Power contactor including pyrotechnic actuator

Abstract

A power contactor (100) comprises: a fixed part; a movable part capable of contacting the fixed part and moving between an open position and a closed position of the contactor, the movable part comprising at least one power contact (110); an auxiliary contact (120) and a pyrotechnic actuator (130), the auxiliary contact and the pyrotechnic actuator being placed in parallel with the power contact, and the pyrotechnic actuator being configured to be triggered during suspension of the contactor to move the contactor into the open position; and a motor configured to actuate the movable part and bring the movable part into contact with the fixed part, characterized in that the power contact and the auxiliary contact are asynchronous in that when the contactor is closed, the power contact contacts the fixed part before the auxiliary contact, and when the contactor is opened, the auxiliary contact opens before the power contact.

Description

Technical Field

[0001] The present invention relates to the general field of electrical protection components such as electromechanical contactors and electrical contactors, and more particularly to triggering the opening of these protection components. Prior art

[0002] A power contactor is an electrical protection component that is generally composed of a fixed part and a movable part that may or may not be in contact with the fixed part.

[0003] In order to close the contactor and thus bring the movable part into contact with the fixed part so that current can flow between the fixed part and the movable part, the motor of the contactor is energized, which will make it possible to apply a force to the movable part and thus allow current to flow between the movable part and the fixed part.

[0004] When the current flowing between the two parts exceeds a defined threshold, an electromagnetic repulsive force will be applied to the movable part and compensate or even exceed the force applied to the movable part by the motor. This leads to suspension of the contactor, i.e., an undesired disconnection of the contactor between the fixed part and the movable part. In addition, during this phase, i.e., during the application of the repulsive force before suspension, the contact resistance between the fixed part and the movable part of the contactor increases and generates local heating (proportional to the square of the contact resistance multiplied by the current), which can lead to destruction of the movable part, irreversible damage to the contactor and / or welding of the movable part to the fixed part in the event that the movable part falls back onto the fixed part.

[0005] Currently, there are several solutions to avoid damage to contactors in overcurrent or short circuit conditions:

[0006] - The current flowing through the circuit is measured and processing means detect a current above a given threshold to open the contactor before it floats. However, the measurement acquisition, processing and action times are not always compatible with the dynamic currents which can be extremely fast depending on the impedance of the source or short circuit. The contactor can include a circuit-breaking element, but this complicates the structure of the contactor.

[0007] The opening of the contactor can be triggered by fast actuation means, for example of the thermoelectric switch type, but depending on certain dynamic currents, the system for actuation and detection of the current may also be too slow.

[0008] It is therefore desirable to have a new power contactor with which the triggering of the disconnection in the event of an overcurrent is accelerated and the risk of damage is reduced. Summary of the invention

[0009] The present invention relates to a power contactor, comprising:

[0010] -Fixed parts;

[0011] - a movable part capable of contacting the fixed part and moving between an open position and a closed position of the contactor, the movable part comprising at least one power contact (110);

[0012] - an auxiliary contact (120) and a pyrotechnic actuator (130) placed in parallel with the power contact and configured to be triggered during suspension of the contactor in such a way as to move the contactor to the open position; and

[0013] - a motor configured to actuate the movable part and bring the movable part into contact with the fixed part,

[0014] It is characterized in that the power contacts and the auxiliary contacts are not synchronized in that during closing of the contactor the power contacts come into contact with the fixed part before the auxiliary contacts and during opening of the contactor the auxiliary contacts open before the power contacts.

[0015] The presence of a pyrotechnic actuator allows the power contacts to be opened quickly, for example in less than 2 milliseconds, in the event that the contactor is suspended.

[0016] Due to the desynchronization of the power contacts and the auxiliary contacts, the pyrotechnic actuator can be powered via the auxiliary contacts without the risk of triggering or melting the pyrotechnic actuator under nominal operation of the contactor. It is therefore possible to use the contactor of the invention with a high voltage source, for example a power supply delivering a voltage of 800V.

[0017] According to a particular feature of the invention, the contactor also comprises a transient voltage suppression diode connected in parallel with the pyrotechnic actuator.

[0018] A transient voltage suppression diode, also called a Transil diode or a Transzorb diode, makes it possible to limit the voltage across the terminals of the pyrotechnic actuator and protect them in the event that the voltage would increase too quickly across the terminals of the power contacts.

[0019] According to another particular feature of the invention, the pyrotechnic actuator comprises an igniter and a piston, the igniter being configured to trigger the pyrotechnic actuator by melting and releasing the piston to open the contactor.

[0020] Another subject of the invention is a method according to the invention for closing a power contactor in an open position, comprising bringing a power contact into contact with a fixed part and then bringing an auxiliary contact into contact with the fixed part.

[0021] Another subject of the invention is a method according to the invention for opening a power contactor in a closed position, comprising opening the contact between the auxiliary contact and the fixed part and then opening the contact between the power contact and the fixed part.

[0022] Due to the closing method of the invention, when the power contact is closed, the current flows through this contact instead of through the pyrotechnic actuator. The voltage in the branch including the power contact is equal to the voltage drop of the power contact (of the order of hundreds of millivolts). Then, when closing the auxiliary contact, a small part of the current flows through the pyrotechnic actuator, because the voltage is applied by the parallel branch including the power contact. This current is therefore insufficient to trigger the pyrotechnic actuator.

[0023] When the contactor opens, the auxiliary contacts open first to be able to isolate the pyrotechnic actuator, then the power contacts open and an arc is generated. The voltage gradually rises in the two parallel branches to the voltage of the power supply connected to the contactor, but the voltage across the terminals of the pyrotechnic actuator remains lower.

[0024] When the contactor is closed, i.e. the power contacts and the auxiliary contacts are closed, and the current is too high, the contactor may float, i.e. the power contacts will be lifted. An arc may be created and an arc voltage occurs. The current in the branch comprising the pyrotechnic actuator increases and triggers the pyrotechnic actuator, which opens the power contacts. By opening the power contacts during the suspension of the contactor, it is avoided in particular that the power contacts close again and weld to the fixed parts due to the local heating generated by the current increase, which makes it possible to limit damage to the contactor.

[0025] BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Other characteristics and advantages of the present invention will become apparent from the description given below, with reference to the accompanying drawings, which illustrate exemplary embodiments thereof without any limitation.

[0027] [ Figure 1A ] Figure 1A A power contactor according to an embodiment of the invention is schematically and partially represented in an open position.

[0028] [ Figure 1B ] Figure 1B A power contactor according to an embodiment of the invention is schematically and partially represented between an open position and a closed position.

[0029] [ Figure 1C ] Figure 1C A power contactor in a closed position is schematically and partially represented according to an embodiment of the invention.

[0030] [ Figure 1D ] Figure 1DA power contactor according to an embodiment is schematically and partially represented in an open position.

[0031] [ Figure 2 ] Figure 2 A power contactor is schematically and partially represented in an open position after triggering of a pyrotechnic actuator according to an embodiment of the invention.

[0032] [ Figure 3 ] Figure 3 A method for closing a power contactor according to an embodiment of the invention is schematically represented.

[0033] [ Figure 4 ] Figure 4 A method for opening a power contactor according to an embodiment of the invention is schematically represented. DETAILED DESCRIPTION

[0034] Figure 1A , 1B , 1C, 1D and 2 schematically and partially represent the power contactor 100 in different positions: during the nominal operation of the contactor, Figure 1A and 1D In the disconnected position; Figure 1C In the closed position; Figure 1B between the open position and the closed position; and Figure 2 In the embodiment of the present invention, after triggering the pyrotechnic actuator 130, it is in the off position. In these figures, each item is represented by the same reference numeral.

[0035] The power contactor 100 includes a fixed part 108 and a movable part 109, and the movable part 109 can contact the fixed part and move between the open position and the closed position of the contactor 100. The movable part of the contactor 100 includes a movable power contact 110 and an auxiliary contact 120. The contactor 100 also includes a pyrotechnic actuator 130, which includes an igniter. The auxiliary contact 120 and the pyrotechnic actuator 130, more specifically, the auxiliary contact 120 and the igniter (i.e., trigger) of the pyrotechnic actuator 130 are placed in parallel with the movable power contact 110. In addition, the movable part can also include a resistor 140 placed in series between the auxiliary contact 120 and the pyrotechnic actuator 130.

[0036] The pyrotechnic actuator 130 is configured to be triggered during the suspension of the contactor 100, that is, when the current across the contactor 100 is too high, when an arc is formed between the movable part and the fixed part, and when the movable part is lifted, either by directly striking the entire movable part 109 or by striking the movable power contact 110 alone, thereby opening the contactor 100. For example, the pyrotechnic actuator 130 can be triggered at a current greater than or equal to 10A.

[0037] The contactor 100 further includes a motor 170. Figure 1D , the motor is configured to actuate the movable part and bring it into contact with the fixed part. The motor is, for example, a linear mechanical motor.

[0038] An electrical load 160 may be connected to the contactor 100 .

[0039] The contactor 100 may be placed between a voltage source 150 and a load 160. The voltage source 150 may be a high voltage source that delivers a voltage of 800V, for example.

[0040] exist Figure 1A In the open position of the contactor 100 under nominal operation shown in FIG, the fixed part and the movable part are not in contact and no current flows between the two. In other words, the auxiliary contact 120 and the power contact 110 are disconnected and no current can flow between the source 150 and the load 160. The voltage ΔU in the two branches of the contactor 100 (the branch including the power contact 110 and the branch including the auxiliary contact 120 and the pyrotechnic actuator 130) is equal to the voltage of the voltage source 150.

[0041] When the contactor 100 is closed, the power contact 110 and the auxiliary contact 120 are not closed at the same time. More specifically, when the contactor 100 is closed, the power contact 110 contacts the fixed part of the contactor 100 before the auxiliary contact 120. Similarly, when the contactor 100 is opened, the power contact 110 and the auxiliary contact 120 are not opened at the same time. More specifically, the auxiliary contact 120 opens before the power contact 110. In other words, the power contact 110 and the auxiliary contact 120 are not synchronized. Figure 1B Such states of the contactor 100 between opening and closing are explained above.

[0042] The asynchronism of the power contacts 110 and the auxiliary contacts 120 is achieved, for example, by placing these contacts at different distances from the fixed part 108. In the open position of the contactor, the power contacts are arranged, for example, at a distance d1 from the fixed part, and the auxiliary contacts are arranged at a distance d2 from the fixed part, the distance d2 being greater than the distance d1.

[0043] In the closed position of the contactor 100 (in Figure 1C ), the fixed part and the movable part are in contact in such a way that the current flows between the two parts. In other words, the auxiliary contact 120 and the power contact 110 are closed and the current flows through the two branches of the contactor 100.

[0044] When the contactor 100 is closed, the voltage in the branch including the power contact 110 is equal to the voltage drop of the power contact 110, i.e., of the order of 100 millivolts. Then, the auxiliary contact 120 is closed, and the voltage in the branch including the pyrotechnic actuator 130 is also 100 millivolts. The value of the resistor 140 is selected in such a way that the current flowing through the pyrotechnic actuator 130 remains below the triggering threshold current of the pyrotechnic actuator 130. For example, the resistor 140 is 2 ohms.

[0045] When the contactor 100 opens, the auxiliary contact 120 opens first and makes it possible to isolate the igniter of the pyrotechnic actuator 130. Then, the power contact 110 opens, an arc is generated on this contact 110, and the voltage in the two branches of the contactor 100 gradually increases until it reaches the voltage of the voltage source 150. Therefore, due to the previous opening of the auxiliary contact 120, the voltage across the terminals of the pyrotechnic actuator 130 and the current passing therethrough are zero.

[0046] Due to the desynchronization of contacts 110 and 120, the igniter of pyrotechnic actuator 130 is never affected by the voltage of voltage source 150 and is therefore protected and does not run the risk of catching fire or being improperly triggered.

[0047] When the contactor 100 is closed and the current becomes too high (e.g., reaches 2 kA), the power contact 110 may rise and suspend the contactor 100. This generates an arc and an arc voltage appears. The voltage in the two parallel branches of the contactor 100 increases together with the current flowing through the igniter of the pyrotechnic actuator 130. This has the effect of triggering the pyrotechnic actuator 130, which will open or close the power contact 110. In the case of suspension, the triggering of the disconnection of the contactor 100 is therefore faster than the prior art, because it does not require any device for measuring current or voltage. The triggering of the disconnection is, for example, one millisecond faster in speed compared to the prior art.

[0048] In the exemplary embodiment, pyrotechnic actuator 130 includes an igniter 132 and a piston 131. When the current flowing through pyrotechnic actuator 130 increases, igniter 132 melts and triggers pyrotechnic actuator 130 by releasing piston 131. After being released, piston 131 prevents power contacts 110 from closing again, as shown in FIG. Figure 2 This makes it possible to prevent the power contact 110 from falling back to the fixed component and being welded to the fixed component after the contactor is suspended. Therefore, damage to the contactor 100 is avoided.

[0049] The contactor 100 may also include a transient voltage suppression diode (also called a Transil diode or Tranzorb diode) placed in parallel with the pyrotechnic actuator 130 and the resistor 140. This diode makes it possible to limit the voltage to protect the igniter 132 and the resistor 140, in particular in the event that the voltage across the terminals of the power contact 110 increases too quickly. In addition, the contactor 100 has been described as having a single power contact 110 and a single auxiliary contact 120, but it may include two or more power contacts that will always be asynchronous with respect to the auxiliary contact 120. In this case, the auxiliary contact 120 is always connected to the same pyrotechnic actuator 130 and the pyrotechnic actuator 130 actuates the different power contacts in a synchronous manner.

[0050] Figure 3 A method 300 for closing a power contactor according to an embodiment of the invention is schematically represented.

[0051] The contactor is initially in the open position 310 so that the fixed contacts and the movable contacts are not in contact and no current flows between the two components.

[0052] To move the contactor to the closed position 320, the motor is powered in a manner that applies pressure to the movable part of the contactor and first brings the power contacts into contact with the fixed part (step 301) and then brings the auxiliary contacts into contact with the fixed part (step 302).

[0053] Figure 4 A method 400 for opening a power contactor according to an embodiment of the present invention is schematically represented.

[0054] The contactor is initially in the closed position 410 so that the fixed component and the movable component are in contact and current flows between the two components.

[0055] To move the contactor to the open position 420, the power supply to the motor is cut off and the auxiliary contact is first opened (step 401). Therefore, it is no longer in contact with the fixed part of the contactor, and then the power contact is opened (step 402).

Claims

1. A power contactor, comprising: -Fixed parts; - a movable part capable of coming into contact with the fixed part and moving between an open position and a closed position of the contactor, the movable part comprising at least one power contact; - an auxiliary contact and a pyrotechnic actuator, the auxiliary contact being connected in series with the pyrotechnic actuator, the auxiliary contact and the pyrotechnic actuator being placed in parallel with the power contact and the pyrotechnic actuator being configured to be triggered during the suspension of the contactor in such a way as to move the contactor to the open position, and - a motor configured to actuate the movable part and bring it into contact with the fixed part, It is characterized in that the power contact and the auxiliary contact are asynchronous in that during closing of the contactor the power contact comes into contact with the fixed part before the auxiliary contact and during opening of the contactor the auxiliary contact opens before the power contact.

2. The power contactor according to claim 1, characterized in that: Also included is a transient voltage suppression diode connected in parallel with the pyrotechnic actuator.

3. The power contactor according to any one of claims 1 or 2, characterized in that: The pyrotechnic actuator includes an igniter and a piston, the igniter being configured to trigger the pyrotechnic actuator by melting and release the piston to open the contactor.

4. A method for closing a power contactor as claimed in any one of claims 1 to 3 in an open position, comprising bringing the power contact into contact with the fixed component and subsequently bringing the auxiliary contact into contact with the fixed component.

5. A method for opening a power contactor according to any one of claims 1 to 3 in a closed position, comprising opening the contact between the auxiliary contact and the fixed component and subsequently opening the contact between the power contact and the fixed component.

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