FR2947113A1 - Electric power supply battery charging i.e. contactless charging, method for car, involves adapting frequency of charging device to value equal to resonance frequency value to transmit power without contact between coils - Google Patents

Abstract

The method involves searching a resonant frequency of a resonant charging device formed by a charging transmitter (12) and a charging receiver when a motor vehicle is positioned on a parking space (24). Frequency of the charging device is adapted to a value equal to the resonance frequency value of the charging device, so to transmit optimal power without contact between a primary coil of the transmitter and a secondary coil of the receiver. Independent claims are also included for the following: (1) a charging receiver comprising a resonant circuit provided with a capacitor (2) a charging arrangement for charging a battery of a motor vehicle and comprising a charging transmitter provided with a control device for controlling charging of the battery.

Description

The present invention relates to a method of charging a motor vehicle battery. It also relates to a transmitter and a receiver implementing such a method of charging a battery. It also relates to a motor vehicle as such equipped with such a receiver to implement the charging method of its battery. Finally, it relates to an arrangement for charging a motor vehicle battery.

Motor vehicles that only operate with electrical energy are equipped with a battery that is recharged by a charger when it is discharged.

A first family of charging solutions of a motor vehicle battery, said contact, is based on a direct and continuous electrical connection between the battery and the charger, the latter thus delivering an electric current to the battery through this connection which allows charging of the battery. A first approach is to use the power grid: this allows the battery to be charged from low power, of the order of 3 kW, which requires a long charging time of several hours. According to a second approach, powerful chargers are used, for example offering a power of up to 100 kW. Handling such chargers may present risks. All contact battery charging solutions also have the following drawbacks: - Corrosion of the electrical contacts at the connection between the charger, the battery and the AC mains reduces their reliability, and even leads to tripping risks. fire; - The connection with contact loses efficiency in a humid environment, also leading to the risk of electric shock; - The connection with contact requires electrical manipulations and is not friendly or dangerous.

A second family of automotive battery charging solutions, said non-contact, based on a remote charge via a charging device, called charger, provided with a transmitting primary part including a primary coil, what we call more simply issuer, which cooperates with a receiving secondary part including including a secondary coil, which we call more simply receiver, mounted on the motor vehicle and connected to the battery to recharge. The primary coil thus transmits a magnetic field sufficient to induce the charge current required by the battery at the secondary coil. The disadvantage of existing contactless solutions is that they require very precise relative positioning of the two primary and secondary coils. Document FR2750267 illustrates a solution for charging a non-contact battery and the mentioned positioning problem. To answer this problem, this document proposes two combined approaches: the first is to propose a portable transmitter, which makes it possible to move it relative to the motor vehicle if its positioning is imperfect, and the second consists of a guiding device allowing to to increase the positioning accuracy of the motor vehicle relative to the transmitter during a parking maneuver. Finally, the contactless charging solutions have the following disadvantages: they require a precise positioning of the vehicle relative to the transmitter, to avoid a drop in efficiency of the charging phase; this precise positioning induces delicate handling of chargers and / or very precise maneuvers of the motor vehicle, which is not user-friendly and not applicable on a large scale.

Thus, the object of the invention is to propose a charging solution for a motor vehicle battery which does not have all or some of the disadvantages of the state of the art.

More specifically, a first object of the invention is to provide a user-friendly solution for charging a motor vehicle battery, not requiring manipulation of a charging device or rigorous maneuvers of a motor vehicle.

A second object of the invention is to provide an efficient charging solution, to obtain the full charge of a battery in a minimum time.

For this purpose, the invention proposes a method of charging a battery for powering a motor vehicle, from a charging device comprising on the one hand a charger transmitter, comprising an ACIDC converter, a inverter and a primary coil, disposed within a parking space for a motor vehicle, and on the other hand a charger receiver, comprising a secondary coil arranged within the motor vehicle, characterized in that it comprises the following steps when: a motor vehicle is positioned in the parking space, search for the resonance frequency (fo) of the resonant charging device formed by the charger transmitter and the charger receiver; adapting the frequency (f) of the charging device to a value substantially equal to the resonance value (f 0) of the charging device, so as to transmit an optimal power in a non-contact manner between the primary coil and the secondary coil .

The second step of adapting the frequency (f) may comprise the modification of the switching frequency (f) of the inverter to a value substantially equal to the resonance value (fo).

The method of charging a battery may further include the following additional step: modifying the voltage (Vdc) of the AC / DC converter to increase the power transmitted to the secondary circuit.

The first step may comprise the following substeps: sending low amplitude currents by scanning different frequencies; 10 - measurement of the resulting induced current for each frequency; - At the end of the scan, determining the maximum induced current obtained, the resonant frequency (fo) being set equal to the frequency corresponding to this maximum value of the induced current.

The method of charging a battery can define a reference frequency corresponding to the resonant frequency in the case where the two primary and secondary coils are perfectly superimposed, coaxially, and the frequency sweep can be first realized. around this reference frequency. The second step of adapting the switching frequency (f) to a value substantially equal to the resonance value (fo) of the charging device can be carried out in an initial phase of the charging process and / or being charged. of the battery in case of detection of a change in the charging conditions. The invention also relates to a charger transmitter for a motor vehicle power supply battery, comprising an AC / DC converter, an inverter and a primary coil, characterized in that it comprises a control device which sets all or part of the charging process as described above.

The charger transmitter for a motor vehicle power supply battery may represent a resonant circuit comprising the inverter, a capacitor and the coil, whose reference resonance frequency (fo) is determined by: fol = 1 / [4. rr 2 (Lp Cp)] where Cp is the capacity of the capacitor and Lp is the inductance of the coil.

The invention also relates to a receiver for a power supply battery of a motor vehicle, characterized in that it comprises a control device which implements all or part of the charging method as described above.

The receiver for a motor vehicle power supply battery may represent a resonant circuit comprising a capacitor and a coil, whose reference resonance frequency (fo) is determined by: f02 = 1 / [4.rr2 (LsCs) where Cs is the capacity of the capacitor and Ls is the inductance of the coil.

The invention also relates to a motor vehicle characterized in that it comprises a battery for the power supply of its engine, characterized in that it comprises a receiver as described above for the charge of its battery.

The invention also relates to an arrangement for charging a motor vehicle battery comprising a charger transmitter fixed on a parking space for a motor vehicle, characterized in that the charger transmitter is as described above.

The parking space may have a dimension such that it allows an off-center positioning of up to 30 centimeters from a motor vehicle relative to a reference position in which the two primary and secondary coils respectively of the charger transmitter and of the loader receiver of the motor vehicle are perfectly superimposed, coaxially.

These objects, features and advantages of the present invention will be set forth in detail in the following description of a particular embodiment made in a non-limiting manner in relation to the appended figures among which:

FIG. 1 is a diagrammatic side view of an automobile vehicle in the charging phase of its battery according to one embodiment of the invention.

Figure 2 schematically shows a side view of the transmitter / receiver arrangement of the charging device according to the embodiment of the invention.

3 schematically shows a top view of a parking space equipped with a transmitter according to the embodiment of the invention.

Figure 4 schematically shows in the top view of the parking space the problem solved by the invention.

FIG. 5 diagrammatically represents the electric circuit of the charging device of a battery according to the embodiment of the invention. FIG. 6 more specifically represents an inverter of the charger according to the embodiment of the invention.

Figure 7 shows more precisely an AC / DC converter of the embodiment of the invention.

FIG. 8 represents the variation of the power transmitted by the transmitter to the on-board receiver in the motor vehicle as a function of the frequency and the output voltage of the AC / DC converter to illustrate the effect of the execution mode of the invention.

According to the embodiment of the invention, an electric motor vehicle 1, whose engine is only powered by a battery, is equipped in its underside of a non-contact receiver 2 connected to the battery not shown , which receives a power 9 transmitted by a transmitter 12 through a space 7 between the transmitter and the receiver, while the vehicle rests on the ground 8 of a parking space equipped with a battery charger transmitter, such as The charging device of the vehicle battery therefore consists of two main components that cooperate without contact, a transmitter 12 fixed to the ground 8 and a receiver 2 mounted on the motor vehicle.

The transmitter 12 mainly comprises a so-called primary coil 13, which is fixedly positioned at a parking space of a motor vehicle, powered by a resonant circuit which will be described later. This transmitter 12 is advantageously integrated into a volume arranged within the parking space, so that the portion of the transmitter 12 comprising the primary coil 13 does not exceed or slightly above the ground level 8 on which is placed a motor vehicle . Alternatively, the transmitter can be disposed entirely above the ground 8 to facilitate its positioning.

FIG. 2 illustrates the embodiment of the invention in which the coil 13 of the transmitter 12 protrudes slightly above the ground level 8, so as to be at a distance e below the so-called coil secondary 3 of the receiver 2 arranged within the motor vehicle, in a vertical direction z. The secondary coil 3 is adapted to receive a power 9 transmitted by the primary coil 13 through the space 7 separating them, called gap. The receiver 2 is advantageously arranged in the underside of the motor vehicle, integrated in the chassis of the vehicle, to minimize the distance e and optimize the power transfer through the space 7. This battery charging device can correspond to the front or rear part of the vehicle.

The concept of the invention is therefore based on the principle of non-contact charging of a battery, and allows the transfer of charge power through the air present in the space 7, without the need for a physical electrical connection at the level of the battery. motor vehicle.

FIG. 3 represents a top view of a parking space 24, of rectangular shape similar to conventional parking spaces, of dimensions that may be 3 meters by 5 meters, including an arrangement for charging a motor vehicle battery, comprising for this, a transmitter 12 of battery fixed on the ground 8. Alternatively, the parking space could have other geometries, without impeding the implementation of the concept of the invention will be detailed below.

FIG. 4 illustrates the situation in practice when charging the battery of a motor vehicle positioned in the parking space 24. The transmitter 12 emits power in a radiation surface represented schematically by the circular shape 14, substantially symmetrically distributed around the primary coil of the transmitter 12. The motor vehicle should ideally be positioned centrally on the parking space so that its so-called secondary coil 3 is perfectly superimposed on the primary coil 13, as shown in Figure 2 i.e., so that the two coils 3, 13 are coaxially aligned in the vertical direction. In practice, the motor vehicle can be shifted relative to this ideal reference position, so that the receiving surface of its secondary coil 3 can correspond to the disks 5 or 6, according to the schematic representation chosen. In these staggered positions of the motor vehicle, the load does not have the same characteristics as in the ideal position and its efficiency drops quickly.

The concept of the invention optimizes the charge of the battery of the motor vehicle, regardless of the position of the motor vehicle relative to the transmitter 12 in a parking space, even in the offset positions 5, 6. The invention thus has the advantage of achieving an effective load in all positions of the motor vehicle in a predefined parking space, without requiring the very precise positioning of the motor vehicle that can have space either on its sides or towards the front or rear, allowing the raising and lowering of passengers, access to the trunk or the front cover, etc., as in a simple conventional parking of a vehicle in a parking space.

FIG. 5 schematically represents the electrical diagram of the charging device of a battery 10 of a motor vehicle. The transmitter 12 comprises a connection 15 to the sector 16, an AC / DC converter 17 whose function is to transform the AC current of the sector 16 into a DC current, supplying a DC voltage Vdc at the input of an inverter 18 whose function is to transmit an oscillating power at the level of the primary coil 13. The receiver 2 arranged within the motor vehicle comprises a secondary coil 3 which receives the power transmitted by the primary coil 13, whose generated magnetic field induces a current electrical power within the secondary coil 3 through the space 7. This electric current passes through a regulator or rectifier 4 and a filter 11 before reaching the battery 10, thus allowing charging. The charger is further controlled by a controller 19 whose function will be detailed later.

Figure 6 allows to detail more precisely the electrical diagram of the resonance converter used for power transfer. The inverter 18 is a high frequency switching inverter, operating for frequencies between 20 kHz and 100 kHz), which mainly comprises four IGBT type transistors 30 associated with a resonant circuit defined by the combination of a capacitor 31 of capacitance Cp associated in series with the primary coil 13 of inductance Lp. A resonance detection block 42 is interposed between the resonant primary circuit and the control device 19. On the motor vehicle side, the receiver therefore comprises a secondary coil 3 of inductance Ls associated in series with a capacitor 41 of capacitance Cs. A rectifier 4 and a filter 11 consisting of a single capacitor are then arranged between the secondary resonant circuit and the battery, not shown.

According to the invention, the resonance converter operates at a switching frequency f close to the resonance frequency fo of the primary and secondary circuits, respectively defined by the parameters Lp-Cp, Ls-Cs.

The resonance frequency is related to these parameters by the following equations: wo = 2rrfo and w02 = 1 / (Lp Cp) = 1 / (Ls Cs) is fol = 1 / [4. Tr 2 (Lp Cp)]

The relative displacement of a motor vehicle relative to the transmitter at a parking space causes the secondary coil to shift relative to the reference center situation, which is translated at the electrical level by a modification of the inductances. Lp and Ls of the primary and secondary coils and thus a modification of the resonant frequency. Thus, such displacement causes a modification of the reference electrical circuit described above, whose operating frequency is no longer optimized, no longer corresponds to the desired resonance frequency.

According to the concept of the invention, the operating conditions of the charger are adapted to the position of the vehicle in order to get as close as possible to the resonance frequency of the equivalent electrical circuit formed by the two primary and secondary devices as they are arranged. relative to each other. Thus, the solution always seeks the optimization of power transmission by the charger in all positions of the vehicle, which greatly minimizes the impact of a shift of the vehicle position.

According to the embodiment of the invention, the charger is adapted to the positioning of the vehicle by changing the switching frequency of the inverter 18, to get as close as possible to the resonance frequency of the equivalent electric circuit.

In addition to the adaptation of the frequency explained above, it is also possible to optimize the operation of the charger by adapting in a second time the output voltage Vdc of the converter ACIDC 17 to the new configuration of the modified circuit in order to optimize its performance. By way of example, FIG. 7 shows the electronic circuit diagram of the AC / DC converter, which can convert the mains voltage into a DC voltage, by absorbing the sinusoidal current of the sector in phase with the mains voltage. The power supply of the sector is three-phase for the high powers (of the order of 20 kW for example).

The effect sought by the invention is illustrated in FIG. 8. As can be seen from the curves presented by way of example, the maximum power transmitted by the transmitter to the receiver is obtained for a frequency f equal to the resonance frequency f 0 of the device. On the other hand, this maximum power is obtained for a particular value Vdc1 of the output voltage of the AC / DC converter.

Finally, the battery charging device therefore comprises a control device 15 which implements the battery charging method on the basis of the following essential steps: El - when a motor vehicle is parked, search for the resonance frequency fo equivalent electrical circuit; E2 adaptation of the switching frequency f of the inverter to a value substantially equal to the resonance value fo.

Alternatively, the operating frequency of the charging device could be changed by acting on any other electrical component than the inverter. The method may advantageously implement the following additional step: E3 adaptation of the voltage Vdc of the AC / DC converter to optimize the power transmitted to the secondary circuit.

The first step E1 can comprise the following sub-steps: sending low amplitude current by scanning different frequencies; - measurement of the induced induced current; the resonance frequency corresponds to the maximum induced current.

The frequency sweep may preferably be performed around the resonance frequency in the perfect alignment configuration of the two primary and secondary coils, which serves as the reference frequency.

Alternatively, the detection of the resonant frequency can be achieved by regulating the phase between the intensity and the voltage to obtain a zero phase.

The preceding charging method is implemented after the parking of a vehicle, in advance of the actual charge of its battery. It may, however, be put back into operation during charging, if the device 15 detects an anomaly, following a slight movement of the vehicle for example.

Finally, this charging method enables the efficient charging of a vehicle battery for a high air gap, for example between 22 and 30 centimeters, and for offsets of up to 30 centimeters from the motor vehicle relative to its reference position. . The invention is therefore well suited for a parking space of size allowing a possible shift of a motor vehicle up to 30 centimeters from its reference position. This charging method is implemented by a device for controlling the charging device, which may comprise software and / or hardware elements (hardware and / or software). The control device comprises for example mainly one or more microprocessors. It may be disposed at the transmitter, or alternatively at the receiver, or partially at each of the two components. The control device implements, in particular, a regulation of the load power, of the PWM type, using a reference power.

The invention has been described on the basis of a battery transmitter fixed at ground level. However, the concept of the invention remains compatible and applicable to a portable, mobile transmitter.

On the other hand, it has been illustrated according to some electrical diagrams as an example. It is applicable to any equivalent implementation at the electrical level. For example, the reels can have any shape, circular, rectangle, square, etc. The inverter can be in any form, with other numbers of transistors, for example only two, with other types of transistor, etc. The combination of capacitor and inductor Cp Lp-Cs Ls could have other configurations, these two elements could for example be connected in parallel and not in series, both at the primary circuit and secondary.

Thus, the invention achieves the desired objects and finally has the following advantages: it is very user-friendly since the positioning of the motor vehicle is done in the usual way, by parking in a relatively large space without requiring precision particular positioning. In addition, it does not require any manipulation of dangerous electrical devices; -The battery charge is optimized and effective in all positions of the vehicle, with a wide tolerance on variations in its positioning.

Claims (6)

Claims: 1 Method for charging a battery (10) for powering a motor vehicle, from a charging device comprising on the one hand a charger transmitter (12) comprising an AC / DC converter (17), an inverter (18) and a primary coil (13) disposed within a parking space (24) for a motor vehicle and on the other hand a charger receiver (2) comprising a secondary coil (3) arranged in the motor vehicle, characterized in that it comprises the following steps: (El) - when a motor vehicle (1) is positioned in the parking space (24), search for the resonance frequency (fo) the resonant charging device formed by the charger transmitter (12) and the charger receiver (2); (E2) adapting the frequency (f) of the charging device to a value substantially equal to the resonance value (f0) of the charging device, so as to transmit optimum power in a non-contact manner between the primary coil (13); ) and the secondary coil (3). 2. Method for charging a battery (10) according to the preceding claim, characterized in that the second step of adapting the frequency (f) comprises modifying the switching frequency (f) of the inverter (18). ) at a value substantially equal to the resonance value (fo). 3. A method of charging a battery (10) according to one of the preceding claims, characterized in that it comprises the following additional step: (E3) ù modification of the voltage (Vdc) of the AC / DC converter for increase the power transmitted to the secondary circuit. 15Process of charging a battery (10) according to the preceding claim, characterized in that it defines a reference frequency corresponding to the resonant frequency in the case where the two primary and secondary coils are perfectly superimposed, coaxially, and in that the frequency sweep is first performed around this reference frequency. Method for charging a battery (10) according to one of the preceding claims, characterized in that the second step of adapting the switching frequency (f) to a value substantially equal to the resonance value (fo) of the Charging device is performed in an initial phase of the charging process and / or charging of the battery in case of detection of a change in charging conditions. Battery charger transmitter (10) for powering a motor vehicle, comprising an AC / DC converter (17), an inverter (18) and a primary coil (13), characterized in that it comprises a device command (19) which implements all or 4. A method of charging a battery (10) according to one of the preceding claims, characterized in that the first step (El) comprises the following sub-steps: - sending low amplitude currents by scanning different frequencies; - measurement of the resulting induced current for each frequency; - At the end of the scan, determining the maximum induced current obtained, the resonant frequency (fo) being set equal to the frequency corresponding to this maximum value of the induced current. 10 5. 15 20 6. Part of the charging method according to one of the preceding claims. 8. Charger transmitter battery (10) for power supply of a motor vehicle according to the preceding claim, characterized in that it represents a resonant circuit comprising the inverter (18), a capacitor (31) and the coil (13), whose reference resonant frequency (fo) is determined by: fol = 1 / [4. rr 2 (Lp Cp)] where Cp is the capacity of the capacitor (31) and Lp is the inductance of the coil (13). 9. Receiver for battery (10) for powering a motor vehicle, characterized in that it comprises a control device (19) which implements all or part of the charging method according to one of the preceding claims. . 10. Receiver for battery (10) for powering a motor vehicle according to the preceding claim, characterized in that it represents a resonant circuit comprising a capacitor (41) and a coil (3), whose resonance frequency reference (fo) is determined by: fol = 1 / [4. u 2 (Ls Cs)] where Cs is the capacity of the capacitor (41) and Ls is the inductance of the coil (3). 11. Motor vehicle characterized in that it comprises a battery (10) for the power supply of its engine, characterized in that it comprises a receiver according to claim 9 or 10 for the charge of its battery. 12. Arrangement for charging a motor vehicle battery comprising a charger transmitter (12) fixed to a parking space (24) for a motor vehicle, characterized in that the charger transmitter (12) is in accordance with the invention. one of claims 7 or 8. 13. Arrangement for charging a motor vehicle battery according to the preceding claim, characterized in that the parking space has a dimension such that it allows an off-center positioning of up to 30 centimeters of a motor vehicle relative to a reference position in which the two primary coils (13) and secondary (3) respectively of the charger transmitter and the charger receiver of the motor vehicle are perfectly superimposed, coaxially.