Electric circuit for charging at least one electrical energy storage unit by means of an electrical network

Abstract

An electric circuit (5) for charging at least one electrical energy storage unit (4) by means of an electrical network, the circuit (5) comprising: an inductive cell (6) configured to interact with an inductive cell of the electrical network to exchange energy by electromagnetic induction, a rectifier (13) disposed downstream from the inductive cell (6) and whereof the positive output terminal (17) and the negative output terminal (20) are each connected to a conductor (18, 21) of a DC bus (19), a capacitor (22) mounted between the two conductors (18, 21) of the DC bus (19), a power stage (25) whereof the positive input terminal (26) and the negative input terminal (27) are respectively connected to one of the conductors (18, 21) of the DC bus (19), and which is configured to adapt the value of the DC voltage between the positive input terminal (26) thereof and the negative input terminal (27) thereof to the electrical energy storage unit (4), the power stage comprising, at most, two voltage converters, and the electrical energy storage unit (4).

Claims

1. An electric circuit for charging at least one electrical energy storage unit by means of an electrical network, the circuit comprising: an inductive cell configured for interacting with an inductive cell of the electrical network to exchange energy by electromagnetic induction; a first rectifier arranged downstream of the inductive cell and whose positive output terminal and negative output terminal are each linked to one conductor of a DC bus; a capacitor connected between the two conductors of the DC bus; a power stage whose positive input terminal and negative input terminal are respectively linked to one of the two conductors of the DC bus, and which is configured for matching a value of the DC voltage between its positive input terminal and its negative input terminal to the electrical energy storage unit, the power stage comprising at most two voltage converters; the electrical energy storage unit; and a connector connected in parallel with the inductive cell upstream of the first rectifier, said connector being configured for connection to an additional connector of the electrical network.

2. The circuit as claimed in claim 1, the first rectifier comprising electronic switches configured for rectifying an AC voltage, the frequency of which is between 100 kHz and 200 kHz.

3. The circuit as claimed in claim 1, a voltage across the terminals of the capacitor being equal to a voltage between the input terminals of the power stage and to a voltage between the output terminals of the first rectifier.

4. The circuit as claimed in claim 1, the electrical energy storage unit having a nominal voltage between 280 V and 350 V.

5. The circuit as claimed in claim 1, the power stage being a DC/DC voltage converter.

6. The circuit as claimed in claim 1, the electronic switches of the first rectifier being configured for rectifying an AC voltage, the frequency of which is in the order of 50 Hz or 60 Hz.

7. The circuit as claimed in claim 1, comprising a connector and a second rectifier, the connector being connected to the input of the second rectifier, the output of which is connected in parallel with the output of the rectifier that is downstream of the inductive cell.

8. The circuit as claimed in claim 7, the second rectifier comprising electronic switches configured for rectifying a voltage the frequency of which is in the order of 50 Hz or 60 Hz.

9. The circuit as claimed in claim 1, further comprising a charging mode selection unit that detects which of the connector and the inductive cell receives energy from the electrical network and that links whichever of said connector or said inductive cell is powered to the rest of the electric circuit to charge the electrical energy storage unit from the electrical network.

10. A method for charging an electrical energy storage unit by means of an electrical network using an electric circuit comprising a charging mode selection unit as claimed in claim 9, the method comprising: detecting that one of the inductive cell and the connector is powered by the electrical network, and whichever of the inductive cell and the connector is powered by the network is linked to the rest of the electric circuit whose electronic switches are controlled so as to charge the electrical energy storage unit from the electrical network.

11. An electric circuit for charging at least one electrical energy storage unit by an electrical network, the circuit comprising: an inductive cell configured for interacting with an inductive cell of the electrical network to exchange energy by electromagnetic induction; a first rectifier arranged downstream of the inductive cell and whose positive output terminal and negative output terminal are each linked to one conductor of a DC bus; a capacitor connected between the two conductors of the DC bus; a power stage whose positive input terminal and negative input terminal are respectively linked to one of the two conductors of the DC bus, and which is configured for matching a value of the DC voltage between the positive input terminal and the negative input terminal to the electrical energy storage unit, the power stage comprising at most two voltage converters; and the electrical energy storage unit, wherein the power stage is formed by the series combination of an additional inverter and a second rectifier.

Description

(1) The invention will be better understood upon reading the following description of non-limiting exemplary implementations of the latter and upon examining the appended drawings in which:

(2) FIG. 1, already described, shows the electrical structure of the charging station and the electric circuit for charging a vehicle of the prior art,

(3) FIG. 2 schematically shows a charging station and a vehicle comprising an electric circuit for charging according to an exemplary implementation of the invention,

(4) FIG. 3 shows, in a manner similar to FIG. 1, an example of the electrical structure of the charging station and of a part of the electric circuit for charging according to an exemplary implementation of the invention,

(5) FIG. 4 schematically shows the electric circuit for charging in FIG. 3,

(6) FIG. 5 corresponds to FIG. 3 in which the whole of an example of an electric circuit for charging according to the invention is shown,

(7) FIGS. 6 and 7 show two variants of the electric circuit in FIG. 5 allowing either charging by electromagnetic induction wired charging,

(8) FIG. 8 shows an example of a charging mode selection unit that can be incorporated into the electric circuit shown in FIG. 6, and

(9) FIG. 9 shows an example of an architecture of the piloting unit in FIG. 8.

(10) FIG. 2 shows a vehicle 1 interacting with a charging station 3 of an electrical network 2 for charging an electrical energy storage unit 4 by means of an electric charging circuit 5. The electrical network 2 distributes a single-phase or multi-phase, for example three-phase, AC voltage with a frequency of 50 Hz or 60 Hz in particular.

(11) The electrical energy storage unit 4 is for example formed by one or more batteries connected in parallel or in series, or else by several parallel arms with the batteries connected in series. The electrical energy storage unit 4 has for example a nominal voltage between 280 V and 350 V, notably in the order of 330 V, and it is used to electrically power an electric motor for driving a hybrid or electric vehicle.

(12) The charging circuit 5 comprises an inductive cell 6, configured for generating an AC voltage when it is immersed in a magnetic field. In the example under consideration, the inductive cell 6 is a coil. This inductive cell 6 interacts with an inductive cell 8 of the recharging station 3. As shown in FIG. 3, the electrical structure of the charging station 3 can be similar to that shown in FIG. 1, i.e. it can comprise a rectifier 10 converting the voltage of the network 2 into a DC voltage and an inverter 11 converting the DC voltage into an AC voltage having a frequency for example between 100 kHz and 180 kHz, being for example in the order of 140 kHz. Such frequency values are matched to the transfer of energy by electromagnetic induction. The electromagnetic waves for this transfer of energy are generated by the inductive cell 8 which is for example an antenna.

(13) As can be seen by comparing FIGS. 1 and 3, one of the aspects of the invention consists in adapting the conventional wired charging circuit 109 to use it directly at the output of the inductive cell 6, without needing the additional stage formed by the rectifier 106 and the inverter 107.

(14) FIG. 4 schematically shows an example of a charging circuit 5 for charging the electrical energy storage unit 4 from the electrical network 2.

(15) As shown, the voltage induced across the terminals of the inductive cell 6 is applied to a rectifier 13 including electronic switches 15. In the example described, these switches 15 are diodes but, in non-represented variants, controllable switches can be used for the rectifier 13. These electronic switches 15 are configured for rectifying the voltage applied to the rectifier 13, the frequency of which can be between 100 kHz and 180 kHz. Optionally, a capacitor 16 can be interposed between the inductive cell 6 and the rectifier 13. The capacitor 16 notably makes it possible to perform impedance matching between the inductive cell 6 and the input of the rectifier 13, in order to ensure operation at resonance.

(16) The positive terminal 17 of the rectifier 13 is linked to a first conductor 18 of a DC bus 19 whereas the negative terminal 20 of the rectifier 13 is linked to a second conductor 21 of the DC bus 19.

(17) A capacitor 22 is connected between the first conductor 18 and the second conductor 21 and this capacitor 22 can have a capacitance between 1500 μF and 2500 μF. The capacitor 22 is, in the example shown, connected in parallel with the output of the rectifier 13 and the input of a power stage 25. This power stage 25 comprises at most two voltage converters and it is configured for matching the value of the DC voltage across the terminals of the capacitor 22 to the electrical energy storage unit 4.

(18) The power stage 25 can exhibit a positive input terminal 26 linked to the conductor 18 of the DC bus 19 and a negative input terminal 27 linked to the conductor 21 of the DC bus 19.

(19) The power stage 25 can be formed by a DC/DC voltage converter. It can for example be a series chopper or a parallel chopper (also called buck converter and boost converter respectively).

(20) In a variant, and as shown in FIG. 5, the power stage 25 can comprise an inverter 28, the output of which forms the input of a rectifier 29. In this case, the electric circuit 3 for charging the electrical energy storage unit 4 comprises three voltage converters whereas it only comprises two in the case where the power stage 25 is formed by a DC/DC voltage converter.

(21) In the examples in FIGS. 3 to 5, the charging circuit 5 only allows the charging of the electrical energy storage unit 4 by electromagnetic induction. The invention is, however, not limited to these examples but can make it possible to switch between two charging modes, namely charging by electromagnetic induction and wired charging, as will be seen.

(22) In all the examples under consideration, the piloting of the electronic switches of the voltage converters can be provided by a piloting unit, not shown, the latter comprising for example one or more microcontrollers.

(23) In the example in FIG. 6, a charging mode selection unit 33 is arranged upstream of the rectifier 13, so that the input of the rectifier 13 corresponds to the output 34 of the unit 33. As can be seen in FIG. 8, the charging mode selection unit 33 comprises inputs 35 linked to the inductive cell 6 and inputs 36 linked to a connector, for example a connection point, configured for being connected to an additional connector of the electrical network 2, for example a plug, to provide for wired charging of the electrical energy storage unit 4. A grounding conductor 39 can bypass the charging mode selection unit 33, as shown in FIG. 8.

(24) The charging mode selection unit 33 can be powered by the on-board network 40 of the vehicle 1, the latter delivering for example a voltage in the order of 12 V which serves as power supply and control supply for the unit 33. A detailed exemplary implementation of the unit 33 is illustrated in FIG. 9.

(25) As shown, the charging mode selection unit 33 can comprise a plurality of cells 42. The cells 42 can be paired, two cells of one and the same pair 43 being linked to one and the same output of the charging mode selection unit 33, whereas one of the cells of the pair 43 has its inputs linked to the inductive cell 6 and the other of the cells of said pair has its inputs linked to the connector.

(26) Each cell 42 can comprise two electrical wires 46 and 47 each extending between two ends respectively forming an input and an output of the cell 42. A switch 48 can be arranged between the ends of each wire. Each cell 42 moreover includes a coil 49 which, when it is electrically powered, modifies the position of the switches 48 of the cell. Each cell 42 can thus form an electromechanical relay and convey an electric current of at least 32 A.

(27) The charging mode selection unit 33 further comprises two main cells 50 connected in parallel. One of these main cells 50 controls the supply of electrical power to all the coils 49 of the cells whose wires 46 and 47 are linked to the inductive cell 6 whereas the other main cell 50 controls the supply of electrical power to all the coils 49 of the cells 42 whose wires 46 and 47 are linked to the connector.

(28) Each main cell 50 also comprises, in the example shown, a switch 51 interposed between the on-board network 40 and the coils 49 of each cell 42. Each main cell 50 also comprises in this example a coil 53 that can be electrically powered by the on-board network 40 according to choice. When the coil 53 of a main cell 50 is electrically powered, it moves the switch 51 from said cell, which, according to its position, enables or does not enable the supply of power to all the coils 49 downstream of said switch.

(29) Whether or not the charging mode selection unit 33 is produced as illustrated in FIG. 9, it can exhibit the following properties: not switching the grounding conductor 39 visible in FIG. 8 and linked to the connector, introducing a wait time for passing from one charging mode to the other, for example in the order of a few seconds, reducing the self-discharging phenomenon of the electrical energy storage unit 4 when the vehicle is parked and no charging is in progress, protecting the electrical network 2.

(30) In the example shown in FIG. 6, the rectifier 13 is configured for rectifying either an AC voltage with a frequency between 100 kHz and 180 kHz or an AC voltage with a frequency for example of 50 Hz or 60 Hz. To be able to operate satisfactorily whatever the value of the frequency of the AC voltage to be rectified, the switches of the rectifier 13 can switch at any frequency within a range of values extending from 50 Hz to 180 kHz in the case of operation by natural switching when the electronic switches 15 are diodes.

(31) When the electronic switches 15 are controllable, they can be controlled in such a way as to switch at any frequency within a range of values extending for example from 100 Hz to 360 kHz, according to whether they rectify a voltage at 50 or 60 Hz or a voltage at 140 kHz for example. An example of an electronic switch that can be used to do this is the series or parallel combination of IRF 150 N-channel MOSFET transistors marketed by the MAGNATEC® company.

(32) According to the charging mode of the electrical energy storage unit, the piloting unit—not shown—can control the electronic switches of the electric circuit 5, for example those of the power stage 25, in such a way as to supply a DC voltage of a value matched to the electrical energy storage unit 4.

(33) In the variant shown in FIG. 7, the electric circuit 5 comprises an additional stage 30 dedicated to wired charging, this stage 30 comprising a connector, not shown, for example a connection point, similar to that described with reference to FIG. 6 and a rectifier 31. This rectifier 31 is configured for rectifying the AC voltage delivered via the connector by the electrical network 2, i.e. a signal the frequency of which is for example in the order of 50 Hz or 60 Hz. In this example, the rectifier 13 can be called a “high-frequency rectifier” whereas the rectifier 31 can be called a “low-frequency rectifier”, without this restrictively limiting the values of the frequency range of the signal rectified by each rectifier.

(34) In this variant, each rectifier is thus dedicated to one charging mode. A charging mode selection unit can be provided to activate the rectifier 13 or 31 at the input of which a voltage is applied due to the powering by the electrical network 2. The input 61 or 62, of the rectifier 13 or 31 respectively, can be an output of this charging mode selection unit.

(35) The electric circuit 5 according to all the examples above can exhibit the same energy performance as the circuit 109 for conventional wired charging in FIG. 1 although it has a different operating station. This circuit can guarantee a total harmonic distortion on the electrical network 2. This circuit 5 can make it possible to deliver to the electrical energy storage unit 4 a power in the order of 3.5 kW over approximately 6 hours of charging.

(36) The invention is not limited to the examples that have just been described.

(37) The expression “including a” must be understood to be a synonym of the expression “including at least one”, except when specified to the contrary.