METHOD FOR MANAGING THE POWER SUPPLY OF AN ELECTRICAL ACTUATOR

Abstract

The invention relates to a method for managing the power supply current of an electric actuator (4, 5) intended for use in a motor vehicle. The electric actuator comprises a sensor for measuring a physical quantity. The method comprises the following steps: Determining a sliding time window associated with the measured physical quantity; When a value of the physical quantity within the sliding time window exceeds a predetermined upper threshold value, triggering a power limitation at the electric actuator; When the value of the physical quantity within the sliding time window is below a predetermined lower threshold value, or less than or equal to the upper threshold value, deactivating the previously triggered power limitation. Figure 1

Description

Title of the invention: METHOD FOR MANAGING THE SUPPLY CURRENT OF AN ELECTRIC ACTUATOR TECHNICAL FIELD OF THE INVENTION

[0001] The invention relates, in general, to the technical field of managing the supply current of an electrical machine, in particular of an electrical machine in an electrified motor vehicle, hybrid or not. STATE OF PRIOR ART

[0002] In the automotive field, an electric traction machine is often intended to be installed within several electrified motor vehicle platforms, and therefore with different electrical environments: batteries, low voltage electrical circuits, etc. Basically, the electric machine is designed to respond to the platform requiring the most power.

[0003] In the current state of the art, in order to be compatible with platforms having lower power electrical requirements and therefore with lower class low voltage components, adaptations are made: • resizing of all low-voltage components between the battery and the electrical machine (fuses, electrical harnesses, connectors, etc.). This results in additional costs, as well as an increase in the volume and mass of the components; • addition of current sensors in the battery dedicated to the electrical circuit supplying the electric machine in order to control and limit any excursions or even temperature sensors to control the exceeding of critical temperatures. This again results in additional cost and is not always compatible with the available space in the battery junction box; • provide current limitation strategies in the vehicle supervisor of the powertrain including the electric machine. However, this does not always allow the ASIL level necessary to be reached to protect the architecture or it is necessary to have a dedicated current sensor connected directly to this supervisor. • limit the power of the electrical machine. This is not always possible, particularly to limit the continuous power which is a consequence of thermal “derating”, or lightening of the load according to the temperature, which serves to protect sensitive electrical components. • develop dedicated electrical machines for each application. This increases the diversity of electrical machines as well as development costs.

[0004] There is therefore a need to develop a solution enabling the development of a single electric machine for electrified motor vehicles requiring different performance needs and therefore with electrical components (fuses, electrical harnesses, connectors, etc.) of different sizes, while ensuring the correct level of protection against overheating in particular. Statement of the invention

[0005] The invention aims to remedy all or part of the drawbacks of the state of the art by proposing in particular a solution making it possible to develop only a single electrical machine for all or part of the platforms to be equipped.

[0006] To do this, according to a first aspect of the invention, a method is proposed for managing the supply current of an electric actuator intended to be implemented in a motor vehicle, the electric actuator comprising a sensor for measuring a physical quantity, the method comprising steps of: a. Determining a sliding time window associated with the measured physical quantity; b. When a value of the physical quantity in the sliding time window is greater than a predetermined high threshold value, triggering of a power limitation at the level of the electric actuator; c. When the value of the physical quantity in the sliding time window is lower than a predetermined low threshold value, lower than or equal to the high threshold value, deactivation of the previously activated power limitation.

[0007] According to one embodiment, the triggering of the power limitation of step b) is carried out after a first predetermined confirmation time.

[0008] According to one embodiment, the deactivation of the power limitation of step c) is carried out after a second predetermined confirmation time.

[0009] According to one embodiment, the physical quantity is a current flowing in the electric actuator or a temperature.

[0010] According to one embodiment, the method determines two or more sliding time windows associated with the physical quantity, each of the windows being associated with specific high and low threshold values.

[0011] According to one embodiment, the method for managing the supply current of an electrical machine according to the invention comprises a mechanism for prioritizing sliding time windows associated with the electrical actuator.

[0012] According to another aspect of the invention, it relates to a powertrain for electrified motor vehicle comprising an electric machine acting as an electric actuator, as well as a computer arranged to implement a method for managing the supply current of an electric actuator having at least one of the preceding technical characteristics.

[0013] According to yet another aspect of the invention, it relates to an electrified motor vehicle comprising such a powertrain. BRIEF DESCRIPTION OF THE FIGURES

[0014] Other characteristics and advantages of the invention will emerge on reading the description which follows, with reference to the appended figures, which illustrate: • [Fig.l]: a diagram of a generic electrical architecture intended to implement a method for managing the supply current of an electric actuator according to the invention; • [Fig.2]: a chronograph illustrating traces of effective currents on a line of an electric machine without the method for managing the supply current of an electric actuator according to the invention during an operating cycle; • [Fig.3]: a chronograph illustrating traces of effective currents on the line of the electric machine of [Fig.2] with the method for managing the supply current of an electric actuator according to the invention during the same operating cycle.

[0015] For clarity, identical or similar elements are identified by identical reference signs throughout the figures. DETAILED description of an embodiment

[0016] [Fig.l] illustrates a generic electrical architecture 1 comprising a reversible electrical energy source 6, here, a battery. A distribution device 10 is electrically connected to the electrical energy source 6 via a main line Ap. The main line Ap therefore makes it possible to transmit electrical energy between the distribution box 10 and the electrical energy source 6. It comprises, in practice, connection bars, connectors and electrical harnesses.

[0017] Within the distribution device 10, the current of the main line Ap passes through an insulation 11, then a main protection 12. The insulation 11 is, here, a device making it possible to cut off and isolate the electrical energy source 6 from the rest of the generic electrical architecture 1. The main protection 12 makes it possible to protect the main line Ap from overloads and short circuits (fuse).

[0018] A distribution node 13 makes it possible to distribute electrical energy to lines Al... Ax, here represented as two in number. Within the distribution box 10, each of the lines Al... Ax comprises a line protection 14, 15 dedicated. As previously for the main protection 12, it protects the line Al... Ax from overloads and short circuits (fuse). Each of the lines Al... Ax supplies an electric actuator 4,5. Here, an electric actuator is understood to mean any actuator that can consume and / or produce electrical energy, such as, for example, an electric traction machine of an electrified motor vehicle, air conditioning, etc. Each of the lines Al... Ax therefore allows electrical energy to be transmitted between the distribution box 10 and its dedicated electric actuator 4,5. In practice, it includes connection bars, connectors and electrical harnesses.

[0019] Finally, the generic electrical architecture 1 includes a computer 2 allowing supervision and control of the various electrical actuators 4,5.

[0020] Generally speaking, in this generic electrical architecture, it is necessary to avoid overheating of the electrical components of the lines (connection bar, electrical harness, fuse, connector). To do this, it is necessary to keep an effective current below a threshold value beyond which overheating occurs. In particular, a portion of these electrical components are in practice within the battery acting as an electrical energy source 6 and pass above the cells of said battery. Overheating of these electrical components will cause a battery cell fire: it is therefore necessary to protect the main line Ap comprising them with a high level of reliability, i.e. an ASIL D level. This implies measuring the current passing through these components with the same level of reliability.

[0021] However, it is easy to limit an instantaneous power of an electric actuator 4,5 and therefore an instantaneous current, but the limitation of the power over a long time is not really controlled, it is the consequence of a strategy aimed at not exceeding certain temperatures of the internal components (coils, magnets, etc.) of said electric actuator.

[0022] In the case of an electric traction machine delivering high traction powers, the latter is equipped with oil cooling, allowing it to have, for this purpose, a high continuous power and ultimately too high at certain operating points compared to the needs and the sizing of the electrical components of the generic electrical architecture 1. However, an electric machine is naturally equipped with alternating current sensors on each of the phases and a direct current sensor at the input of an inverter of the electric machine. The current information from each of these sensors maintains at least an ASIL A reliability level, which can easily make it possible to have information on the direct current flowing in the line Al... Ax at an ASIL D reliability level.

[0023] Generally, the electric actuators 4,5 are equipped with sensors of current allowing to know the direct current circulating on the line Al... AX associated between the distribution node 13 and the electric actuator 4,5.

[0024] With reference to [Fig. 2], we will describe an operation of the generic electrical architecture 1 within an electrified electric vehicle with an electric traction machine acting as an electric actuator 4, during a given operating cycle, and this, without the method for managing the supply current of an electric actuator according to the invention

[0025] The timing diagram in [Fig.2] illustrates traces of effective currents on line A1 of the electric traction machine (electric actuator 4). In the example illustrated, two sliding time windows have been calibrated, represented on the timing diagram by the middle graph "Effective peak current" and by the bottom graph "Continuous effective current", both measured by the current sensors of the electric traction machine.

[0026] The top graph "limitation level" indicates the level of limitation carried out by the computer 2 on the components of the generic electrical architecture 1. Level 1 indicates that there is no limitation applied. Level 2 indicates that the limitation applied is due to the peak RMS current only. Level 3 indicates that the limitation applied is due to the continuous RMS current only. And level 4 indicates that the limitation applied is due to both the peak RMS current and the peak RMS current.

[0027] Here, we note that, during the illustrated operating cycle, the electric traction motor then operates only according to predetermined usual constraints, the effective current values, whether peak or continuous, remain at significant values ​​during the periods when the electric traction machine is under power demand. In particular, the continuous effective current remains very high beyond six hundred seconds of power demand, while the peak effective current remains very present.

[0028] The timing diagram in [Fig.3] shows the same life situations as that in [Fig.2], but with management of the generic electrical architecture 1 according to the method for managing the supply current of an electric actuator according to the invention.

[0029] Generally speaking, the method for managing the supply current of an electric actuator according to the invention records information concerning the direct current value at the input of the electric actuator 4, 5 and then determines the effective current over one or more sliding time windows. Here, illustrated, two sliding time windows are determined: “peak effective current” and “continuous effective current”.

[0030] When the effective current value I_RMS_n over a time window n exceeds a threshold value I_limit_n_sup during a predetermined confirmation time Time_Conf_limit_n, then the method for managing the supply current of an electric actuator according to the invention controls the electric actuator considered to limit a value of the electric power by applying the formula: (U_entrée_acteur * I_limit_n_sup) for the discharge (i.e. in traction in the case where the electric actuator is an electric traction machine) and (-U_entrée_acteur * I_limit_n_sup) in charge (i.e. in generator in the case where the electric actuator is an electric traction machine), U_entrée_acteur being a value of the input voltage of the electric actuator.

[0031] When the effective current value I_RMS_n on the sliding window n falls below a threshold value I_limit_n_inf during a confirmation time Time_Conf_Unlimit_n, then the method for managing the supply current of an electric actuator according to the invention no longer commands the electric actuator to limit its electrical power value as a function of I_limit_n_sup, but as a function of its own predetermined usual constraints. I_limit_n_inf is less than I_limit_n_sup.

[0032] In the case where several sliding time windows are used, the method for managing the supply current of an electric actuator according to the invention sets up a prioritization mechanism between the different time windows to apply the limitation of the most restrictive window.

[0033] Let's take the example of two sliding time windows with I_limit_l_sup > I_limit_2_sup.

[0034] If I_RMS_1 <= I_limit_l_sup and I_RMS_2 <= I_limit_2_sup, then the method for managing the supply current of an electric actuator according to the invention does not apply any electrical power limitation (level 1 of limitation).

[0035] If I_RMS_1 > I_limit_l_sup and I_RMS_2 <= I_limit_2_sup, then the method for managing the supply current of an electric actuator according to the invention applies a power limitation to (U_actuator_input * I_limit_l_sup) in discharge and (-U_actuator_input * I_limit_l_sup) in charge (level 2 of limitation).

[0036] If I_RMS_1 <= I_limit_l_sup and I_RMS_2 > I_limit_2_sup, then the method for managing the supply current of an electric actuator according to the invention applies a power limitation to (U_actuator_input * I_limit_2_sup) in discharge and (-U_actuator_input * I_limit_2_sup) in charge (level 3 of limitation).

[0037] If I_RMS_1 > I_limit_l_sup and I_RMS_2 > I_limit_2_sup, then the method for managing the supply current of an electric actuator according to the invention applies a power limitation to (U_actuator_input * I_limit_l_sup) in discharge and (-U_actuator_input * I_limit_l_sup) in charge (limitation level 4). Window 1 is prioritized here.

[0038] In all cases, the electric actuator 4,5 considered informs the computer 2 implementing the method for managing the supply current of an electric actuator according to the invention of active power limitations. On the other hand, when the electric actuator 4,5 considered passes from one limitation level to another, the method for managing the supply current of an electric actuator according to the invention controls a variation in electrical power by applying predetermined ramps.

[0039] Returning to [Fig.3], the illustrated timing diagram shows a practical application of the method for managing the supply current of an electric actuator according to the invention with two sliding time windows where I_RMS_1 = RMS_Peak_s, I_limit_l_sup = RMS_Peak_Lim_High, I_limit_l_inf = RMS_Peak_Lim_Low, I_RMS_2 = RMS_Continue_s, I_limit_2_sup = RMS_Continue_Lim_High, and I_limit_2_inf = RMS_Continue_Lim_Low.

[0040] For example, during time tl, the method for managing the supply current of an electric actuator according to the invention triggers a level 2 limitation as soon as RMS_Peak_s is greater than RMS_Peak_Lim_High and then returns to level 1 limitation when RMS_Peak_s is less than RMS_Peak_Lim_Low, while RMS_Continue_s remains less than RMS_Continue_Lim_High.

[0041] During time t2, the method for managing the supply current of an electric actuator according to the invention triggers a level 3 limitation, as soon as RMS_Continue_s is greater than RMS_Continue_Lim_High during a time t3 (corresponding to Time_Conf_limit_n associated with the sliding time window considered), RMS_Continue_Lim_Low, RMS_Peak_s being less than RMS_Peak_Lim_High. The method for managing the supply current of an electric actuator according to the invention returns to a level 1 limitation as soon as RMS_Continue_s is lower, RMS_Continue_Lim_Low, RMS_Peak_s being less than RMS_Peak_Lim_High.

[0042] It should be noted that during time t2, the method for managing the supply current of an electric actuator according to the invention triggers, during a time t4, a level 4 power limitation, because during this time t4, RMS_Peak_s is greater than RMS_Peak_Lim_High and the sliding time window of the peak effective current has priority over the sliding time window of the continuous effective current. At the end of time t4, the method for managing the supply current of an electric actuator according to the invention returns to a level 3 limitation, because RMS_Continue_s has remained greater than RMS_Continue_Lim_High.

[0043] By comparing the two timing diagrams of figures 2 and 3, we note in particular on the graph of the direct effective current of [Fig.3] that the effective current decreases from the moment when the method for managing the supply current of an electric actuator according to the invention is implemented, unlike the previous case ([Fig.2]) without a method for managing the supply current of an electric actuator according to the invention.

[0044] The implementation of the method for managing the supply current of an electric actuator according to the invention as described above therefore makes it possible to limit the value of the current within the components of the electrical architecture comprising the electric actuator(s) thus controlled. Thus, in the context of an electrified motor car, a single electric traction machine can be developed for all the platforms, only the other electrical components being different depending on the power required for a given platform. The latter are protected by the implementation of the method for managing the supply current of an electric actuator according to the invention described above.

[0045] In an alternative embodiment of the invention, the method for managing the supply current of an electric actuator according to the invention is based on measurements and estimations of the temperature of the electrical components to be protected from the electrical architecture (connection bars, fuses, electrical harnesses, connectors, etc.).

[0046] If the practical application of the method for managing the supply current of an electric actuator according to the invention has been described in the context of an electric traction motor of an electrified motor vehicle, the method for managing the supply current of an electric actuator according to the invention can be implemented with other electrical actuators / components equipped with one or more current / temperature sensors such as direct current converters, alternating current to direct current converters, an electric compressor, an electric heating system, air conditioning.

[0047] Naturally, the invention is described in the above by way of example. It is understood that those skilled in the art are able to carry out different variant embodiments of the invention without departing from the scope of the invention.

[0048] It is emphasized that all features, as they emerge for a person skilled in the art from the present description, the drawings and the attached claims, even if they have been specifically described only in relation to other determined features, both individually and in any combinations, may be combined with other features or groups of features disclosed herein, provided that this has not been expressly excluded or that technical circumstances make such combinations impossible or devoid of sense.

Claims

Claims

1. Method for managing the supply current of an electric actuator (4, 5) intended to be implemented in a motor vehicle, the electric actuator comprising a sensor for measuring a physical quantity, the method comprising steps of: a. Determining a sliding time window associated with the measured physical quantity; b. When a value of the physical quantity in the sliding time window is greater than a predetermined high threshold value, triggering a power limitation at the level of the electric actuator; c. When the value of the physical quantity in the sliding time window is less than a predetermined low threshold value, less than or equal to the high threshold value, deactivating the previously triggered power limitation.

2. Method according to claim 1, characterized in that the triggering of the power limitation of step b) is carried out after a first predetermined confirmation time.

3. Method according to claim 1 or 2, characterized in that the deactivation of the power limitation of step c) is carried out after a second predetermined confirmation time.

4. Method according to one of claims 1 to 3, characterized in that the physical quantity is a current flowing in the electric actuator or a temperature.

5. Method according to one of claims 1 to 4, characterized in that the method determines two or more sliding time windows associated with the physical quantity, each of the windows being associated with specific high and low threshold values.

6. Method according to claim 5, characterized in that the method for managing the supply current of an electrical machine according to the invention comprises a mechanism for prioritizing sliding time windows associated with the electrical actuator.

7. Powertrain for an electrified motor vehicle comprising an electric machine acting as an electric actuator, characterized

8. in that it comprises a computer arranged so as to implement the method according to one of claims 1 to 6. Electrified motor vehicle, characterized in that it comprises a powertrain according to claim 7.

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