FR3143461A1 - MOTOR VEHICLE COMPRISING A MEANS FOR HEATING BATTERY CELLS ON THE BASIS OF AN INVERTER ALTERNATING CURRENT, AND METHOD AND PROGRAM ON THE BASIS OF SUCH A VEHICLE - Google Patents

Abstract

The invention relates to a motor vehicle comprising an electrical architecture which comprises: - an electric machine (ME); - an inverter module (MO); - a battery (B) of at least one cell; characterized in that The architecture includes a filter capacity module (MC) connected in parallel with the inverter module (MO), the filter capacity module (MC) comprising a switch (S). The invention further relates to a method and a program based on such a vehicle. Figure 1

Description

MOTOR VEHICLE COMPRISING A MEANS FOR HEATING BATTERY CELLS ON THE BASIS OF AN INVERTER ALTERNATING CURRENT, AND METHOD AND PROGRAM BASED ON SUCH A VEHICLE

The invention relates to the field of motor vehicles with electric traction motor, equipped with a traction battery.

In this area the temperature of the battery influences its performance so that in case of low temperature it is necessary to heat the battery cells.

Patent EP3675273B1 proposed a cell heating strategy with alternating current, but the heating performance can still be improved.

An objective of the present invention is to remedy the defects of the prior art, and in particular to propose an electrical architecture of a motor vehicle making it possible to improve heating performance on the basis of an alternating current from the inverter.

To achieve this objective, the invention proposes a motor vehicle comprising an electrical architecture which comprises:
- an electric machine;
- an inverter module;
- a battery of at least one cell;
characterized in that the electrical architecture comprises a filtering capacity module connected in parallel with the inverter module, the filtering capacity module comprising a switch

Advantageously, the invention makes it possible to heat the cells using an alternating current produced by the inverter, without requiring an additional heating system to the architecture described above.

Furthermore, it has the advantage of increasing the dissipated thermal power (~+50%) compared to the process defined in patent EP3675273B1. This is done by adding the switch on the filtering capacitor branch. When this switch is in the "open" position, the heating signal generated by means of the inverter makes it possible to increase the heating power at the cell level.

According to one embodiment, the filtering capacity module comprises a capacity branch connecting a capacity device to the switch, so as to activate or deactivate the capacity branch.

This allows you to activate the heating mode by ordering the switch to open or to activate the filtering by ordering the switch to close.

According to one variant, the filtering capacity module comprises two capacity branches each connecting a capacity device to the switch, so as to activate one or the other capacity branch.

This allows the heating mode to be activated by a specific branch with a capacity specially sized for this purpose; and a filtering mode by a specific branch with a capacity specially sized for this purpose.

The invention also relates to a method of heating a battery for a motor vehicle of the invention, characterized in that it comprises the following steps:
- control the inverter module to generate alternating current; and
- heat the battery by opening the switch.

Another subject of the invention relates to a computer program comprising program code instructions for executing the steps of the heating method according to the invention, when said program operates on a computer.

The invention will be further detailed by the description of non-limiting embodiments, and on the basis of the appended figures illustrating variants of the invention, in which:
- schematically illustrates an electrical architecture for a vehicle according to a first preferred variant;
- schematically illustrates battery current profiles in the architecture of the , with switch open or with switch closed;
- schematically illustrates current profiles similar to those of the , where the frequency of the corresponding signal is increased;
- schematically illustrates an electrical architecture for a vehicle according to a second preferred variant.

The invention makes it possible, within the framework of an electrical architecture comprising a battery pack B of at least one cell, an inverter MO including a filtering capacity MC, and at least one electrical machine ME, to heat the cells by means of an alternating current produced by the inverter MO.

The invention thus makes it possible to heat the battery without requiring an additional heating system to the architecture described above, illustrated in .

Furthermore, the invention has the advantage of increasing the dissipated thermal power (~+50%) compared to the method defined in patent EP3675273B1. This is done by adding a switch on the filtering capacitor branch. When this switch is in the "open" position, the heating signal generated by means of the MO inverter makes it possible to increase the heating power at the cell level.

In a conventional powertrain, the cells are heated by means of a high-voltage heating resistor. The water in the heat transfer circuit is thus heated and then circulates to the battery pack B to heat the cells. This therefore results in indirect heating of the cells by means of water. With this invention, the heating of the cell is direct, so there is no energy lost due to heating the volume of water in the heat transfer circuit. The invention therefore makes it possible not to use a heating resistor.

Since cells have a non-zero internal resistance, when an alternating current is generated at their terminals, heat will be released by the Joule effect within the cell, and therefore heat it up.

Alternating current can be produced at the cell level using the following architecture:
- an ME electric machine;
- an MO inverter;
- an MC filtering capacity in parallel with the MO inverter with a switch S allowing this circuit to be opened or closed;
- a battery B consisting of at least one cell; and
- at least one computer to control the MO inverter and the ME machine, and to collect certain measurements taken at vehicle level.

This architecture differs from that of patent EP3675273B1 in that it has a switch S on the branch of the filtering capacity MC.

The MO inverter can then be controlled so as to generate an alternating current at the level of the battery pack B. The control modes of the MO inverter to produce the current profiles are identical to those described in patent EP3675273B1.

The driving modes of the MO inverter to produce the current profiles can be identical to those described in patent EP3675273B1. With sequential driving of inverter elements two by two, the current profiles I illustrated in at the cell level. Reference O1 concerns the open switch S; and reference C1 concerns the closed switch S.

It can be seen that the current profiles I are modified when the switch S on the filtering capacitor MC is in the open position O1 or closed C1.

In the closed position C1, we see that a significant part of the negative current peak is attenuated by the MC filtering capacity.

When the switch S is in the open position O1, the energy restored by the electric machine ME is not at all attenuated by the filtering capacitor MC, and consequently the minimum current peak is greater. We also note that the duration of the plateau at 0A is extended in this configuration.

The heating power at the cell depends mainly on the RMS intensity of the signal. To increase this value it is necessary to reduce the time spent on the plateau at 0 A. This can be achieved in the configuration where the switch S is in the "open" position by increasing the frequency of the signal (reference O2) until the plateau at 0 A disappears.

We then obtain the current profiles I of the . Reference C2 concerns the closing of switch S.

It can be seen that the RMS intensity can thus be increased by up to 50% when the switch S is driven in the "open" position O2. Consequently, the thermal power dissipated at the cell level increases in the same proportion.

An alternative architecture can be proposed (illustrated in ) also allowing to improve the heating power at the cell level.

In this architecture, two MC filtering capacities are arranged in parallel with the battery B and the MO inverter. One of these capacities corresponds to the capacity used when the AC cell heating mode is disabled, and the second is used only when the cell heating strategy is enabled. The filtering capacity used in heating mode is sized to obtain the desired heating power.

The position of the switch S for selecting the capacity to be used will be determined by the computer depending on the activation status of the heating strategy. If the heating is activated, the corresponding capacity will be activated.

Claims (5)

Motor vehicle comprising an electrical architecture which includes:
- an electric machine (EM);
- an inverter module (MO);
- a battery (B) of at least one cell;
characterized in that the electrical architecture comprises a filtering capacity module (MC) connected in parallel with the inverter module (MO), the filtering capacity module (MC) comprising a switch (S). Motor vehicle according to claim 1, characterized in that the filtering capacity module (MC) comprises a capacity branch connecting a capacity device to the switch (S), so as to activate or deactivate the capacity branch. Motor vehicle according to any one of claims 1 to 2, characterized in that the filtering capacity module (MC) comprises two capacity branches each connecting a capacity device to the switch (S), so as to activate one or the other capacity branch. Battery heating method for a motor vehicle according to any one of claims 1 to 3, characterized in that it comprises the following steps:
- control the inverter module (MO) to generate alternating current; and
- heat the battery (B) by opening the switch (S). A computer program comprising program code instructions for carrying out the steps of the heating method according to claim 4, when said program runs on a computer.