Charging range detection method for wireless charging system

Abstract

The invention discloses a method for detecting the charging range of a wireless charging system, which is used for identifying the alignment positions of a transmitting coil and a receiving coil based on a mutual inductance principle so as to reliably detect the charging range of the wireless charging system. The wireless charging system comprises a transmitting end and a receiving end, and is characterized in that the transmitting end comprises a direct-current power supply, a high-frequency inverter, a first compensation inductor, a first group of compensation capacitors and a transmitting coil; the receiving end comprises a receiving coil, a second group of compensation capacitors, a second compensation inductor, a rectifying and filtering module and a system load; # imgabs0 # Ucf2 = (j.omega.Lf2 + RLf2 + RL). ILf2 can be obtained by listing a Kirchhoff voltage equation of a secondary side, so that the impedance of # imgabs1 # is equal to that of Lf2 and Cf2 at the frequency of 85.5 kHz, and when RL tends to 0, the mutual inductance detection value of the system # imgabs3 # can be obtained by # imgabs2 #

Description

Technical Field

[0001] The present invention relates to the technical field of wireless charging, and in particular to a charging range detection method for a wireless charging system. Background Art

[0002] With the development of new energy charging technology in my country, wireless charging technology for electric vehicles has gradually become popular due to its advantages of portability, aesthetics, durability and safety.

[0003] The wireless charging technology for electric vehicles uses the principle of electromagnetic induction to transmit electrical energy to the internal battery of the electric vehicle for charging through electromagnetic coupling between a transmitter installed on the ground and a receiver installed at the bottom of the car.

[0004] When charging an electric vehicle, the user cannot directly see the relative positions of the receiving device inside the electric vehicle and the transmitting device on the ground, and thus cannot determine whether the required wireless charging area range is reached. Therefore, how to detect the charging range of the charging area of ​​the wireless charging system becomes particularly important. Summary of the invention

[0005] In view of the above problems, the present invention provides a charging range detection method for a wireless charging system, which identifies the alignment position of a transmitting coil and a receiving coil based on the principle of mutual inductance, and thus reliably detects the charging range of the wireless charging system.

[0006] A method for detecting a charging range of a wireless charging system, wherein the wireless charging system includes a transmitting end and a receiving end, and is characterized in that:

[0007] The transmitting end includes a direct current power supply, a high-frequency inverter, a first compensation inductor, a first group of compensation capacitors, and a transmitting coil;

[0008] The receiving end includes a receiving coil, a second group of compensation capacitors, a second compensation inductor, a rectifier and filter module, and a system load;

[0009] By writing Kirchhoff's voltage equation on the secondary side, we can get

[0010]

[0011] U cf2 =(j·ω·L f2 +R Lf2 +R L )·I Lf2

[0012] Then get

[0013]

[0014] By Lf2 and C f2 At 85.5kHz, the impedance is equal. When R L When it approaches 0,

[0015]

[0016] The mutual inductance detection value of the system can be obtained as

[0017]

[0018] Wherein, ω is the resonant frequency of the wireless charging system, L1 is the self-inductance of the transmitting coil, L2 is the self-inductance of the receiving coil, I1 is the current of the transmitting coil, I2 is the current of the receiving coil, M is the mutual inductance between the transmitting coil and the receiving coil, L f2 To compensate for the inductance, C2, C f2 is the capacitance value of the second group of compensation capacitors, U cf2 is the compensation capacitor C f2 The voltage across the capacitor;

[0019] By comparing the calculated mutual inductance detection value M of the wireless charging system with the set mutual inductance setting threshold, the alignment position of the transmitting coil and the receiving coil is determined and identified, thereby reliably detecting the charging range of the wireless charging system.

[0020] It is further characterized by:

[0021] The steps for obtaining the mutual inductance detection value M of the mutual inductance detection are as follows:

[0022] S1, controlling the rectifier network to be short-circuited, with no current output;

[0023] S2, sampling the current I on the transmitting coil 1；

[0024] S3, sampling the receiving end compensation inductance L f2 The current I Lf2 ;

[0025] S4, according to the receiving end compensation inductance L f2 , the current I1 of the transmitting coil, the compensation inductance L of the receiving end f2 The current I Lf2 , the mutual inductance detection value of the wireless charging system is obtained by calculating the formula:

[0026]

[0027] It is further characterized by:

[0028] When the wireless charging system issues a charging instruction, the wireless charging system detects the mutual inductance value of the transmitting coil and the receiving coil. When the mutual inductance detection value is greater than or equal to the mutual inductance setting threshold, it is determined that the current is within the chargeable area and meets the charging requirements, and the rectification network is controlled to output current, wherein the mutual inductance setting threshold is the minimum mutual inductance value within the chargeable area of ​​the system, and is also the critical value of the chargeable area; when the mutual inductance detection value of the wireless charging system is less than the mutual inductance setting threshold, it is determined that the current position exceeds the chargeable area and does not meet the charging requirements, and the rectification network is controlled to be in a short-circuit state, and no current is output;

[0029] After the wireless charging system issues a charging instruction, the mutual inductance detection value is detected. When the mutual inductance detection value is less than the mutual inductance setting threshold value, the wireless charging system will repeat the detection. During this stage, the rectifier network is always in a short-circuit state. When the mutual inductance detection value is greater than or equal to the mutual inductance setting threshold value, that is, when it reaches the chargeable area, the rectifier network is controlled to output current to charge the system load.

[0030] After adopting the present invention, before charging the load, the relative position of the receiving end and the transmitting end is determined by identifying the mutual inductance of the transmitting coil and the receiving coil. Charging is started only when the detected mutual inductance detection value is greater than or equal to the mutual inductance setting threshold. This technical solution does not require adding additional circuits, has simple steps, and has fast identification. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a system circuit diagram of the present invention;

[0032] Figure 2 is a system equivalent circuit diagram of the present invention;

[0033] Figure 3 This is a flow chart of charging area detection of the present invention;

[0034] Figure 4 It is a schematic diagram of the positions of the receiving end and the transmitting end of the present invention;

[0035] The names corresponding to the serial numbers in the figure are as follows:

[0036] DC power supply 1, high frequency inverter 2, transmitting coil module 3, receiving coil module 4, rectifying and filtering module 5, system load 6. DETAILED DESCRIPTION

[0037] A wireless charging system charging range detection method, see Figure 1-Figure 4 :It is applicable to a wireless charging system, and the corresponding wireless charging system includes a transmitter and a receiver, the transmitter includes a DC power supply 1, a high-frequency inverter 2, a transmitting coil module 3, and the transmitting coil module 3 includes a first compensation inductor L f1, the first group of compensation capacitors, the transmitting coil, the first group of compensation capacitors includes capacitor C1, capacitor C f1 ;

[0038] The receiving end includes a receiving coil module 4, a rectifier filter module 5, and a system load 6. The receiving coil module 4 includes a receiving coil, a second group of compensation capacitors, and a second compensation inductor L f2 The second group of compensation capacitors includes capacitor C2, capacitor C f2 ;

[0039] The output end of the DC power supply 1 is connected to the input end of the high-frequency inverter 2, the output end of the high-frequency inverter 2 is connected to the input end of the transmitting coil module 3, the output end of the receiving coil module 4 is connected to the input end of the rectifying and filtering module 5, and the output end of the rectifying and filtering module 5 is connected to the system load 6;

[0040] By writing Kirchhoff's voltage equation on the secondary side, we can get

[0041]

[0042] U cf2 =(j·ω·L f2 +R Lf2 +R L )·I Lf2

[0043] Then get

[0044]

[0045] By L f2 and C f2 The impedance is equal at 85.5kHz. L When it approaches 0,

[0046]

[0047] The mutual inductance detection value of the system can be obtained as

[0048]

[0049] Where ω is the resonant frequency of the wireless charging system, L1 is the self-inductance of the transmitting coil, L2 is the self-inductance of the receiving coil, I1 is the current of the transmitting coil, I2 is the current of the receiving coil, M is the mutual inductance between the transmitting coil and the receiving coil, L f2 To compensate for the inductance, C2, C f2 is the capacitance value of the second group of compensation capacitors, U cf2 is the compensation capacitor C f2 The voltage across the capacitor;

[0050] By comparing the calculated mutual inductance detection value M of the wireless charging system with the standard mutual inductance setting threshold, the alignment position of the transmitting coil and the receiving coil can be determined and identified, thereby reliably detecting the charging range of the wireless charging system.

[0051] The steps for obtaining the mutual inductance detection value M of the mutual inductance detection are as follows:

[0052] S1, control the rectifier network to short circuit, no current output;

[0053] S2, sampling the current I on the transmitting coil 1；

[0054] S3, sampling receiving end compensation inductor L f2 The current I Lf2 ;

[0055] S4, according to the receiving end compensation inductance L f2 , the current I1 of the transmitting coil, the compensation inductance L at the receiving end f2 The current I Lf2 , the mutual inductance value of the wireless charging system is obtained, which is calculated by the formula:

[0056]

[0057] When the wireless charging system issues a charging instruction, the wireless charging system will detect the mutual inductance value of the transmitting coil and the receiving coil. When the mutual inductance detection value is greater than or equal to the mutual inductance setting threshold, it is determined that the current is within the chargeable area and meets the charging requirements, and the rectification network is controlled to output current. Among them, the mutual inductance setting threshold is the minimum mutual inductance value within the chargeable area of ​​the system, and is also the critical value of the chargeable area; when the mutual inductance detection value of the wireless charging system is less than the mutual inductance setting threshold, it is determined that the current position exceeds the chargeable area and does not meet the charging requirements, and the rectification network is controlled to be in a short-circuit state, and no current is output;

[0058] When the wireless charging system issues a charging command, the mutual inductance detection value is detected. When the mutual inductance detection value is less than the mutual inductance setting threshold, the wireless charging system will repeat the detection. During this stage, the rectifier network is always in a short-circuit state. When the mutual inductance detection value is greater than or equal to the mutual inductance setting threshold, that is, when it reaches the chargeable area, the rectifier network output current is controlled to charge the system load.

[0059] In a specific embodiment, the operating frequency of the system is 85.5kHz, and the DC input voltage V DC is 400V, the mutual inductance threshold of the system is set to 10μH, and the compensation inductance L of the transmitter is f1 The compensation capacitor C is 25μH. f1is 138.6nF, the compensation capacitor C1 is 123.8nF, the transmitting coil L1 is 53μH, the receiving coil L2 is 53μH, and the compensation inductance L of the receiving end is f2 The compensation capacitor C is 25μH. f2 It is 138.6nF and the compensation capacitor C2 is 123.8nF.

[0060] When the system issues a power-on command, the control Figure 1 As shown, the MOSFET tubes S5 and S6 at the receiving end are continuously turned on, so that the rectifier network at the receiving end is in a short-circuit state. The DC power supply passes through the high-frequency inverter to be an 85.5kHz AC current through the transmitting coil and generates an induced current on the receiving coil. Since the rectifier network is in a short-circuit state, the receiving end will not output current, and the system enters the mutual inductance detection link.

[0061] S1, control the rectifier network to be in a short-circuit state, with no current output;

[0062] S2, the current I1 on the sampling transmitting coil is 36A;

[0063] S3, sampling receiving end compensation inductor L f2 The current on is 17A;

[0064] S4, through the formula:

[0065]

[0066] The calculated mutual inductance detection value M is 11.8μH, which is greater than the mutual inductance setting threshold of 10μH set by the system. The system enters the charging state and controls the PWM wave duty cycle corresponding to the MOSFET tubes S5 and S6 at the receiving end, so that the rectifier network outputs current to charge the load.

[0067] When the corresponding positions of the receiving end and the transmitting end change, the corresponding mutual inductance value will also change, such as Figure 4 As shown, the mutual inductance value detected at this time gradually decreases as the relative positions of the receiving end and the transmitting end change. When the mutual inductance value detected by the system is less than the set value of 10μH, the range of the receiving end at this time exceeds the chargeable area set by the system, and the system does not charge.

[0068] Before charging the load, the relative positions of the receiving end and the transmitting end are determined by identifying the mutual inductance of the transmitting coil and the receiving coil. Charging is started only when the detected mutual inductance value is greater than or equal to the mutual inductance set threshold. This technical solution does not require the addition of additional circuits, has simple steps and fast identification.

[0069] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0070] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for detecting a charging range of a wireless charging system, wherein the wireless charging system comprises a transmitting end and a receiving end, and wherein: The transmitting end includes a direct current power supply, a high-frequency inverter, a first compensation inductor, a first group of compensation capacitors, and a transmitting coil; The receiving end includes a receiving coil, a second group of compensation capacitors, a second compensation inductor, a rectifier and filter module, and a system load; By writing Kirchhoff's voltage equation on the secondary side, we can get U cf2 =(j·ω·L f2 +R Lf2 +R L )·I Lf2 Then get By L f2 and C f2 The impedance is equal at 85.5kHz. L When it approaches 0, The mutual inductance detection value of the system can be obtained as Wherein, ω is the resonant frequency of the wireless charging system, L1 is the self-inductance of the transmitting coil, L2 is the self-inductance of the receiving coil, I1 is the current of the transmitting coil, I2 is the current of the receiving coil, M is the mutual inductance between the transmitting coil and the receiving coil, L f2 To compensate for the inductance, C2, C f2 is the capacitance value of the second group of compensation capacitors, U cf2 is the compensation capacitor C f2 The voltage across the capacitor; By comparing the calculated mutual inductance detection value M of the wireless charging system with the set mutual inductance setting threshold, the alignment position of the transmitting coil and the receiving coil is determined and identified, thereby reliably detecting the charging range of the wireless charging system.

2. The method for detecting charging range of a wireless charging system according to claim 1, characterized in that: The steps for obtaining the mutual inductance detection value M of the mutual inductance detection are as follows: S1, controlling the rectifier network to be short-circuited, with no current output; S2, sampling the current I on the transmitting coil 1； S3, sampling the receiving end compensation inductance L f2 The current I Lf2 ; S4, according to the receiving end compensation inductance L f2 , the current I1 of the transmitting coil, the compensation inductance L of the receiving end f2 The current I Lf2 , the mutual inductance detection value of the wireless charging system is obtained by calculating the formula:

3. The method for detecting charging range of a wireless charging system according to claim 1, characterized in that: When the wireless charging system issues a charging instruction, the wireless charging system detects the mutual inductance value of the transmitting coil and the receiving coil. When the mutual inductance detection value is greater than or equal to the mutual inductance setting threshold, it is determined that the current is within the chargeable area and meets the charging requirements, and the rectification network is controlled to output current, wherein the mutual inductance setting threshold is the minimum mutual inductance value within the chargeable area of ​​the system and is also the critical value of the chargeable area; when the mutual inductance detection value of the wireless charging system is less than the mutual inductance setting threshold, it is determined that the current position exceeds the chargeable area and does not meet the charging requirements, and the rectification network is controlled to be in a short-circuit state without current output.

4. The method for detecting charging range of a wireless charging system according to claim 1, characterized in that: After the wireless charging system issues a charging instruction, the mutual inductance detection value is detected. When the mutual inductance detection value is less than the mutual inductance setting threshold, the wireless charging system will repeat the detection. During this stage, the rectifier network is always in a short-circuit state. When the mutual inductance detection value is greater than or equal to the mutual inductance setting threshold, that is, when it reaches the chargeable area, the rectifier network is controlled to output current to charge the system load.

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