Patent Application
20230207920
The invention relates to the field of switchable battery devices. More particularly, it relates to a device and a method which allows carrying out a heating of one or more element(s) of a switchable battery device, in particular when the output of the latter is short-circuited.
An architecture of a device with switchable batteries or cells is known for example from the following documents: FR2972305 and FR3007210. Other documents such as FR2972307, FR2977986, FR2951320, FR2944161 also describe architectures of a device with switchable batteries or cells.
In the documents FR2972305 and FR3007210, the output/exchange current is directly related to the output current Iout of the pack that supplies the application or which originates from a charger. This current is controlled to meet the needs of the application and is not optimised for heating the elements, even though one might prefer the use of one element rather than another one to heat one element in priority with respect to another one; yet, at the same time, this element is discharged more substantially in comparison with the others. Furthermore, upon shut-down of the system, it is impossible to achieve a pre-heating of the battery pack since there is no current Iout exchanged with the outside.
In other words, if the output current is zero, the known documents, mentioned hereinabove, do not provide a solution allowing achieving heating of some elements of the battery pack.
Hence, the problem of being able to perform heating of the different elements of an architecture of a switchable-type battery “pack” arises, when the latter is disconnected from the load or supplies a zero voltage.
The objective of the invention is to be able to perform a heating of one or more element(s) of a battery pack when the latter is disconnected from the load or supplies it at a zero voltage.
The invention also provides a mechanism enabling a switchable battery device to heat one or more element(s) or one or more cell(s) even when the system is disconnected from the load or else if it supplies a zero voltage at the output.
To this end, the invention relates to a battery pack type device including a first terminal, a second terminal and a plurality of energy storage elements between said first element and said second terminal, each element may include:
a)—a plurality of energy storage cells in series, each associated with switch means for connecting it, for example in series, with at least one other element, or to disconnect it from one or more other element(s);
b) conductor means for conducting a current, called main current, parallel to the element, or via a parallel circuit or route (including at least one conductor) parallel to the element, called “bypass” circuit or route, when this element is disconnected or is not connected with one or more other element(s);
preferably, the device includes:
c)—means for establishing a short-circuit between a first terminal and a second terminal of the battery when the latter is disconnected or supplies a zero voltage;
d) control means, specifically adapted to select at least one first energy storage element, for example in a first state-of-charge, and at least one second energy storage element, for example in a second state-of-charge, at least one of these two elements being to be heated up and to make a current circulate from the first element to the second element when the first terminal and the second terminal of the device are short-circuited.
In the present application, a “bypassed” element is an element that is disconnected yet with means, forming for example a parallel or alternative circuit (which may include one or more conductor element(s), for example a transistor) or route, enabling the circulation of a current, called main current, in the battery; the current then flows through these means, for example through this route parallel or alternative to that of the element, for example through one or more parallel cell(s) which has/have remained connected or through one or more conductor element(s) which has/have remained connected to the flow route of said current; this parallel circuit or route conveys the current by closure of a means forming a power switch while a series power switch (or the switch means for connecting the element in series with at least one other element) of the element is open; a “bypass” route of an element can therefore be a circuit portion or an alternative route for the current of the battery or of the pack.
Preferably, the switch means (for example a power switch) associated to the element, for example in series with the latter, are opened before the parallel route is closed, for example by switch means (for example a power switch), which avoids any risk of short-circuiting the element; for this purpose, one could provide for a dead time between opening of the switch means associated with the power switch and closure of the parallel route.
The control means may further be specifically adapted to stop the current when at least one setpoint temperature for at least one or more cell(s) of the pack, for example at least one of the 2 cells hereinabove and/or for a portion of the battery pack and/or for the battery pack is reached and/or when at least 2 cells have substantially the same temperature or a neighbouring temperature. By neighbouring, or substantially the same temperature, or the same temperature, it should be understood a temperature discrepancy by less than 10° C., advantageously by less than 5° C.
The invention also relates to a method for heating or balancing the temperature of a battery pack type device of the above-described type.
The invention also relates to a method for heating or balancing temperature in a battery pack type device, for example as described hereinabove in the context of the present invention, including a first terminal, a second terminal and a plurality of energy storage elements, for example in series, between said first terminal and said second terminal, each associated with switch means to connect it to or disconnect it from one or more other element(s), this method including:
a) the establishment of a short-circuit between a first terminal and a second terminal of the battery pack when the latter is disconnected or supplies a zero voltage;
b) the selection of at least one first energy storage element, for example in a first state-of-charge, and at least one second energy storage element, for example in a second state-of-charge, at least one of these two elements should be heated up;
c) the circulation of a current between the first element and the second element.
The circulation of this current can be stopped when at least one setpoint temperature for at least one or more element(s) of the pack, for example at least one of the 2 elements hereinabove and/or for at least one portion of the battery pack and/or for at least the battery pack is reached and/or when at least 2 elements have the same temperature or a neighbouring temperature.
According to the invention, it is possible to close the electrical circuit (by short-circuiting the output of the battery pack) and make the current flow through the battery pack, which could then circulate in one or more element(s) and thus heat them.
Hence, it is possible to exchange current between the elements of the battery pack to heat up one or more of these elements.
The output of the back being short-circuited, the exchange current is controlled by the battery itself via a regulation loop of the current that flows in the short-circuit of the output, which has the following advantages:
It is possible to make a current flow back-and-forth between the cells or the elements, which, on average, does not significantly modify their state-of-charge: for example, one element gives in charges that it recovers afterwards, preferably at frequency that is high enough (for example a frequency>0.01 Hz) so that the state-of-charge of each element does not significantly oscillate. Yet, this back-and-forth current creates ohmic losses in the bricks (or elements), which heats them up. In a method according to the invention, the circulation of a current between the first element and the second element may include a current back-and-forth flow between these 2 elements, the current exchanged between these 2 elements being zero on average.
The current, for example the average root mean square current, of each element can be regulated so as to control the temperature of the considered element(s). The root mean square current corresponds to the root square of the squared average of the current. For a sinusoidal current, the root mean square value is equal to the peak amplitude divided by the square root of 2 and the average current is zero (i.e. the exchanged power is zero on average); it is possible to use current of different forms, as explained later on in the present application. This current may have a continuous component to ensure, at the same time, a power exchange function (for a readjustment, for example, of balancing, of availability, of efficiency inter alia).
According to the present invention, charge imbalances are intentionally created, by circulation of the charges between the elements of the pack, then it is possible to cancel these imbalances, by circulation of the charges in the reverse way, in order to heat up the elements or the cells. Preferably, charge imbalances that are created last a short time and in one way then in the other, in order to heat up one or more element(s).
The invention allows avoiding the implementation of a heating device, for example an electrical one, external to the battery pack (for example by an electrical heating device).
In addition, it allows bringing in heat to the core of the cells of the battery (where it is useful), and minimises peripheral losses.
Steps a)-c) can be implemented by control means of the battery pack.
A device according to the invention may include means allowing reversing the voltage of at least one element or group of elements (for example of a module); a method according to the invention may include a step of reversing the voltage of at least one element or group of elements (for example of a module). This allows directing a current from the element or from the group of element(s), whose voltage has been reversed, to another element or group of element(s).
In a device or a method according to the invention, each element may include one or more electrochemical cell(s) and/or one or more capacitance(s) and/or one or more supercapacitance(s) and/or one or more storage cell(s).
An element of a device or in a method according to the invention may include:
The control means may be specially adapted, and/or a method according to the invention includes a step, to calculate at least the value and/or the profile of a heating current (Iout_set_eff) according to:
The control means may further be specially adapted to calculate one, and/or a method according to the invention may include a step of calculating one, heating current (Iout_set_eff) according to a waveform of the current.
According to one embodiment, the current has:
According to another embodiment:
In a method or a device according to the invention, the current may have a form optimised to maximise heat-up; for example, it has a frequency for which the real component of an impedance of at least one cell is maximum.
The control means may further be specially adapted to, and/or a method according to the invention includes a step of:
The control means may further be specially adapted to, and/or a method according to the invention includes a step to, maximise the number of elements involved in the groups G1 and G2 and/or to maximise |UG1|+|UG2|, UG1 (resp. UG2) being the voltage supplied by the group G1 (resp. G2).
A device according to the invention may include a current regulation loop. In a method according to the invention, the current may be regulated using a regulation loop.
For example, said current regulation loop determines a number (NG1) of first energy storage elements and a number (NG2) of second energy storage elements, as well as the voltage (VG1) supplied by all of the first energy storage elements and the voltage (VG2) supplied by all of the second energy storage elements.
The following strategies can be implemented using a device or a method according to the invention:
The invention may apply to all storage systems based on a switchable architecture, i.e. a battery or a set of batteries, composed by cells or elements, for example by modules, able to be set in series, or set in parallel, or replaced by a short-circuit or set in series with a possible reversal in the polarity. An “element” may be an elementary cell, for example an electrochemical cell, or a group of such elementary cells connected in series and/or in parallel. In general, the invention also applies to the cases where the elements are associated with DC/DC converters.
The invention can also apply to batteries including several accumulators of different technologies (for example different battery chemistries, capacitances, supercapacitances . . . ) and/or of different generator technologies (fuel cell, solar panels . . . ).
In the present application, a reference to one or more switchable cell(s) should be understood as also covering a combination of several electrochemical cells, and/or several capacitances, and/or several fuel cells, and/or several energy sources/generators . . .
A combination of several cells that can be connected in series and/or in parallel is also called “module”.
In general, in the present application, the state-of-health can be defined by the degradation of the amount of charge that a cell (or more generally an element) can store/deliver, in comparison with its original state (before any use), at equal current. A 100% SoH applies when there is no degradation, a 0% SoH means that the cell can no longer store energy. It is also possible to define the capacity ratio in Ah between the capacity of the cell (or more generally an element) at a time point t and its capacity when it was new. The capacity of a cell is the number of Amps-hour (Ah) (the Ah is a unit homogeneous with Coulomb) that the cell can deliver following a complete charging.
Amps-hours correspond to an integration of the current, for the capacity, this consists in integrating the current between the start and the end of discharge. One could also find a definition of the SoH in the following link:
https://www.labellebatterie.com/soh-batterie-et-capacite-ce-quil-faut-comprendre/
Embodiments of the invention will now be described with reference to the appended drawings wherein:
Such a pack may include M modules (Ei, (1≤i≤M)) 12, 14, 16, each module including a plurality of N cells 121-124, 141-144, 161-164. In
This architecture with switchable cells allows:
In the context of the present text, an “element” may include one cell or a group of elementary cells which may be set in series and/or in parallel (forming a module); the step of the voltage supplied by one element may be for example in the range of 3.6V, 12V or 24V, 48V or any other value.
As indicated hereinabove, each cell can be set in series or in parallel with other cells of the same module and/or replaced by a short-circuit. To this end, power switches, for example transistors, are provided. In this example, like the other examples or embodiments of the present application, the power switches may be made using power transistors, preferably of the NMOS type, or bipolar, or FET, or JFET, or IGBT transistors.
The power switches thus implemented allow using, or not, some cells and/or some modules of cells depending on needs and/or achieving an optimisation of the use of the battery pack.
In the illustrated example, each cell is provided (only some power switches associated with the cell 121 are numbered in
The battery pack and/or each cell, or one or more cell(s), may be provided with one or more temperature sensor(s); possibly one or more cell(s) may be provided with a sensor for measuring charging of the cell and/or with a sensor for measuring the voltage at the terminals of the cell and/or with a sensor for measuring the mechanical deformation of the cell and/or with a sensor for measuring gas in the cell (for example to detect an overcharging, or an overheat or a leak that might cause the generation of gases) and/or with an acoustic sensor (either to detect a chemical reaction in the cell, or else, if it consists of an ultrasonic-type sensor, to characterise the cell, similarly to the sonography principle or in the form of a characterisation of an acoustic channel) and/or a chemical sensor, for example to measure the density of free ions Li or others in the element.
The device may include a control circuit or a controller 30 which allows, in particular, controlling opening and closure of the power switches of the different cells. The signals that originate from the sensor(s) can be transmitted to this control circuit.
More accurately, as illustrated in
Specific electronics (not represented in the figures) may be associated to each module 12, 14, 16. In this case, the control unit 30 can advantageously communicate with each specific piece of electronics of each module, for example via a communication bus, still for example a common and galvanically-isolated bus. For example, the control circuit 30 can:
According to a particular embodiment, the means (or circuits) 302 and 303 and/or 301 may be integrated within the same unit.
A control circuit of the means 20 can be separate from, or possibly be associated with a general measuring circuit (one could notice that the output current measurement can be useful for the regulation of the current).
Each module may also include a H-bridge 13, 15, 17 placed between the 1st terminal and the 2nd terminal of the module, which allows reversing, or not, the polarity of all elements connected to the bridge; in one variant, not represented in the figures, it is possible to implement a controlled switch or a controlled changeover switch, for example an electromechanical relay which serves as a changeover switch (next, only the variant implementing H-bridges will be described, but the invention could also be adapted to the case of changeover switches). This bridge includes the power switch means 13i1, 13i2, 13′i1, 13′i2 . . . (only the power switches of the H-bridge 13 associated with the module 12 are numbered in
Each module 12, 14, 16 of the example of
Since each module is independent, its H-bridge can be oriented in any manner with respect to that of the other modules.
Means 20 allow achieving a short-circuit between the input terminal 101 and the output terminal 102 of the pack; these means 20 include for example a power switch, for example a transistor of the type mentioned hereinabove, disposed between this input and this output. For example, these means 20 are controlled by the control means 30 or by an electromechanical relay. One could notice that, alternatively, a manual control is possible, although this is less interesting because it is less certain, it can be associated with a locking mechanism to prevent an actuation at the wrong time.
An example of a balancing method according to the invention, implementing a short-circuit mode using the means 20; is as follows:
The temperature of the element or of the elements can be measured and compared with a setpoint temperature.
Hence, the invention allows proceeding with heating of one or more element(s), for example one or more cell(s) or else one or more module(s).
Yet, alternatively to heating one or more element(s), or complementarily, it allows
Herein again, the temperature can be measured and compared with a setpoint temperature that should be reached. Or, when it is desired to balance the temperatures of 2 or more elements, the temperatures of these elements can be measured and compared.
According to an embodiment of the invention, based on the information relating to all of the cells or of the modules to be heated up, the mean 30 can perform a distribution of these cells or modules into two groups G1 and G2, for example substantially equivalent in terms of needs for heat-up (this need being for example expressed in overall thermal Wh).
Afterwards, it is possible to proceed with a regulation of an exchange current between the groups G1 and G2 allowing for example following a setpoint current, which can be preprogrammed or calculated for example according to the properties of the bricks (or elements) (for example according to a capacity to accept a current and/or a “C-rate” limit and/or the current state of one or more element(s) or cell(s) (for example the temperature and/or the state-of-charge and/or the state-of-health).
One could notice that:
Preferably, the regulation is performed while maximising the number of elements involved in the groups G1 and G2: the smallest group substantially determines the number of elements that can be used in the largest group. Hence, the maximum number of elements involved is substantially twice the number of elements of the smallest group; maximising the use of the elements of the smallest group amounts to maximising the total number of elements involved. Preferably, we have 2 identical or relatively similar groups in terms of number of elements and heat-up need. Thus, if the two groups are identical or similar, the current is not more limited by one group than by the other one and likewise for the number of elements. A maximisation of this number of elements in each of the groups can be carried out as follows.
The group G1 supplies a first voltage UG1 and the group G2 supplies a second voltage UG2 with a reverse polarity (with polarity reversal means, for example the above-described H-bridges in
The current evolves substantially according to i=(UG1+UG2)/(L*t) if losses are neglected, L representing the inductance placed at the output, for example like in . In some cases, the self-impedance of the cables and of the cells can be enough to filter the current (for example if the drive frequency is high enough with regards to the length of wiring).
The current actually depends on the discrepancy ΔU=UG1−(−UG2), the current regulation loop acting on this ΔU to regulate the exchanged current.
The same ΔU can be obtained for different values of UG1 and of UG2 and it is possible to obtain the desired value of ΔU by a regulation loop with the pair (UG1, UG2) that maximises |UG1|+|UG2|. This corresponds to the maximisation of the number of cells involved in the exchanges: for the same exchanged current, if the voltage is maximised, the number of connected elements is maximised and therefore the number of heated elements.
To obtain this maximisation, it is known that UG1=−UG2+ΔU or UG2=−UG1+ΔU. For example, UG2 is set at its minimum value UG2min and UG1calculated=−UG2min+ΔU is calculated:
It is also possible to set a reversed voltage polarity. In this case, UG2 is set at its maximum value UG2max and UG1calculé=−UG2max+ΔU is calculated:
Thus, a maximum value and a minimum value of the voltage are defined during the current exchange; afterwards, it is possible to take on the maximum voltage, or the minimum voltage or else alternate between the maximum voltage and the minimum voltage, for example according to a square-like signal. Alternatively, it is possible to adopt any waveform for the voltage, for example a sinusoidal form whose swing varies from the minimum voltage to the maximum voltage thus calculated.
Alternatively, the operation may be as follows (without seeking to maximise the amplitude of the voltages UG1 et UG2 and/or the number of elements involved among the groups G1 and G2): for example an amplitude lower than Min(UG1max, UG2max), for example ½ Min(UG1max, UG2max) or else: , is defined,
Min(UG1max, UG2max)−Marge,
the “Margin” may, for example, be enough so that the current regulation loop, which adjusts the voltage around this target value, does not reach the voltage limit too often, which might make it unstable.
Hence, an algorithm or a method implemented according to the invention may include the following steps, each of which has been described in details hereinabove:
The means 30 can:
Consequently, the determination of the temperature(s) and/or of the current to circulate and/or the open and/or close strategy of the different switches of the battery pack, and/or these openings and/or closures of the different switches of the battery pack, can be carried out or determined by the means 30.
These means 30 can also stop temperature balancing, for example when a setpoint temperature is reached for all or part of the pack or else when several elements reach the same temperature, by opening the power switch 20.
Regardless of the strategy retained to define G1, G2 and/or the associated voltages, the heat-up is caused by the root mean square value of the current. Hence, it is possible to heat up the elements or the cells with an exchanged current that is zero on average.
Hence, this current can have any form, for example a periodic form that is zero on average (square-like or sinusoidal, or triangular) to which it is possible to superimpose a continuous component for example to ensure state-of-charge balancing between the bricks. Alternatively, the current may be constant and the voltages UG1 et UG2 are alternating and can possibly include a continuous component. Finally, it is possible to have both (voltage and current variables), with a periodic instantaneous power and possibly including a non-zero component to ensure balancing.
Balancing, for example charge balancing, of a battery pack according to the invention could also have been performed beforehand (for example upon stoppage of the vehicle), heating according to the invention being performed afterwards, for example at a currant that is almost zero on average for a heated cell and by performing current back-and-forth flows.
Charge balancing between the elements may be carried out, for example after an extended shutdown, for example in case of a non-homogeneous self-discharge effect or a relief effect leading to non-homogeneous relieved voltages. It is then possible to carry out balancing, with an average current relatively low compared to the nominal current. On the contrary, the currents exchanged back-and-forth to heat up according to the invention are significantly higher in amplitude (at least by a factor of 3). Heat-up related to the continuous component can be neglected most of the time, nonetheless it is possible to take it into account by reducing as much the AC component to reach the desired heat-up root mean square current.
This regulation loop allows regulating the output current Iout to make it follow a setpoint current Iout set.
All control elements (left subtractor, 304, 305, 306, 306′, etc.) of the regulation loop of
The regulation loop, with the output of the pack short-circuited by the means 20, regulates the current Iout that flows in these means 20 based on a setpoint current Iout_set; Iout also corresponds to the current that is exchanged between the groups G1 and G2. The discrepancy between Iout and Iout_set is input in a regulator (corrector 304) which can be of any type, for example a PID (Proportional Integral Derivative) or integrating prediction ore reverse model mechanism. This corrector 304 determines the discrepancy, at all times, in the number N of bricks between the groups G1 and G2, the groups G1 and G2 having opposite polarities (ΔN=NG1+NG2).
The block 305 “ΔN distribution”, determines the number of bricks |NG1| to be used in the group G1 and the number |NG2| to be used in the group G2, and that being so while meeting the condition NG1+NG2=ΔN. In other words, since there are several combinations (NG1, NG2) that can produce the same ΔN, a selected or arbitrary function can be implemented, herein by the means 305. These means can retain or select a combination, from among the possible combinations, for example one that maximises the number of elements involved (selection criterion). More generally, it is possible to select different options:
The block 306′ “|NG2| bricks selection+polarity” has the same function, but for the group G2.
The block 307 «+/−Σ∀briques_G1» represents the operation of the system, i.e. an estimation of the voltage VG1 generated by all of the bricks of the group G1 selected and connected in series and including the polarity (+/−) of this connection, the elements of the group G1 being connected according to a polarity reversed with respect to the bricks of the group G2.
The block 307′ «+/−Σ∀briques_G2» has the same function but for the group G2.
The “adder” block 311, placed at the output of the previous 2 blocks, determines the voltage at the terminals of the impedance Z, this impedance Z representing the equivalent impedance of the battery pack completed by a possible complementary impedance placed on the feedback route at the output of the pack, for example an inductance. The impedance Z may be a complex impedance with a real part (resistive component of the impedance) and an imaginary part (inductive component of the impedance).
As indicated hereinabove, heat-up of the different elements depends on the root mean square current that flows through the bricks (losses=RI2, it should nevertheless be noted that the real component “R” of the impedance of the battery cells depends on the frequency, in which case “R” is considered with regards to the frequency of the current as seen by the cells).
The means 313 (for example a calculator (such as a microcontroller, or processor, or FPGA, or ASIC . . . ; these means being advantageously located in the means 30) determine the value/the profile of this root mean square current Iout_set_eff, for example, according to:
The “Normalised waveform” block 314 of
Thus, by multiplying this waveform by the intermediate setpoint Iout_set_eff, a waveform that has a root mean square value corresponding to this setpoint is obtained.
The frequency of the waveform can be optimised to maximise heat-up, it is for example the frequency where the real component of the impedance of the cell is maximum, yet with frequency limits fmin et fmax:
Finally, in the case of an alternating waveform, it is possible to add a continuous component to ensure a power transfer that is not zero on average, also allowing achieving balancing between the cells and/or the modules, for example a state-of-charge balancing.
For example, the current is regulated in real-time by acting on ΔN, then a pair (NG1, NG2) that selects at all times the bricks that should be heated up in priority while meeting the condition NG1+NG2=ΔN is determined.
If NG1 has a positive polarity and NG2 has a negative polarity: ΔN−NG1−|NG2|
More generally, ΔN corresponds to the difference of connected elements between the groups G1 and G2. In the example, the group G2 is connected according to a negative polarity and it is assumed that the voltages VG1 et VG2 are proportional respectively to NG1 and NG2. Therefore, it is herein assumed that the discrepancy VG1−|VG2| is proportional to ΔN. Moreover, it is considered that the impedance Z has a resistive behaviour which results in a positive ΔN inducing a positive current and a negative ΔN inducing a negative current. Moreover, the impedance Z has an inductive component which tends to smooth the current I.
Over the portion A, NG1 is greater than |NG2|(ΔN>0) which leads to a positive current I which follows a positive sine alternation. Over the portion B, NG1 is smaller than |NG2|(ΔN>0) which leads to a negative current I which follows a negative sine alternation.
In practice, ΔN operates substantially in the same manner as a PWM to induce a current that follows a setpoint current, herein sinusoidal.
Alternatively, it is possible that the current setpoint Iout_set is not modulated by an alternating waveform, and instead, it is the polarity of the groups G1 and G2 which is modulated, as illustrated in
In
Over the entire length of the profile, ΔN=NG1+NG2 oscillates between 0 and 1, its moving average value is always positive resulting in a current I that is always positive yet with a slight variation because the positive pulses are slightly larger to the left than to the right inducing a moving average and therefore a current that is slightly higher to the left than to the right.
This is the case in particular of an example wherein at least 4 elements should be heated in each group G1 and G2 during the first two phases A, B; during the third phase C, only 2 elements are still to be heated in the group G2 (and 3 elements in G1).
Using an alternating current or an alternating voltage allows obtaining an exchanged power that is zero on average over time: <UG1*Iout>=<UG2*Iout>≈0. At the period level, we have during one half-period, a power transfer in one way, then during the second half-period, a power transfer in the other way. The duration of one period is typically at least 100 times as short as the charging/discharge duration of the battery, so that the variation in the state-of-charge over a half-period remains low/negligible. At the charging/discharge end, this period can be reduced so as not to overcharge/undercharge.
Alternatively, or complementarily, the amplitude of the current can be reduced when approaching the charging/discharge end. In practice, for a reduced period for example to is, the exchanged amount of energy is extremely reduced compared to the energy that can be stored in the battery (the ratio (exchanged amount of energy)/(amount of energy that can be stored) is for example<1/1,000) for a 3C current (3C=3 times the capacity C of the cell in Ah, 1 Ah implying a current of 3×1 Ah=3 A).
It should be noted that, according to
For example, a portion of the battery is kept at a temperature Tset2, for example high enough to supply inrush currents should an application be turned on, and over another portion of the pack a minimum temperature Tset1 for preserving the battery is guaranteed. For example, this second portion of the battery may become fully available only after having powered the application for some time.
Still for example, in the case of
Alternatively to the diagram of
All of the above-described methods can be implemented with the device described before in connection with
Alternatively, illustrated in
A variant is illustrated in
With such a component in series at the output of the system, the voltage between the positive pole and the negative pole will not be completely zero during balancing. A second power switch 60 may then be useful to avoid powering the equipment plugged to the battery pack with this residual voltage:
All of the methods described hereinabove can be implemented with the device that has just been described, whether in connection with
According to one example, the invention can be applied to heat a battery of a vehicle.
One could consider the example of an electric vehicle used in cold weather, for example in mountains in the winter. The vehicle is parked in the morning, the battery cools down during the day and, at the time of leaving, the battery is too cold to be used (for example the temperature is −30° C.). The elements located at the boundary of the battery pack have cooled down to a temperature lower than those of the centre of the battery. An alternating current is then exchanged between the elements, with a root mean square current that is even higher as the temperature of the considered brick is low. This mechanism then allows making the temperature of each of the elements of the battery rise to a setpoint temperature.
Alternatively, the elements of the battery are kept above a minimum temperature throughout the entire day, so as to increase their service lifespan and/or to make the battery available at any time.
| Number | Date | Country | Kind |
|---|---|---|---|
| 21 14455 | Dec 2021 | FR | national |
