System and method for heating a battery with an additional inductive component

Abstract

The invention relates to a system for heating a battery (100) of an electric or hybrid vehicle, comprising: - the battery (100), which is capable of delivering a battery voltage (100); - a main inverter (101) connected to the battery (100) and comprising a plurality of main inverter legs (B1, B2, B3); - an additional inverter (201) different from the main inverter (101) and connected to the main inverter (101); - an electric machine (102) connected to the main inverter (101) and comprising a stator, the stator comprising a plurality of stator coils (L1, L2, L3) capable of storing energy in the form of a magnetic field, each stator coil (L1, L2, L3) being connected to a corresponding main inverter leg (B1, B2, B3); - an additional inductive component (200) external to the electric machine (102) and connected to the additional inverter (201). The invention further relates to a method for heating the battery of an electric or hybrid vehicle.

Description

[0001] DESCRIPTION

[0002] TITLE: System and method for heating a battery with an additional inductive component

[0003] Technical field of the invention

[0004] The present invention relates to a battery heating system, particularly for an electric or hybrid vehicle.

[0005] State of the art

[0006] Lithium batteries in general, and lithium iron phosphate (LFP) batteries in particular, offer several advantages that have led to their increasing use in electric and hybrid vehicles. For example, lithium batteries provide enhanced safety thanks to improved thermal and chemical stability, thus reducing the risk of overheating and fire. Furthermore, these batteries are more durable, withstanding a greater number of charge-discharge cycles, which extends their lifespan. Lithium batteries are also more environmentally friendly because they use less toxic materials. Finally, their production cost is often lower, making them attractive for a wide range of applications, including the manufacture of electric vehicles.

[0007] Lithium batteries experience a performance degradation in cold conditions, such as winter. At low temperatures, the electrochemical reaction inside the battery slows down, reducing its power output. This results in a shorter range and longer charging times. Furthermore, cold temperatures increase the battery's internal resistance, leading to a loss of energy efficiency.

[0008] These combined factors therefore make lithium batteries less efficient in cold climates, which can pose challenges for their use in electric vehicles or energy storage systems in regions where winter temperatures are severe.

[0009] For example, an electric car owner with a lithium battery who parks their vehicle outside on a cold winter day will have to wait longer to recharge because the low temperatures degrade the battery's power. Therefore, there is a need to warm the battery, especially in cold weather, to compensate for the degradation in its performance.

[0010] One existing solution is to use auxiliary heating devices such as PTC immersion heaters in the cooling circuit, or a heating mat placed in the bottom of the battery tray.

[0011] However, these solutions have several drawbacks: they are expensive and require an additional, time-consuming manufacturing step during the production of electric vehicles. Furthermore, adding these ancillary components increases the risk of electric vehicle failure. In addition, these ancillary components heat up all the battery modules, including the casing and the water circuit, whereas only heating the electrochemistry of the cells is necessary, resulting in wasted energy.

[0012] Object of the invention

[0013] The technical problem that the present invention aims to solve is to improve the efficiency of battery heating by generating heat losses directly inside the cells to be heated, which allows for more homogeneous and efficient heating.

[0014] This goal can be achieved through the development of a system to heat the battery of an electric or hybrid vehicle, comprising:

[0015] - the battery capable of supplying a battery voltage,

[0016] - a main inverter connected to the battery and comprising a plurality of main inverter arms,

[0017] - an additional inverter, separate from the main inverter and connected to the main inverter,

[0018] - an electrical machine connected to the main inverter and comprising a stator, the stator comprising a plurality of stator coils capable of storing energy in the form of a magnetic field, each stator coil being connected to a corresponding main inverter arm,

[0019] - an additional inductive component external to the electrical machine and connected to the additional inverter,

[0020] the main inverter being configured to allow the transfer of electrical energy from the battery to the stator coils via the main inverter and the transfer of at least part of the energy stored in the stator coils to the battery via the main inverter, the additional inverter being configured to allow the transfer of electrical energy from the battery to the additional inductive component via the additional inverter and the transfer of at least part of the energy stored by the additional inductive component to the battery via the additional inverter,

[0021] the transfer of at least part of the energy stored in the stator coils and / or in the additional inductive component to the battery ensuring battery heating.

[0022] The system may also exhibit one or more of the following characteristics, taken alone or in combination.

[0023] According to a feature of the system, the additional inverter is controlled independently from the main inverter.

[0024] According to one feature, the main inverter and the additional inverter are controlled by a single control unit.

[0025] According to one characteristic, the additional inverter is mounted on the same electronic board as the main inverter.

[0026] According to one characteristic, the additional inverter is mounted on a different electronic board than the main inverter.

[0027] According to one feature, the system includes a cooler, specifically a cooler comprising a heat transfer fluid, the cooler being configured to allow heat transfer from the additional inductive component to the battery.

[0028] The invention further relates to an electric or hybrid vehicle comprising the system described above.

[0029] The invention further relates to a method for heating the battery of an electric or hybrid vehicle of the system described above, comprising the following steps:

[0030] - Control of the main inverter to allow the transfer of electrical energy from the battery to the stator coils via the main inverter,

[0031] - detection of an initial current threshold in the arms of the main inverter and / or in the stator coils,

[0032] - upon detection of the first current threshold, the main inverter is controlled to allow the transfer of at least part of the energy stored in the stator coils to the battery; - upon detection of a second current threshold in the arms of the main inverter and / or in the stator coils,

[0033] - upon detection of the second threshold, switching of the main inverter so as to allow a transfer of electrical energy from the battery to the stator coils via the main inverter.

[0034] According to a characteristic of the process, the process comprises the following steps:

[0035] - Control of the additional inverter to allow the transfer of electrical energy from the battery to the additional inductive component via the additional inverter,

[0036] - detection of a third current threshold in the arms of the additional inverter and / or in the additional inductive component,

[0037] - upon detection of the third current threshold, the additional inverter is controlled to allow the transfer of at least part of the energy stored in the additional inductive component to the battery,

[0038] - detection of a fourth current threshold in the arms of the additional inverter and / or in the additional inductive component,

[0039] - upon detection of the fourth threshold, switching of the additional inverter so as to allow a transfer of electrical energy from the battery to the additional inductive component via the additional inverter.

[0040] According to one characteristic, the control of the additional inverter is independent of the control of the main inverter.

[0041] Brief description of the drawings

[0042] Other aspects, objectives, advantages, and features of the invention will become clearer upon reading the following detailed description of preferred embodiments thereof, given by way of non-limiting example, and made with reference to the accompanying drawings in which:

[0043] [Fig. 1] represents a system for heating the battery of an electric or hybrid vehicle.

[0044] Detailed description

[0045] In the figures and throughout the description, the same reference numerals represent identical or similar elements. Furthermore, the various elements are not drawn to scale to ensure clarity. Moreover, the different embodiments and variants are not mutually exclusive and can be combined.

[0046] The invention relates to a system for heating a 100 battery of an electric or hybrid vehicle. An example of the system is shown in Figure 1.

[0047] The system includes a battery (100) that we want to heat and which is capable of supplying a voltage of 100. This battery can be a lithium battery, specifically an LFP battery. For example, the battery can supply a voltage of 800V. The battery can be any type of electrical battery with prismatic or cylindrical cells, or even a plate battery.

[0048] The system also includes a main inverter 101 connected to the battery 100 and comprising a plurality of inverter arms B1, B2, B3. In the example in Figure 1, the main inverter 101 comprises three inverter arms B1, B2, B3. Each inverter arm may comprise two transistors P1, P2, P3, P4, P5, P6, for example IGBTs or MOSFETs, capable of switching in a complementary manner at a predetermined switching frequency which may be at least 100 Hz.

[0049] The main inverter 101 can be a three-phase inverter and can convert the DC voltage supplied by the battery 100 into an AC voltage, including a three-phase AC voltage.

[0050] The system also includes an additional inverter 201, separate from the main inverter 101, which is connected to the main inverter 101. In the example shown in Figure 1, the additional inverter 201 comprises two additional inverter arms, A1 and A2. In other words, the additional inverter 201 is an H-bridge. Each inverter arm, A1 and A2, comprises two transistors, T1, T2, T3, and T4, which can be, for example, MOSFETs or IGBTs.

[0051] The system further includes an electrical machine 102 connected to the main inverter 101 and comprising a stator. The stator comprises a plurality of stator coils L1, L2, L3 capable of storing energy in the form of a magnetic field.

[0052] Each stator coil L1, L2, L3 is connected to a corresponding main inverter arm B1, B2, B3.

[0053] The system also includes an additional inductive component 200 external to the electric machine 102 and connected to the main inverter 101. The external inductive component 200 can be a single-phase coil. The external inductive component 200 can be connected between the arms of the additional inverters A1 and A2 of the additional inverter 201.

[0054] By "external to the electrical machine", we mean that the external inductive component is not integrated into the electrical machine 102, and that its inductance is different from the inductances of the stator L1, L2, L3.

[0055] Advantageously, the additional inductive component 200 allows simple and easy control of the total inductance value of the system in order to act on the total inductance value of the system and to allow, for example, limiting the electric current in the stator of the electric machine 102.

[0056] The main inverter 101 is configured to transfer electrical energy from the battery 100 to the stator coils L1, L2, and L3 via the main inverter 101, and to transfer at least some of the energy stored in the stator coils L1, L2, and L3 back to the battery 100 via the main inverter 101. In other words, the battery 100 provides a direct current (DC) voltage, which is converted into an alternating current (AC) voltage by the main inverter 101. This AC voltage is then supplied to the stator coils L1, L2, and L3. When current flows through the stator coils L1, L2, and L3, they store energy in the form of a magnetic field. The AC voltage supplied to the stator coils L1, L2, and L3 creates a rotational torque in the electric machine 102.

[0057] By "via the main inverter 101", we mean that the transfer of electrical energy takes place through the main inverter 101.

[0058] The additional inverter 201 can transfer electrical energy from battery 100 to the additional inductive component 200 via the additional inverter 201, and at least some of the energy stored by the additional inductive component 200 can be transferred back to battery 100 via the additional inverter 200. In other words, battery 100 provides a direct current (DC) voltage, which is converted into alternating current (AC) by the additional inverter 201, and this AC voltage is supplied to the additional inductive component 200. When current flows through the additional inductive component 200, it stores energy in the form of a magnetic field. At least some of this energy can be returned to battery 100 via the additional inverter 201 to heat battery 100.

[0059] The total inductance of the additional inductive component 200 can be determined so that the current flowing through each of the stator inductors L1, L2, and L3 is less than a stator current limit. This makes it possible to reduce the power dissipated in the electrical machine 102. For example, the stator current limit could be 500 A in absolute value.

[0060] The transfer of at least part of the energy stored in the stator coils L1, L2, L3 and / or in the additional inductive component 200 to the battery 100 ensures heating of the battery 100.

[0061] Heating the battery is particularly useful in cold weather, for example when the outside temperature is below 5 degrees Celsius.

[0062] Advantageously, the system allows heat losses to be generated within the cells of the battery 100 itself, which is more efficient since the heat is generated directly within the chemistry of the battery 100 without heating non-targeted components such as the battery casing, for example.

[0063] The system also ensures even heating. The additional inverter 201 can be controlled independently of the main inverter 101.

[0064] Advantageously, the system allows the battery to be heated even while the vehicle is in motion, since the stator coils L1, L2, L3 create a rotational torque to make the vehicle move, while the inductance of the additional inductive component 200 allows the battery 100 to be heated during this time while the vehicle is in motion.

[0065] The main inverter 101 and the additional inverter 201 can be controlled by a single control unit. The control unit can, for example, be a microprocessor or a microcontroller.

[0066] The control unit can be connected to a current sensor capable of detecting a current threshold.

[0067] Advantageously, the control unit can thus manage the synchronization of the commands of the main inverter 101 and additional inverter 201.

[0068] For example, the control unit can control the transfer of energy from battery 100 to the stator inductors L1, L2, L3 via the main inverter and, at the same time, the transfer of energy from the additional inductive component 200 to battery 100 via the additional inverter 201. In the circuit of Figure 1, component 400 represents the impedance of battery 100 and of the cables which connect the battery to the various components.

[0069] The system may further include a DC 500 coupling capacitor connected between the battery 100 and the main inverter as can be seen in Figure 1.

[0070] The DC coupling capacitor 500 filters and stabilizes the DC voltage transmitted from battery 100 to the main inverter 101. The DC coupling capacitor 500 reduces voltage ripple and provides a stable power supply to the main inverter 101.

[0071] The additional inverter 201 can be mounted on the same electronic board as the main inverter 101. By integrating the two inverters onto a single board, the system's footprint is reduced.

[0072] Alternatively, the additional inverter 201 can be mounted on a different electronic board than the main inverter 101. Thus, in the event of failure or need for system upgrade, it is simpler to replace or repair an individual board without affecting the other.

[0073] According to an example embodiment of the system, the stator inductances L1, L2, L3 and the inductance of the additional inductive component 200 can each have a value between 200 mH and 1000 mH and DC coupling capacitor 500 can have a capacitance value between 100 pF and 700 pF.

[0074] The system may include a cooler, specifically one containing a heat transfer fluid such as water or oil. The cooler may be configured to allow heat transfer from the additional inductive component 200 to the battery 100.

[0075] The invention further relates to an electric or hybrid vehicle comprising the system described above.

[0076] The invention further relates to a method for heating the battery 100 of an electric or hybrid vehicle for the system described above.

[0077] The process includes the steps described below, which can be repeated cyclically. By "repeated cyclically," we mean that the steps are repeated at each switching cycle of the main inverter 101.

[0078] First, the main inverter 101 is controlled to allow the transfer of electrical energy from the battery 100 to the stator coils L1, L2, and L3 via the main inverter 101. In this configuration, transistors P1, P3, and P6 are conducting or closed, while transistors P2, P4, and P5 are blocked or open. Thus, in the first configuration, the battery 100 is connected to the stator of the electric machine 102 and to the additional inductive component 200. The stator current increases until it reaches an initial current threshold.

[0079] The first current threshold is then detected in the arms of the main inverter 101 and / or in the stator coils L1, L2, L3.

[0080] Still in the first configuration, and according to an alternative, it is possible to use only two inverter arms, and in this case, transistors P5, P6 are always open, while P1 and P4 are closed to increase the current in the inverter arms, therefore to also increase the stator current.

[0081] More generally, the first configuration involves a combination of state (open or closed) for the transistors allowing current to flow from the battery 100 to the stator coils L1, L2, L3 and to the additional inductive component 200.

[0082] Upon detection of the first current threshold, the main inverter 101 is activated to change its configuration, allowing the transfer of at least some of the energy stored in the stator coils L1, L2, and L3 to the battery 100. In this configuration, transistors P1, P3, and P6 are either blocked or open, while transistors P2, P4, and P5 are conducting or closed. The stator current then decreases until it reaches a second current threshold.

[0083] Still in the second configuration, and according to an alternative, it is possible to use only two inverter arms, and in this case, transistors P5, P6 are always open, while P2 and P3 are closed to decrease the current in the inverter arms, therefore to also decrease the stator current and in the additional inductive component 200.

[0084] More generally, the second configuration involves a combination of state (open or closed) for the transistors allowing current to flow from the stator coils L1, L2, L3 and the additional inductive component 200 to the battery 100.

[0085] The second current threshold is then detected in the arms of the main inverter and / or in the stator coils L1, L2, L3. Upon detection of the second threshold, the main inverter 101 is controlled so as to allow the transfer of electrical energy from the battery 100 to the stator coils L1, L2, L3 again. And so on.

[0086] The process may also include the steps described below, which may be repeated cyclically. "Repeated cyclically" means that the steps are repeated with each switching cycle of the additional inverter 201.

[0087] First, the additional inverter 201 is controlled to allow the transfer of electrical energy from the battery 100 to the additional inductive component 200. In this configuration, transistors T1 and T4 are closed, while transistors T2 and T3 are open. The current in the additional inductive component 200 increases until it reaches a third current threshold. This third current threshold may be equal to the first current threshold. Alternatively, the third current threshold may be different from the first current threshold.

[0088] The third current threshold is then detected in the arms of the additional inverter and / or in the additional inductive component 200.

[0089] Upon detection of the third current threshold, the additional inverter 201 is activated to allow the transfer of at least part of the energy stored in the additional inductive component 200 to the battery 100. In other words, at least part of the energy stored in the additional inductive component 200 is returned to the battery 100 in order to heat the battery 100. In this configuration, transistors T2, T3 are closed while transistors T1, T4 are open.

[0090] Next, a fourth current threshold is detected in arms A1 and A2 of the additional inverter 201 and / or in the additional inductive component 200. The fourth current threshold may be equal to the second current threshold. Alternatively, the fourth current threshold may be different from the second current threshold.

[0091] Upon detection of the fourth threshold, the additional inverter 201 is switched on so as to allow the transfer of electrical energy from the battery 100 to the additional inductive component 200 again. And so on.

[0092] The control of the additional inverter 201 can be independent of the control of the main inverter 101. In other words, the additional inverter 201 is controlled independently of the main inverter 101. The two inverters can operate independently of each other. This is particularly advantageous because the main inverter 101 can be used to generate rotational torque in the electric machine 102, while the additional inverter 201 can simultaneously be used to heat the battery 100.

Claims

DEMANDS 1. System for heating a battery (100) of an electric or hybrid vehicle comprising: - the battery (100) capable of supplying a battery voltage (100), - a main inverter (101) connected to the battery (100) and comprising a plurality of main inverter arms (B1, B2, B3), - an additional inverter (201) different from the main inverter (101) and connected to the main inverter (101), - an electrical machine (102) connected to the main inverter (101) and comprising a stator, the stator comprising a plurality of stator coils (L1, L2, L3) capable of storing energy in the form of a magnetic field, each stator coil (L1, L2, L3) being connected to a corresponding main inverter arm (B1, B2, B3), - an additional inductive component (200) external to the electrical machine (102) and connected to the additional inverter (201), the main inverter (101) being configured to allow a transfer of electrical energy from the battery (100) to the stator coils (L1, L2, L3) via the main inverter (101) and a transfer of at least part of the energy stored in the stator coils (L1, L2, L3) to the battery (100) via the main inverter (101), the additional inverter (201) being configured to allow a transfer of electrical energy from the battery (100) to the additional inductive component (200) via the additional inverter (201) and a transfer of at least part of the energy stored by the additional inductive component (200) to the battery (100) via the additional inverter (200), the transfer of at least part of the energy stored in the stator coils (L1, L2, L3) and / or in the additional inductive component (200) to the battery (100) ensuring heating of the battery (100).

2. System according to claim 1 in which the additional inverter (201) is controlled independently of the main inverter.

3. System according to any one of the preceding claims in which the main inverter (101) and the additional inverter (201) are controlled by a single control unit.

4. System according to any one of the preceding claims wherein the additional inverter (201) is mounted on the same electronic board as the main inverter (101).

5. System according to any one of claims 1 to 3 in which the additional inverter (201) is mounted on an electronic board different from the main inverter (101).

6. System according to any one of the preceding claims comprising a cooler, in particular a cooler comprising a heat transfer fluid, the cooler being configured to permit heat transfer from the additional inductive component (200) to the battery (100).

7. Electric or hybrid vehicle comprising the system according to one of the preceding claims.

8. A method for heating the battery (100) of an electric or hybrid vehicle implemented by the system according to any one of claims 1 to 6, comprising the following steps: - control of the main inverter (101) so as to allow a transfer of electrical energy from the battery (100) to the stator coils (L1, L2, L3) via the main inverter (101), - detection of a first current threshold in the arms (B1, B2, B3) of the main inverter (101) and / or in the stator coils (L1, L2, L3), - upon detection of the first current threshold, control of the main inverter (101) so as to allow a transfer of at least part of the energy stored in the stator coils (L1, L2, L3) to the battery (100), - detection of a second current threshold in the arms (B1, B2, B3) of the main inverter (101) and / or in the stator coils (L1, L2, L3), - upon detection of the second threshold, switching of the main inverter(101) so as to allow a transfer of electrical energy from the battery (100) to the stator coils (L1, L2, L3) via the main inverter (101).

9. A method according to claim 8 comprising the following steps: - control of the additional inverter (201) so as to allow a transfer of electrical energy from the battery (100) to the additional inductive component (200) via the additional inverter (201), - detection of a third current threshold in the arms (A1, A2) of the additional inverter (201) and / or in the additional inductive component (200), - upon detection of the third current threshold, control of the additional inverter (201) so as to allow a transfer of at least part of the energy stored in the additional inductive component (200) to the battery (100), - detection of a fourth current threshold in the arms (A1, A2) of the additional inverter (201) and / or in the additional inductive component (200), - upon detection of the fourth threshold, switching of the additional inverter (201) so as to allow a transfer of electrical energy from the battery (100) to the additional inductive component (200) via the additional inverter (201).

10. Method according to claim 9 wherein the control of the additional inverter (201) is independent of the control of the main inverter (101).

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