Patent Application
20150336461
The invention relates to an electrical network for an automotive vehicle comprising at least one high-power component transiently activating itself. More particularly, the invention concerns an electrical network furthermore comprising an electrical generator, an energy store which stores the electrical energy generated by the said generator and an energy consumer device of the vehicle, hereinafter called an “electrical consumer” ensuring, for example, functions of ventilation and lighting.
In the context of this application, a high-power component means an electrical consumer requiring an electrical power greater than that of the energy consumer device. In particular, the high-power component may transiently require a large amount of electrical energy, for example when it is activated. For example, the high-power consumer may comprise any power component that consumes high current, in the order of 400-500 A, for a limited duration, between 0 and 10 s (during the transient activation period of the component).
In the context of this application, power store means any energy store having a high power density. For example, a power store is an energy store whose P/E (Power/Energy) ratio is greater than a pre-defined value, for example P/E>20.
On activation of the high-power component, a high current draw is transiently produced on the electrical network of the vehicle. The intensity of the drawn current depends on the desired response time required by this high-power component for its activation. As an example, on activation of an electrical supercharger, the speed of rotation of the turbine of said supercharger must rise from 4000 RPM to 70000 RPM in 350 ms. The power required on activation may be between 1 and 7 kW. Thus, such a component requires considerable electrical power at the time of its activation. Now, a drop in the component's performance, in order to avoid high current draw, is undesirable. The energy required during the start-up phase of such a power component is provided by the energy store and not by the generator because the generator's response time is usually longer than that of the high-power component. However, the energy store of a vehicle electrical network is limited in voltage. For a vehicle battery, the battery voltage is preferably around 12 V. This voltage is insufficient for optimum assurance of both the activation of the high-power component and the supply of the other energy consumers.
In fact, the activation of a high-power component causes a drop in voltage on the electrical network which can lead to outages or malfunctions of other consumer devices of the vehicle. These consumer devices, which operate at a voltage higher than a minimum voltage threshold, may be vehicle safety or comfort components, for example the vehicle's headlights. Their operation must be ensured at all times for the safety of the vehicle's passengers.
Furthermore, since the high-power component is supplied by the energy store of the vehicle network, the lifetime of the energy store is reduced by the high current draws that it must undergo on activation of the high-power component. A more powerful battery would therefore need to be installed on the on-board network, but that would involve high costs.
The invention aims to remedy all or some of the above drawbacks and notably to propose a cheaper electrical network for an automotive vehicle which is protected against voltage drops on activation of high-power components without degrading the performance of the network energy store or its lifetime.
Consequently, one aspect of the invention relates to an electrical network for an automotive vehicle comprising:
characterised in that the electrical network furthermore comprises a means of switching between the first subnetwork and the second subnetwork, the said switching means being configured to electrically connect the first subnetwork and the second subnetwork when the voltage across the terminals of the second energy store becomes equal to the voltage across the terminals of the first energy store, so as to ensure a supplying of the second consumer by the electrical generator.
The network therefore comprises a first electrical subnetwork, intended for the vehicle's first electrical energy consumer, also called the electrical charge of the vehicle, requiring a voltage stabilised and supplied by the energy store or by the electrical generator. The network also comprises a second electrical subnetwork intended for the second consumer. The second consumer is in particular a component that causes drops in voltage, for example a high-power component activating itself transiently. The first subnetwork is isolated from the second subnetwork by the DC/DC converter of the electrical network. The energy store of the second subnetwork is charged by the electrical generator or the energy store of the first subnetwork by means of the DC/DC converter. The second energy store can thus supply the second component with sufficient voltage on the activation thereof. In particular, the DC/DC converter amplifies the voltage that it encounters at the input, i.e. the voltage of the first electrical subnetwork. In the case of a standard vehicle, the voltage of the first electrical subnetwork is around 12 V. The second energy store is sized on the basis of the second component arranged in the second electrical subnetwork. As the first subnetwork is isolated from the second subnetwork by the DC/DC converter, it is not affected by the voltage drops that occur on activation of the second component.
In particular, the first energy store is configured to supply the first electrical consumer. In particular, the second energy store is configured to supply the second electrical consumer.
For example, the first electrical subnetwork is linked to the input of the DC/DC converter and the second electrical subnetwork is linked to the output of the DC/DC converter.
In particular, the switching means connect the input of the DC/DC converter to the output of the DC/DC converter. The switching means allow the supply to be changed over from the second component to the first subnetwork, and thus to the electrical generator, if the activation of the second component is long or if the second energy store discharges too quickly i.e. when the energy required for the activation of the second component is greater than the energy that can be used in the second energy store. Thus the electrical generator can take over and ensure the supply of power for the rest of the activation phase of the second component. The changeover of power from the second component to the first subnetwork is achieved by closing the switching means. The closure of said switching means can be achieved by control means that are, for example, controlled by a sensor of the voltage across the terminals of the energy store of the second subnetwork.
In addition to the main characteristics just mentioned in the preceding paragraph, the electrical network according to the invention can have one or more complementary characteristics among those listed below, considered individually or in accordance with technically possible combinations:
The invention also concerns a method of managing the supply of the components of an electrical network for an automotive vehicle, the said network comprising a first electrical subnetwork, the said first electrical subnetwork comprising in parallel:
characterised in that the said method comprises a step of closing the switching means to electrically connect the first subnetwork and the second subnetwork when the voltage across the terminals of the second energy store is equal to the voltage across the terminals of the first energy store, so as to ensure a supply to the second consumer by the electrical generator.
According to one of its aspects, the invention also concerns an electrical network for an automotive vehicle comprising:
In other words, in this aspect of the invention, the third component has one terminal in common with the first switch. This same terminal of the third component is also in common with the second switch. In particular, the third component has a connected terminal to ground the network, and another terminal connected at one end to a terminal of the first switching means and at the other end to a terminal of the second switching means.
Thus, in this aspect of the invention, the electrical connection comprising the third electrical consumer is located between the first switching means and the second switching means. This third consumer can therefore be supplied by the first subnetwork and/or by the second subnetwork, regardless of the other electrical consumers.
The network according to this aspect of the invention can have one or more of the above-described characteristics that are compatible with it.
In a variation, the DC/DC converter can be a reversible converter. In other words, the converter can not only allow a transmission of an electrical signal from the first subnetwork to the second subnetwork, but also a transmission of an electrical signal from the second subnetwork 3 to the first subnetwork. Thus, the second store can advantageously supply the first subnetwork when the second store has a sufficient charge.
For example, the power store can be charged during a regenerative braking phase. The electrical generator then produces electrical energy from a mechanical braking of the vehicle. All or part of this energy is transmitted to the second store. Afterwards, the energy stored in the second energy store can be used to supply the second consumer and/or to supply the first subnetwork by means of the reversible DC/DC converter.
Further features and advantages of the invention will emerge from the following description, with reference to the accompanying drawings, in which:
For the sake of clarity, identical or similar elements bear the same reference numerals in all of the Figures.
The battery 22 is charged in a known way by the electrical generator 21. Once the battery 22 is charged by the electrical generator, control means can ensure that the electrical generator 21 supplies only the electrical consumer 23. The said control means can be connected to a means to measure the current of the battery 22 (not shown in the Figures) which can be arranged on one of the positive or negative terminals of the battery 22, allowing the state of charge of the battery 22 to be detected. Once the battery 22 is in its optimum state, the generator 21 supplies only the electrical consumer 23 of the vehicle by means of a “zero battery current” voltage regulator allowing an overall zero current to be obtained at the battery 22.
The DC/DC converter 4 takes the energy in the first subnetwork 2 to charge the super-condenser 31. In the embodiment shown in
Thus, the voltage across the terminals of the super-condenser 31 varies between, firstly, a zero voltage and the voltage across the terminals of the battery 22, then between the voltage across the terminals of the battery 22 and the maximum voltage that the super-condenser 31 can withstand. This maximum voltage that the super-condenser 31 can withstand depends on the response time required of the electrical supercharger 32, this response time dimensioning the intensity and duration of the current draw during activation.
During activation of the supercharger 32, command means allow the super-condenser 31 to supply the supercharger 32 with sufficient voltage. The super-condenser 31 discharges in the supercharger 32. Thus, only the second electrical subnetwork 3 is disturbed by the activation of the high-power component 32. The super-condenser 31, once discharged, is recharged by the DC/DC converter 4 in order to be able to respond to a new demand from the electrical supercharger 32.
Control means in particular cause the switching means to change over between an on-state and an off-state. In its off-state, the operation of the electrical circuit is identical to that previously described with reference to
This lack of power of the store 31 of the second subnetwork may be the result of the transient activation phase of the supercharger 32 lasting too long or an insufficient charging of the super-condenser 31. In these cases, the switching means 5 change over to the on-state and short-circuit the DC/DC converter 4. The supercharger 32 is supplied by the electrical generator 21 of the first subnetwork 2 or possibly by the battery 22.
Note that when the operation of the supercharger 32 is prolonged, it is then at a stabilised speed, for example at 70000 RPM. The power required by the supercharger 32 is then less than that required during its activation. When the switching means 5 change to the on-state, the supercharger 32 does not therefore cause a drop in voltage on the first subnetwork 2.
The second switch 6 allows the operating modes of the second subnetwork 3 to be varied. The supercharger 32 and the starter 33 can be isolated from the first subnetwork 2 (the first switch 5 is open) and supplied by the super-condenser 31 (the second switch 6 is closed). Thus, on starting the vehicle, the starter 33 whose activation could disturb the operation of the electrical consumer 23 due to the current draw created, is isolated from the first subnetwork 2 and the super-condenser 31 ensures its supply. The supercharger 32 and the starter 33 can both be supplied by the same subnetwork 2 (the first and second switches 5, 6 are closed). Alternatively, the supercharger 32 is supplied by the super-condenser 31 while the starter 33 is supplied by the first subnetwork 2 (first switch 5 closed and second switch 6 open).
Clearly, the invention is not limited to the examples described. In particular, the supercharger 32 and the starter 33 can be other high-power components.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1259378 | Oct 2012 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/FR2013/052354 | 10/3/2013 | WO | 00 |
