Patent ID: 12249471

DESCRIPTION OF THE EMBODIMENTS

FIGS.1A,1B,1C,1D and2represent, schematically and partially, a power contactor100in different positions: in the open position, during a nominal operation of the contactor, inFIGS.1A and1D, in the closed position inFIG.1C, between an open and a closed position inFIG.1Band in the open position inFIG.2following the triggering of the pyrotechnic actuator130. On these figures, the items are denoted by the same reference number.

The power contactor100comprises a fixed part108and a movable part109able to come into contact with the fixed part and move between an open position and a closed position of the contactor100. The movable part of the contactor100comprises a movable power contact110and an auxiliary contact120. The contactor100also comprises a pyrotechnic actuator130comprising an igniter. The auxiliary contact120and the pyrotechnic actuator130, and more particularly the auxiliary contact120and the igniter (i.e. the trigger) of the pyrotechnic actuator130are placed in parallel with the movable power contact110. In addition, the movable part may also comprise a resistance140placed in series between the auxiliary contact120and the pyrotechnic actuator130.

The pyrotechnic actuator130is configured to be triggered during a levitation of the contactor100, i.e. when electric arcs form between the movable part and the fixed part and when the movable part lifts when the electric current traversing the contactor100is too high, in such a way as to directly strike the entire movable part109or the movable power contact110alone, to open the contactor100. For example, the pyrotechnic actuator130can be configured to be triggered at currents greater than or equal to 10 A.

The contactor100also comprises a motor170, represented inFIG.1D, configured to actuate the movable part and to put it in contact with the fixed part. The motor is for example a linear mechanical motor.

An electric charge160can be connected to the contactor100.

The contactor100can be placed between a voltage source150and a load160. The voltage source150can be a high voltage source which for example delivers a voltage of 800 V.

In the open position under nominal operation of the contactor100, shown inFIG.1A, the fixed part and the movable part are not in contact and no electric current flows between the two. In other words, the auxiliary120and power110contacts are open and no electric current can flow between the source150and the load160. The voltage AU in the two branches (that comprising the power contact110and that comprising the auxiliary contact120and the pyrotechnic actuator130) of the contactor100is equal to that of the voltage source150.

When the contactor closes100, the power110and auxiliary120contacts do not close at the same time. More specifically, the power contact110comes into contact with the fixed part of the contactor100before the auxiliary contact120when the contactor100closes. Similarly, when the contactor100opens, the power110and auxiliary120contacts do not open at the same time. More specifically, the auxiliary contact120opens before the power contact110. In other words, the power110and auxiliary120contacts are desynchronized. This state of the contactor100, between opening and closing, is illustrated onFIG.1B.

The desynchronization of the power contact110and of the auxiliary contact120is for example effected by placing these contacts at different distances from the fixed part108. In the open position of the contactor, the power contact is for example placed at a distance d1from the fixed part and the auxiliary contact is placed at a distance d2from the fixed part, the distance d2being greater than the distance d1.

In the closed position of the contactor100, represented inFIG.1C, the fixed part and the movable part are in contact in such a way that an electric current flows between the two parts. In other words, the auxiliary120and power110contacts are closed and the electric current flows through both branches of the contactor100.

When the contactor100is closed, the voltage in the branch comprising the power contact110is equal to the voltage drop of the power contact110, i.e. in the order of a hundred millivolts. Then the auxiliary contact120closes and the voltage in the branch comprising the pyrotechnic actuator130is also of a hundred millivolts. The value of the resistance140is chosen in such a way that the current flowing through the pyrotechnic actuator130remains below the trigger threshold current of the pyrotechnic actuator130. For example, the resistance140is of 2 Ohms.

When the contactor100opens, the auxiliary contact120opens first and makes it possible to isolate the igniter of the pyrotechnic actuator130. Then the power contact110opens, electric arcs are created on this contact110and the voltage rises gradually in both branches of the contactor100until the voltage of the voltage source150is reached. Thus the voltage across the terminals of the pyrotechnic actuator130and the current traversing it are zero owing to the preliminary opening of the auxiliary contact120.

Owing to the desynchronization of the contacts110and120, the igniter of the pyrotechnic actuator130is never subjected to the voltage of the voltage source150, and it is thus protected and does not run the risk of catching fire or being triggered inappropriately.

When the contactor100is closed and the current becomes too high, for example reaches 2 kA, the power contact110can be lifted up and make the contactor100levitate. This creates electric arcs and an are voltage appears. The voltage in the two parallel branches of the contactor100increases, along with the current flowing through the igniter of the pyrotechnic actuator130. This has the effect of triggering the pyrotechnic actuator130which will open or prevent the closing of the power contact110. The triggering of the opening of the contactor100, in the event of levitation, is thus faster than the prior art, since it does not require any means for measuring the current or voltage. The triggering of the opening for example gains one millisecond in speed by comparison with the prior art.

In this exemplary embodiment, the pyrotechnic actuator130comprises an igniter132and a piston131. When the current flowing through the pyrotechnic actuator130increases, the igniter132melts and triggers the pyrotechnic actuator130by releasing the piston131. Being released, the piston131prevents the power contacts110from closing again, as illustrated onFIG.2. This makes it possible to prevent the power contact110from dropping back onto the fixed part and being soldered to the fixed part following the levitation of the contactor100. Thus, damage to the contactor100is avoided.

The contactor100may also comprise a transient-voltage-suppression diode (also known as a transil diode or transzorb diode), placed in parallel with the pyrotechnic actuator130and with the resistance140. This diode makes it possible to limit the voltage to protect the igniter132and the resistance140, particularly if the voltage increases too fast across the terminals of the power contact110.

In addition, the contactor100has been described with a single power contact110and a single auxiliary contact120, but it may comprise two or more power contacts which will always be desynchronized with respect to the auxiliary contact120. In this case, the auxiliary contact120is always connected to the same pyrotechnic actuator130and the pyrotechnic actuator130actuates the different power contacts in a synchronized manner.

FIG.3represents, schematically, a method300for closing a power contactor according to an embodiment of the invention.

The contactor is initially in the open position310, so the fixed and movable contacts are not in contact and no electric current flows between these two parts.

For the contactor to move into the closed position320, the motor is powered in such a way as to apply a pressure force to the movable part of the contactor, and the power contact is first put in contact with the fixed part (step301), then the auxiliary contact is put in contact with the fixed part (step302).

FIG.4represents, schematically, a method400for opening a power contactor according to an embodiment of the invention.

The contactor is initially in the closed position410, so the fixed and movable parts are in contact and an electric current flows between these two parts.

For the contactor to move into the open position420, the power to the motor is cut and the auxiliary contact opens first (step401). It is therefore no longer in contact with the fixed part of the contactor, then the power contact opens (step402).