EP3515746A1

EP3515746A1 - Air pulser for a motor vehicle powered by two voltages

Info

Publication number: EP3515746A1
Application number: EP17768834.8A
Authority: EP
Inventors: Jonathan FOURNIER; Mickael Bigey; William LAPIERRE
Original assignee: Valeo Systemes Thermiques SAS
Current assignee: Valeo Systemes Thermiques SAS
Priority date: 2016-09-23
Filing date: 2017-08-25
Publication date: 2019-07-31
Also published as: FR3056709A1; FR3056709B1; WO2018055250A1; US20190379200A1

Abstract

The invention relates to an air pulser (1) for a motor vehicle, designed to be powered by a first voltage (U1) and a second voltage (U2), according to which the air pulser (1) comprises: a first interface (I48) for connecting to a power supply network (G48) supplying the second voltage (U2); a second interface (ILW) for connecting to a communication bus (BLW); a functional module (11) connected to the first connection interface (I48); a main switch (Q2) connected to the functional module (11), designed to enable signals (DAT) to travel through the communication bus (BLW); and a first protection module (10) for isolating the communication bus (BLW) from the power supply network (G48) when there is an overvoltage (USS) between the functional module (11) and the second connection interface (ILW).

Description

AIR PULSE FOR MOTOR VEHICLE POWERED BY TWO

TENSIONS

DOMAI N E TECH N I A L OF THE I NVE NTI ON

The present invention relates to an air blower for a motor vehicle adapted to be powered by a first voltage and a second voltage.

It finds a particular application, but not limited to motor vehicles.

I NV E NTI ON I N A T I N A T I N A T IO N E R T

In the field of air blowers for a motor vehicle, it is known to supply an air blower with two voltages, one being a high voltage adapted for driving loads of the blower and the other being a lower voltage adapted for current control elements in the driving loads. The motor loads and the control elements are part of the same functional module. For this purpose, the air blower comprises a communication bus on which air flow instructions can be sent to it and a connection interface with a power supply network, said high power power supply network, which provides strong tension. The communication bus is powered by the same power supply network as the control elements.

A disadvantage of this state of the art is that if a problem, such as a short circuit in a non-limiting example, occurs in the functional module comprising said control elements, there is a risk that the high voltage supplied by the high power power network is found on the communication bus, creating a dangerous voltage, called surge, which may damage it. In this context, the present invention aims to solve the aforementioned drawback.

I NV E NTI ON G ENERAL C OMMITTEE

To this end, the invention proposes an air blower for a motor vehicle adapted to be powered by a first voltage and a second voltage, according to which the air blower comprises:

a first connection interface with a power supply network adapted to supply the second voltage;

a second connection interface with a communication bus; a functional module connected to the first connection interface;

a main switch connected to the functional module adapted to pass signals on the communication bus;

a first protection module adapted to isolate the communication bus from the power supply network when there is an overvoltage between the functional module and the second connection interface.

Thus, as will be seen in detail below, the first protection module will detect an overvoltage between the functional module and the second connection interface, and will disable the main switch so that it is open following the detection of such an overvoltage. This will result in disconnecting the power supply network from the communication bus. The latter will therefore not be impacted by said overvoltage and will therefore be protected.

According to non-limiting embodiments, the air blower may further comprise one or more additional characteristics from the following:

According to a non-limiting embodiment, the first protection module comprises:

an overvoltage detection module comprising: - a protection diode;

a first protective switch adapted to close when the protective diode becomes conducting;

a secondary switch adapted to open when said overvoltage exists so as to open the main switch;

- A second protective switch adapted to open when the first protective switch closes so as to open the secondary switch.

Opening the secondary switch prevents currents flowing from the power supply network to the communication bus. This makes it possible to protect the communication bus against an overvoltage.

According to a non-limiting embodiment, the signals are low logic signals.

According to a non-limiting embodiment, the low logic signals are 0 volt signals.

According to a non-limiting embodiment, said overvoltage is generated by a short circuit in the power supply network.

According to a non-limiting embodiment, the air blower further comprises a protective diode adapted to protect the communication bus if the first voltage is greater than a threshold voltage of said protection diode. This makes it possible to protect said communication bus.

According to a non-limiting embodiment, the air blower further comprises a secondary non-return diode adapted to prevent a current flowing in the second protective switch. This protects said second protective switch.

According to a non-limiting embodiment, the air blower further comprises a main return resistance adapted to ensure the opening of the main switch when said overvoltage. According to a nonlimiting embodiment, the air blower further comprises a secondary resistor adapted to ensure the opening of the secondary switch when said overvoltage.

According to a non-limiting embodiment, the air blower further comprises a base resistor adapted to ensure the closure of the secondary switch when a current flows in said secondary switch.

According to a non-limiting embodiment, the air blower further comprises a self-resettable fuse adapted to protect the communication bus against an overcurrent. This makes it possible to protect said communication bus.

According to a non-limiting embodiment, the air blower further comprises a tertiary anti-return diode adapted to ensure that the main switch remains open.

According to a non-limiting embodiment, the air blower further comprises a protection diode adapted to protect the main switch against an increase of said first voltage. This prevents it from being damaged.

According to a non-limiting embodiment, the first voltage is lower than the second voltage.

According to a non-limiting embodiment, the first voltage is substantially equal to 12Volts.

According to a non-limiting embodiment, the second voltage is substantially equal to 48Volts.

According to a non-limiting embodiment, the first voltage is generated from the second voltage. It is therefore fixed and does not undergo variations from a battery voltage for example.

According to a non-limiting embodiment, the air blower comprises a voltage regulator adapted to generate the first voltage from the second voltage. According to a non-limiting embodiment, the communication bus is a LIN bus or a PWM bus. A LIN bus allows you to use only one wire for sending and receiving signals. Thus, only one wire is used for two different functions, namely a diagnostic function and a setpoint function. It is also possible to use any other type of communication bus that makes it possible to have bidirectional communication. A PWM bus is used to receive or send signals with a controlled duty cycle.

According to one nonlimiting embodiment, the functional module comprises a control module adapted to be powered by the first voltage and to receive and / or transmit signals via the communication bus. The functional module can thus exchange information with another electronic device via its control module. It can send diagnostic information and receive set information.

According to one nonlimiting embodiment, the functional module comprises at least one driving load powered by the second voltage and at least one associated driving element powered by the first voltage, said driving element being adapted to drive said at least one driving load. . In particular, said control element is adapted to control the current of said driving load.

According to a non-limiting embodiment, the first connection interface is connected to a common ground, and the air blower further comprises a second protection module adapted to isolate the communication bus from the power supply network when a loss of the common mass.

According to a non-limiting embodiment, the second protection module the second protection module comprises:

- said secondary switch;

said second protective switch;

said secondary anti-return diode. Thus, a portion of the components of the first protection module is used to protect the communication bus against a common loss of mass. This reduces the cost and complexity of the architecture of the air blower 1 for the protections.

The invention also applies to an electric heating device for a motor vehicle. Thus, according to a non-limiting embodiment, it is also proposed an electric heater for a motor vehicle adapted to be powered by a first voltage and a second voltage, wherein the electric heating device comprises:

a second connection interface with a communication bus;

a functional module connected to the first connection interface;

BRIEF DESCRIPTION OF THE FIGURES

The invention and its various applications will be better understood on reading the following description and examining the figures that accompany it:

FIG. 1 represents a diagram according to a non-limiting embodiment of the invention of an air blower for a motor vehicle, said blower being supplied by a first and by a second voltage and connected to a bus of communication and comprising a first overvoltage protection module and a second protection module against loss of mass; - Figure 2a shows a diagram of the air blower of Figure 1 with the detail of the electronic components of the first protection module according to a non-limiting embodiment;

- Figure 2b shows a diagram of the air blower of Figure 1 with the detail of the electronic components of the second protection module according to a non-limiting embodiment;

- Figure 3 shows a diagram of the air blower of Figure 1 when there is a short circuit in the power supply network according to a non-limiting embodiment;

- Figure 4 shows a diagram of the air blower of Figure 1 when the mass is lost according to a non-limiting embodiment;

- Figure 5 shows a diagram of the air blower of Figure 1 when it receives signals from another electronic device, according to a non-limiting embodiment;

- Figure 6 shows a diagram of the air blower of Figure 1 when it sends signals to another electronic device, according to a non-limiting embodiment.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Identical elements, structure or function, appearing in different figures retain, unless otherwise specified, the same references.

The air blower 1 for a motor vehicle is described with reference to Figures 1 to 6 according to a non-limiting embodiment.

By motor vehicle, we mean any type of motorized vehicle.

In a non-limiting embodiment, an air blower 1 is used in an air conditioning, ventilation and / or heating device (not shown), called in English HVAC "Heating Ventilation and Air Conditioning", for a motor vehicle or for cooling the motor (not shown) of the motor vehicle. The air blower 1 is powered by a first voltage U1 and a second voltage U2. The first voltage U1 is generated from the second voltage U2. A G48 power supply network is adapted to provide the second voltage U2. In the remainder of the description, the terms power supply network and network will be used interchangeably.

As illustrated in FIG. 1, the air blower 1 comprises:

a first I48 connection interface with the G48 power supply network;

a second ILW connection interface with a BLW communication bus;

a functional module 1 1 connected to the first connection interface I48;

a main switch Q2 connected to the functional module 1 1 and adapted to pass DAT signals on the communication bus BLW; - A first protection module 10 adapted to isolate the BLW communication bus of the G48 power supply network when there is a USS overvoltage between the functional module 1 1 and the second ILW connection interface.

The air blower 1 is part of a NLW communication network.

In a non-limiting example, a USS overvoltage appears between the functional module 1 1 and the second connection interface ILW, when there is a short circuit CC in the functional module 1 1.

Such a short circuit CC is taken as a non-limiting example in the following description. In the following description, a DC short circuit in the functional module 1 1 will also be simply cited as short circuit DC. It will be noted that when a DC short circuit occurs in the functional module 1 1, it means that the elements of the functional module 1 1 whose DLW control module will be defective are destroyed.

As will be seen in detail below, during a short circuit DC on the functional module 1 1 which generates such overvoltage USS, all the components of the functional module 1 1 rise to the potential of the second voltage U2 supplied by the power supply network G48. This causes the appearance of potential differences and consequently of currents flowing between said functional module 1 1 and:

the first protection module 10;

- the BLW communication bus.

These currents and voltages can damage in particular the BLW communication bus. The first protection module 10 makes it possible to protect the communication bus BLW against said currents and voltages. In particular, the first protection module 10 will make it possible to isolate the second connection interface ILW and consequently the communication bus BLW from a dangerous voltage, namely of said overvoltage USS. Indeed, this second ILW connection interface which is dimensioned for a low voltage (here 12V) can not withstand too great a voltage, for example greater than 40V.

The first protection module 10 comprises:

an overvoltage detection module 100 comprising:

a protection diode D1;

a first protective switch Q1;

a secondary switch Q6;

- a second protection switch Q4.

As described in detail below, when there is a DC short circuit that causes a USS overvoltage, the first protective switch Q1 will close which will cause the opening of the second protective switch Q4. The opening of the second protective switch Q4 will cause the opening of the secondary switch Q6. Finally, the opening of the secondary switch Q6 will cause the opening of the main switch Q2. Opening the main switch Q2 will isolate the second ILW connection interface G48 network and therefore isolate the BLW communication bus network G48. The communication bus BLW is thus protected from said overvoltage USS. In a non-limiting embodiment, the air blower 1 further comprises a protection diode D7.

In a non-limiting embodiment, the air blower 1 further comprises a main return resistor R7.

In a non-limiting embodiment, the air blower 1 further comprises a secondary return resistor R15.

In a non-limiting embodiment, the air blower 1 further comprises a secondary anti-return diode D1 1.

In a non-limiting embodiment, the air blower 1 further comprises a base resistor R14.

The different elements of the air blower 1 are described in more detail below.

• Inî.erfaces.de connection .148,. J LW _l . ! GND

The first connection interface 148 is adapted to connect the air blower 1 with the G48 power supply network. It is an input that can receive a voltage supplied by the G48 power supply network.

The network G48 is connected to a battery (not shown) of the motor vehicle which is a voltage generator.

In a non-limiting embodiment, the first voltage U1 is lower than the second voltage U2.

In a non-limiting embodiment, the first voltage U1 is substantially equal to 12V (volts). It is a low power voltage. In a non-limiting embodiment, the second voltage U2 is substantially equal to 48V (volts). It is a high power voltage. The G48 network is also called a high power network.

Note that a battery, connected to the G48 network, which usually provides a voltage of 48V can provide a voltage that can go up to 58V. In a non-limiting embodiment, the first voltage U1 is generated from the second voltage U2. For this purpose, in a non-limiting embodiment, the air blower 1 further comprises a voltage regulator. More particularly, the functional module 1 1 comprises said voltage regulator. In non-limiting variants, the voltage regulator is a DC / DC converter (illustrated in FIGS. 2a and 2b) or a linear regulator adapted to perform the conversion from 48V to 12V.

A DC / DC converter or a linear regulator being known to those skilled in the art, they are not described here. The DC / DC converter or the linear regulator thus make it possible to provide a first voltage U1 which is fixed, ie which does not undergo variations due to variations of a battery voltage, since said first voltage U1 is generated internally.

In the remainder of the description, we will speak indifferently of first voltage U1 or voltage U1, and second voltage U2 or voltage U2.

In the following description, the voltages of 12V for the voltage U1 and 48V for the voltage U2 will be taken as non-limiting examples.

In a non-limiting embodiment, the first connection interface I48 is connected to a ground GND, also called GND common ground.

It is connected by a ground cable CX (shown in Figure 1 for example) to said GND common ground.

The second ILW connection interface is adapted to connect the air blower 1 with a BLW communication bus. It's an entrance.

The connection interfaces I48, ILW thus comprise electrical connections adapted to make the connections respectively to the power supply network G48 and the communication bus BLW.

In a first non-limiting embodiment, the communication bus BLW is a LIN communication bus ("Local

Internetconnect Network "). The air blower 1 is part of a communication network NLW said LIN. A LIN communication bus is a bus from bidirectional communication. Thus, a LIN communication network makes it possible to use only one wire for the communication of the signals.

In a second non-limiting embodiment, the communication bus BLW is a PWM communication bus ("Puise Modulation Width"). The air blower 1 is thus part of a NLW communication network called PWM. A PWM communication bus is a unidirectional bus. Thus, in this case, the air blower 1 comprises two unidirectional PWM communication buses, one being used for receiving signals, and the other being used for sending signals.

The communication bus BLW makes it possible to convey DAT signals from the air blower 1 to an external electronic device 2 (described below) and / or from the external electronic device 2 to the air blower 1. It will be noted that there exists an internal LLW communication line to the air blower 1 (illustrated in FIG. 1 for example) between the functional module 1 1 and the second connection interface ILW over which said signals of the functional module 1 1 pass. . In a non-limiting embodiment, this communication line is an electronic track.

As illustrated in Figure 1 also, in a non-limiting embodiment, the air blower 1 further comprises a mass interface IGND. The IGND mass interface is an output. It will be noted that in a nonlimiting example, the ground cable CX connects the ground interface IGND to the chassis of the motor vehicle which forms a ground plane.

In a non-limiting embodiment, the first protection module 10, the functional module 1 1 and the main switch Q 2 are part of the same printed circuit board, called PCBA card (in English "Printed Circuit Board Assembly") . This PCBA printed circuit board is thus connected to the ground plane formed by the chassis of the motor vehicle.

As illustrated in Figure 1, in a non-limiting embodiment, the second ILW connection interface is part of a BNLW connector.

As illustrated in FIG. 1, in a non-limiting embodiment, the first connection interface I48 and the ground interface IGND make part of the same BN48 connector. This makes it possible not to multiply the connectors.

• I. Π î.e. rru pte _: ur pr in cipaj. Q2

The main switch Q2 is adapted to pass DAT signals on the communication bus BLW.

For this purpose, it is connected to the BLW communication bus via the second ILW connection interface. It is arranged between the communication bus BLW and the functional module 1 1, in particular its DLW control module (described below).

In a non-limiting embodiment, the main switch Q2 is a MOSFET transistor. In a non-limiting variant embodiment, it is an N-channel transistor. In this case, the gate G of the transistor receives the first voltage U1, namely the voltage of 12V in the non-limiting example taken, the source S is connected to the BLW communication bus via the second ILW connection interface, and the drain D is connected to the DLW control module.

The main switch Q2 has a threshold voltage Vgsth.

The main switch Q2 is closed when its voltage Vgs is equal to the voltage U1 provided by the first network G12, namely here 12V. When the DAT signals flowing on the communication bus BLW are at 0V in a non-limiting embodiment, the drain D and the source S are at potential 0V. Since the gate G is powered by the voltage U1 of 12V, the voltage Vgs is therefore at 12V. Vgs being greater than a threshold voltage Vgsth, the main switch Q2 closes well. In a non-limiting example, Vgsth = 2V.

In a non-limiting embodiment, the main switch Q2 comprises a breakdown voltage greater than 48Volts. In a non-limiting embodiment variant, the breakdown voltage is substantially equal to 100Volts. The main switch Q2 thus supports the voltage U2, here 48V, which it receives (in particular between the source S and the drain D in the mode of non-limiting embodiment of the MOSFETS) during a USS overvoltage or when the GND common ground is lost.

The main switch Q2 is open when the voltage Vgs is lower than the voltage Vgsth, that is when Vgs is substantially equal to 0V in a non-limiting example. As we will see below, the main switch Q2 opens:

thanks to the first protection module 10 when there is a USS overvoltage; and

thanks to the second protection module when the common ground GND is lost.

Thus, as will be seen later in the description, the first protection module 10 makes it possible to protect the communication bus BLW against an overvoltage USS, while the second protection module 20 makes it possible to protect the communication bus BLW against a GND common mass loss.

° Period of protection. D3

In a non-limiting embodiment, the air blower 1 further comprises a protection diode D3 associated with the main switch Q2, illustrated in Figure 2a or 2b.

It is arranged in parallel with the main return resistor R7 (described later) and the tertiary anti-return diode D6 (described later). Its anode A is connected to the source S of the main switch Q2 and its cathode K is connected to the gate of the main switch Q2.

This protection diode D3 is adapted to protect the main switch Q2 against an increase of the first voltage U1, in particular against a too high voltage between its gate G and its source S. Indeed, if a fault occurs on the node N1 , the first voltage U1 that it provides can greatly increase and end up on the gate-source voltage VGS of the main switch Q2 so as to damage it. In a non-limiting example, a fault can occur in the case of a fault of the alternator or the starter of the motor vehicle. In a non-limiting embodiment, the protective diode D3 is a Zener diode. The Zener diode D3 comprises a threshold voltage VS3. If the voltage V _G s of the main switch Q2 becomes greater than or equal to this voltage VS3, the Zener diode closes said voltage V _G s so that it is equal to the threshold voltage VS3. Thus, in a non-limiting example, the threshold voltage VS3 is equal to 20V. The main switch Q2 is thus protected.

° Fusj.bJ.e _" autp-jéarmapJe R6

In a non-limiting embodiment, the air blower 1 further comprises a self-resetting fuse R6 illustrated in Figure 2a or 2b.

This self-resetting fuse R6 is arranged in series with the main switch Q2, in particular between said main switch Q2 and the communication bus BLW.

It is suitable for protecting the BLW communication bus against overcurrent. An overcurrent is a current that is too strong and that said BLW communication bus can not support.

Indeed, during the linear regime of the main switch Q2, namely during the switching phase, the main switch Q2 behaves like a resistor. However, when there is a DC short circuit which generates an overvoltage USS, there is a potential difference between the drain D (V _D = 48V) and the source S (V _s = 0V when the DAT signals are emitted). generates a current (not shown) of the order of a few amperes. This current, called sur-courant, is dangerous because the BLW communication bus does not support this level of over-current. This may damage said BLW communication bus or cut communications between the external electronic module 2 (described below) and the functional module 1 1 of the air blower 1.

When an overcurrent is generated and passes through the self-resetting fuse R6, the latter heats up and opens, thus preventing said current from crossing the communication bus BLW. When new normal conditions are reached (there is no more overcurrent), the auto-resettable fuse R6 closes. o Anti-return diode ertiajre.D6

In a non-limiting embodiment, the air blower 1 further comprises a tertiary anti-return diode D6 (shown in Figure 2a or 2b) adapted to ensure that the main switch Q2 remains open.

The tertiary anti-return diode D6 is arranged in series with the main return resistor R7. Its anode A is connected to the gate G of the main switch Q2 and its cathode K is connected to the source S of the main switch Q2 via the main return resistor R7.

When the main switch Q2 is open, there is the source voltage V _s = 0V or 12V respectively if the DAT signals are emitted or not. When V _s = 12V, this voltage of 12V can be found on the gate voltage V _G , namely node N4 shown in Figure 2a or 2b.

If the voltage V _s returns to 0V (DAT signals are emitted), the voltage of the source V _s is found on the grid voltage V _G , but the latter does not return immediately to 0V due to the parasitic capacitances of the main switch Q2. Thus, for a very short period, V _G s may be greater than the threshold voltage Vgsth of the main switch Q2. For example, we have V _G = 2.5V and V _s = 0V. This has the effect of turning on the main switch Q2. Thus, the main switch Q2 may close when it should remain open.

With the tertiary anti-return diode D6, when it is blocked, this prevents the source voltage V _s from being found on the gate voltage V _G. This ensures that the main switch Q2 remains open. This prevents the main switch Q2 from closing when it is open.

The tertiary anti-return diode D6 is blocked when the potential difference V _A K <VS6, with VS6 the threshold voltage of the tertiary anti-return diode D6. In a non-limiting example VS6 = 0.6V. It will be noted that the main switch Q2 opens when the secondary switch Q6 opens. When the secondary switch Q6 opens, the node N5 illustrated in FIG. 2a or 2b is at OV and when the voltage V _s = OV (when the DAT signals are emitted) of the main switch Q2, there is the voltage at the anode A of the tertiary diode D6 V _A = 0V and the voltage at the cathode K of the diode D6 V _K = 0V (the cathode K being connected to the source S). This has the consequence that the tertiary anti-return diode D6 is blocked.

• Functional module

The functional module 1 1 is connected to the first connection interface I48 via the BN48 connector previously seen. It can thus be powered by the second voltage U2 provided by the G48 network.

In a non-limiting embodiment, the functional module 1 comprises a voltage regulator, here a DC / DC converter, adapted to convert the second voltage U2 to the first voltage U1. The functional module 1 1 is thus also powered by the first voltage U1.

The functional module 1 1 is also connected to the GND common ground via the BN48 connector.

An electrical node N1, called the first node, connects the functional module 1 1 to the second connection interface ILW via the secondary switch Q6 and the main switch Q2 described below.

The functional module 1 1 comprises a DLW control module described below (called "electronic driver").

An electrical node N2, called the second node, connects the functional module 1 1, in particular its control module DLW, and the main switch Q2 via the communication line LLW.

An electrical node N3, called the third node, connects the functional module 1 1 and the first protection module 10 at the common ground GND.

The third node N3 is thus connected to the common ground GND via said functional module 1 1.

In the remainder of the description, an electrical node is also called a node. When a DC short-circuit occurs that causes a USS overvoltage, the 1 1 functional module rises to the 48V potential.

This implies a USS overvoltage at the N1, N2 and N3 electrical nodes that can rise to 48V. It will be noted that the overvoltage USS can arrive on one, two, or all of these nodes N1, N2, N3.

At the first node N1, a potential difference of 48V-12V appears (between the first node N1 and the second connection interface ILW) which causes the appearance of the current 11 (shown in Figure 3) flowing from the functional module 1 1 to the BLW communication bus (via the second ILW connection interface) which may damage it as well as the second ILW connection interface. The first protection module 10 (in particular the protection diode D7) described below prevents such a current from circulating (via the secondary switch Q6) and thus protects the communication bus BLW and the second connection interface ILW. These are not damaged.

At the second node N2, on the drain side D of the main switch Q2 described below, a potential difference of 48V-0V or 48V-12V (between the second node N2 and the second connection interface ILW) appears. leads to the appearance of a current i2 (illustrated in FIG. 3) flowing from the control module DLW to the communication bus BLW (via the second connection interface ILW) which risks damaging it, as well as the second connection interface ILW. The first protection module 10 (in particular the protection diode D1) described below and the main switch Q2 prevent such a current i2 from circulating and thus protects the communication bus BLW and the second connection interface ILW. These are not damaged.

At the third node N3, a potential difference of 48V-0V between this third node N3 and the communication bus BLW (all the functional module 1 1 being mounted up to the potential of 48V) which causes the creation of a current i3 (illustrated in FIG. 3) between said third node N3 and said communication bus BLW. The first protection module 10 (in In particular, the secondary non-return diode D1 1) described below prevents such a current i3 from circulating and thus protects the communication bus BLW and the second connection interface ILW. These are not damaged.

In a nonlimiting embodiment, the functional module 1 1 comprises at least one driving load 1 10 (illustrated in FIG. 1 and 3) and at least one driving element 1 1 1 (shown in FIGS. 1 and 3) associated for driving the current in said at least one driving load 1 10.

Said driving load 1 10 is connected to the first connection interface 148. Thus in the nonlimiting example taken, the driving element 1 1 1 is powered by the low power voltage U1 of 12V and said driving load 1 10 is fed by the U2 high power voltage of 48V.

Said driving load 1 10 makes it possible to turn the motor of the air blower 1.

It will be noted that an air blower 1 comprises:

an electric motor adapted to be powered by the driving load 1 10;

a centrifugal type wheel mounted on an axis of the electric motor;

an engine support comprising a housing in which the electric motor can be housed.

All of these elements are configured to be mounted in an air conditioning, ventilation and / or heating device via said motor support.

In a non-limiting embodiment, a control element 1 1 1 is mounted on the motor support of the air blower 1. In another non-limiting embodiment, a control element 1 1 1 is mounted at a distance from the air blower 1 on or in the air conditioning, ventilation and / or heating device.

Such air blowers are known to those skilled in the art, they are not described in detail here.

In a non-limiting embodiment, a control element 1 1 1 comprises an electronic component such as a switch, which is in a non-limiting example, a MOSFET. It makes it possible to drive the current which supplies said driving load 1 10. The current control in motor loads is known to those skilled in the art, it is not described here. Conventionally, the air blower 1 comprises a plurality of control elements. A control element 1 1 1 cooperates with a DLW control module of the functional module 1 1 which sends DAT signals to it. A DLW control module can control one or more control elements 1 1 1.

The DLW control module is described below. o Steering module

As illustrated in FIGS. 1 to 6 on which the DLW control module is schematically illustrated, the DLW control module comprises a switch Q8 in series with a pulling resistor R8. It is connected to the main switch Q2 of the air blower 1.

The DLW control module is described below with reference to FIGS. 5 and 6 in its operating mode when:

- there is no short circuit DC and therefore when there is no overvoltage USS;

- the GND common ground is not lost.

For simplicity, the operating mode is described with a bidirectional BLW communication bus.

The DLW control module is adapted to be powered by the first voltage U1. It is thus connected to the voltage regulator of the functional module 1 1 and GND common ground via the functional module 1 1. It is connected to the voltage regulator via its pulling resistor R8 and GND common ground via its switch Q8.

The DLW control module is adapted to receive and / or transmit DAT signals via the BLW communication bus. It transmits the received signals DAT to the control element 1 1 1 of the functional module 1 1, said control element 1 1 1 interpreting these signals DAT so as to drive the motor loads 1 10. In a non-limiting embodiment, said air blower 1 is adapted to operate in slave mode, it forms a slave module. As illustrated in FIGS. 5 and 6, the DLW control module is adapted to receive and transmit DAT signals on the communication bus BLW to and from an external electronic device 2 called the master module.

In a non-limiting embodiment, the DAT signals are low logic signals. In a non-limiting example, the low logic DAT signals are 0V signals. Note that in the case of the LIN protocol, the low logic signals are so-called dominant signals.

When the switch Q8 is open (FIG. 5), the pulling resistor R8 brings the drain D of the main switch Q2 of the slave module 1 to 12V. When the switch Q8 is closed (FIG. 6), the switch brings the drain D of the main switch Q2 of the slave module 1 to the common ground GND.

The external electronic device 2 operates in master mode and comprises a switch Q9 and a pulling resistor R9. The master module 2 is powered by a low power voltage.

The master module 2 is connected to a low-power power supply network via its pulling resistor R9 and to the GND common ground via switch Q9.

When the switch Q9 is open (FIG. 6), the pulling resistor R9 brings the communication bus BLW to 12V, which causes the source S of the main switch Q2 of the slave module 1 to be 12V. When the switch Q9 is closed (FIG. 5), the switch brings the communication bus BLW to ground, which causes the source S of the switch Q2 of the slave module 1 to be at 0V.

Note that by default (ie when the air blower 1 is powered or not) switches Q8 and Q9 are open. This corresponds to their initial state. The LIN protocol and the master-slave operation prevent them from closing at the same time. Note that for the PWM protocol which is unidirectional, it is not possible to have such collisions. A slave module 1 and the master module 2 form a communication network NLW. In a non-limiting embodiment, the communication network NLW can comprise a plurality of slave modules 1. In a non-limiting embodiment, the switches Q8 and Q9 are NPN switches.

In a non-limiting embodiment, the master module 2 is the engine control ECU of the motor vehicle or an electronic device connected to the dashboard of the motor vehicle.

In this case, the DAT signals are in a non-limiting example:

- Air flow instructions sent from the master module 2 to the air blower 1; and

- diagnostic information sent to the master module 2 by the air blower 1. In non-limiting examples, this information indicates short-circuits, overvoltages, under-voltages, over-temperatures, faulty equipment, the electrical consumption of the air blower 1 etc.

As illustrated in FIGS. 5 and 6, the master module 2 is powered by a voltage of 12V in the nonlimiting example taken as illustrated in FIGS. 5 and 6.

FIG. 5 illustrates the sending of DAT signals from the master module 2 to the air blower 1 and FIG. 6 illustrates the sending of DAT signals of the air blower 1 to the master module 2.

When the master module 2 communicates with the slave module 1, it sends DAT signals to it. For this purpose, the switch Q9 switches so that signals 0V (corresponding to a logic signal 0) or 12V (corresponding to a logic signal 1) are sent on the communication bus BLW to the slave module 1. When the switch Q9 closes, a logic signal 0 is sent, when the switch Q9 opens, a logic signal 1 is sent. Switch Q8 always remains open.

When the slave module 1 responds to the master module 2, the switch Q8 switches so that 0V signals (corresponding to a logic signal 0) or 12V (corresponding to a logic signal 1) are sent on the communication bus BLW to the master module 2. When the switch Q8 closes, a logic signal 0 is sent, when the switch Q9 opens, a signal logic 1 is sent. Switch Q9 remains open to him.

Thus, as illustrated in FIG. 5, when the master module 2 sends DAT signals to the air blower 1, it imposes a zero on the communication bus BLW (in the case where the DAT signals are of low logic) , the latter then being at GND ground potential. For this purpose, it closes its switch Q9. On the source S, there is therefore 0V and on the gate 12V (since the main switch Q2 receives on its gate G 12V of the connection interface 112). The voltage Vgs of the main switch Q2 is equal to 12V (and therefore greater than a threshold voltage Vgsth) which causes that said main switch Q2 is closed. The DAT signals therefore arrive at the input of the DLW control module.

As illustrated in FIG. 6, when the slave module, here the air blower 1, sends DAT signals to the master module 2, it imposes a zero (in the case where the DAT signals are of low logic) on the drain D of the main switch Q2. For this purpose, the slave module 1 closes its switch Q8. The switch Q8 is closed, the drain D is at ground potential GND, ie at 0V.

It will be noted that the communication network NLW comprises a master module 2 and may comprise a plurality of slave modules 1, at least one slave module of which is powered by the first voltage U1 and the second voltage U2. The other slave modules 1 can be powered in the same way or only by the first voltage U1.

It will be noted that the communication bus BLW makes it possible to route DAT signals from the master module 2 to all the slave modules 1. Thus, if a DC short circuit occurs which generates an overvoltage USS on the air blower 1 described above which is a slave module, it disconnects from the communication network NLW thanks to the first protection module 10, but the module master 2 and the other slave modules 1 continue to operate without being disturbed by the faulty slave module (the one that has been overvoltage). The NLW communication network is thus protected from a USS overvoltage on one of its slave modules 1.

Thus, by protecting the communication bus BLW, one also protects the other slave modules 1 which have not undergone overvoltage USS.

Thus, the first protection module 1 0 prevents:

the destruction of the other slave modules 1; or

- the disturbance of the communication between the other slave modules and the master module 2.

° PiQds.de.rgute Jjbre D2

Note that as shown in Figures 5 and 6, in a non-limiting embodiment, the main switch Q2 comprises a freewheel diode D2 (called "body diode").

The freewheeling diode D2 is adapted to ensure the closing of the main switch Q2.

The freewheeling diode D2 is arranged between the drain D and the source S of the main switch Q2.

When the drain D is at 0V, the freewheeling diode D2 becomes conducting.

It is recalled that a freewheeling diode is conducting when the voltage V _A K equal to the potential difference between V _at its anode A and V _k its cathode K is greater than or equal to a threshold voltage VS2 (given by the manufacturer) . In a non-limiting example, VS2 = 0.6V.

Thus, when the drain D is at 0V, the voltage V _k is at 0V. Furthermore, V _A is at 1 2V since before the switch Q8 closes, the source of the main switch Q2 was at 1 2V (thanks to the pull resistance R9 seen previously). Thus, there is V _A K which is equal to 12V, ie greater than 0.6V. The freewheeling diode D2 when conducting imposes 0.6V on the source S of the main switch Q2, and raises the voltage Vgs from 0V (when Q2 is open, Vgs = 0V) to 1 1, 4V ( 12V-0.6V). This voltage value Vgs is sufficient for the main switch Q2 to close. When it closes, connects its drain voltage D to its source S so that Vds is substantially equal to OV (at a resistance Rdson near) and the voltage Vgs is substantially equal to 1 2V. Thus, the DAT to OV signals arrive at the input of the master module 2.

The freewheeling diode D2 thus makes it possible to close the main switch Q2 correctly. In the opposite case, the source S would remain at the potential of 1 2V and the gate being at 12V, one would have Vgs <Vgsth and said main switch Q2 would remain open. It is recalled that in a non-limiting example, Vgsth = 2V.

Note that when the main switch Q2 is open (blocked state) (for example during a USS overvoltage or a GND common ground loss as described below), it is not controlled and Vgs <Vgsth is Vgs = 0V in a non-limiting example and V _A K ≠ OV (V _A K can go up to 48V) and the freewheeling diode D2 returns to a blocked state. It will be noted that the freewheeling diode D2 is not destroyed by this high voltage since the breakdown voltage of the main switch Q2 is greater than 48V.

Note that if there is no overvoltage USS, and when the switches Q8 and Q9 are open (default), the gate G and the source S of the main switch Q2 are 1 2V, we have V _gs = 0V. The main switch Q2 is then open. Similarly, if the common ground GND is correctly connected and the switches Q8 and Q9 are open (default), the gate G and the source S of the main switch Q2 are at 1 2V, we have V _gs = 0V. The main switch Q2 is then open. · Diode of prpteptipn.D7

In a non-limiting embodiment, the air blower 1 further comprises a protection diode. D7.

The protection diode _. D7 comprises a threshold voltage VS7. In a non-limiting embodiment, the threshold voltage VS7 is equal to 22V.

D7 protection diode is suitable for protecting the BLW communication bus as well as the second ILW connection interface against a dangerous increase of the voltage U1, in particular if the voltage U1 on the node N1 is greater than or equal to its threshold voltage VS7. Indeed, there may be failures in the power supply network G48 that can cause failures in the voltage regulator. This has the consequence that the voltage U1 generated by said voltage regulator rises strongly in potential.

Similarly, there may be faults directly in the voltage regulator (DC / DC converter or linear regulator) which can also cause the voltage U1 generated by said voltage regulator to rise significantly in potential. This rise in potential can damage the communication bus BLW if it is too big.

The protection diode D7 is connected between the emitter E of the first protective switch Q1 and the emitter E of the secondary switch Q6. The protection diode _. D7 is adapted to close the first protective switch Q1 when the voltage U1> VS7.

In a non-limiting embodiment, the protection diode .D7 is a Zener diode. If the voltage U1 is greater than or equal to its threshold voltage VS7, the Zener diode D7 becomes conducting. A current i7 (illustrated in FIG. 2a) then passes through said Zener diode D7. This current i7 supplies the first protective switch Q1 which closes.

Closing the first protective switch Q1 causes the opening of the second protective switch Q4. This opening causes the opening of the secondary switch Q6 and therefore the opening of the main switch Q2 as described below. The BLW communication bus is protected.

As seen above, when the regulation of the voltage U1 is no longer ensured, there is a potential rise up to 48V and on the node N1 there is a potential difference of 48V-0V (0V corresponding to the signals DAT). At that moment U1> VS7. This potential difference causes the appearance of a current il which could flow from the functional module 1 1 to the communication bus BLW (via the secondary switch Q6 and via the second ILW interface) and damage it. Or if U1> VS7, the protection diode D7 can open the secondary switch Q6 as seen above. The secondary switch Q6 thus prevents the current 11 from circulating towards the communication bus BLW. The current will go back to the functional module 1 1.

• Pre.Hier ..i "Protection" .10

The first protection module 10 is illustrated in detail in FIG. 2a.

The first protection module 10 is adapted to isolate the communication bus BLW from the power supply network G48 when there is a USS overvoltage between the functional module 1 1 and the second connection interface ILW.

Such overvoltage USS is found on the first node N1, on the second node N2 and on the third node N3.

It is recalled that an overvoltage USS exists when the voltage between the functional module 1 1 and the second connection interface ILW is greater than the voltage U1.

In a non-limiting embodiment, the first protection module 10 comprises:

an overvoltage detection module 100 comprising:

a protection diode D1;

a first protective switch Q1 adapted to close when the protection diode D1 becomes conducting;

a secondary switch Q6 adapted to open when there is such a surge USS so as to open the main power switch Q2;

- A second protective switch Q4 adapted to open when the first protective switch Q1 closes so as to open the secondary switch Q6.

The different elements of the protection module 10 are described in detail below. o Module of detection of

The overvoltage detection module 100 is illustrated in detail in FIG. 2a.

^■ P.iQde de roteçtj n. D1.

The protection diode D1 is arranged between the main switch Q2 and the first protective switch Q1. Its cathode K is connected to the drain D of the main switch Q2 and its anode A is connected to the base B of the first protective switch Q1 and GND common ground via a resistor R1 described below.

In a non-limiting embodiment, the protective diode D1 comprises a threshold voltage VS1 greater than the voltage U1, namely greater than 12 volts.

In a non-limiting example, the threshold voltage VS1 = 22V.

The protection diode D1 is on when V _A K≥ - VS1.

When there is a DC short circuit which generates an overvoltage USS, the voltage U1 0 (illustrated in FIGS. 2a, 2b and 3) on the second node N2 and therefore on the communication line LLW is equal to the overvoltage USS generated. by the short circuit DC and is therefore greater than the voltage U1 (equal to 1 2V in the non-limiting example taken). So we have Vk = U1 0 and V _A = 0V (because the anode is connected to the GND common ground via the resistor R1). We therefore have VKA = U1 0 and therefore V _K A≥22V. There is thus a current ΔKA which flows from the cathode K to the anode A of the protection diode D1. The protection diode D1 thus becomes conducting.

In a non-limiting embodiment, the protective diode D1 is a Zener diode. Thus, if the voltage U1 0 becomes greater than or equal to this voltage VS1, the Zener diode D1 closes said voltage U1 0 so that it is equal to the threshold voltage VS1.

When the protective diode D1 is on, this causes the closing of the first protective switch Q1 because the latter is in this case powered by the voltage U1 0. In this case, there is indeed the voltage on the base BV _B = U1 0 (clipped), the voltage on the emitter EV _E = 0V because the emitter E is connected to the GND common ground, and therefore V _B E = U10 (clipped), which is greater than the conduction threshold voltage of the protective diode D1. The protection diode D1 has thus made it possible to detect an overvoltage USS. It will be noted that the detection time of a USS overvoltage is of the order of one microsecond.

■ P. emjerjnJust switch _^ de.pro

The first protection switch Q1 is connected to the second protection switch Q4.

In a non-limiting embodiment, the first protective switch Q1 is a bipolar transistor. In a non-limiting embodiment, the bipolar transistor Q1 is of the NPN type. Its collector C is connected to the base B of the second protection switch Q4. The node N7 illustrated in FIG. 2a forms the connection between the base B of the second protective switch Q4, the collector C of the first protective switch Q1 and a resistor R3 illustrated in FIG. 2a. Moreover, its emitter E is connected to the GND common ground, and its base B is connected to the protective diode D1 and the resistor R1 (described later).

The resistor R3 makes it possible to apply to the collector C of the first protective switch Q1 the first voltage U1, namely 12V.

By default, the first protection switch Q1 is open.

When the first protective switch Q1 is open, the base B of the second protection switch Q4 is connected to 12V via a resistor R3. The resistor R3 in fact reduces the potential 1 2V on the base B of the second protection switch Q4. The resistor R3 makes it possible to drive the second protective switch Q4 and thus makes it possible to keep the second protective switch Q4 closed.

When the first protective switch Q1 closes, its emitter E is found at the GND common ground and the node N7 is therefore connected to the GND common ground. The base B of the second protective switch Q4 is then connected to the common ground GND. This has the consequence that there is no longer any circulating current Ib4 in the second protection switch Q4. The latter opens. It is no longer driven by resistance R3.

It will be noted that the first protective switch Q1 comprises an internal resistance between its base B and its emitter E and a basic internal resistance B. These internal resistances make it possible to close the first protective switch Q1 when the protective diode D1 becomes conducting. It will be noted that the fact of using internal return resistors makes it possible to save space.

It is recalled that the first protective switch Q1 closes when there is a DC short circuit and therefore a USS overvoltage as seen above.

^■ Resistance.RJ.

In a non-limiting embodiment, the first protection module 10 further comprises a resistor R1.

The resistor R1 is connected to the common ground GND and to the protective diode D1 seen previously.

The resistor R1 is adapted to operate the protection diode D1 so as to drive the first protective switch Q1 through its internal resistors. The resistor R1 allows a current to flow through the protective diode D1. Indeed, as seen above, when there is a DC short circuit, there is a potential difference across the protective diode D1, with V _K = U10 clipped and V _A = 0V. Thanks to the resistor R1, there is thus a current _{K K} A which flows from the cathode K to the anode A of the protective diode D1. The protection diode D1 thus becomes well.

It will be noted that the voltage across the resistor R1 is the clipped voltage U1 seen previously. In a non-limiting example, the current (not shown) passing through the resistor R1 and thus by the protective diode D1 is of the milliampere order. o Second switch.protection Q4

The second protection switch Q4 is adapted to open: - during a USS overvoltage; or

- during the loss of the GND common mass

so as to open the secondary switch Q6.

The second protection switch Q4 is connected to the voltage regulator which supplies the first voltage U1 via a resistor R3. Note that the second protective switch Q4 is not directly connected to the voltage regulator.

The resistor R3 is adapted to drive the second protection switch Q4. The resistor R3 is adapted to limit a current that could flow between the voltage regulator and the base B of the second protection switch Q4 in the event that the first protective switch Q1 closes. Indeed, in this case, without resistance R3, between the voltage regulator and the GND common ground, there would be a short circuit that would generate a current in the second protective switch Q4 a few thousand amperes. Said second protective switch Q4 could not withstand such a strong current. Resistor R3 thus makes it possible to protect said second protective switch Q4 by limiting the current flowing in its base B, referenced Ib4. The resistor R3 is thus sized to have a current Ib4 base B adapted to the second protective switch Q4. Similarly, the resistor R3 is adapted to limit a current that could flow between the voltage regulator and the base B of the first protection switch Q1. Resistor R3 is a so-called "pull-up" resistor.

The second protection switch Q4 is arranged between the first protective switch Q1 and the secondary switch Q6.

In a non-limiting embodiment, the second protective switch Q4 is a bipolar transistor. In a non-limiting embodiment variant, the bipolar transistor Q4 is of the NPN type. Its collector C is connected to the base resistor R14 (described below), its emitter E is connected to the GND common ground (via the secondary non-return diode D1 1 described below), its base B is connected to the collector C of the first switch protection Q1.

The third node N3 connects in particular the functional module 1 1 and the second protective switch Q4.

The second protection switch Q4 is closed by default. When closed, the second protection switch Q4 is controlled by the resistor R3. The second protective switch Q4 further comprises an internal resistor (illustrated but not referenced) located between its base B and its emitter E and an internal resistor resistor located between the resistor R3 and its base B. These internal return resistors with the resistor R3 make it possible to apply to the emitter E of the second protective switch Q4 the first voltage U1, namely 12V.

The fact of using internal return resistors saves space. The second protective switch Q4 is closed when the first protective switch Q1 is opened as previously seen.

The second protection switch Q4 opens when the first protective switch Q1 closes as previously seen.

When there is a DC short circuit, as seen above, a USS overvoltage is detected by the overvoltage detection module 100 (in particular the protection diode D1 or the protection diode D7), which causes the closing of the first switch Q1. At this time, the second protective switch Q4 opens because there is more current Ib4 flowing in the second protective switch Q4 as previously seen.

The opening of the second protection switch Q4 causes the base resistor R14 (described below) to be disconnected from the common ground GND. The base B of the secondary switch Q6 is no longer connected to the GND common ground, it becomes floating. The potential 12V is installed therefore. Indeed, thanks to the secondary resistor R15 (described later), the base B of the secondary switch Q6 rises to 12V. A potential difference is thus obtained between the emitter E and the base B which is zero V _B E = 0 (the emitter E of the secondary switch Q6 being at potential of 12V), which has the consequence of opening the secondary switch Q6.

Thus, when the second protective switch Q4 opens, it causes the opening of the secondary switch Q6, and therefore the opening of Q2 (as described below) so that the communication bus BLW is disconnected from the G48 power supply network. It is no longer disturbed by a DC short circuit and therefore by a USS overvoltage.

When GND common ground loss occurs, the emitter E of the second protective switch Q4 is floating. In this case, no current can pass in the emitter E. The current ie4 (not shown) in the emitter E is therefore zero. Since we have ie4 = ib4 + ic4 and ib4 and ic4 (not shown) can not be negative so ib4 = 0, so the second protection switch Q4 opens. The opening of the second protective switch Q4 causes the opening of the secondary switch Q6, the latter causing the opening of the main switch Q2 as described below. o Secondary switch Q6

The secondary switch Q6 is adapted to open:

- during a USS overvoltage; or

- during the loss of the GND common mass

so as to open the main switch Q2.

The secondary switch Q6 is closed by default.

In a non-limiting embodiment, the secondary switch Q6 is a bipolar transistor. In a non-limiting embodiment variant, the bipolar transistor Q6 is of the PNP type. Its base B is connected to the collector C of the second protection switch Q4, its emitter E is connected to the voltage regulator (here DC / DC), and its collector C is connected to the gate G of the main switch Q2.

When a DC short circuit occurs which causes an overvoltage USS, the base B of the secondary switch Q6 is open circuit, the second protection switch Q4 has been opened. Base B is floating (as previously described) because it is no longer connected to the GND common ground. We then have the base current Ib6 (current flowing in the base B of the secondary switch Q6) equal to 0, which causes the said secondary switch Q6 opens. It is said that he is in a secure state.

When a DC short circuit occurs which generates a USS overvoltage, the second node N2 rises to the potential 48V and a potential difference, here of 48V-0V (DAT signals are emitted) thus appears on the second node N2 and on the module control circuit DLW, which generates the current i2 which flows on the communication bus BLW via the main switch Q2 if the latter is closed and if DAT signals circulate on the communication bus BLW, said DAT signals being at 0V as described. previously. The DLW control module and the BLW communication bus do not support such a current i2 and may therefore be damaged. The secondary switch Q6 (which opened as previously seen following the detection of the overvoltage USS by the protective diode D1) opens the main switch Q2 and thus prevents such a current i2 to flow in the bus BLW communication (via the second ILW connection interface). The latter is thus protected as well as the second ILW connection interface.

Indeed, when the secondary switch Q6 opens, the main switch Q2, in particular its gate G (connected to the collector C of the secondary switch Q6) in the non-limiting example of the MOSFET, is no longer powered by the voltage U1, namely 12V, and therefore the potential of the gate G is equal to 0V. Indeed, the tertiary anti-return diode D6 prevents the main return resistance R7 from allowing a voltage to pass from the source S to the gate G.

Since the source S of the main switch Q2 is either at the potential of 12V or at the potential of 0V as a function of the switching of the switches Q8, Q9 described above, we have V _G s = -12V or V _G s = 0V, which which does not allow the closing of the main switch Q2 because V _G s is lower than the threshold voltage Vgsth of the main switch Q2 which is 2V in a non-example limiting. The main switch Q2 opens.

Thus there is more current i2 that flows on the communication bus BLW. The second ILW connection interface and the BLW communication bus are thus protected. By opening the main switch Q2 during a DC short-circuit and thus during a USS overvoltage, the G48 network was disconnected from the communication bus BLW.

During a GND common ground loss, the second protective switch Q4 opens as seen above, which causes the opening of the secondary switch Q6, it is in a blocked state. When the secondary switch Q6 opens, this opens the main switch Q2. By opening the main switch Q2 during the common ground loss GND, the G48 network was disconnected from the communication bus BLW.

• Resistance of. rappej.prinçip.aj.e R7

The return resistor R7 is adapted to guarantee the opening of the main switch Q2 when said main switch Q2 must open (during a USS overvoltage or when a common mass loss GND). The main return resistor R7 is connected to the cathode K of the tertiary diode D6 and to the source S of the main switch Q2. It is recalled that a resistor resets to initialize the state of the gate G of a switch.

By default, the applied control level (ie the value of the voltage applied) to the gate G of the main switch Q2 is undetermined (the grid does not see the voltage 12V or 0V). It is in a floating state, and could force it to enter conduction, either totally (with risk of erratic operation of the air blower 1), or partially (with risk of destruction of the main switch Q2).

When the air blower 1 is powered, and there is no fault such as a DC short circuit or GND common ground loss, the potential for the gate G of the main switch Q2 is 12V because the secondary switch Q6 is closed. When the secondary switch Q6 is closed, the node N4 (and the node N5) illustrated in Figure 2a is at the potential of the voltage U1, namely 12V in the example.

When the secondary switch Q6 opens (due to a USS overvoltage or GND common ground loss), the main switch Q2 opens. The node N4 corresponds to the gate voltage V _G of the main switch Q2. Node N4 (as well as node N5) becomes floating. There is therefore a potential difference between the source S (which is at OV because of the DAT signals) of the main switch Q2 and the node N4, ie the gate G of the main switch Q2. This potential difference generates a current (not shown) which will flow in the tertiary anti-return diode D6 and the main return resistor R7 and will go to the source S and the auto-resettable fuse R6. The node N4 (as well as the node N5) will thus descend to the potential OV of the source S. The resistor R7 allows the node N4 and thus the gate G of the main switch Q2 to be at OV quickly . This will have the voltage Vgs to OV which guarantees the opening of the main switch Q2.

The main return resistor R7 is a so-called pull-up resistor. · Resjstance of. rappeJ.secondaire.R.15.

The secondary resistor R15 is adapted to guarantee the opening of the secondary switch Q6 when said secondary switch Q6 must open (during a USS overvoltage or when a common mass loss GND).

The secondary resistor R15 is connected to the base B and to the emitter E of the bipolar transistor Q6.

The secondary return resistor R15 makes it possible to control the secondary switch Q6 when it opens when its base B is floating, namely when the second protective switch Q4 opens as described. previously. Indeed, this secondary resistor R15 can initialize the voltage V _B E of the secondary switch Q6 to OV (it is therefore by default to OV) which ensures the opening of the secondary switch Q6 when there is no current Ib6 flowing in the base B of said secondary switch Q6.

The secondary return resistor R15 is a so-called "pull-up" resistor.

• PjQde.antj.:retour.seco

The secondary anti-return diode D1 1 is adapted to prevent a current i3 from circulating in the second protective switch Q4. It thus ensures the protection of the second protective switch Q4 during a DC short-circuit.

The secondary non-return diode D1 1 is arranged between the functional module 1 1 and the second protective switch Q4. The third node N3 thus connects in particular the functional module 1 1 and the secondary anti-return diode D1 1. The secondary non-return diode D1 1 is connected to the common ground GND via the functional module 1 1. In particular, the anode A of the secondary anti-return diode D1 1 is connected to the emitter E of the second protective switch Q4, and its cathode K is connected to the common ground GND.

When there is a DC short circuit which generates an overvoltage USS, from the point of view of the emitter E of the second protection switch Q4, the node N3 rises to the potential of 48V (all the functional module 1 1 being mounted up to the potential of 48V), namely the emitter E is found at 48V. Therefore, there is a potential difference of 48V-12V between the emitter E of the second protective switch Q4 and its base B, the latter being at 12V (when the first protective switch Q1 is open). This therefore generates a current i3 which is found on the emitter E of the second protective switch Q4 and is too large for the second protective switch Q4. The second switch Q4 protection may then break. Therefore the protection of the main switch Q2 is no longer assured.

It is the same when the common mass GND is lost.

The secondary non-return diode D1 1 is adapted to prevent such a current i3 from circulating in the second protective switch Q4. It thus protects said second protective switch Q4.

The secondary anti-return diode D1 1 prevents the current i3 from passing when it is in a blocked state. For this purpose, the secondary anti-return diode D1 1 is in a blocked state when its voltage V _A K equal to the potential difference V _A at its anode A and V _K at its cathode K is less than its threshold voltage VS1 1 (given by the manufacturer). In a non-limiting example, VS1 1 = 0.6V. We have such a difference when there is a USS overvoltage. Indeed, in this case, there is V _A = 1 2V (the voltage 1 2V being applied to the emitter E of the second protective switch Q4 via the resistor R3 and its internal resistor located between its base B and its emitter E, transmitter E connected to the anode A of the secondary nonreturn diode D1 1) and V _K = 48V (the third node N3 being mounted up to the potential of 48V). So we have VAK negative <VS1 1.

When the secondary non-return diode D1 1 is blocked, there is no potential difference across the second protective switch Q4. Indeed, we have V _E = 1 2V (the voltage 12V being applied via the resistor R3 and its internal return resistance situated between its base B and its emitter E) and V _B = 1 2V (Q1 open, the node N7 is at 1 2V). We obtain V _EB = 0V. Note that it is the same when the common mass GND is lost.

It will be noted that the secondary anti-return diode D1 1 is conducting when V _A K> Vs. This is obtained when there is no short circuit CC. Indeed, in this case, there is V _A at potential 1 2V and V _k at the ground potential. Note that it is the same when the common mass GND is not lost. · RJ 4 base resistance

In a non-limiting embodiment, the air blower 1 comprises in besides a basic resistance R14.

The base resistor R14 is adapted to size the base current Ib6 which flows in the secondary switch Q6.

The base resistor R14 is arranged between the secondary switch Q6 and the second protective switch Q4. In particular, the base resistor R14 is connected to the base B of the secondary switch Q6 and to the collector C of the second protective switch Q4.

The basic resistance R14 makes it possible to drive the secondary switch Q6 on closing by means of the basic current Ib6 that it supplies. Indeed, the sizing of the base current Ib6 ensures the closure of the secondary switch Q6. In addition it avoids having a current Ib6 too important which could break the component Q6.

It is recalled that the threshold value of Ib6 for the secondary switch Q6 to close is Ib6> 1c / β, with the collector current and β the current amplification of the secondary switch Q6 given by the manufacturer of the secondary switch Q6.

• • • • • • • • • • •

The second protection module 20 is illustrated in detail in FIG. 2b. The second protection module 20 is adapted to isolate the communication bus BLW from the power supply network G48 during a loss of the common ground GND.

The GND common ground is lost when the ground connecting cable CX which connects the first connection interface 148 to the GND common ground is cut as shown in FIG. 4.

The second protection module 20 is part of the first protection module 10. In fact, it comprises:

the secondary switch Q6 described previously;

the second protection switch Q4 previously described;

the secondary anti-return diode D1 1 previously described;

the secondary return resistor R15 described above;

the basic resistance R14 described above. In a non-limiting embodiment, the second protection module 20 further comprises the main return resistor R7.

When the GND common ground is lost, all the components of the functional module 1 1 rise to the potential of the voltage U2 provided by the power supply network G48. This causes the appearance of potential differences and consequently of currents flowing between said functional module 1 1 and:

the second protection module 20;

- the BLW communication bus.

These currents may particularly damage the BLW communication bus. The second protection module 20 protects these elements against said currents as follows.

When the common ground GND is lost, the functional module 1 1 rises to the potential of 48V. The electrical nodes N1, N2 and N3 become floating because they are no longer referenced to the common ground. They then rise to the potential of 48V.

At the first node N1, a potential difference of 48V-12V appears (between the first node N1 and the second connection interface ILW) which causes the appearance of the current 11 (shown in Figure 4) flowing from the functional module 1 1 to the BLW communication bus (via the second ILW connection interface) which may damage it as well as the second ILW connection interface. The second protection switch Q4 cascades the secondary switch Q6 and the main switch Q2 (as previously described) which allows the secondary switch Q6 to prevent such a current from circulating.

At the second node N2, on the drain side D of the main switch Q2, a potential difference of 48V-0V (between the second node N2 and the communication bus BLW) appears which causes the appearance of a current i2 (shown in FIG. 4) flowing from the DLW control module to the communication bus BLW (via the second connection interface ILW) which risks damaging them. The second protection switch Q4 cascade the secondary switch Q6 and the main switch Q2 (as described above) which allows the main switch Q2 to prevent such a current i2 to flow in the communication bus BLW. The latter is thus protected as well as the second ILW connection interface.

Moreover, when the GND common ground is lost, the DLW control module is no longer referenced to ground. It rises to the potential of 48V (all the functional module 1 1 being mounted up to the potential of 48V). Without the second protection module 20, the DLW control module would see at its terminals a potential difference of 48V-0V which corresponds to the difference between the potential of 48V (applied to the functional module 1 1) and the potential of 0V of the DAT signals transmitted on the BLW communication bus. This potential difference causes the appearance of a current i2 (shown in Figure 4) flowing in said DLW control module which may damage it. Indeed, the DLW control module does not support such a significant difference in potential. In a non-limiting example, it supports a potential difference of less than or equal to 24V. The second protection switch Q4 cascades the secondary switch Q6 and the main switch Q2 (as previously described) which allows the main switch Q2 to prevent the current i2 from circulating when the common ground GND is lost, there will be no potential difference across the DLW control module and therefore more current flowing i2. The DLW control module will only be at 48V potential. It will not be damaged.

Thus, unlike a DC short circuit which occurs in the functional module 1 1 where the DLW control module will surely be defective or even destroyed, said DLW control module will be protected in case of GND common mass loss. Thus, the DLW control module is not protected by the first protection module 10 against a DC short-circuit, but it is protected by the second protection module 20. At the third node N3, a potential difference of 48V-0V between this third node N3 and the communication bus BLW (all the functional module 1 1 being mounted up to the potential of 48V) which causes the creation of a current i3 (illustrated in FIG. 4) between said third node N3 and said communication bus BLW. Indeed, in this case, the third node N3 rises to the potential of 48V while the communication bus BLW is at the potential of 0V due to the signals DAT at OV. During a GND common ground loss, the second protection switch Q4 opens as previously seen. It thus prevents such a current i3 from circulating and thus protects the communication bus BLW as well as the second connection interface ILW.

It will be noted that with the first protection module 10, a USS overvoltage detection is converted into a detection of the loss of the common ground GND. Common components are used to protect the second ILW connection interface (and thus the BLW communication bus) against the loss of the GND common ground and against said USS overvoltage. Indeed, on detection of a USS overvoltage, the second protective switch Q4 opens which has the consequence that the base resistor R14 disconnects from the GND common ground as seen above, which corresponds to a loss of the GND common mass. After the detection of a USS overvoltage, the continuation of the operation of the protection against a USS overvoltage or against a GND loss of mass is the same for the first protection module 10 and for the second protection module 20 as previously seen.

Of course, the description of the invention is not limited to the embodiments described above.

Thus, in another non-limiting embodiment, the secondary switch Q6 may be a MOSFET transistor or an IGBT transistor. In these cases, the basic resistance R14 is not necessary. Thus, bidirectional or unidirectional protocols other than the LIN or PWM protocol can be used.

Thus, the invention can also be applied to an electric heating device 1 for a motor vehicle. Thus, according to a non-limiting embodiment, the electric heating device 1 for a motor vehicle comprises:

a first I48 connection interface with a G48 power supply network adapted to supply the second voltage U2;

a second ILW connection interface with a BLW communication bus;

a functional module 1 1 connected to the first connection interface I48;

a main switch Q2 connected to the functional module 1 1 adapted to pass DAT signals on the communication bus BLW;

- A first protection module 10 adapted to isolate the BLW communication bus of the G48 power supply network when there is a USS overvoltage between the functional module 1 1 and the second ILW connection interface.

In this case, the functional module 1 1 comprises at least one resistive heating element 1 10 powered by the first voltage U1 and at least one associated control element 1 1 1 powered by the second voltage U2 and adapted to drive said resistive heating element 1 10. In a non-limiting example, the resistive heating element 1 10 is a heating resistor. In another non-limiting example, the resistive heating element 1 10 is a resistive track. In the two nonlimiting examples, the heat produced by the resistive heating element 1 10 is transmitted via a fluid circulation duct (not shown) to a fluid which can thus be heated.

Such electric heaters being known to those skilled in the art, they are not described in detail here.

Thus, the disclosed invention has the following advantages in particular: it is a simple solution to implement and inexpensive;

it allows, thanks to the first protection module 10 and the main switch Q2, during a USS overvoltage (in particular in case of short circuit DC) in the G48 power supply network and therefore during a USS overvoltage isolating the communication bus BLW from the first connection interface I48, and thus from the power supply network G48. It will not be damaged;

it makes it possible, thanks to the second protection module 20 and to the main switch Q2, during a common ground loss GND, to isolate the communication bus BLW from the first connection interface I48, and therefore from the network of G48 power supply. It will not be damaged;

it makes it possible, thanks to the second protection module 20 and the main switch Q2, to protect the control module DLW during a common mass loss GND.

Claims

1. Air blower (1) for a motor vehicle adapted to be powered by a first voltage (U1) and a second voltage

(U2), wherein the air blower (1) comprises:

a first connection interface (I48) with a power supply network (G48) adapted to supply the second voltage (U2);

a second connection interface (ILW) with a communication bus (BLW);

a functional module (1 1) connected to the first connection interface (I48);

- a main switch (Q2) connected to the functional module (1 1) adapted to pass signals (DAT) on the communication bus (BLW);

a first protection module (10) adapted to isolate the communication bus (BLW) from the power supply network (G48) when there is an overvoltage (USS) between the functional module (1 1) and the second interface of connection (ILW).

2. Air blower (1) according to claim 1, wherein the first protection module (10) comprises:

an overvoltage detection module (100) comprising:

a protection diode (D1);

- a first protection switch (Q1) adapted to close when the protection diode (D1) becomes conductive;

- a secondary switch (Q6) adapted to open when said overvoltage (USS) exists so as to open the main switch

(Q2); - a second protective switch (Q4) adapted to open when the first protective switch (Q1) closes so as to open the secondary switch (Q6).

3. Air blower (1) according to claim 1 or claim 2, wherein the air blower (1) further comprises a protection diode (D7) adapted to protect the communication bus (BLW) if the first voltage (U1) is greater than a threshold voltage (VS7) of said protection diode (D7).

4. Air blower (1) according to claim 2, wherein the air blower (1) further comprises a secondary non-return diode.

(D1 1) adapted to prevent a current (i3) from circulating in the second protection switch (Q4).

5. Air blower (1) according to any one of claims 1 to 4, wherein the air blower (1) further comprises a main return resistance (R7) adapted to ensure the opening of the main switch (Q2) when there is said overvoltage (USS).

6. Air blower (1) according to claim 2, wherein the air blower (1) further comprises a secondary return resistor (R15) adapted to ensure the opening of the secondary switch (Q6) when There is said overvoltage (USS).

7. Air blower (1) according to claim 2, wherein the air blower (1) further comprises a base resistor (R14) adapted to ensure the closure of the secondary switch (Q6) when current (Ib6) flows in said secondary switch (Q6).

8. Air blower (1) according to any one of claims 1 to

7, according to which the air blower (1) further comprises a self-resetting fuse (R6) adapted to protect the communication bus (BLW) against an overcurrent.

9. Air blower (1) according to any one of claims 1 to

8, wherein the air blower (1) further comprises a tertiary discharge diode (D6) adapted to ensure that the main switch (Q2) remains open.

10. Air blower (1) according to any one of claims 1 to

9, wherein the air blower (1) further comprises a protection diode (D3) adapted to protect the main switch (Q2) against an increase of said first voltage (U1).

1 1. Air blower (1) according to any one of claims 1 to 10, wherein the first voltage (U1) is generated from the second voltage (U2).

12. Air blower (1) according to any one of claims 1 to 1 1, wherein the functional module (1 1) comprises a control module (DLW) adapted to be powered by said first voltage (U1) and to receive and / or transmit signals (DAT) via the communication bus (BLW).