FR3056037A1 - ELECTRIC POWER TRANSFER SYSTEM - Google Patents

Abstract

An electric power transfer system (1) comprising: a rotating electrical machine (20) comprising a stator, said stator comprising a coil (30) adapted to be electrically connected to a first and second electrical network (27, 28); an inverter (21) disposed between the first electrical network and the winding (30); a first connection terminal (S) for connecting the inverter (21) to said first electrical network (28); a winding terminal (104) for connecting the winding (30) to said second electrical network (27). The system is provided with a selection switch (101) disposed between the second power grid (27) and the first (S) and second network terminals (104) for selectively connecting the second power grid (27) to the first power grid (27). connection terminal (S) or to the winding terminal (104).

Description

Holder (s): VALEO ELECTRIC EQUIPEMENTS MOTOR Simplified joint-stock company.

Extension request (s)

Agent (s): VALEO EQUIPEMENTS ELECTRIQUES MOTOR Simplified joint-stock company.

FR 3 056 037 - A1

104) ELECTRIC POWER TRANSFER SYSTEM.

©) Electric power transfer system (1) comprising:

-a rotary electrical machine (20) comprising a stator, said stator comprising a winding (30) adapted to be electrically connected to a first and a second electrical network (27, 28);

an inverter (21) disposed between the first electrical network and the winding (30);

a first connection terminal (S) for connecting the inverter (21) to said first electrical network (28);

a winding terminal (104) for connecting the winding (30) to said second electrical network (27).

The system is expected to include a selector switch (101) disposed between the second electrical network (27) and the first (S) and second network terminals (104) for selectively connecting the second electrical network (27) to the first connection terminal (S) or to the winding terminal (104).

ELECTRIC POWER TRANSFER SYSTEM

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a system for transferring electrical power between two electrical networks using part of the components of a rotating electrical machine, this transfer system being found in a motor vehicle.

TECHNOLOGICAL BACKGROUND

Motor vehicles fitted with an internal combustion engine also include an electric machine capable of operating in alternator mode or in engine mode. During the engine mode, the electric machine exerts an engine torque on a crankshaft of the motor vehicle while during the alternator mode the electric machine exerts a resistance torque on the crankshaft of the motor vehicle.

It is known from patent application FR2803447A1 a power generation system, for a dual-voltage electrical network comprising a first electrical network 28 and a second electrical network 27, comprising an electrical machine of the three-phase alternator type whose stator phases are rectified to generate the desired power on the first electrical network 28 operating at a first voltage value Us, and the stator of which is wound in a star so as to have a neutral point N to which the second electrical network 27 operating at a second value is connected voltage Ub lower than the first, the system further comprising electronic control means 22 and regulation of the voltages Us and Ub of the two electrical networks.

A functional diagram repeating the principle of patent application FR2803447A1 is reproduced in FIG. 1. FIG. 1 illustrates a power production system 1 for a dual-voltage electrical network which comprises a three-phase electrical machine 20 of the alternator type, which can be synchronous with wound rotor or magnet or else mixed wound and magnet. The stator phases are rectified to generate the desired power on the first electrical network 28 operating at a first voltage value Us.

It can also be an asynchronous alternator. It is wound in a star to the stator so as to present a neutral point N to which the second electrical network 27 is connected operating at a second voltage value Ub lower than the first voltage value Us.

To rectify the current of the stator phases of the alternator, these three phases are connected to a three-phase inverter 21, which delivers a voltage Us, equal to 42 volts in the particular case of a current motor vehicle, and which consists of six switches H1 to H3 and L1 to L3. They are arranged in three arms of two switches each, connected in series and in the same direction, one Li low-side between the ground and one of the phases and the other Hi high-side between the phase and the higher voltage Us These switches are MOSFET or IGBT or bipolar or other type transistors, whether or not associated with a reverse diode.

They are controlled by electronic command and regulation means 22 which receive instructions for regulating the voltages Us and Ub of the two electrical networks, coming from a computer 99 establishing electronic strategies for managing the electrical energy of the network. These control means 22 can also receive information on the position of the rotor relative to the stator from a position sensor 32.

Two filtering means 23 and 24 can be respectively arranged at the input of each of the two electrical networks, either at the neutral point N, towards the second network 27 at 14 volts and at the output S of the regulation circuit, to the first network 28 to 42 volts.

These means consist for example of capacitors associated with inductors dimensioned to deliver filtered DC voltages remaining within the tolerances accepted for the application, in terms of emission and electromagnetic susceptibility.

These two electrical networks can each be connected to a battery, referenced respectively 25 and 26, and supply the electrical networks 27 and 28 operating at 14 volts and 42 volts respectively.

When the electric machine 20 is in motion, in alternator mode driven by the vehicle engine or in starter mode to on the contrary drive the engine, the connection of its neutral point N to the second electrical network 27 at 14 volts requires the average polarization of the three stator phases at the same potential Ub of 14 volts, whose impedances in continuous mode are equivalent to the resistances of the windings.

Voltage regulation on the second 14 volt electrical network 27 is obtained by adjusting the average value of the three phase voltages, i.e. by adjusting the three machine control signals three-phase electrical power supplied by the electronic circuit for controlling and regulating the voltages Us and Ub of the dual-voltage network. There are two conventional methods for controlling this alternator, or alternator starter.

According to a first alternative embodiment, the regulation of these two voltages is carried out according to a method of pulse width modulation of the control signals of the transistors constituting the arms of the inverter, in order to generate three periodic waves on the three phases, sinusoidal, trapezoidal, triangular for example, 120 ° out of phase with each other. This process is applicable to electrical machines of the wound rotor type or of the permanent magnet type.

According to a second alternative embodiment, the regulation is carried out according to a full-wave control method of the synchronous rectification type, applicable only to synchronous electric machines with wound rotor.

In the case of the two methods, the average voltage Umoy of the three stator voltages must be controlled, on the three output points P1, P2 and P3 of the phases, at a reference voltage necessary for regulating the second network 27 to 14 volts.

In the case of the first alternative embodiment using a pulse width modulation method, the regulation of the upper voltage Us, equal in particular to 42 volts, is carried out by two parameters: the adjustment of the amplitude of the phase setpoints and the adjustment either of the excitation of the rotor in the case of a synchronous alternator with wound rotor, or of the slip of speed existing between the speed of the stator rotary field and the mechanical speed of rotation of the rotor in the case of an alternator asynchronous, that is to say the phase shift between the stator magnetic field and the rotor flux in the case of a synchronous alternator with permanent magnet.

When the electric machine is stopped, that is to say when the rotor is not turning, in voltage converter mode, suitable control of the three arms of the inverter, by the control circuit 22, makes it possible to carry out a transfer of energy from one of the two networks, 14 or 42 volts, to the other. The structure of the static converter thus obtained is of the voltage raising or lowering type also called Buck according to an English term well known to those skilled in the art.

The principle and the implementation of the control of this system when the machine is stopped, that is to say when the rotor does not turn or in motion, that is to say when the rotor turns, is described in patent application FR2803447A1. to which a person skilled in the art can refer for more details.

This system is satisfactory, however it may be desirable to further improve it.

This type of system has the defect that it does not allow a lot of power to be injected into the second electrical network 27 at least with a reasonable cost and a good yield. Indeed, for an increase in the current of a certain value at the neutral point, it is necessary to provide for an increase of a level equal to this value on each of the three phases. It is therefore necessary to provide a dimensioning of the inverter so that it can support three times the value of increase of the current. This requires using an inverter of another size, the price of which will increase significantly. On the other hand, still supporting three times the current increase value, the joule losses will increase significantly so that the efficiency will decrease.

Thus, with this system, and in particular when the power to be transferred is large, the gain of one gram of carbon dioxide per kilometer will represent a significant cost.

OBJECT OF THE INVENTION

The object of the invention is to respond to this wish while remedying at least one of these aforementioned drawbacks.

According to the invention, an electrical power transfer system is proposed comprising:

a rotary electrical machine comprising a rotor and a stator, said stator comprising a winding which is provided with at least three phase windings and which is capable of being electrically connected on the one hand to a first electrical network having a high voltage and on the other hand to a second electrical network having a low voltage;

a first connection terminal able to be connected to the first electrical network;

a second connection terminal able to be connected to the second electrical network;

an inverter arranged between the first connection terminal and the winding, the inverter comprising for each of the phase windings at least one switch capable of assuming a blocked or passing state;

a winding terminal connected directly to the stator winding;

a switch control module configured to be able to control the state of the switches of the inverter so that the potential of the winding terminal is of the order of the low voltage;

According to a general characteristic, the transfer system comprises a selection switch disposed between on the one hand the second connection terminal and on the other hand the first connection terminal and the winding terminal for selectively connecting the second connection terminal to the first connection terminal or to the winding terminal in order to transfer electrical power to the second network from the first connection terminal or the winding terminal.

In other words, the first connection terminal is adapted to connect the inverter to said first electrical network while the winding terminal is adapted to connect the winding to said second electrical network.

For example, provision may be made for the second connection terminal to be connected directly to the second electrical network.

Using the transfer of power from the electric machine to the second network when the electric machine operates in low voltage mode, the transferable power is increased without additional cost and with satisfactory efficiency. In fact, with a higher power to be transferred, the same inverter can be kept and the losses by the joule effect increase only moderately.

In addition, while retaining the possibility of transferring power from a winding terminal to the second network, it is possible, on the one hand, to use energy stored in a battery connected to the first network if necessary. On the other hand, it is possible to continue using the rotary electrical machine in connection with the first network while allowing power to be supplied to the second network and, where appropriate, to a low voltage battery linked to the second network.

Thus, the number of grams of carbon dioxide saved per kilometer can be significantly increased with a cost related to the amount of grams of carbon dioxide saved that is low. Furthermore, the efficiency is greatly improved compared to a power transfer only from the winding terminal.

To check the potential of the winding terminal, the state of the inverter switches can be controlled so that a continuous value is added to the potential of each of the three output points P1, P2 and P3 of the phase windings. It is also possible, when the rotor of the electric machine does not rotate, to provide that the control module is configured to control the state of the switches of the inverter so that the windings of the winding form a storage element of a type converter. Buck.

To check the potential of the first connection terminal, it is possible, when the electric machine is operating in low voltage mode, to lower the output voltage of the rotating electric machine so that it reaches, for example, 12 volts.

For this, it is possible, in relation to an operation of the electrical machine during which it operates in high voltage mode with the first electrical network, to reduce the current which enters the winding of the rotor if necessary. It can also be defluxed according to an electric machine control principle known to those skilled in the art and explained below.

According to other characteristics taken individually or in combination:

the phase windings are coupled in a star so that the winding includes a neutral point, said winding terminal being connected directly to the neutral point.

In the case of a three-phase double winding comprising one or more neutral points, it is possible to choose to use only a single neutral point to be connected to the winding terminal. The use of the neutral point allows a simple control of the potential of the winding terminal.

each phase winding comprising a phase output point, said winding terminal is connected directly to one of the phase output points.

In particular in the case where the windings are coupled in a triangle and in the absence of a neutral point, then the winding terminal can be connected to one of the phase windings.

the electrical power transfer system is configured to operate with a first and a second electrical network having a ratio between the low voltage and the high voltage of between 35% and 65%.

It is thus possible to operate the electric machine with good efficiency on the one hand and while limiting iron losses on the other hand.

In fact, in order to operate the electric machine with good efficiency, a maximum excursion of the amplitude of the potential of each of the phase output points is ensured. For this, their ripple must be centered on half of the high voltage of the first network and we then obtain that the neutral potential takes substantially the value of half of the high voltage.

By choosing a low voltage which is also of the order of half of the high voltage, we limit, when the excursion of the amplitude of the potential of each of the phase output points is maximum, the potential difference between the low voltage and potential of the winding terminal which limits iron losses during power transfer.

the electrical power transfer system is configured to operate with first and second electrical networks having a high voltage of between 20 and 30 volts and a low voltage of between 11 and 15 volts.

It is an embodiment according to which the transfer system can operate in particular with a first network having a high voltage of 24 volts and a second network having a low voltage of 12 volts. These two values are widely used in the automotive field and therefore allow the system according to this configuration to be easily integrated into a vehicle.

the electrical power transfer system comprises a safety switch capable of assuming a passing or blocked state disposed between the first connection terminal and the first electrical network.

The safety switch can take a blocked state in order to avoid a short circuit between the first connection terminal and the high voltage battery when the potential of the first connection terminal is different from high voltage, especially when the electric machine is operating in mode. low tension.

the control module is configured to control the state of the safety switch and of the selection switch so that the safety switch assumes the blocked state when the first connection terminal is connected to the second connection terminal.

It is thus possible to disconnect the high voltage battery when the first connection terminal is connected to the second electrical network. Indeed, without this disconnection there would be a risk of short circuit due to the electrical connection of the second electrical network having a low voltage to the high voltage battery.

the first connection terminal is connected directly to the first electrical network.

In the case of a first electrical network connected to an ultra capacity, the voltage at its terminals being adjustable, there is no risk of short circuit.

the rotor comprises a winding for generating a magnetic field, the winding of the rotor being electrically connected to the first connection terminal.

For example, to electrically connect the rotor winding to the first connection terminal, a collector and brushes are used.

-the rotor winding is connected to the first connection terminal via a regulator and the control module is configured to act on the regulator to lower the current in the rotor winding so that the potential of the first connection terminal is of the order of low voltage.

Thus, in low voltage mode of the electric machine, it is possible to decrease the potential of the first connection terminal to approach it of the low voltage and thus allow a transfer of power from the first connection terminal to the second electric network.

the rotor winding is electrically connected to the winding terminal via a pass-through diode for the positive current flowing from the winding terminal to the winding of the rotor.

Thus, a supply of the rotor winding can be ensured via the first connection terminal or the winding terminal.

the system comprises a first filtering capacity connected in parallel with the first connection terminal and a second filtering capacity connected in parallel with the second connection terminal.

One of these filtering capabilities can be used to make the transfer system work like a Buck converter.

the switches of the inverter each comprise a switch and a diode, these two elements being mounted in parallel.

Diodes and switches can also be used to make the transfer system work like a Buck converter.

-the switches of the inverter include MOSFET transistors.

The MOSFET transistors can participate in the role of a Buck converter and also allow sophisticated control, which is useful for example for defluxing.

the control module is configured to control the state of the switches of the inverter so that the potential of the first connection terminal is of the order of the low voltage of the second network.

It is then a command to operate the electric machine in low voltage mode. For example, it is a defluxing command which lowers the total flux of the stator winding by adding using the switches of the inverter, a voltage phase shifted with the electromotive force of the stator winding. The defluxing control can be used in particular when the rotor has no winding but permanent magnets.

BRIEF DESCRIPTION OF THE FIGURES

Other characteristics and advantages of the invention will appear on examining the detailed description of modes of implementation and embodiments, in no way limiting, and the appended drawings in which:

FIG. 1, already described, represents a functional diagram of a power transfer system according to the state of the art;

FIGS. 2 and 3 represent a functional diagram of a power transfer system according to a first embodiment of the invention;

FIG. 4 represents a functional diagram of a power transfer system according to a second embodiment of the invention;

FIG. 5 represents a functional diagram of part of a power transfer system according to a third embodiment of the invention; and

FIG. 6 represents a functional diagram of part of a power transfer system according to a fourth embodiment of the invention.

Identical, similar, or analogous elements keep the same reference from one figure to another.

DESCRIPTION OF EXAMPLES OF EMBODIMENT OF THE INVENTION

In the following description, operating modes of the transfer system 1 are defined as well as operating modes of the electric machine. For an operating mode of the transfer system, several operating modes of the electric machine are possible.

By direct connection on a component is meant being connected to this component directly without any other electrical component except a wire or a connecting means. The term “component electrically connected to another component” means that electrical contact is possible between the two components directly or through other electrical components. The term component capable of being connected to another component means that electrical contact is possible between the two components, in particular intermittently.

FIG. 2 represents a functional diagram of a power transfer system according to a first embodiment of the invention. FIG. 3 also represents a more detailed functional diagram of this first embodiment of the invention.

The power transfer system 1 according to the first embodiment differs from that of the state of the art illustrated in FIG. 1 in particular in that it provides for a selection switch 101.

Thus the power transfer system 1 according to the first embodiment, comprises:

a rotary electrical machine 20 comprising a rotor 29 and a stator, said stator comprising a winding 30 which is provided with at least three phase windings 31, 35, 33 and which is capable of being electrically connected on the one hand to a first electrical network 28 having a high voltage Us for example continuous and on the other hand to a second electrical network 27 having a low voltage Ub for example continuous;

a first connection terminal S able to be connected to the first electrical network 28;

a second connection terminal 105 capable of being connected to the second electrical network 27;

an inverter 21 arranged between the first connection terminal S and the winding 30, the inverter comprising for each of the phase windings at least one switch H1, L1, H2, L2, H3, L3 which can take a blocked or passing state;

a winding terminal 104 connected directly to the winding 30 of the stator; and

a control module 22 of the switches configured to be able to control the state of the switches of the inverter 21 so that the potential of the winding terminal 104 is of the order of the low voltage Ub,

The selection switch 101 is arranged between on the one hand the second connection terminal 105 and on the other hand the first connection terminal S and the winding terminal 104 to selectively connect the second connection terminal 105 to the first connection terminal S or to the winding terminal 104 in order to transfer electrical power to the second network 27 coming from the first connection terminal S or from the winding terminal 104.

Thus, the selection switch 101 allows the power transfer system 1 to operate according to two operating modes. More specifically, when the selection switch 101 connects the second connection terminal 105 to the first connection terminal S then the transfer system 1 operates according to a first operating mode called mode A allowing transfer of electrical power to the second network by coming from the first connection terminal S. And, when the selection switch 101 connects the second connection terminal 105 to the winding terminal 104 then the transfer system 1 operates according to a second operating mode called mode B allowing transfer of electrical power to the second network from the winding terminal 104.

For example, as illustrated in FIGS. 2 and 3, the first network 28 is connected to a high voltage battery 26 having as continuous voltage the high voltage Us while the second network 27 is connected to a low voltage battery 25 having as nominal voltage continues the low voltage Ub. It can be expected that the ratio between the low voltage Ub of the second network 27 and the high voltage Us of the first network 28 is between 35% and 65%. For example, the high voltage Us of the first network 28 is between 20 and 30 volts and the low voltage Ub of the second network 27 is between 11 and 15 volts.

In addition, as illustrated in FIG. 3, the rotor 29 can comprise a winding 34 for generating a magnetic field, said rotor winding 34 being electrically connected to the first connection terminal S. It is for example possible to provide that the winding of the rotor 34 is electrically connected to the winding terminal 104 via a pass-through diode 103 for the positive current flowing from the winding terminal 104 to the winding of the rotor 34. The rotor 29 is thus supplied on the one hand by the first connection terminal S but also by the winding terminal 104. This supply by the winding terminal 104 occurs due to the diode 103, in the case where the potential of the winding terminal 104 is greater than that of the first terminal of connection S.

As illustrated in FIG. 3, for the winding 30, each phase winding 31, 35, 33 comprises a phase output point P1, P2, P3. According to the first embodiment of the invention, the phase windings 31, 35, 33 are coupled in a star so that the winding comprises a neutral point N, said winding terminal 104 being connected directly to the neutral point N. Furthermore , the control module is advantageously connected to a position sensor 32 to provide it with information on the position of the rotor 29 relative to the stator.

According to mode A of the transfer system 1, the electric machine 20 operates in low voltage mode Ub with the second electrical network 27 and when it is used as an alternator delivers a direct voltage of the order of low voltage Ub, for example 12 volts. The expression low voltage mode of the electric machine 20 is understood to mean an operating mode in which the electric machine 20 operates with the second electric network. It can then operate according to operating modes such as Alternator, but also Regen and Boost, according to Anglo-Saxon terms well known to those skilled in the art and defined below.

In mode A of the transfer system 1, so that the electrical machine 20 works with the second electrical network, the control module 22 controls the state of the switches H1, H2, H3, L1, L2, L3 of the inverter 21 of so that the potential of the first connection terminal S is of the order of the low voltage Ub of the second network 27.

For this, it is possible, according to a first example, to lower the flux of the stator winding by defluxing caused by the addition using the switches H1, H2, H3, L1, L2, L3 of the inverter, of a phase-shifted voltage the electromotive force of the stator winding 30. The defluxing is applicable even when the rotor has no winding and is provided with a permanent magnet.

For this, it is possible according to a second example when the rotor is provided with a winding 34 to adjust the current in the rotor winding 34 so that the potential of the first connection terminal S is of the order of the low voltage Ub.

In the case where the first network 28 is connected to a high voltage battery 26, the system can then include a safety switch 102 which can assume a passing or blocked state disposed between the first connection terminal S and the high voltage battery 26.

The use of this safety switch 102 is advantageous according to mode A. In fact, when the first connection terminal S is connected to the second electrical network 27, then the electrical machine 20 operates in low voltage mode Ub so that the connection between the first connection terminal S and the first network would cause a short circuit.

The control module 22 is then configured to control the state of the safety switch 102 and of the selection switch 101 so that the safety switch 102 assumes the blocked state when the first connection terminal S is connected to the second electrical network 27.

According to mode B of the transfer system 1, the electric machine 20 operates in high voltage mode Us with the first electrical network 28 and when it is used as an alternator it delivers a direct voltage of the order of high voltage Us. However , according to mode B of the transfer system 1, the winding terminal 104 is connected to the second connection terminal 105 to supply a low voltage voltage Ub to the second electrical network. By high voltage mode of the electric machine 20 is meant an operating mode in which the electric machine 20 operates with the first electric network. It can then operate according to operating modes such as Alternator, but also Ftecrank, Ftegen and Boost, according to Anglo-Saxon terms well known to those skilled in the art and defined below.

For the winding terminal 104 to reach the low voltage Ub, reference may be made to patent FR2803447 which details the control of the control module 22 on the state of the switches H1, L1, H2, L2, H3, L3 of the inverter 21 so that the potential of the winding terminal 104 is of the order of the low voltage Ub depending on whether the rotor 29 of the electric machine is driven in rotation or is stopped.

Furthermore, according to mode B, while the winding terminal 104 supplies a voltage to the second electrical network 27, the electrical machine 20 can continue to be used to operate as an alternator, but also to make Regen, Boost, Recrank according to Anglo-Saxon terms well known to those skilled in the art and defined below. This is in particular possible by means of the control of the rotor and stator currents via the switches of the inverter 21 in the case where these switches comprise MOSFET transistors.

The operating mode of the Regen electric machine consists, for example, in operating the electric machine in a pulse mode, each pulse lasting from 5-30 seconds. During each pulse, the electric machine is then used in alternator mode with a strong rotor and stator current which generates a high resistance torque on the crankshaft which makes it possible to brake the motor vehicle. Thus, the electrical power delivered to the first electrical network is of the order of 10 kW.

The operating mode of the Boost electric machine also called Torque Assist according to another English term well known to those skilled in the art, for example consists in operating the electric machine according to a pulse mode, each pulse lasting from 5-30 seconds. . During each pulse, the electric machine is then used in engine mode with strong rotor and stator currents which generate a strong engine torque on the crankshaft which makes it possible to accelerate the motor vehicle. For example, the electric power consumed by the rotating electric machine is then of the order of 10 kW. For this, the electric machine is supplied for example by the second electrical network or by the first electrical network.

The operating mode of the alternator electric machine consists, for example, in operating the electric machine in a continuous mode. The electric machine is used in alternator mode with rotor and stator currents which generate a resistance torque on the crankshaft which allows generation of electric power stored in the high voltage battery 26. For example, the electric power is then around 3 kW.

The operating mode of the Recrank electric machine consists, for example, of operating the electric machine in a pulse mode, each pulse lasting less than a second. During each pulse, the electric machine is then used in engine mode and generates an engine torque on the crankshaft which makes it possible to start the engine of the motor vehicle. For this, the electrical machine is supplied for example by the first electrical network.

For example, a first filtering capacity 24 is connected in parallel with the first connection terminal S and a second filtering capacity 23 is connected in parallel with the second connection terminal 105 on the other hand.

In other words, the first filtering capacity 24 is connected to the first connection terminal S on the one hand and to a ground of the power transfer system. Likewise, the second filtering capacity 23 is connected to the second connection terminal 105 on the one hand and to a ground of the power transfer system on the other hand.

In addition, the switches H1, H2, H3, L1, L2, L3 of the inverter 21 may each include a switch and a diode, these two elements being mounted in parallel.

In mode B of the transfer system 1, these diodes and these filtering capacities can participate in the role of a Buck converter from the first network to the second network, in particular when the rotor 29 is not driven. In fact, to make this type of converter, the following three elements are required:

a cutting element, these are the switches of the switches H1, H2, H3, L1, L2, L3;

a storage element these are the windings 31, 33, 35; and

a rectifying element, this is the filtering capacity 23 or 24 and the diodes.

Of course, in the case where the switches comprise MOSFET transistors, operation in Buck converter mode is also possible, the chopping being carried out using the MOSFET transistors.

Furthermore, using the control module 22, it is possible to initiate operation according to mode A or mode B according to two main criteria, namely the state of charge of the high-voltage battery 26 hereinafter called SOCHT and the electrical load of consumers such as air conditioning, the seat heating function on the second electrical network 27 hereinafter called LOADBT.

More precisely, two high and low levels are defined for the two criteria SOCHT and LOADBT and we obtain operating triggers according to mode A and mode B as below:

- LOADBT = high and SOCHT = high: mode B of the transfer system with an electric machine command according to which only the Recrank mode can be activated and the other operating modes of the electric machine such as Alternator, Regen, Boost are not not activated. For example, in the case where the rotor does not rotate, the switches H1, H2, H3, L1, L2, L3 can simply be controlled so that the power transfer system 1 operates like a Buck converter.

- LOADBT = high and SOCHT = low: the transfer system must switch to operation in mode A, and the electric machine in low voltage mode. When switching from mode B to mode A, provision can be made to avoid a transient voltage drop in the second network 27 not to immediately activate a consumer of the vehicle connected to the second network requiring a lot of power during a transition period, for example 500 ms . Then, when the electric machine operates in low voltage mode in continuous mode, the consumer is activated, a time load shedding is then carried out.

- LOADBT = low and SOCHT = high: mode B of the transfer system with an electric machine control according to which other operating modes such as Alternator, Regen, Boost or Recrank are activatable. In addition, in the case where the rotor does not rotate, one can simply control the switches H1, H2, H3, L1, L2, L3 so that one has an operation of the power transfer system 1 as a Buck converter.

- LOADBT = low and SOCHT = low: mode A of the transfer system, the electric machine then operates in low voltage mode. In this case, in addition to the A mode, operation of the Regen, Recrank or Boost modes can be provided by intermittently activating the B mode.

These trips are advantageous, since when the SOCHT is high, it is advantageous to operate the electric machine 20 with the first network and to use the charge from the high voltage battery 26 to discharge it to the low voltage battery 25.

FIG. 4 represents a functional diagram of a power transfer system according to a second embodiment of the invention.

The second embodiment differs from the first mode in that the phase windings 31, 33, 35 are coupled in a triangle and in this case the winding terminal 104 is connected directly to one of the phase output points P1, P2, P3.

One can indeed, similarly to the voltage regulation of a neutral point, regulate the potential of one of the phase output points, here P1 so that it is of the order of the voltage Ub.

FIG. 5 represents a functional diagram of part of a power transfer system 1 according to a third embodiment of the invention.

This figure illustrates the filtering capacity 24 and the first connection terminal S connected to the first electrical network 28, the first electrical network being connected to an ultra high-capacity capacity 37 in place of the high-voltage battery 26.

This third embodiment differs from the first and from the second embodiment in that the first connection terminal S is connected directly to the first electrical network 28.

Indeed, in the case of an ultra capacity 37, the voltage at its terminals being adjustable, there is no risk of short circuit when the electric machine 20 operates in low voltage mode while the power transfer system 1 is in operating mode A. It is therefore not necessary to have the safety switch 102 between the connection terminal S and the first electrical network 28.

FIG. 6 represents a functional diagram of a part of a power transfer system according to a fourth embodiment of the invention. This figure illustrates:

the first connection terminal S;

the filtering capacity 24;

the winding terminal 104;

diode 103;

the electric machine 20 comprising the stator comprising the winding 30 having a neutral point N and the rotor 29 provided with a winding 34; and

a regulator 36 disposed between the diode 103 and the first connection terminal S on the one hand and the winding of the rotor 34 on the other hand.

The fourth embodiment of the invention is distinguished from the first, second and third embodiments by the presence of this regulator 36.

Thus, in the case where the rotor 29 comprises a coil 34 for generating a magnetic field, this coil of the rotor 34 can according to the fourth embodiment, be connected to the first connection terminal S via the regulator 36, the control module 22 being configured to act on regulator 36.

It is thus possible in particular to lower the current in the rotor winding 34 so that the potential of the first connection terminal S is of the order of the low voltage Ub when the electric machine 20 is used in low voltage mode with the second network. electric 27 when the transfer system is in mode A.

Claims (15)

1. Electric power transfer system (1) comprising: a rotary electric machine (20) comprising a rotor (29) and a stator, said stator comprising a winding (30) which is provided with at least three phase windings (31, 35, 33) and which is capable of being electrically connected on the one hand to a first electrical network (28) having a high voltage (Us) and on the other hand to a second electrical network (27) having a low voltage (Ub); a first connection terminal (S) capable of being connected to the first electrical network (28); a second connection terminal (105) able to be connected to the second electrical network (27); an inverter (21) disposed between the first connection terminal (S) and the winding (30), the inverter comprising for each of the phase windings at least one switch (H1, L1, H2, L2, H3, L3) can take a blocked or passing state; a winding terminal (104) connected directly to the winding (30) of the stator; and a control module (22) for the switches configured to be able to control the state of the switches of the inverter (21) so that the potential of the winding terminal (104) is of the order of the low voltage (Ub ), characterized in that the transfer system (1) comprises a selection switch (101) arranged between on the one hand the second connection terminal (105) and on the other hand the first connection terminal (S) and the winding terminal (104) for selectively connecting the second connection terminal (105) to the first connection terminal (S) or to the winding terminal (104) in order to transfer electrical power to the second network (27) by from the first connection terminal (S) or the winding terminal (104). 2. electric power transfer system (1) according to claim 1, characterized in that the phase windings (31, 35, 33) are star-coupled so that the winding (30) comprises a neutral point (N) , said winding terminal (104) being connected directly to the neutral point (N). 3. electric power transfer system (1) according to claim 1 or 2, characterized in that each phase winding (31, 35, 33) comprising a phase output point (P1, P2, P3), said terminal winding (104) is directly connected to one of the phase output points (P1, P2, P3). 4. electric power transfer system (1) according to one of the preceding claims, characterized in that it is configured to operate with a first (28) and a second (27) electrical networks having a ratio between the low voltage (Ub) and high voltage (Us) between 35% and 65%. 5. electric power transfer system (1) according to one of the preceding claims, characterized in that it is configured to operate with a first (28) and a second (27) electrical networks having a high voltage (Us) between 20 and 30 volts and a low voltage (Ub) between 11 and 15 volts. 6. electric power transfer system (1) according to one of the preceding claims, characterized in that it comprises a safety switch (102) capable of assuming a passing or blocked state disposed between the first connection terminal (S) and the first electrical network (28). 7. electric power transfer system (1) according to the preceding claim, characterized in that the control module (22) is configured to control the state of the safety switch (102) and the selection switch (101) of so that the safety switch (102) assumes the blocked state when the first connection terminal (S) is connected to the second connection terminal (105). 8. electric power transfer system (1) according to one of claims 1 to 5, characterized in that the first connection terminal (S) is connected directly to the first electric network (28). 9. electric power transfer system (1) according to one of the preceding claims, characterized in that the rotor (29) comprises a coil (34) for generating a magnetic field, the coil of the rotor (34) being electrically connected to the first connection terminal (S). 10. Electric power transfer system (1) according to the preceding claim, characterized in that the rotor winding (34) is connected to the first connection terminal (S) via a regulator (36) and in that the control module (22) is configured to act on the regulator (36) to lower the current in the rotor winding (34) so that the potential of the first connection terminal (S) is of the low voltage order (Ub). 11. Electric power transfer system (1) according to claim 9 or 10, characterized in that the rotor winding (34) is electrically connected to the winding terminal (104) via a pass-through diode ( 103) for the positive current flowing from the winding terminal (104) to the rotor winding (34). 12. Electric power transfer system (1) according to one of the preceding claims, characterized in that it comprises a first filtering capacity (24) connected in parallel with the first connection terminal (S) and a second capacity filter (23) connected in parallel with the second connection terminal (105). 13. Electric power transfer system (1) according to one of the preceding claims, characterized in that the switches (H1, H2, H3, L1, L2, L3) of the inverter (21) each include a switch and a diode, these two elements being mounted in parallel. 14. electric power transfer system (1) according to one of claims 1 to 12, characterized in that the switches (H1, H2, H3, L1, L2, L3) of the inverter (21) include transistors MOSFET. 15. Electric power transfer system (1) according to one of the preceding claims, characterized in that the control module (22) is configured to control the state of the switches (H1, H2, H3, L1, L2, L3) of the inverter (21) so that the potential of the first connection terminal (S) is of the order of the low voltage (Ub) of the second network (27). 1/6