METHOD FOR DETECTING AN OBJECT TO BE CHARGED AND ASSOCIATED CHARGING DEVICE

Abstract

A method for detecting an object to be charged by an induction-charging device including at least one transmitting coil. The method includes transmission, by the at least one coil, of an electrical pulse the value of which is within a window of values predetermined using test receivers, and the object to be charged generating a communication signal in response. The method including, if charging conditions are favorable, the modulation of the value of the electrical pulse outside of the window of predetermined values according to the presence and/or the value of the communication signal, in order to detect the presence of an object to be charged.

Claims

1. A method for detecting an object to be charged by an induction-charging device comprising at least one transmitting coil, the method comprising: transmitting, by the at least one coil, an electrical pulse the value of which is within a window of values predetermined using test receivers in a certification phase, and the object to be charged generating a communication signal in response; and if charging conditions are favorable, and in the absence of a communication signal or a communication signal of maximum value, the modulation of the value of the electrical pulse outside of the window of predetermined values in order to detect the presence of an object to be charged.

2. The method for detecting an object to be charged by a charging device as claimed in claim 1, comprising at least one transmitting coil, the method further comprising the following steps for each coil: a) detecting the presence of an object on a charging surface of said device; b) checking charging conditions; c) if the charging conditions are favorable: i) transmitting, to the object, an electrical pulse the value of which is within a window of values predetermined beforehand using test receivers in a certification phase; ii) if the object transmits a communication signal lower than a maximum value in response, then an object to be charged is detected, otherwise: iii) in the absence of a communication signal, or a communication signal of maximum value, then transmitting, to the object, a modified electrical pulse the value of which is located outside of the window of predetermined values: a. if the object transmits a communication signal in response, then an object to be charged is detected; b. otherwise a parasitic object is detected.

3. The detection method as claimed in claim 2, wherein, in the absence of a communication signal, the modified electrical pulse has a voltage higher than an upper limit predetermined beforehand using test receivers in a certification phase.

4. The detection method as claimed in claim 2, wherein if the object transmits a communication signal of maximum value, the modified electrical pulse has a voltage lower than a lower limit predetermined beforehand using test receivers in a certification phase.

5. The detection method as claimed in claim 1, wherein if the charging conditions are unfavorable, then the electrical pulse has a voltage lower than a lower limit predetermined beforehand using test receivers in a certification phase.

6. The detection method as claimed in claim 1, wherein when the charging conditions are unfavorable for a coil, the method is stopped for said coil.

7. The detection method as claimed in claim 1, wherein, the charging device comprises a plurality of transmitting coils, the method is repeated for each coil.

8. The detection method as claimed in claim 1, further comprising a prior step of calibrating the voltage values of the modified electrical pulse outside of the window of predetermined values according to various types of objects to be charged.

9. The detection method as claimed in claim 1, wherein the checking of favorable charging conditions comprises measuring at least one parameter of the at least one transmitting coil and comparing said measurement with predetermined threshold values of the same parameter, obtained beforehand for various types of objects to be charged.

10. The detection method as claimed in claim 9, wherein the parameter is a quality factor, and/or a variation in resistance and/or a variation in inductance, and/or a variation in a resonant frequency of the transmitting coil.

11. A device for charging an object, comprising at least one transmitting coil, the device comprising: a) means for detecting an object on the charging surface; and, for each coil: b) means for checking charging conditions; c) means for detecting the reception of a communication signal and for comparing the value of said received communication signal with a maximum value; and d) means for modulating a value of an electrical pulse transmitted by the at least one coil, outside of a window of values predetermined beforehand using test receivers in a certification phase, according to the result of said check and according to the presence and/or the value of the communication signal.

12. The device for charging an object as claimed in claim 11, wherein the checking means comprise means for measuring at least one parameter of the transmitting coil and means for comparing the measurement with predetermined threshold values of the same parameter, obtained beforehand for various types of objects to be charged.

13. The charging device as claimed in claim 12, wherein the parameter is a quality factor, and/or a variation in resistance and/or a variation in inductance, and/or a variation in a resonant frequency of the transmitting coil.

14. A non-transitory computer program product comprising program code instructions for carrying out the steps of the detection method as claimed in claim 1, when said program is executed on a computer.

15. A motor vehicle comprising a charging device as claimed in claim 11.

16. The detection method as claimed in claim 3, wherein if the object transmits a communication signal of maximum value, the modified electrical pulse has a voltage lower than a lower limit predetermined beforehand using test receivers in a certification phase.

Description

DESCRIPTION OF THE DRAWINGS

[0050] Other features and advantages of the invention will become more apparent from reading the description which follows. This description is purely illustrative and should be read with reference to the appended drawings, in which:

[0051] FIG. 1 schematically shows an object to be charged T located at one end of a charging device D;

[0052] FIG. 2 is a graph showing the digital pings of identical voltage values sent by each of the transmitting coils, according to the prior art;

[0053] FIG. 3 is a graph showing modified digital pings sent by each of the transmitting coils, according to a first variant of the detection method according to the invention;

[0054] FIG. 4 is a graph showing modified digital pings sent by each of the transmitting coils, according to a second variant of the detection method according to the invention;

[0055] FIG. 5 is a flowchart showing the various steps of the detection method according to the invention;

[0056] FIG. 6a schematically shows a detection region for an object to be charged on a charging surface of a charging device according to the prior art;

[0057] FIG. 6b schematically shows a detection region for an object to be charged on a charging surface of a charging device according to the invention.

DESCRIPTION OF THE EMBODIMENTS

[0058] As explained above, the initiation of charging or the charging of an object may be inhibited since the value of the rectified voltage Vr of the object to be charged, induced by the transmission of a digital ping by the charging device, is above or below limits that have been set by the manufacturers of said objects via the Qi standard. To avoid exceeding these limits, the voltage values of the digital ping are determined beforehand in a phase of certification to the Qi standard using test receivers.

[0059] This problem of charging not being initiated is mainly due to the intrinsic construction of the object to be charged T (size of the receiving coil, position of the coil in the object, object having a high metal component) and/or its position on the charging surface S of the charging device D. These are actual charging conditions which differ significantly from the optimal charging conditions used in the certification phase.

[0060] The invention proposes a method for detecting an object to be charged T and a charging device D that make it possible to overcome the drawbacks mentioned above.

[0061] To that end, the charging device D according to the invention comprises at least one transmitting coil B1 and means for controlling said coil, i.e. means for generating and controlling charging, i.e. an electromagnetic field directed toward an object to be charged T. This is known from the prior art and will not be described in more detail here.

[0062] The charging device D comprises a charging surface S on which the object to be charged T is placed. The object may be a smartphone, a tablet, or even any connected object that can be charged using the Qi standard, i.e. the Wireless Power Consortium standard for induction charging.

[0063] The charging device D is intended to be installed on board a motor vehicle and, to that end, its charging surface is sized to accommodate any type of object to be charged T of varying size. In this example, said device comprises no means for securing or for holding the object to be charged T to the charging surface S. Thus, most objects to be charged T placed on the charging surface S will be able to slide freely over said surface S depending on the vehicle's movements. Specifically, the problem of initiation of charging being inhibited arises for this type of charging device D especially, since as the vehicle moves, the object to be charged T may move into a corner of the charging device and charging stops as explained above.

[0064] According to the invention, the charging device D comprises means M1 for detecting that an object has been placed on the charging surface S. These detection means consist of means for transmitting an electrical pulse, i.e. an analog ping, and means for measuring parameters such as the variation in voltage, in impedance, or in resonant frequency of the transmitting coils. The detection means M1 may also comprise sensors, such as capacitive sensors, means for detecting GSM (Global System for Mobile Communication) coupling, i.e. means for detecting 2G communication with a cellphone, or an NFC antenna. These detection means are known to those skilled in the art and will not be described in more detail here.

[0065] The device D also comprises means M2 for checking charging conditions for each of the coils. In this example, a device D equipped with three transmitting coils B1, B2, B3 will be considered, as illustrated in FIG. 1.

[0066] These means M2 consist of measurements of parameters of the transmitting coils B1, B2, B3, such as: [0067] a. the quality factor Q of the coils B1, B2, B3; and/or [0068] b. the variation in resistance ΔR of said coils; and/or [0069] c. the variation in inductance ΔL of said coils; and/or [0070] d. the variation in the resonant frequency ΔFres of said coils; [0071] and means for comparing these measurements with predetermined threshold values.

[0072] What is meant by “variation” in the resistance ΔR, inductance ΔL and resonant frequency ΔFres parameters is the difference, for each of these parameters, between the “no-load” value of the parameter, i.e. without any object placed on the charging surface S, and the value of the same parameter with an object placed on the charging surface S.

[0073] The predetermined threshold values are minimum and maximum values determined beforehand for each coil and for various types of objects to be charged T, for example for various types of cellphone, with or without a protective metal shell, phones comprising very few metal parts or, conversely, phones with a lot of metal, phones comprising a small receiving coil or, conversely, a very large receiving coil, etc.

[0074] For example, the value of the quality factor Q1 of a first coil B1 is compared with a minimum value Q1min and a maximum value Q1max determined beforehand for this same first coil B1.

[0075] Similarly, the value of the variation in resistance ΔR1 for the first coil B1 is compared with a minimum value of the variation in resistance ΔR1min and a maximum value of the variation in resistance ΔR1max determined beforehand for this same first coil B1.

[0076] This applies similarly for the variation in inductance ΔL and for the variation in resonant frequency ΔFres for each of the three coils B1, B2, B3 as will be explained further on.

[0077] The device also comprises means M3 for detecting the reception of an SSP communication signal and for comparing the value of said received communication signal with a maximum value SSPmax. The detection and comparing means comprise a demodulator in order to demodulate the received communication signal and software means in order to compare the value of said signal with a predetermined maximum value SSPmax.

[0078] Lastly, the charging device D comprises means M4 for modulating the values of the electrical pulse, or digital ping, transmitted by each of the coils B1, B2, B3 outside of windows of predetermined values which have been defined beforehand using test receivers in a phase of certifying the device to the Qi standard. The one or more coils then transmit a modified electrical pulse DPm. Said modulation of the value of the electrical pulse is performed according to the result of said check of favorable conditions and according to the presence and/or the value of the SSP communication signal. What is meant by “value” is, for example, the voltage of the electrical pulse.

[0079] The modulation means M4 may comprise modified electrical pulse values DPm that are outside of the window of predetermined values depending on various types of objects to be charged T. Thus, the means for checking M2 the charging conditions may indicate the type of the object to be charged, and the voltage of the modified electrical pulse DPm that is applied is then chosen from among values calibrated beforehand according to the type of object T and stored in the charging device, for example in the modulation means M4.

[0080] The means for checking favorable conditions M2 and the means M3 for detecting the reception of an SSP communication signal and for comparing the value of said received communication signal with a maximum value SSPmax, and the means M4 for modulating the values of the electrical pulse, preferably take the form of software and are based in a microcontroller located in the device D.

[0081] The method for detecting an object to be charged T, illustrated in FIG. 5, will now be described.

[0082] In a prior step (step E0), it is detected that an object has been placed on the charging surface S of a charging device D. This object may be an object to be charged, i.e. an object compatible with induction charging according to the Qi standard, but it may also be a “parasitic” object such as a paper clip or a coin.

[0083] This detection is achieved by the transmitting coils B1, B2, B3 of the charging device D transmitting analog ping-type electromagnetic pulses at a regular frequency and measuring the variation in parameters such as voltage, impedance or resonant frequency, or this detection is achieved using capacitive sensors or other means for detecting the presence of an object. If significant variations in said parameters are measured, then this means that an object has been detected as having been placed on the charging surface S.

[0084] In a first step E1, the detection method according to the invention proposes checking what are called “environmental” charging conditions.

[0085] In this step, the parameters such as: [0086] a. the quality factor Q of the coils B1, B2, B3, and/or; [0087] b. the variation in resistance ΔR of said coils; and/or [0088] c. the variation in inductance ΔL of said coils; and/or [0089] d. the variation in the resonant frequency ΔFres of said coils
are measured for each transmitting coil B1, B2, B3 in a first stage.

[0090] According to the invention, just one parameter may be used, or a combination of two, of three or of four parameters to check the charging conditions. The number or type of parameter may vary according to the transmitting coil B1, B2, B3 in question.

[0091] Next, in a second stage, the values thus measured for each transmitting coil B1, B2, B3 are compared with predetermined threshold values.

[0092] The threshold values have been determined beforehand for various types of object to be charged T exhibiting different characteristics: phone with few metal parts, phone with many metal parts, phone with a large receiving antenna A1, or phone with a small receiving coil A1.

[0093] Thus, it is possible to check for each receiving coil B1, B2, B3 that:

Qi min<Qi<Qi max  [Math 1]

where
Qi: quality factor of the ith coil
Qimin: minimum quality factor of the ith coil
Qimax: maximum quality factor of the ith coil

[0094] Likewise, it is also possible to check that:

ΔRi min<ΔRi<ΔRi max  [Math 2]

where
ΔRi: variation in resistance of the ith coil
ΔRimin: minimum variation in resistance of the ith coil
ΔRimax: maximum variation in resistance of the ith coil

[0095] Similarly, it is possible to check that:

ΔLi min<ΔLi<ΔLi max  [Math 3]

where
ΔLi: variation in inductance of the ith coil
ΔLimin: minimum variation in inductance of the ith coil
ΔLimax: maximum variation in inductance of the ith coil

[0096] Lastly, it is possible to check that:

ΔFresi min<ΔFresi<ΔFresi max  [Math 4]

where
ΔFresi: variation in resonant frequency of the ith coil
ΔFresimin: minimum variation in resonant frequency of the ith coil
ΔFresimax: maximum variation in resonant frequency of the ith coil

[0097] As explained above, the checking of just one parameter may be enough on each of the transmitting coils B1, B2, B3 to conclude that the charging conditions are favorable. The checks on these parameters are not necessarily combinable to determine whether the charging conditions are favorable.

[0098] The charging conditions are said to be favorable for a transmitting coil when at least one of the check criteria is met.

[0099] Two cases are then possible: [0100] a. either the charging conditions are favorable, and the method continues on to step E3 with at least one of the coils B1, B2, B3 of the charging device D sending a digital ping DP; [0101] b. or the charging conditions are unfavorable, and the method stops (step E7b) and no coil transmits a digital ping DP.

[0102] In one variant of the method, if the conditions are unfavorable, the method continues and proposes that the charging device transmit a modified digital ping DPm the value of which (the voltage here) is below a lower (voltage) limit determined beforehand using test receivers in a phase of certification to the Qi standard, as explained above.

[0103] Once the charging conditions have been checked, if they are favorable, specifically if the one or more parameters chosen from among the four parameters listed above are indeed within the predetermined threshold values for at least one transmitting coil B1, B2 or B3 (step E2), then the charging device D transmits a digital ping DP (step E3) via this transmitting coil. If the charging conditions are met for all of the coils, then the transmitting coils each transmit in turn a digital ping DP to the object (step E2).

[0104] If the object responds to this digital ping DP by sending a communication signal, called an “SSP” (“signal strength packet”) signal (step E4a), i.e. a signal containing a value representative of the voltage induced Vr by the received signal, with a value lower than a maximum value SSPmax (step E4b), then induction charging is initiated (step E7a). Specifically, the “SSP” signal is a value representative of a ratio of the value of the rectified voltage Vr across the terminals of the voltage rectifier of the receiving coil A1 induced by receiving the electromagnetic field created by the digital ping DP to the maximum rectified voltage that the object to be charged is able to withstand when receiving a digital ping DP.

[0105] In a first embodiment of the method according to the invention, if the object does not send an “SSP” signal, then either it is a parasitic object or it is an object to be charged but one that has a rectified voltage value Vr that is too low with respect to the rectified voltage limits specified by cellphone manufacturers to initiate charging, this insufficiently high rectified voltage not allowing it to send an “SSP” communication signal to the charging device D in order to initiate charging.

[0106] In that case, if the object to be charged does not return an “SSP” communication signal, then the method according to the invention proposes that the charging device send a modified digital ping DPm with a value (voltage here) that is higher than the upper limit determined in the certification phase, i.e. a value that would result in a rectified voltage Vr in the test receivers higher than the limits specified by the Qi standard.

[0107] Once the modified digital ping DPm has been sent, two cases are possible: either the object returns an SSP communication signal (step E6) and charging starts (step Ela) or no SSP communication signal is sent and charging is not initiated (step E7b).

[0108] FIG. 2 shows, in a graph, the digital pings DP sent by each of the transmitting coils B1, B2, B2 according to the prior art. These are all of the same voltage equal to the upper voltage limit Vmax defined in the certification phase so that all of the test receivers respond to the charging device D by sending an SSP signal without their rectified voltage exceeding the maximum values dictated by the standard.

[0109] FIG. 3 shows, in a graph, a first example of modified digital pings DPm sent by each of the coils B1, B2, B3 according to the method of the invention. The modified digital pings DPm vary in value from coil to coil and in this case each have a voltage higher than the upper voltage limit Vmax of the prior art. The voltage of the digital pings DPm has increased by X1%, X2%, and X3% with respect to the voltage Vmax for the first coil B1, the second coil B2 and the third coil V3, respectively.

[0110] In a second embodiment of the method according to the invention, if the object to be charged returns an SSP signal of maximum value SSPmax (step E4b), the maximum value being dictated by the Qi standard and equal to SSPmax=255, (a demodulator in the microcontroller of the charging device demodulates the SSP communication signal sent by the object to be charged and compares it with the maximum value of 255), then the method proposes that the charging device D send a modified digital ping DPm, this time with a value (voltage here) that is lower than the lower limit Vmin determined in the certification phase, i.e. a value that would result in a rectified voltage Vr in the test receivers lower than the limits specified by the Qi standard.

[0111] FIG. 4 shows, in a graph, a second example of modified digital pings DPm sent by each of the coils B1, B2, B3. The modified digital pings DPm vary from coil to coil and in this case each have a voltage lower than the lower limit Vmin of the prior art. The voltage of the digital pings has decreased by Y1%, Y2%, and Y3% with respect to the lower limit Vmin for the first coil B1, the second coil B2 and the third coil V3, respectively.

[0112] Of course, the method may comprise a prior step of calibrating the voltage values of the modified electrical pulse DPm outside of the window of predetermined values, this window being defined by the upper limit and the lower limit Vmin, Vmax according to various types of objects to be charged T. Thus, the charging conditions may indicate the type of object to be charged, and the voltage of the modified electrical pulse DPm that is applied is then chosen from among values calibrated beforehand and stored in the charging device according to the type of object T.

[0113] It may also be possible for the transmitting coils B1, B2, B3 of the same charging device D to transmit modified digital pings the voltage of which is either lower or higher than the lower or upper limits Vmin, Vmax of the prior art, or even for a coil not to transmit any digital ping at all, as explained above.

[0114] FIG. 6a illustrates the region Z1 for placing an object to be charged T on the surface of a charging device D that allows charging to be initiated according to the prior art.

[0115] FIG. 6b illustrates the region Z2 for placing an object to be charged T on the surface of a charging device D that allows charging to be initiated with the detection method according to the invention. It is clearly apparent from comparing the two graphs 6a and 6b that the region Z2 that allows charging to be activated is significantly larger than the region Z1 of the prior art by virtue of the detection method according to the invention.

[0116] The detection method according to the invention therefore allows the drawbacks of the prior art to be overcome. Specifically, the method of the invention allows better identification of compatible objects to be charged with respect to parasitic objects placed on the charging surface and, above all, it allows the size of the region on the charging surface of the charging device that allows charging to be increased.