should also be understood that the terms “comprises,” “comprising,” “includes,” and / or “including” specify, when used, the presence of the stated feature, integer, step, operation, process, action, element, and / or component, but do not preclude the presence or addition of one or more other features, integers, steps, operations, processes, actions, elements, components, and / or any combination thereof.

[0013] It should be understood that when an element is referred to as "connected" or "coupled" to another element, that element can be directly connected or coupled via one or more intermediate elements. If "or" is used to combine two elements A and B, this should be understood to disclose all possible combinations: A only, B only, and both A and B. An alternative wording for the same combination is "at least one of A and B." The same applies to combinations of more than two elements.

[0014] Therefore, while further examples may have various modifications and alternative forms, the figures show some specific examples, which will be described in detail thereafter. However, this detailed description does not limit the further examples to the specific forms described. Further examples may cover all modifications, equivalents, and alternatives falling within the scope of this disclosure. Throughout the description of the figures, the same numerals refer to the same or similar elements that, when compared with each other, may be implemented identically or in modified form while providing the same or similar function.

[0015] Pre-charging methods typically involve charging the direct current (DC) link capacitor via a separate circuit, usually consisting of resistors and discrete pre-charge relays. Alternative methods include a bidirectional DC-DC converter that transforms the low voltage of the system's auxiliary battery into a high voltage to charge the DC link capacitor, or active pre-charging, which is similar to the aforementioned method with discrete components but utilizes inductors instead of resistors. When using conventional or active pre-charging, the need to drive additional components and connections to pre-charge the DC link capacitor before closing the main contactor increases implementation costs when implemented as a bidirectional DC-DC converter.

[0016] An integrated pre-charge contactor is provided according to embodiments of this disclosure, wherein a set of auxiliary contacts supports the function of the pre-charge contactor in the same component as the main contactor. The auxiliary contacts on the integrated pre-charge contactor are intermittently connected at a specific voltage to provide the same function as a discrete pre-charge relay. The pre-charge contactor and the main contactor are controlled by the same coil circuit, and pre-charging is performed through the auxiliary contacts. By incorporating the pre-charge relay into the main contactor, the function of a conventional pre-charge contactor is achieved, while minimizing the component size by combining the main contactor and pre-charging function into a single component. This further minimizes the connection and control logic by using the same coil connection as the main contactor.

[0017] from Figure 1 Initially, an exemplary method and apparatus for an integrated pre-charge contactor according to this disclosure are described with reference to the accompanying drawings. For further explanation, Figure 1 A side view of an example integrated precharge contactor assembly 100 according to at least one embodiment of the present disclosure is shown. Figure 2 Showing Figure 1 An example is an isometric top view of an integrated precharge contactor assembly 100. Figure 3 Showing Figure 1 An example is an isometric top view of the integrated precharge contactor assembly 100. Figures 1-3For clarity, certain elements of the example integrated precharge contactor assembly 100, including the housing, internal support structure, and actuation solenoid or magnetic coil, have been omitted. Those skilled in the art will understand the arrangement of these features.

[0018] Figures 1-3 The example integrated precharge contactor assembly 100 includes a pair of fixed main contacts 102, 104, respectively coupled to or integrated with a pair of main terminals 103, 105, which are supported by a housing portion 110. The example integrated precharge contactor assembly 100 further includes a movable contact assembly 190 coupled to an actuator shaft 118 and supported by a spring 116. The movable contact assembly 190 includes a movable main contact 106.

[0019] When the actuating solenoid (not shown) is energized, the actuator shaft 118 is driven upward by the magnetic flux, thereby moving the movable main contact to contact the fixed main contacts 102 and 104, thus closing the main contactor circuit. When the actuating solenoid (not shown) is de-energized, the spring 116 pulls the movable contact 106 away from contact with the fixed main contacts 102 and 104, thereby disconnecting the main contactor circuit.

[0020] Figures 1-3 The example integrated precharge contactor assembly 100 also includes a pair of fixed auxiliary contacts 114, 115, which are coupled or integrated with a pair of fixed auxiliary terminals 112, 113 via a housing portion 110, respectively. The fixed auxiliary terminals can be connected to a precharge circuit (not shown) including a DC link capacitor. In the example integrated precharge contactor assembly 100, the movable contact assembly further includes a movable auxiliary contact 107 coupled to an actuator shaft 118 and / or a movable main contact 106. When the actuation solenoid (not shown) is energized, the actuator shaft 118 is driven upward by a magnetic flux, thereby moving the movable auxiliary contact 107 to contact the fixed auxiliary contacts 114, 115, thus closing the precharge contactor circuit. When the actuation solenoid (not shown) is de-energized, a spring 116 pulls the movable auxiliary contact 107 away from contact with the fixed auxiliary contacts 114, 115, thereby disconnecting the precharge contactor circuit. Therefore, when the auxiliary movable contact is installed above the movable main contact, the auxiliary contact closes before the main contact closes and when the main contact is not closed.

[0021] As further described below, the controller can be configured to control the integrated pre-charge contactor 100 by controlling the voltage applied to the actuation solenoid around the actuator shaft 118. Changing the solenoid voltage can change the position of the actuation shaft and the position of the movable contact assembly relative to the fixed contacts. In a particular embodiment, the actuator shaft is configured to move the movable contact assembly between an open position, a pre-charge position, and a closed position relative to a plurality of fixed main contacts and a plurality of fixed auxiliary contacts. In the pre-charge position, the movable auxiliary contacts are in contact with the plurality of fixed auxiliary contacts, and the movable main contacts are out of contact with the plurality of fixed main contacts. In the closed position, the movable auxiliary contacts are in contact with the plurality of fixed auxiliary contacts, and the movable main contacts are in contact with the plurality of fixed main contacts. In the open position, the movable auxiliary contacts are out of contact with the plurality of fixed auxiliary contacts, and the movable main contacts are out of contact with the plurality of fixed main contacts. In a particular embodiment, the movable contact assembly can move sequentially from the open position to the pre-charge position and then to the closed position.

[0022] To further explain, Figure 4 A block diagram of an example integrated precharge contactor system 400 according to at least one embodiment of the present disclosure is depicted. The integrated precharge contactor system 400 includes: an integrated precharge contactor 402 (e.g., including...). Figures 1-3 The integrated pre-charge contactor assembly 100, main circuit 404, pre-charge circuit 406, and controller 408. Figure 4 In example system 400, a power source (battery 410) is coupled to a set of contacts of the actuation solenoid of an integrated precharge contactor 402. A controller 408 controls the voltage / current applied by the power source to the actuation solenoid of the integrated precharge contactor 402. When a first voltage / current level is applied, the actuator assembly in the integrated precharge contactor 402 moves a movable auxiliary contact to contact a fixed auxiliary contact, thereby closing the precharge circuit 406. When a second voltage / current level higher than the first voltage / current level is applied, the actuator assembly in the integrated precharge contactor 402 moves a movable main contact to contact a fixed main contact, thereby closing the main circuit 404. Thus, the same controller 408 controls both the precharge contactor and the main contactor of the integrated precharge contactor 402 by applying power to it. In this way, the auxiliary contacts of the integrated precharge contactor 402 can be intermittently connected at a specific voltage, functioning similarly to a discrete precharge relay, thereby facilitating the precharging of the DC link capacitor before closing the main contactor.

[0023] In implementation, Figure 4An example integrated precharge contactor system 400 includes a high-voltage battery 410 and a capacitor circuit (not shown), with a precharge circuit 406 configured to charge the capacitor circuit. A main circuit 404 is coupled to the high-voltage battery 410 and the capacitor circuit connected in parallel with the precharge circuit 406. An integrated precharge contactor 402 is coupled to the precharge circuit 406 and the main circuit 404, such that the integrated precharge contactor acts as a first switch for the precharge circuit 406 and a second switch for the main circuit 404. For example, the integrated precharge contactor system 400 can be implemented with a high-voltage battery in an electric vehicle.

[0024] To further illustrate, Figure 5 A flowchart illustrating an example operation method of an integrated precharge contactor system according to at least one embodiment of the present disclosure is shown. The method includes coupling the integrated precharge contactor 502 to a precharge circuit and a main circuit. For example, the precharge circuit may be used to precharge a capacitor circuit connected in parallel with the main circuit of a high-voltage battery. The integrated precharge contactor may implement a first switch for the precharge circuit and a second switch for the main circuit.

[0025] Figure 5 The method further includes applying a first voltage 504 to the magnetic coil of an integrated precharge contactor, wherein the integrated precharge contactor closes a precharge circuit in response to the first voltage. In some examples, applying the first voltage 504 causes the actuator of the integrated precharge contactor to move a movable auxiliary contact to contact a pair of fixed auxiliary contacts to close the precharge circuit. The first voltage causes the magnetic coil to apply a first magnetic flux to drive the actuator shaft to a first position to close the precharge circuit.

[0026] Figure 5 The method further includes applying a second voltage 506 to the magnetic coil of the integrated precharge contactor, wherein the integrated precharge contactor closes the main circuit in response to the second voltage. In some examples, applying the second voltage 506 causes the actuator of the integrated precharge contactor to move a movable main contact to contact a pair of fixed main contacts to close the main circuit. The second voltage causes the magnetic coil to apply a second magnetic flux to drive the actuator shaft to a second position where the main circuit is closed.

[0027] In view of the foregoing, it should be understood that the integrated pre-charge contactor according to this disclosure has many advantages, including but not limited to: ● By integrating the function of the pre-charge contactor into the main contactor with the intermittent auxiliary switch, the function of the pre-charge relay is integrated into the main contactor; ● Eliminates the need for separate switching components for the pre-charger and main contactor; ●Reduce the number of parts and complexity; ● By integrating them into a single component, the space occupied by the main contactor and pre-charge contactor is reduced; and ● By using the same coil to connect both the main contactor and the pre-charge contactor, the connection and control logic are reduced.

[0028] The advantages and features of this disclosure can be further described by the following statements:

[0029] 1. An integrated precharge contactor assembly, comprising: a plurality of fixed main contacts; a plurality of fixed auxiliary contacts; a movable contact assembly including movable main contacts and movable auxiliary contacts; and an actuation shaft coupled to the movable contact assembly and configured to move the movable contact assembly relative to the plurality of fixed main contacts and the plurality of fixed auxiliary contacts between an open position, a precharge position, and a closed position.

[0030] 2. The integrated pre-charge contactor assembly according to statement 1, wherein, in the pre-charge position, the movable auxiliary contact is in contact with a plurality of fixed auxiliary contacts, and the movable main contact is separated from a plurality of fixed main contacts.

[0031] 3. The integrated precharge contactor assembly according to statement 1 or 2, wherein, in the closed position, a movable auxiliary contact contacts a plurality of fixed auxiliary contacts, and a movable main contact contacts a plurality of fixed main contacts.

[0032] 4. The integrated precharge contactor assembly according to any one of statements 1-3, wherein, in the open position, the movable auxiliary contact is separated from a plurality of fixed auxiliary contacts, and the movable main contact is separated from a plurality of fixed main contacts.

[0033] 5. The integrated precharge contactor assembly according to any one of statements 1-4, wherein actuation of the actuator shaft causes a movable auxiliary contact to move to contact a plurality of auxiliary contacts before the movable main contact moves to contact a plurality of fixed main contacts.

[0034] 6. The integrated pre-charge contactor assembly according to any one of statements 1-5, wherein a plurality of fixed auxiliary contacts and movable auxiliary contacts constitute the pre-charge contactor, and wherein a plurality of fixed main contacts and movable main contacts constitute the main contactor.

[0035] 7. The integrated precharge contactor assembly according to any one of statements 1-6 further includes a magnetic coil configured to apply a first amount of magnetic force to the actuator shaft in response to a first voltage, and to apply a second amount of magnetic force to the actuator shaft in response to a second voltage.

[0036] 8. The integrated precharge contactor assembly according to any one of statements 1-7, wherein the movable contact assembly moves to the precharge position in response to an applied first magnetic force, and the movable contact assembly moves to the closed position in response to an applied second magnetic force.

[0037] 9. An integrated pre-charge contactor system, comprising: a high-voltage battery; a capacitor circuit; a pre-charge circuit configured to charge the capacitor circuit; a main circuit coupled to the high-voltage battery and the capacitor circuit, the capacitor circuit being connected in parallel with the pre-charge circuit; and an integrated pre-charge contactor coupled to the pre-charge circuit and the main circuit, wherein the integrated pre-charge contactor implements a first switch for the pre-charge circuit and a second switch for the main circuit.

[0038] 10. The integrated pre-charge contactor system according to statement 9, wherein the integrated pre-charge contactor includes: a plurality of fixed main contacts; a plurality of fixed auxiliary contacts; a movable contact assembly including movable main contacts and movable auxiliary contacts; and an actuation shaft coupled to the movable contact assembly and configured to move the movable contact assembly relative to the plurality of main contacts and the plurality of fixed auxiliary contacts between an open position, a pre-charge position, and a closed position.

[0039] 11. The integrated pre-charge contactor system according to statement 9 or 10, wherein actuation of the actuator shaft causes a movable auxiliary contact to move to contact a plurality of auxiliary contacts before the movable main contact moves to contact a plurality of fixed main contacts.

[0040] 12. The integrated pre-charge contactor system according to any one of statements 9-11, wherein a plurality of fixed auxiliary contacts and movable auxiliary contacts realize a first switch for a pre-charge circuit, and wherein a plurality of fixed main contacts and movable main contacts realize a second switch for a main circuit.

[0041] 13. The integrated precharge contactor system according to any one of statements 9-12, further comprising a magnetic coil configured to apply a first amount of magnetic force to the actuator shaft in response to a first voltage and to apply a second amount of magnetic force to the actuator shaft in response to a second voltage.

[0042] 14. The integrated precharge contactor system according to any one of statements 9-13, further comprising a controller configured to control the application of a first voltage and a second voltage to a magnetic coil.

[0043] 15. A method of operating an integrated precharge contactor, the method comprising: coupling the integrated precharge contactor to a precharge circuit and a main circuit; applying a first voltage to the magnetic coil of the integrated precharge contactor, wherein the integrated precharge contactor closes the precharge circuit in response to the first voltage; and applying a second voltage to the magnetic coil of the integrated precharge contactor, wherein the integrated precharge contactor closes the main circuit in response to the second voltage.

[0044] 16. The method of statement 15, wherein the integrated precharge contactor comprises: a plurality of fixed main contacts; a plurality of fixed auxiliary contacts; a movable contact assembly including movable main contacts and movable auxiliary contacts; and an actuation shaft coupled to the movable contact assembly and configured to move the movable contact assembly relative to the plurality of main contacts and the plurality of fixed auxiliary contacts between an open position, a precharge position, and a closed position.

[0045] 17. The method according to statement 15 or 16, wherein actuation of the actuator shaft causes the movable auxiliary contact to move to contact the plurality of fixed auxiliary contacts before the movable main contact moves to contact the plurality of fixed main contacts.

[0046] 18. The method according to any one of statements 15-17, wherein a plurality of fixed auxiliary contacts and movable auxiliary contacts realize a first switch for a pre-charging circuit, and wherein a plurality of fixed main contacts and movable main contacts realize a second switch for a main circuit.

[0047] 19. The method according to any one of statements 15-18, wherein a first amount of magnetic force is applied to the actuator shaft in response to a first voltage, and a second amount of magnetic force is applied to the actuator shaft in response to a second voltage.

[0048] 20. The method according to any one of statements 15-19, wherein, in response to an applied first magnetic force, the movable contact assembly moves to a pre-charged position, and in response to an applied second magnetic force, the movable contact assembly moves to a closed position.

[0049] As can be understood from the foregoing description, various modifications and alterations can be made to the embodiments of this disclosure without departing from the true spirit of this disclosure. The descriptions in this specification are for illustrative purposes only and should not be construed as restrictive. The scope of this disclosure is defined only by the language of the claims.

Claims

1. An integrated pre-charge contactor assembly, comprising: Multiple fixed main contacts; Multiple fixed auxiliary contacts; A movable contact assembly, the movable contact assembly including a movable main contact and a movable auxiliary contact; as well as An actuation shaft, coupled to the movable contact assembly, is configured to move the movable contact assembly relative to the plurality of fixed main contacts and the plurality of fixed auxiliary contacts between an open position, a pre-charge position, and a closed position.

2. The integrated pre-charge contactor assembly according to claim 1, wherein, In the pre-charge position, the movable auxiliary contact is in contact with the plurality of fixed auxiliary contacts, and the movable main contact is separated from the plurality of fixed main contacts.

3. The integrated pre-charge contactor assembly according to claim 1, wherein, In the closed position, the movable auxiliary contact is in contact with the plurality of fixed auxiliary contacts, and the movable main contact is in contact with the plurality of fixed main contacts.

4. The integrated pre-charge contactor assembly according to claim 1, wherein, In the disconnected position, the movable auxiliary contact is separated from the plurality of fixed auxiliary contacts, and the movable main contact is separated from the plurality of fixed main contacts.

5. The integrated pre-charge contactor assembly according to claim 1, wherein, The actuation of the actuator shaft causes the movable auxiliary contact to move to contact the plurality of auxiliary contacts before the movable main contact moves to contact the plurality of fixed main contacts.

6. The integrated pre-charge contactor assembly according to claim 1, wherein, The plurality of fixed auxiliary contacts and the movable auxiliary contacts constitute a pre-charge contactor, wherein the plurality of fixed main contacts and the movable main contacts constitute a main contactor.

7. The integrated precharge contactor assembly of claim 1, further comprising a magnetic coil configured to apply a first amount of magnetic force to the actuator shaft in response to a first voltage, and to apply a second amount of magnetic force to the actuator shaft in response to a second voltage.

8. The integrated pre-charge contactor assembly according to claim 7, wherein, The movable contact assembly moves to the pre-charge position in response to the applied first magnetic force, and the movable contact assembly moves to the closed position in response to the applied second magnetic force.

9. An integrated pre-charge contactor system, comprising: High-voltage batteries; Capacitor circuit; A pre-charging circuit is configured to charge the capacitor circuit. The main circuit is coupled to the high-voltage battery and the capacitor circuit, and the capacitor circuit is connected in parallel with the pre-charge circuit; as well as An integrated pre-charge contactor is coupled to the pre-charge circuit and the main circuit, wherein the integrated pre-charge contactor implements a first switch for the pre-charge circuit and a second switch for the main circuit.

10. The integrated pre-charge contactor system according to claim 9, wherein, The integrated pre-charge contactor includes: Multiple fixed main contacts; Multiple fixed auxiliary contacts; A movable contact assembly, comprising a movable main contact and a movable auxiliary contact; and An actuation shaft is coupled to the movable contact assembly and configured to move the movable contact assembly between an open position, a pre-charge position, and a closed position relative to a plurality of main contacts and a plurality of fixed auxiliary contacts.

11. The integrated pre-charge contactor system according to claim 10, wherein, The actuation of the actuator shaft causes the movable auxiliary contact to move to contact the plurality of auxiliary contacts before the movable main contact moves to contact the plurality of fixed main contacts.

12. The integrated pre-charge contactor system according to claim 10, wherein, The plurality of fixed auxiliary contacts and the movable auxiliary contacts constitute a first switch for the pre-charging circuit, and wherein the plurality of fixed main contacts and the movable main contacts constitute a second switch for the main circuit.

13. The integrated precharge contactor system of claim 10, further comprising a magnetic coil configured to apply a first amount of magnetic force to the actuator shaft in response to a first voltage, and to apply a second amount of magnetic force to the actuator shaft in response to a second voltage.

14. The integrated precharge contactor system of claim 13, further comprising a controller configured to control the application of the first voltage and the second voltage to the magnetic coil.

15. A method of operating an integrated pre-charge contactor, the method comprising: The integrated pre-charge contactor is coupled to the pre-charge circuit and the main circuit. A first voltage is applied to the magnetic coil of the integrated pre-charge contactor, wherein the integrated pre-charge contactor closes the pre-charge circuit in response to the first voltage; and A second voltage is applied to the magnetic coil of the integrated precharge contactor, wherein the integrated precharge contactor closes the main circuit in response to the second voltage.

16. The method according to claim 15, wherein, The integrated pre-charge contactor includes: Multiple fixed main contacts; Multiple fixed auxiliary contacts; A movable contact assembly, comprising a movable main contact and a movable auxiliary contact; and An actuation shaft is coupled to the movable contact assembly and configured to move the movable contact assembly between an open position, a pre-charge position, and a closed position relative to a plurality of main contacts and a plurality of fixed auxiliary contacts.

17. The method according to claim 16, wherein, The actuation of the actuator shaft causes the movable auxiliary contact to move to contact the plurality of fixed auxiliary contacts before the movable main contact moves to contact the plurality of fixed main contacts.

18. The method according to claim 16, wherein, The plurality of fixed auxiliary contacts and the movable auxiliary contacts constitute a first switch for the pre-charging circuit, and wherein the plurality of fixed main contacts and the movable main contacts constitute a second switch for the main circuit.

19. The method of claim 16, wherein, In response to the first voltage, a first magnetic force is applied to the actuator shaft, and in response to the second voltage, a second magnetic force is applied to the actuator shaft.

20. The method according to claim 19, wherein, In response to the first applied magnetic force, the movable contact assembly moves to the pre-charged position, and in response to the second applied magnetic force, the movable contact assembly moves to the closed position.

Images