FR3083393A1 - METHOD FOR DETECTING AVALANCHE OF A POWER BRIDGE - Google Patents

Abstract

The invention relates in particular to a switching arm (10) comprising a first switch (Q1) and a second switch (Q11) characterized in that it comprises an avalanche detection device (110, 330, X1) comprising: - a first circuit (110) adapted to generate a first detection voltage representative of the voltage between the second current input terminal and the second current output terminal; - a second circuit (330) designed to generate a second and a third detection voltage, said second detection voltage being at the potential of the ground terminal (GND) and said third detection voltage being at a positive potential when the first voltage detection is less than a threshold value; and - a voltage comparator (X1) configured to compare the second detection voltage with the third detection voltage and to generate an avalanche detection voltage (ASC HS) according to the result of the comparison.

Description

"Avalanche detection method for a power bridge"

Technical area

The present invention is in the field of power bridges comprising at least one switching arm and intended to control or be powered by a rotating electric machine. To this end, the invention relates in particular to a method for detecting an avalanche transistor in a power bridge driving a rotary electric machine, as well as a power bridge implementing said method and such a rotary electric machine.

State of the art

In a motor vehicle, an on-board network is used to supply various electrical equipment equipping said motor vehicle. An electrical power supply for the on-board network is provided by at least one battery which can be recharged, when the motor vehicle is in motion, by a rotary electric machine which is connected to a heat engine of said motor vehicle. The rotating electrical machine then converts mechanical energy from rotation of the heat engine into electrical energy which is supplied to the network and / or at least one battery.

By rotary electrical machine is meant more generally any rotary electrical machine, preferably whose stator is polyphase, used for the production of a direct current supplying the on-board network. By way of nonlimiting example, it may in particular be an alternator or an alternator-starter. More particularly still, the context of the present invention is that of rotary electrical machines with permanent magnets.

According to a first mode of operation, the rotary electrical machine is connected to a power bridge comprising power components to supply the on-board network with direct electric current. According to a second mode of operation, the rotary electrical machine is supplied electrically by the power bridge operating as an inverter.

In case of failure of the power bridge or one of its power components, the electric currents flowing in said power bridge can quickly damage its power components. In particular, in the event of separation of an electrical connection from one of the power components, an avalanche phenomenon may appear, causing an exponential rise in the electric current passing through the power component in an avalanche. Such an avalanche electric current can reach several tens of amps, or even a few hundred amps, and it can destroy the power bridge and / or the electrical equipment of the on-board network.

- 2 Consequently, it is necessary to detect as quickly as possible a mode of advancement of one of the power components of the power bridge and to secure the said power bridge as quickly as possible.

The object of the present invention is therefore to propose a new method for detecting the deviation of a power bridge in order to respond at least in large part to the preceding problems and also to lead to other advantages.

Statement of the invention

According to a first aspect of the invention, at least one of the abovementioned objectives is achieved with a switching arm comprising:

~ a ground terminal intended to be connected to a ground in an electrical network;

~ a power supply terminal intended to be connected to a positive terminal of the electrical network;

~ a first switch comprising:

O a first current input terminal,

O a first current output terminal, and

O a first control terminal making it possible to switch the first switch from a closed state to an open state and vice versa, the first input terminal being electrically connected to the power supply terminal;

~ a second switch comprising:

O a second current input terminal,

O a second current output terminal, and

O a second control terminal making it possible to switch the second switch from a closed state to an open state and vice versa, the second current output terminal being electrically connected to the ground terminal, the first current output terminal being connected to the second current input terminal at a midpoint, said midpoint being intended to be electrically connected to an electrical phase of a rotary electrical machine;

said switching arm being characterized in that it further comprises an avalanche detection device comprising:

O a first circuit designed to generate a first detection voltage representative of the voltage between the second current input terminal and the second current output terminal;

- 3 O a second circuit designed to generate a second and a third detection voltage, said second detection voltage being at the potential of the ground terminal and said third detection voltage being at a positive potential when the first detection voltage is lower at a threshold value; and

O a voltage comparator configured to compare the second detection voltage to the third detection voltage and to generate an avalanche detection voltage as a function of the result of the comparison.

The switching arm according to the first aspect of the invention may advantageously comprise at least one of the improvements below, the technical characteristics forming these improvements can be taken alone or in combination:

~ the threshold value is negative;

~ the switches are MOSFETs;

~ the avalanche detection voltage is at a positive value when an avalanche is detected;

~ the first circuit comprises a first detection resistor and a first detection capacitor connected in series at a first intermediate point, the series association of said first detection resistor and first detection capacitor being placed in parallel between the second terminal of input and the second output terminal, said first detection voltage being generated at said first intermediate point;

~ the avalanche detection voltage is at a potential different from the ground terminal, preferably at a higher potential than that of the ground terminal when said third voltage is greater than said second voltage;

~ the second circuit includes:

O a first threshold resistor, a first diode and a second threshold resistor connected in series, the cathode of the first diode being connected to a terminal of the second threshold resistor and the anode of the first diode being connected to a terminal of the first threshold resistance, the series association being connected in parallel between the first intermediate point and the ground terminal, said third detection voltage being generated at the cathode of the first diode, and

O a restoring resistor intended to be connected between an auxiliary voltage source and the cathode of the first diode;

~ the second generation circuit further comprises:

O a third switch comprising:

a third current input terminal, a third current output terminal, and a third control terminal making it possible to switch the third switch from a closed state to an open state and vice versa,

O the third current input terminal being connected to the ground terminal, said second detection voltage being generated at the third current output terminal;

O a third threshold resistor and a first zener diode connected in series, the series association of the third threshold resistor and the first zener diode being connected between the anode of the first diode and the third control terminal; and

O a fourth threshold resistor connected between the third current output terminal and the ground terminal;

~ The switching arm further comprises a fifth threshold resistor intended to be connected to the auxiliary voltage source and the third current output terminal.

According to a second aspect of the invention, a power bridge is proposed comprising at least one switching arm in accordance with the first aspect of the invention or according to any one of its improvements.

In a particular embodiment of the invention, the power bridge further comprises a second switching arm comprising:

~ a fourth switch comprising:

O a fourth current input terminal,

O a fourth current output terminal, and

O a fourth control terminal making it possible to switch the fourth switch from a closed state to an open state and vice versa, the fourth input terminal being electrically connected to the power supply terminal;

~ a fifth switch comprising:

O a fifth current input terminal,

O a fifth current output terminal, and

O a fifth control terminal making it possible to switch the fifth switch from a closed state to an open state and vice versa, the fifth current output terminal being electrically connected to the ground terminal, the fourth current output terminal being connected to the fifth input terminal

- 5 of current at a midpoint, said midpoint being intended to be electrically connected to an electrical phase of the rotary electrical machine;

the avalanche detection device further comprising:

O a third circuit designed to generate a fourth detection voltage representative of the voltage between the fifth current input terminal and the fifth current output terminal; and

O the second circuit being designed so that said second detection voltage is also at the potential of the ground terminal and said third detection voltage is also at a positive potential when the fourth detection voltage is less than the threshold value.

In a particular embodiment of the invention, the third circuit comprises a second detection resistor and a second detection capacity connected in series at a second intermediate point, the series association of said second detection resistance and second detection capacity being placed in parallel between the fifth input terminal and the fifth output terminal, said fourth detection voltage being generated at said second intermediate point.

In a particular embodiment of the invention, the second circuit further comprises a sixth threshold resistor, a second diode connected in series, the cathode of the second diode being connected to the cathode of the first diode and the anode of the second diode being connected to a terminal of the sixth threshold resistor, the series association being connected in parallel between the second intermediate point and the cathode of the first diode.

In a particular embodiment of the invention, the second circuit further comprises a seventh threshold resistor and a second zener diode connected in series, the series association of the seventh threshold resistor and the second zener diode being connected between the anode of the second diode and the third control terminal.

According to a third aspect of the invention, a method is proposed for detecting an avalanche transistor in a power bridge in accordance with the second aspect of the invention, said bridge being connected between an electrical network and a rotating electrical machine, said detection method comprising the following steps:

~ a first step of measuring a first detection voltage representative of the voltage between the second current input terminal and the second current output terminal;

- 6 ~ a second step of generating a second detection voltage, said second detection voltage being at the potential of the ground terminal when the first detection voltage is less than a threshold value, ~ a third step of generating a third detection voltage, said third detection voltage being at a positive potential when the first detection voltage is less than a threshold value, ~ a fourth step of comparing the second detection voltage with the third detection voltage, and ~ a fifth step of generating an avalanche detection voltage as a function of the comparison carried out in the fourth step.

In a particular embodiment of the invention, the threshold value is less than or equal to - 20 V, preferably less than or equal to -30V.

In a particular embodiment of the invention, the avalanche detection method further comprises a sixth step of generating a control signal to bring the first switch to the closed state when the detection voltage of avalanche generated during the fifth step indicates that the first transistor is in avalanche.

Various embodiments of the invention are provided, integrating according to all of their possible combinations the different optional characteristics set out here.

Description of the figures

Other characteristics and advantages of the invention will become apparent from the following description on the one hand, and from several exemplary embodiments given by way of non-limiting indication with reference to the appended schematic drawings on the other hand, in which :

~ FIGURE 1 illustrates a schematic view of an electrical network comprising an electrical machine electrically connected to a power bridge according to the invention;

~ FIGURE 2 illustrates a block diagram of an exemplary embodiment of an avalanche detection device associated with a second stage of a switching arm of the power bridge;

~ FIGURE 3 illustrates a diagram of an avalanche detection method in accordance with the third aspect of the invention;

- 7 Of course, the features, variants and different embodiments of the invention can be associated with each other, in various combinations, insofar as they are not incompatible or mutually exclusive of each other. One can in particular imagine variants of the invention comprising only a selection of characteristics described below in isolation from the other characteristics described, if this selection of characteristics is sufficient to confer a technical advantage or to differentiate the invention from in the prior art.

In particular, all the variants and all the embodiments described can be combined with one another if nothing is technically opposed to this combination.

In the figures, the elements common to several figures keep the same reference.

Detailed description of the invention

With reference to FIGURE 1, a rotary electrical machine 2 is electrically connected to a power bridge 1 configured to supply an on-board network B + with direct current from the rotary electrical machine 2 or to supply the rotary electrical machine 2 from of the on-board network B +.

The rotary electric machine is for example of the GMG type (in English “Gear Motor Generator”) developing an electric power of 15 kW. All the numerical values mentioned below relate to this example of a particular electrical machine which in no way limits the scope of the invention.

The on-board network B + is electrically connected to at least one battery 4 ·

Advantageously, the stator 21 of the rotary electric machine 2 is polyphase: the stator 21 comprises a plurality of electric windings 211 inside which electric currents circulate, each electric current flowing in one of the electric phases Φ1- Φ3 · In the embodiment illustrated in FIGURE 1, the stator 21 of the rotary electrical machine 2 comprises three electrical phases Φ1-Φ3, but the invention is understood more generally for an electrical machine whose stator comprises at least an electrical phase.

In general, the rotary electrical machine 2 is advantageously a synchronous permanent magnet electrical machine 221, as shown in FIGURE 1.

In the context of integration in a motor vehicle, the rotary electrical machine 2 is preferably of the type of an alternator or an alternator-starter. A rotor 22 of the machine

- 8 rotating electric 2 is advantageously mechanically coupled to a heat engine of the motor vehicle. The rotor 22 advantageously comprises the permanent magnets 221 as part of a synchronous machine.

The rotating electrical machine 2 is electrically interfaced by the power bridge 1 to the on-board network B +.

The power bridge 1 comprises at least one switching arm 10, and preferably a plurality of electrical branches 10. Each switching arm 10 comprises a first El and a second stage E2, each stage comprising a switch comprising an input terminal of current, a current output terminal as well as a switch control terminal making it possible to switch the switch from a closed state to an open state, and vice versa.

The power bridge 1 is controlled by a control module - not shown - which selectively or collectively configures the control terminals of the switches to place said switches in their open or closed state. The control module thus makes it possible to control the power bridge.

The switches are preferably made by means of power components Ql, Qll.

For each of the electrical branches 10 of the power bridge, the first power component Q1 and the second power component Qll are arranged in series with respect to each other, between the ground terminal GND and the supply terminal of the on-board network B +, each midpoint lla-llc being located between the first power component Ql and the second power component Qll.

The first Ql and the second Qll power component of each switching arm 10 are interconnected at the middle bridge lla-llc located between their respective current output and current input terminals. Line current input terminal Dl of the first transistor Ql is intended to be connected to the on-board network B +; and a current output terminal of the second transistor Q11 is intended to be connected to the ground of the electrical network.

The power bridge 1 is electrically connected to each of the electrical phases Φ1, Φ2, Φ3 of the rotating electrical machine 2 in order to supply DC voltage to the on-board network B + and / or to charge at least one battery 4. D 'In general, the power bridge 1 is used in one or the other of the operating modes of the rotary electric machine 2 described above.

More particularly, each switching arm 10 of the power bridge 1 is electrically connected to one of the electrical phases Φ1, Φ2, Φ3 of the rotating electric machine 2. More particularly still, each switching arm 10 of the power bridge is connected

- 9 electrically to one of the electrical phases Φ1, Φ2, Φ3 of the rotating electrical machine 2 at its midpoint lla-llc located between the first stage El and the second stage E2 of each switching arm 10.

Furthermore, at least part of the second power components Qll of the second stage E2 is electrically connected to an avalanche detection device 3'00 configured to implement the avalanche detection method in accordance with the third aspect of the invention. More particularly, and as will be described below with reference to FIGURES 2, the avalanche detection device 3100 makes it possible to detect the presence of a malfunction of the power component Ql of the switching arm in which the device is connected. avalanche detection 3100 and possibly allow the generation of a control signal allowing the first power components Ql to be controlled in order to put them in safety.

In the following description, each first Ql and second Qll power component are of the MOSFET type doped N. In other words, the drain, the source and the gate of the transistors of the MOSFET type doped N respectively correspond to the terminal d current input, current output terminal and switch control terminal. Of course, the invention is not limited to this single type of power component, and each first Ql and second Qll power component can be of the type of any transistor.

With reference to FIGURE 2, an exemplary embodiment of an avalanche detection device 3100 associated with one of the MOSFETs Qll of the second stages E2 of the first switching arm 10 of the power bridge 1 will now be described.

The avalanche detection device 3100 is configured to detect whether the MOSFET Q1 of the first stage El of the switching arm 10 of the power bridge 1 in which it is inserted is in avalanche.

Recall that an avalanche type malfunction occurs when an overvoltage appears between the drain and source terminals of a power transistor, for example of the MOSFET type, and that such an avalanche type malfunction results in a strong electric current. crossing the MOSFET Ql, Qll of the power bridge, and more particularly an electric current whose intensity increases very rapidly, for example exponentially, and in a prolonged manner. In particular, an avalanche phenomenon can occur when a power transistor is in the open state or when a power transistor is switching from the closed state to the open state.

The avalanche detection system 3100 includes:

- 10 ~ a first circuit 110 designed to generate a first detection voltage representative of the voltage between the second current input terminal and the second current output terminal of the MOSFET Qll;

~ a second circuit 330 designed to generate a second and a third detection voltage, said second detection voltage being at the potential of the ground terminal GND and said third detection voltage being at a positive potential when the first detection voltage is lower at a threshold value PS1; and ~ a voltage comparator X1 configured to compare the second detection voltage with the third detection voltage and to generate an ASCHS avalanche detection voltage as a function of the result of the comparison.

~ a voltage comparator X1 designed to compare the second reference voltage to the representative voltage and to generate an ASC HS avalanche detection voltage as a function of the result of the comparison carried out by the voltage comparator Xl.

In the example described here, the voltage comparator Xl is supplied by a DC voltage source P5- The electrical potential of the voltage source P5 is for example equal to 5 V.

The voltage comparator Xl further comprises a positive input terminal receiving the representative voltage and a negative input terminal receiving the second detection voltage. Comparator Xl also includes an output terminal whose potential is positive when the voltage present on the positive input terminal is greater than the voltage present on the negative input terminal of comparator Xl and whose potential is zero in the case opposite

In the example described in FIG. 2, the first circuit 110 comprises a first detection resistor R8 and a first detection capacitor C1 connected in series at a first intermediate point 111, the association in series of said first detection resistor R8 and first detection capacity Cl being placed in parallel between the second input terminal D2 and the second output terminal S2, said first detection voltage being generated at said first intermediate point 111. In other words, the detection capacity Cl is connected by one of its terminals to the GND earth terminal and by the other of these terminals at an intermediate point 111 to the detection resistor R8,

The first circuit 110 further comprises:

A first discharge diode D2 connected in parallel with the detection resistor R8, the cathode of the first discharge diode being connected to the midpoint 11a,

- 11 • a second discharge diode D7 in series with a discharge resistance R4, the series association of the discharge resistance R4 and the second discharge diode D7 being connected between the intermediate point 111 and the ground terminal GND .

In the example described in FIG. 2, the second circuit 330 also includes a first threshold resistor R3L, a first diode D3I and a second threshold resistor R34 connected in series. The cathode of the first diode D3I is connected to a terminal of the second threshold resistor R34 and the anode of the first diode is connected to a terminal of the first threshold resistor R3I. The series association of the first threshold resistance R3L of the first diode D3I and of the second threshold resistance R34 is connected in parallel between the first intermediate point 111 and the GND ground terminal. By design of the second circuit 330, the third detection voltage is generated at the cathode of the first diode D3I · In other words, the cathode of the first diode D3I is connected to the negative input terminal of the comparator of voltage Xl.

In the example described here and optionally, the second circuit 330 includes a first filtering capacity C3I situated between the ground terminal GND and the cathode of the diode D3I.

In addition, the second circuit 330 also comprises, in the example described, a restoring resistor R35 is connected to the DC voltage source P5 and to the cathode of the first diode D31.

In the example described here, the second circuit 330 also includes a third switch Q3 comprising:

~ a third current input terminal D3, ~ a third current output terminal S3, and ~ a third control terminal G3 making it possible to switch the third switch from a closed state to an open state and vice versa, the third current input terminal D3 being connected to the ground terminal GND, said second detection voltage being generated at the third current output terminal S3.

In the example described here, the transistor Q3 is a p-doped MOSFET transistor.

In the example described here, the second circuit 330 further comprises a third threshold resistor R4I, a first zener diode D42 and a diode D4I connected in series. The series association of these three components being connected between the anode of the first diode D3I and the third control terminal. The cathode of diode D4I is connected to the anode of the first diode D3I ·

- 12 The anode of diode D41 is connected to the anode of the first zener diode D42. The third threshold resistor R4I is connected by one of these terminals to the cathode of the first zener diode D42 and by its second terminal to the third control terminal of the third transistor Q3.

The bias voltage of the zener diode D42 is chosen so that the zener diode D42 becomes biased only when the potential present at the intermediate point 111 becomes very strongly negative and less than the threshold value PS1 which is for example less than or equal to - 20 V, preferably less than or equal to -30V.

In the example described here, the second circuit 330 further comprises a fourth threshold resistor R38 connected between the third current output terminal S3 and the ground terminal GND.

In the example described here, the second circuit 330 further comprises a fifth threshold resistor R37 connected to the DC voltage source P5 and to the third current output terminal S3 of the third transistor Q3.

In the example described here, the second circuit 330 further comprises a third zener diode D47 placed in shunt between the third control terminal of the third transistor Q3 and the third output terminal of the third transistor Q3. The cathode of the third zeneer diode D47 is connected to the third output terminal of the third transistor Q3. In addition, a resistor R44 is also placed in shunt between the third control terminal of the third transistor Q3 and the third output terminal of the third transistor Q3.

The association of the third zener diode D47 and the resistor R44 protects the third transistor Q3 from a possible overvoltage between its third control terminal and its third current output terminal.

In normal operation of the rotary electrical machine 2, the voltage at the intermediate point 111 is substantially zero when the MOSFET Qll is open or closed since in this case the detection capacity Cl takes very little charge when switching the MOSFET Qll and almost discharges immediately via one of the discharge diodes D2 and D7. Thus, the representative voltage present on the positive input terminal of comparator X1 is almost zero.

Furthermore, in normal operation, the zener diode D42 is unpolarized so that the third transistor Q3 is in the open state.

Thus, the second circuit 330 delivers a non-zero and positive voltage to the negative output terminal of the voltage comparator Xl. This non-zero and positive voltage is delivered by the divider bridge formed by the fifth threshold resistor R37 and by the fourth threshold resistor R38.

- 13 In fact, as the voltage present on the positive input terminal of comparator Xl is almost zero while a positive voltage is applied on the negative input terminal of comparator Xl, it follows that the output terminal of comparator Xl is at zero potential and no avalanche is detected on the MOSFET Ql.

On the other hand, if the MOSFET Qll of the second stage E2 is for example broken in the open state while the MOSFET Ql of the first stage El receives an opening command, the MOSFET Ql goes into avalanche because of the presence of the load inductive represented by phase Φ1. In other words, the voltage at the output terminal of the MOSFET Ql decreases until it exceeds the value of -30V, reaching for example a value of -70V.

At the same time, this voltage variation at the level of the output terminal of the MOSFET Ql causes the charging of the capacitor Cl and the voltage at the intermediate point 111 becomes very strongly negative, for example of the order of -70V.

When the potential of the intermediate point becomes lower than the threshold PS1, the Zener diode D42 becomes conducting and polarizes the third transistor Q3 so that this transistor Q3 behaves like a closed switch. Subsequently, the electrical potential at the output terminal S3 of the transistor Q3 is brought to that of the ground terminal GND, that is to say substantially equal to 0 V.

In addition, when the potential at the intermediate point is strongly negative, the first diode D3I prevents this potential from being propagated on the positive input terminal of the voltage comparator X1 and in fact, the voltage seen by this positive input terminal is the voltage delivered by the divider bridge formed by the return resistor R35 and by the second threshold resistor R34 ·

The voltage comparator X1 then compares the voltage value delivered by the divider bridge formed by the return resistor R35 and by the second threshold resistor R34 with a zero voltage present on the negative input terminal due to the closing of the third transistor Q3. Consequently, the voltage generator X1 generates on its output a positive and non-zero ASC HS avalanche detection voltage.

The output of the voltage comparator Xl thus delivers in the form of a voltage a signal for detecting the avalanche of the MOSFET Ql.

Finally, in the example described in FIG. 2, a bias resistor R9 is also located between the control terminal and the current output terminal of the MOSFET Qll.

Furthermore, in the example described in FIG. 2, a MOSFET Qllb of a second switching arm is also connected to a fourth liob circuit at all points identical to the first circuit 110. In other words, the fourth liob circuit is designed to generate a fourth detection voltage at a second intermediate point 111b, this fourth detection voltage being representative of the voltage between the current input terminal D5 and the current output terminal S5 of the MOSFET Qllb of the second arms.

In the example described here, the second circuit 330 further comprises a sixth threshold resistor R32, a second diode D32 connected in series. The cathode of the second diode D32 is connected to the cathode of the first diode D3I and the anode of the second diode D32 is connected to a terminal of the sixth threshold resistor R32. The series association of the sixth threshold resistor R32 and the second diode D32 is connected in parallel between the second intermediate point 111b and the cathode of the first diode D32.

In the example described here, the value of the sixth threshold resistance R32 is equal to the value of the first threshold resistance R3I.

In the example described here, the second circuit 330 further comprises a seventh threshold resistor R42, a second zener diode D45 and a diode D44 connected in series. The series association of these three components being connected between the anode of the second diode D32 and the third control terminal. The cathode of diode D44 is connected to the anode of the second diode D32. The anode of diode D44 is connected to the anode of the second zener diode D45 · The seventh threshold resistor R42 is connected by one of these terminals to the cathode of the second zener diode D45 and by its second terminal to the third control terminal of the third transistor Q3.

In the example described here, the value of the seventh threshold resistance R32 is equal to the value of the third threshold resistance R4I ·

Thus, for the same reasons as explained above if a strongly negative potential appears at the second intermediate point 111b, the voltage comparator X1 generates on its output a positive and non-zero ASC HS avalanche detection voltage.

The output of the voltage comparator X1 thus delivers in voltage form a signal for detecting the avalanche of the MOSFET Qlb from the second branch of the bridge.

Finally, in the example described in FIG. 2, a bias resistor R9b is also located between the control terminal and the current output terminal of the MOSFET Qllb.

With reference to FIG. 3> a method for detecting an avalanche transistor in a switching arm 10 implemented by a power bridge according to the invention will now be described.

During a step E1, a first detection voltage V111 is generated in the example described here at the intermediate point 111 of a first switching arm 10 of the power bridge.

During a step E2, a second detection voltage V2 is generated, this second detection voltage is at the potential of the ground terminal when the first detection voltage is less than the threshold value PS1. This second detection voltage is generated in the example described here by the second circuit 33θ ·

During a step E3, a third detection voltage V3 is generated, said third detection voltage being at a positive potential when the first detection voltage Vlll is less than a threshold value. This third detection voltage is generated in the example described here by the second circuit 33θ ·

During a step E4, the voltage comparator X1 compares the second detection voltage V2 with the third detection voltage V3.

During a step E5, the voltage comparator Xl generates an avalanche detection voltage ASCHS as a function of the comparison carried out in step E4 · Thus, the voltage comparator Xl generates a positive and non-zero voltage when the transistor Ql of the switching arm is in avalanche and zero voltage otherwise.

During a step E6, the power bridge control module detects that the avalanche voltage ASC HS is positive and not zero and generates a control signal SC for passing the first switch Ql of the switching arm over which the avalanche was detected in the closed state.

As a variant, during step E6, the power bridge control module detects that the avalanche voltage ASC HS is positive and not zero and generates a control signal for passing all the first switches Ql of all the arms switching state closed.

Of course, the invention is not limited to the examples which have just been described and numerous modifications can be made to these examples without departing from the scope of the invention. In particular, the different characteristics, forms, variants and embodiments of the invention can be associated with each other in various combinations insofar as they are not incompatible or mutually exclusive of each other. In particular, all the variants and embodiments described above can be combined with one another.

Claims (10)

claims 1. Switch arm (10) comprising: a ground terminal (GND) intended to be connected to a ground in an electrical network; ~ a power supply terminal (B +) intended to be connected to a positive terminal of the electrical network: ^- a first switch (Ql) comprising: O a first current input terminal, O a first current output terminal, and O a first control terminal making it possible to switch the first switch from a closed state to an open state and vice versa, the first input terminal being electrically connected to the power supply terminal (B +); ^- a second switch (Qll) comprising: O a second current input terminal (D ₂ ), O a second current output terminal (S ₂ ), and O a second control terminal (G ₂ ) enabling the second switch to pass from a closed state to an open state and vice versa, the second current output terminal (S2) being electrically connected to the ground terminal, the first current output terminal being connected to the second current input terminal (D2) at a midpoint (lia), said midpoint being intended to be electrically connected to an electrical phase (Φ1) of an electric machine rotating (2); said switching arm (10) being characterized in that it further comprises an avalanche detection device (3100) comprising: O a first circuit (liO) designed to generate a first detection voltage representative of the voltage between the second current input terminal and the second current output terminal; O a second circuit (33θ) designed to generate a second and a third detection voltage, said second detection voltage being at the potential of the ground terminal (GND) and said third detection voltage being at a positive potential when the first voltage detection is less than a threshold value; and 18 O a voltage comparator (Xl) configured to compare the second detection voltage to the third detection voltage and to generate an avalanche detection voltage (ASC_HS) according to the result of the comparison. 2. Switch arm according to claim 1 wherein said first circuit comprises a 5 first detection resistor (R8) and a first detection capacitor (Cl) connected in series at a first intermediate point (ill), the series association of said first detection resistor (R8) and first detection capacitor (Cl) being placed in parallel between the second input terminal (D2) and the second output terminal (S2), said first detection voltage being generated at said first intermediate point. (111). 10 3- switching arm according to claim 1 or 2 wherein the avalanche detection voltage (ASÇ_HS) is at a potential different from the ground terminal, preferably at a higher potential than that of the ground terminal (GND) when said third voltage is greater than said second voltage. 4. Switching arm according to any one of claims 2 to 3 in which the second circuit (330) comprises: ”A first threshold resistor (R31), a first diode (D3l) and a second threshold resistor (R34) connected in series, the cathode of the first diode (D31) being connected to a terminal of the second threshold resistor (R34) and the anode of the first diode being connected to a terminal of the first threshold resistance (R31), the association 20 in series being connected in parallel between the first intermediate point (ill) and the ground terminal ( GND), said third detection voltage being generated at the cathode of the first diode (D31), and _a restoring resistor (R.35) intended to be connected between an auxiliary voltage source (P5) and the cathode of the first diode. (D31). 5. The switching arm (10) according to claim 4, in which the second generation circuit (, 33θ) further comprises: ^- a third switch (Q3) comprising: O a third current input terminal (D3), O a third current output terminal (S3), and 19 O a third control terminal (G3) making it possible to change the third switch from a closed state to an open state and vice versa, ~ the third current input terminal (D3) being connected to the ground terminal (GND), said second detection voltage being generated at the third current output terminal (S3); ^- a third threshold resistor (R41) and a first zener diode (D42) connected in series, the series association of the third threshold resistor (R41) and the first zener diode (D42) being connected between the anode the first diode (D31) and the third control terminal; and ~ a fourth threshold resistor (R38) connected between the third current output terminal (S3) and the ground terminal (GND). 6. Switch arm (10) according to claim 4 and claim 5 further comprising a fifth threshold resistor (R37) intended to be connected to the auxiliary voltage source (P5) and the third current output terminal (S3 ). 7. Power bridge (1) comprising at least a first switching arm according to any one of claims 1 to 6. 8. Power bridge (l) according to the preceding claim, further comprising a second switching arm comprising: ~ a fourth switch comprising: O a fourth current input terminal, O a fourth current output terminal, and O a fourth control terminal making it possible to switch the fourth switch from a closed state to an open state and vice versa, the fourth input terminal being electrically connected to the power supply terminal (B +); ~ a fifth switch (Ql ibis) comprising: O a fifth current input terminal (D5), O a fifth current output terminal (S5), and O a fifth control terminal (G5) enabling the fifth switch to pass from a closed state to an open state and vice versa, - the fifth current output terminal (S5) being electrically connected to the ground terminal, the fourth current output terminal (S4) being connected to the fifth current input terminal (D5) at a midpoint ( 11b), said midpoint being intended to be electrically connected to an electrical phase (Φ2) of the rotary electrical machine (2); 5 the avalanche detection device (110, HOb, 330, Xi) further comprising: O a third circuit (liob) designed to generate a fourth detection voltage representative of the voltage between the fifth current input terminal and the fifth current output terminal; and O the second circuit being designed so that said second detection voltage is 10 also at the potential of the ground terminal (GND) and said third detection voltage is also at a positive potential when the fourth detection voltage is less than the threshold value. 9. Power bridge according to the preceding claim wherein said third circuit (liob) comprises a second detection resistor (R8b) and a second detection capacity 15 (Clb) connected in series at a second intermediate point (IIIb), the association in series of said second detection resistance (R8b) and second detection capacitor (Clb) being placed in parallel between the fifth input terminal (D5 ) and the fifth output terminal (S5), said fourth detection voltage being generated at said second intermediate point (ilib). 10. Power bridge according to claim Ç in which the second circuit (330) comprises In addition to a sixth threshold resistor (R32), a second diode (D32) connected in series, the cathode of the second diode (D32) being connected to the cathode of the first diode (D31) and the anode of the second diode being connected to a terminal of the sixth threshold resistor (R32), the series association being connected in parallel between the second intermediate point (111b) and the cathode of the first diode (D31) · 25 11. Power bridge according to the preceding claim wherein the second circuit further comprises a seventh threshold resistor (R42) and a second zener diode (D45) connected in series, the series association of the seventh threshold resistor (R42 ) and the second zener diode (D45) being connected between the anode of the second diode (D32) and the third control terminal. 2! 12. Method for detecting an avalanche switch (Qll) in a power bridge (1) according to one of claims 7 to 11, said bridge being connected between an electrical network and a rotary electrical machine (2), said detection method comprising the following steps: 5 a first step (El) of measuring a first detection voltage representative of the voltage between the second current input terminal and the second current output terminal; a second step (E2) of generating a second detection voltage, said second detection voltage being at the potential of the ground terminal (GND) when the first detection voltage is less than a threshold value, ~ a third step (E3) of generating a third detection voltage, said third detection voltage being at a positive potential when the first detection voltage is less than a threshold value, ~ a fourth step (E4) of comparing the second detection voltage detection at the third detection voltage, and ~ a fifth step (E5) of generating an avalanche detection voltage as a function of the comparison carried out in the fourth step. 13. An avalanche detection method according to the preceding claim, in which the threshold value (Si) is less than or equal to - 20 V, preferably less than or equal to -30V. 14. An avalanche detection method according to any one of claims 12 to 13 further comprising a sixth step (E6) of generating a control signal to switch the first switch (Ql) to the closed state. when the avalanche detection voltage generated during the fifth step indicates that the first switch is in an avalanche.