Method for controlling the temperature of at least one suitable capacity for an on-board charger.

Abstract

The invention relates to a method for optimizing the lifespan of at least one capacitance of a capacitance module (400) of an electronic device (100), said electronic device (100) being adapted to charge a high-voltage battery (600) of an electric vehicle, said device comprising a power factor correction circuit (300), a DC / DC converter (500), a cooling device (700) adapted to cool at least one capacitance of the capacitance module (400), a second temperature sensor (910) disposed on at least one capacitance of the capacitance module (400) and adapted to measure an actual temperature of said at least one capacitance, the method comprising the following steps: a first step a1) consisting of activating the charger (100) to charge the high-voltage battery (600), a second step a2), consisting of charging the high-voltage battery (600) by the charger (100) with a first setpoint power (P1_cons).Figure for the summary: Fig 3.

Description

Title of the invention: Method for temperature control of at least one suitable capacity for an on-board charger. Technical field

[0001] The invention relates to the field of electric vehicles and more specifically to a method for optimizing the lifespan of at least one capacity for an on-board charger of an electric vehicle. Previous technique

[0002] An electric vehicle comprises at least one high-voltage battery, for example a 400-volt or 800-volt battery, connected to a high-voltage electrical network (the electric vehicle's internal network), and one low-voltage battery, for example a 12-volt battery, connected to a low-voltage electrical network (the electric vehicle's internal network). Both the high-voltage and low-voltage batteries are adapted to deliver and store electrical energy, respectively, on the high-voltage and low-voltage electrical networks.

[0003] To achieve this, the electric vehicle includes an on-board charger, more commonly known as an OBC (On-Board Charger), connected to the high-voltage battery, designated "BHT," via the high-voltage electrical network. The on-board charger is designed, once connected to a power supply network, to convert the alternating voltage supplied by an external electrical network into a high-voltage direct current suitable for recharging the high-voltage battery.

[0004] Fig. 1 represents a schematic diagram of a state-of-the-art on-board electric charger 10 adapted to charge the high-voltage battery 60 dedicated, for example, to powering an electric machine for the propulsion of an electric or hybrid vehicle.

[0005] The on-board electric charger 10 includes an electromagnetic filtering circuit 20 and a power factor correction circuit 30, referred to as "PFC," which may be bidirectional. This power factor correction circuit 30 further includes an AC-DC converter circuit adapted to receive, for example, an electrical current from a domestic AC power supply.

[0006] The on-board electric charger 10 also includes a capacity module 40 disposed between the power factor correction circuit 30 and a DC / DC direct-direct converter 50 adapted to charge the high-voltage battery 60.

[0007] As those skilled in the art know, the charge of the low-voltage power supply battery, not shown in [Fig.l], is carried out by the high voltage battery 60, by a second DC-DC converter, not shown in [Fig.l] connected between the high voltage battery 60 and the low voltage supply battery.

[0008] The high-voltage battery is charged using the on-board electric charger 10 once connected to the electrical network 70.

[0009] The capacitance module 40 is composed of a determined number of electrochemical capacitances whose equivalent value is relatively large to accept a relatively large effective current value during battery charging and to reduce, or sufficiently filter, the ripples of the rectified voltage at the output of the power factor correction circuit 30 so that, said ripples, once filtered, are compatible with the input characteristics of the DC / DC converter 50.

[0010] A well-known solution for those skilled in the art to realize the capacitance module 40 is to implement a relatively large number of capacitances to obtain a large equivalent capacitance value to be able to both control ripples and accept large effective currents (or RMS currents for "Root Mean Square" in English) when charging the high-voltage battery at full power.

[0011] One disadvantage of this solution is the need to increase the surface area of ​​the printed circuit board or PCB to accommodate said capacities, significantly increasing the cost of the on-board charger 10.

[0012] Furthermore, the value of the effective current, and more specifically the maximum value of the effective current, depends on the battery's charge level and the charger's power. For example, an on-board charger may have a rated power of 7 kW.

[0013] Thus, depending on the said maximum value of the effective current through the said capacitances of the module of capacitances 40, the latter heat up and can sometimes reach temperatures equal to or greater than a critical threshold temperature of capacitance Tcritcap which is given by the manufacturer of the capacitances.

[0014] For example, the critical capacity threshold temperature Tcritcap is 85°C. Thus, if, during the charging of the high-voltage battery by the charger, the temperature of the capacitors reaches or exceeds the critical capacity threshold temperature Tcritcap, then the lifespan of said capacitors is reduced compared to using said capacitors at temperatures below the critical capacity threshold temperature Tcritcap.

[0015] To limit the temperature rise of the capacitors in the capacitance module 40, it is common to use a cooling device placed, for example, on said capacitance module 40. The cooling device is adapted to cool the Capacities are dissipated through the capacitor module 40, and also to cool electronic components located on the printed circuit board of the onboard charger 10. Such a solution can utilize air cooling. However, since the amount of heat to be dissipated is relatively significant, the cooling system can also rely on a liquid cooling principle, i.e., water or glycol. This allows for improved heat dissipation from the electronic components and capacitors.

[0016] As mentioned above, it is necessary to control the lifespan of the capacities of the on-board charger 10 because the latter is given for a minimum period of use by the vehicle manufacturer, for example 20000 hours, under normal operating and charging conditions.

[0017] However, sometimes, said charger 10 and therefore the capacities of the capacity module 40 of said charger 10 are used in extreme conditions, for example when charging the electric vehicle on a charging station in full sun in summer in a supermarket parking lot which causes abnormal heating of the capacities and therefore overheating of said charger which can reduce its service life.

[0018] There is therefore a real need to ensure temperature control of the capacities to avoid exceeding the critical temperature in order to avoid prematurely deteriorating said capacities. Description of the invention

[0019] The invention relates to a method for optimizing the lifespan of at least one capacitor in a capacitor module of an electronic device, said electronic device being adapted for charging a high-voltage battery of an electric vehicle, said device comprising a power factor correction circuit, a DC / DC converter, a cooling device adapted for cooling at least one capacitor of the capacitor module, a second temperature sensor disposed on at least one capacitor of the capacitor module and adapted to measure an actual temperature of said at least one capacitor, the method comprising the following steps: • a first step a) consisting of activating the charger to charge the high-voltage battery, • a second step a2), consisting of charging the high-voltage battery by the charger with an initial set power, • a third step a3), consisting of measuring the temperature of at least one capacitor representative of the temperature of all the capacitors in the capacitor module using the second temperature sensor and storing in a memory area a first actual temperature representative of the temperature of all the capabilities of the capabilities module, • a fourth step a4), consisting of waiting for a first determined duration before moving on to a fifth step a5), • the fifth step a5), consisting of recording a second actual temperature of at least one capacitor representative of the temperature of all the capacitors in the capacitor module, and storing the value of the second actual temperature in a memory area, • a sixth step a6) consisting of waiting a second determined duration before moving on to a seventh step a7), • the seventh step a7), consisting of recording a third actual temperature of at least one capacitor representative of the temperature of all the capacitors in the capacitor module, and storing the third actual temperature in a memory area, • an eighth step a8), consisting of calculating a final temperature value of at least one capacitance representative of the temperature of all the capacitances in the capacitance module using a first Equation: • Equation 1: Trelcap2 = Trelcapl + (Tfinalcap-Trelcapl)*exp(-tp1 / tau),

[0020] and a second Equation: • Equation 2: Trelcap3 = Trelcapl + (Tfinalcap-Trelcapl)*exp((-tpl-tp2) / tau),

[0021] the two unknowns being Tfinalcap and tau, the eighth step a8) consisting further of calculating a power setpoint reduction coefficient using a third equation: • Equation 3: Rcons= Tfinalcap / 85°C,

[0022] and to apply a new initial power setpoint value to the charger, • a ninth step a9), consisting of calculating, using Equation 1, the temperature corresponding to the temperature of the capacitor module after the duration of time, and comparing the calculated value to a critical temperature value, and in the case where the value is higher then proceed to the third step a3) otherwise proceed to a tenth step a10), • the tenth step a 10), consisting of waiting a waiting time equal to the duration of tau before moving on to the third step a3). Brief description of the drawings

[0023] Other features and advantages of the invention will become apparent from the following description. This description is purely illustrative and should be read in conjunction with the accompanying drawings, in which:

[0024] Figure 1 is a structural illustration of a prior art charger,

[0025] Fig. 2 presents a structural diagram of the charger according to the invention,

[0026] Fig. 3 is an illustration of the method according to the invention. Description of the implementation methods

[0027] The invention will be presented in the case of an implementation in an electric vehicle comprising at least one electric machine capable of converting electrical energy into mechanical energy in order to drive at least one wheel of the electric vehicle in rotation.

[0028] With reference to [Fig. 2], a schematic diagram of an electronic device 100 is shown, which is, for example, an on-board electric charger 100 according to the invention. Said on-board electric charger 100 is adapted to charge the high-voltage battery 600 dedicated, for example, to powering a three-phase machine for the propulsion of an electric or hybrid vehicle.

[0029] The on-board electric charger 100 can be unidirectional or bidirectional.

[0030] The latter comprises an electromagnetic filtering circuit 200 and a circuit power factor corrector 300 named "PFC" which can be bidirectional, said power factor corrector 300 circuit comprising an AC-DC converter circuit adapted to receive an electrical current from a domestic AC power supply network for example.

[0031] A capacitance module 400 disposed between the power factor correction circuit 300 and a DC / DC converter 500 adapted to charge the high voltage battery 600. The capacitance module 400 is also referred to by those skilled in the art as the “DC LINK” module.

[0032] As those skilled in the art know, the charging of the low voltage supply battery, not shown in [Fig.2], is carried out by the high voltage battery 600, by a second DC-DC converter connected between the high voltage battery 600 and the low voltage supply battery.

[0033] The high-voltage battery is charged using the on-board electric charger 100 once connected to the electrical network.

[0034] Cleverly, the capacitance module 400 is composed of a determined number of capacitors, for example electrochemical capacitors, adapted to accept a relatively high effective current value during battery charging and to sufficiently filter the ripples of the rectified voltage at the output of the power factor correction circuit 300 so that said ripples, once filtered, are compatible with the input characteristics of the DC / DC converter 500. Cleverly, the device of the invention proposes to control an actual temperature of at least one capacitor called Trelcap.

[0035] The on-board charger 100 cleverly incorporates a cooling device The 800 is located, for example, on the capacitance module 400, but also on the power factor correction circuit 300 and on the DC / DC converter 500. The cooling device 800 includes, for example, at least one suitable channel for circulating a coolant. The coolant is suitable for absorbing heat from the heating of the electronic components of the power factor correction circuit 300 and the DC / DC converter 500, but also for absorbing heat generated by the capacitors of the capacitance module 400. The mechanical fastening and thermal coupling between the various elements are obvious to those skilled in the art.

[0036] Advantageously, a first temperature sensor 900 is located on the cooling device 800 pipe, enabling measurements of the coolant temperature Tliq. In an alternative embodiment, the coolant temperature is provided by measuring means located on the electric vehicle's cooling circuit.

[0037] Advantageously, a second temperature sensor 910 is disposed on at least one capacitor of the capacitance module 400. Alternatively, the second temperature sensor 910 is disposed on a package of the capacitance module 400. The second temperature sensor 910 is adapted to measure the actual temperature Trelcap of at least one capacitor representative of the temperature of all the capacitors in the capacitance module 400. Thus, thanks to the device of the invention, it is possible to know the real-time temperature of the capacitance module 400 and, based on this temperature, to activate or not the on-board charger 100.

[0038] The first temperature sensor 900 and the second temperature sensor 910 can use thermistor-type technology or, alternatively, semiconductor technology.

[0039] The invention proposes a method for controlling the temperature of at least one capacitance of controlling the power delivered by an electronic device 100 as a function of an actual temperature of at least one capacitance of said electronic device 100.

[0040] To do this, the method of the invention comprises, as illustrated in [Fig.3], in the case where the electric vehicle is connected to an external voltage outlet and a recharge of the high-voltage battery 600 is required, a first step a1) consisting of activating the charger 100 to charge the high-voltage battery 600.

[0041] In a second step a2), the high-voltage battery 600 is charged by the charger 100 with a first setpoint power Pl_cons. For example, the first setpoint power Pl_cons is that determined by the vehicle manufacturer in the case of optimal charging of the battery 600. For example, in the case of a 1kW charger the first setpoint power Pl_cons has a value of llkW.

[0042] In a third step a3), the method according to the invention proposes to measure the temperature of at least one capacitor representative of the temperature of all the capacitors in the capacitance module 400. To do this, in the third step a3), the temperature of at least one capacitor is measured using the second temperature sensor 910. Thus, a first actual temperature Trelcapl is recorded for at least one capacitor representative of the temperature of all the capacitors in the capacitance module 400. The method also proposes, in this third step a3), to store the first actual temperature Trelcapl in a memory area. Alternatively, n temperature values ​​are measured for at least one capacitor using the second temperature sensor, and then the average of the measured values ​​is calculated before storing the averaged value in memory.

[0043] The process then proposes, in a fourth step a4), to wait for a first determined duration tpi. In one embodiment, the first determined duration tpi has a value of 30 seconds.

[0044] The process proposes, after the elapsed time of the first determined duration tpi, the transition to a fifth step a5).

[0045] The fifth step, a5), consists of measuring the temperature of at least one capacitor using the second temperature sensor 910. This provides a second actual temperature, Trelcap2, of at least one capacitor, representative of the temperature of all the capacitors in the capacitance module 400. The method also proposes, in this fifth step, a5), to store the second actual temperature, Trelcap2, in a memory area. Alternatively, n temperature values ​​are measured for at least one capacitor using the second temperature sensor, and then the average of the measured values ​​is calculated before storing the averaged value in memory.

[0046] The process then proposes, in a sixth step a6), to wait for a second determined duration tp2. In one embodiment, the second determined duration tp2 has a value of 30 seconds.

[0047] The process proposes, after the elapsed time of the second determined duration tp2, the transition to a seventh step a7).

[0048] The seventh step a7) consists of measuring the temperature of at least one capacitor using the second temperature sensor 910. Thus, a third actual temperature Trelcap3 is recorded for at least one capacitor, representative of the temperature of all the capacitors in the capacitance module 400. The method also proposes, in this seventh step a7), to store the third actual temperature Trelcap3 in a memory area. Alternatively, n temperature values ​​are measured for at least one capacity using the second temperature sensor, and then an average calculation of the measured values ​​is performed before storing the averaged value in memory.

[0049] During an eighth step a8), the final temperature Tfinalcap of at least one capacitance representative of the temperature of all the capacitances of the capacitance module 400 is calculated. The final temperature Tfinalcap represents the final stabilized temperature of at least one capacitance representative of the temperature of all the capacitances of the capacitance module 400 following the constant application of the first setpoint power Pl_cons.

[0050] As those skilled in the art know, the evolution of the temperature of a capacitance under a constant power is in the form of a first-order increasing exponential.

[0051] Advantageously, and thanks to the following measurement values, first actual temperature Trelcap1, first determined time tpi, second actual temperature Trelcap2, second determined time tp2, third actual temperature Trelcap3, it is possible to solve the following system of two equations with two unknowns:

[0052] Equation 1: Trelcap2 = Trelcapl + (Tfinalcap-Trelcapl)*exp(-tpl / tau)

[0053] Equation 2: Trelcap3 = Trelcapl + (Tfinalcap-Trelcapl)*exp((-tpl-tp2) / tau)

[0054] The two unknowns are Tfinalcap and tau, tau represents the thermal time constant of the capacitance module 400. The solution of such a system of equations with 2 unknowns is trivial for a person skilled in the art and cleverly to simplify the solution, it is proposed that the value of the second determined time tp2 is an integer multiple of the value of the first determined time tpi; for example, tpl=tp2.

[0055] Then in the same eighth step a8) a power setpoint reduction coefficient, hereinafter referred to as Rcons, is calculated. It is equal to the following equation: Rcons = Tfinalcap / 85°C.

[0056] In the context of the invention, 85°C is selected as the critical temperature value not to be exceeded for the capacitances of the 400 capacitance module in order not to damage them.

[0057] Cleverly, the coefficient Rcons is used to calculate the new first setpoint power PI cons which will not exceed the critical temperature with an optimal setpoint power to obtain an optimal charging time.

[0058] In the case where the new first calculated Plcons setpoint power exceeds the value of the maximum power of the charger, which in the case of our example is 1 IkW, the value of the maximum power of the charger, i.e. 1 IkW, is selected as the new first Plcons setpoint power.

[0059] During this eighth step a8), the new first setpoint power Plcons is applied to the charger. A ninth step is then proposed. a9).

[0060] During the ninth step a9), it is calculated using the previous equation 1, the temperature Ttau corresponding to the temperature of the module of capacities 400 after the duration of the time tau.

[0061] Cleverly, the calculated value of Ttau is compared to a critical temperature value Tcapcrit. For example, the value Tcapcrit is equal to 85°C. If the value of Ttau is greater than Tcapcrit, then it is proposed to proceed to the third step a3); otherwise, it is proposed to proceed to a tenth step a10).

[0062] In the tenth step a10), it is proposed to wait a waiting period equal to the duration of tau before proceeding to the third step a3). This waiting period avoids measurements and calculations of the new first setpoint power Plcons too frequently because the final temperature Tfinalcap will not reach 85°C.

[0063] Thanks to this clever invention, the battery charging time is optimized because it is possible to estimate the optimal setpoint power without exceeding the critical temperature of the capacitors.

Claims

Demands

1. A method for optimizing the lifespan of at least one capacitor in a capacitor module (400) of an electronic device (100), said electronic device (100) being adapted to charge a high-voltage battery (600) of an electric vehicle, said device comprising a power factor correction circuit (300), a DC / DC converter (500), a cooling device (700) adapted to cool at least one capacitor of the capacitor module (400), a second temperature sensor (910) disposed on at least one capacitor of the capacitor module (400) and adapted to measure an actual temperature of said at least one capacitor, the method comprising the following steps: • a first step a1) consisting of activating the charger (100) to charge the high-voltage battery (600), • a second step a2), consisting of charging the high-voltage battery (600) by the charger (100) with a first setpoint power (Pl_cons), • a third step a3), consisting of measuring the temperature of at least one capacitance representative of the temperature of all the capacitances of the capacitance module (400) using the second temperature sensor (910) and storing in a memory area a first real temperature (Trelcapl) representative of the temperature of all the capacitances of the capacitance module (400), • a fourth step a4), consisting of waiting for a first determined duration (tpi) before moving on to a fifth step a5), • the fifth step a5), consisting of recording a second actual temperature (Trelcap2) of at least one capacitor representative of the temperature of all the capacitors in the capacitor module (400), and storing the value of the second actual temperature (Trelcap2) in a memory area, • a sixth step a6) consisting of waiting a second determined duration (tp2) before moving on to a seventh step a7), • the seventh step a7), consisting of recording a third actual temperature (Trelcap3) of at least one capacity sensing the temperature of all the capacities in the capacity module (400), and storing the third actual temperature (Trelcap3) in a memory area, • an eighth step a8), consisting of calculating a final temperature value (Tfinalcap) of at least one capacitance representative of the temperature of all the capacitances of the capacitance module (400) using a first equation: • Equation 1: Trelcap2 = Trelcapl + (Tfinalcap-Trelcap l)*exp(-tp 1 / tau), and a second equation: • Equation2:Trelcap3 = Trelcapl + (Tfinalcap-Trelcapl)*exp((-tpl-tp2) / tau), the two unknowns being Tfinalcap and tau, the eighth step a8) further consists of calculating a power setpoint reduction coefficient (Rcons) using a third equation: • Equation 3: Rcons= Tfinalcap / 85°C, and to apply a new initial power setpoint value (PIcons) to the charger (100), • a ninth step a9), consisting of calculating, using Equation 1, the temperature (Ttau) corresponding to the temperature of the capacitor module (400) after the duration of time (tau), and comparing the calculated value of (Ttau) to a critical temperature value (Tcapcrit), and in the case where the value (Ttau) is greater than (Tcapcrit) then proceed to the third step a3) otherwise proceed to a tenth step a10), • the tenth step (a 10), consisting of waiting a waiting period equal to the duration of tau before moving on to the third step a3).

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