Wireless power transfer system with position detection functionality

Abstract

The application relates to the technical field of wireless power transmission, and particularly discloses a wireless power transmission system with a position detection function. In order to meet the alignment accuracy specified in the standard while reducing the complexity and cost of position detection, the secondary side compensation inductance and the receiving coil are integrated in the same magnetic core, so that the system power density and compactness are improved; by utilizing the monotonic change of mutual inductance between the integrated inductance and the transmitting coil when the position is offset, only the phase difference between the inverter output current and the driving voltage needs to be detected on the primary side, the offset position can be real-time backstepping, no additional sensors or switching devices are needed, and the hardware cost is significantly reduced. Meanwhile, by establishing an accurate time domain model analysis, the detection variable (the phase difference between the inverter output current and the driving voltage) and the phase difference acquisition approach are determined, and the phase difference detection accuracy is improved. The system meets the alignment accuracy requirement of wireless charging, is suitable for scenes such as electric vehicles and industrial robots, and realizes the low-cost and high-reliable alignment guiding function.

Description

Technical Field

[0001] This invention relates to the field of wireless power transmission technology, and more particularly to a wireless power transmission system with location detection function. Background Technology

[0002] Wireless Power Transfer (WPT) technology enables contactless power transfer through magnetic or electric field coupling. It offers significant advantages such as safety, reliability, no electrical wear, and adaptability to harsh environments, leading to widespread attention and application in consumer electronics, home appliances, industrial robots, medical devices, and electric vehicles. In a typical magnetically coupled WPT system, the relative position of the transmitting and receiving coils directly affects the coupling coefficient and mutual inductance, thus determining the system's transmission efficiency, output power, and stability. When the coils are misaligned, the mutual inductance decreases significantly, resulting in reduced efficiency, power drop, and in severe cases, even failure to supply power. Therefore, in many practical applications, accurately aligning the primary and secondary coils before charging or supplying power is a crucial prerequisite for ensuring the efficient and reliable operation of the WPT system.

[0003] Taking wireless charging for electric vehicles as an example, the SAE J2954 standard, as the most authoritative technical specification in this field, sets forth clear requirements for system interoperability and alignment accuracy, recommending methods such as magnetic triangulation and Received Signal Strength (RSS) for position detection and alignment guidance. However, these methods typically require additional detection coils or sensors, increasing the hardware cost and structural complexity of the system. Some literature proposes achieving lateral position detection through coil decoupling and topology switching, but this introduces additional switching devices, also leading to increased cost and reduced reliability. On the other hand, vehicles typically have mechanical limiters or parking blocks in the longitudinal (Y-direction), resulting in relatively small positioning errors; however, the alignment accuracy in the lateral (X-direction) direction mainly depends on driver operation or automatic parking systems, leading to greater uncertainty in offset. These problems are not limited to electric vehicles—in scenarios such as charging industrial mobile robots and wireless power supply tracks, there is a common need for efficiency reduction due to lateral offset and a lack of low-cost detection methods. Summary of the Invention

[0004] This invention provides a wireless power transmission system with position detection function, which solves the technical problem of how to reduce the complexity and cost of position detection while meeting the alignment accuracy specified by the standard.

[0005] To address the above technical problems, this invention provides a wireless power transmission system with location detection functionality. The coupling mechanism employed includes a transmitting mechanism and a receiving mechanism, wherein the transmitting mechanism is equipped with a transmitting coil. The receiving mechanism includes a hierarchically arranged integrated inductor. Receiver coil The integrated inductor The integrated inductor is the compensation inductor in the secondary-side compensation network. Using the receiving coil The transmitting coil when facing directly Decoupled coil structure.

[0006] Preferably, the system further includes a current sensor and a DSP controller, the DSP controller being used to extract the output current of the primary-side inverter. The phase difference between the phase difference and the driving voltage signal is used to determine the lateral offset position based on the calibrated relationship between the phase difference and the offset displacement.

[0007] Preferably, the DSP controller extracts the output current of the primary-side inverter. The specific process of the phase difference between the driving voltage signal and the driving voltage signal is as follows:

[0008] A dual-channel zero-crossing comparator is used to combine the drive voltage signal and the primary-side inverter output current. It is converted into a square wave signal synchronized with the zero-crossing point, and the rising edge of the square wave marks the zero-crossing time of the sine signal;

[0009] The two square waves are then input into an XOR gate, and the duration of the high-level output directly corresponds to the time interval between the two zero-crossing points. ;

[0010] Time interval Converted to phase difference.

[0011] Preferably, by The relationship will be the time interval Converted to phase difference , This represents the system's operating angular frequency.

[0012] Preferably, the transmitting coil and the receiving coil Rectangular coils are used in all cases.

[0013] Preferably, the integrated inductor A bipolar DD-type coil, decoupled from the rectangular coil, is used. The arrangement direction of the two D-type coils of the bipolar DD-type coil is consistent with the offset direction to be detected.

[0014] Preferably, the system includes a transmitter; the transmitter includes a DC power supply. High-frequency inverter, primary-side compensation network and the transmitting coil .

[0015] Preferably, the system includes a receiving end; the receiving end includes the receiving coil. Secondary-side compensation network, rectifier filter circuit and load resistor .

[0016] Preferably, both the primary-side compensation network and the secondary-side compensation network are LCC-type compensation networks.

[0017] Preferably, the primary-side inverter output current The time-domain expression is:

[0018] ,

[0019] in, The primary-side compensation inductor in the primary-side compensation network is... This is the inverter output voltage. For the receiving coil The current, The output current of the secondary-side compensation network is... For the integrated inductor With the transmitting coil Mutual intuition between them For the transmitting coil and the receiving coil Mutual intuition between them This refers to the period when the voltage is positive. This refers to the period when the voltage is negative. Indicates the start time of a cycle. This represents the zero-crossing point in a period. Indicates the end time of a cycle. , They represent and The phase.

[0020] The wireless power transmission system with position detection provided by this invention improves system power density and compactness by integrating the secondary-side compensation inductor and receiving coil into the same magnetic core. Utilizing the monotonic change in mutual inductance between the integrated inductor and transmitting coil during lateral offset, the offset position can be deduced in real time simply by detecting the phase difference between the inverter output current and drive voltage on the primary side, eliminating the need for additional sensors or switching devices and significantly reducing hardware costs. Simultaneously, by establishing a precise time-domain model analysis, the detection variable (the phase difference between the inverter output current and drive voltage) and the phase difference acquisition method are determined, improving phase difference detection accuracy. This system meets the alignment accuracy requirements of wireless charging and is suitable for scenarios such as electric vehicles and industrial robots, achieving low-cost, highly reliable alignment guidance. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the coupling mechanism structure of a wireless power transmission system with position detection function provided in an embodiment of the present invention;

[0022] Figure 2 This is a diagram showing the relative positions of the integrated inductor and the transmitting coil of a wireless power transmission system with position detection function provided in an embodiment of the present invention.

[0023] Figure 3 This is a circuit topology diagram of a wireless power transmission system with position detection function provided in an embodiment of the present invention;

[0024] Figure 4 This is an equivalent circuit diagram of a wireless power transmission system with position detection function provided in an embodiment of the present invention;

[0025] Figure 5 This is a simplified LCC model diagram of the harmonic components of a wireless power transmission system with position detection function provided in an embodiment of the present invention.

[0026] Figure 6 This is a graph showing the theoretical and measured values ​​of mutual inductance as a function of the X-axis in a wireless power transmission system with position detection provided in an embodiment of the present invention.

[0027] Figure 7 This is a diagram showing the correspondence between the position and phase difference of a wireless power transmission system with position detection function provided in an embodiment of the present invention. Detailed Implementation

[0028] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. The embodiments are given for illustrative purposes only and should not be construed as limiting the present invention. The accompanying drawings are for reference and illustration only and do not constitute a limitation on the scope of patent protection of the present invention, because many changes can be made to the present invention without departing from the spirit and scope of the present invention.

[0029] This invention provides a wireless power transmission system with location detection function, the coupling mechanism of which is as follows: Figure 1 As shown, it includes a transmitting mechanism and a receiving mechanism. The transmitting mechanism includes, from bottom to top, a primary magnetic shielding plate (aluminum plate), a primary magnetic core (made of ferrite material), and a transmitting coil. The receiving mechanism includes a hierarchical arrangement of integrated inductors. Receiver coil Secondary magnetic core (made of ferrite material) and secondary magnetic shielding plate (aluminum plate).

[0030] Among them, the transmitting coil and receiving coil Rectangular coils are used in all cases. Taking an electric vehicle as an example, the transmitting coil... and receiving coil The dimensions conform to SAE 2954 requirements. Integrated inductor. The compensation inductor in the secondary compensation network is a bipolar coil (DD-type coil) decoupled from the rectangular coil. The arrangement of the two D-type coils is consistent with the offset direction (X direction) to be detected. Integrated inductor and transmitting coil The relative positional relationship is as follows Figure 2 As shown.

[0031] Integrated Inductor The design improves the system's compactness and integrates inductors. It is a bipolar coil, and the receiving coil Always decoupled from the transmitting coil When facing the transmitting coil It also decouples. However, when a lateral (X-direction) offset occurs, the magnetic flux symmetry is broken, causing the integrated inductor to... With transmitting coil Mutual intuition between The mutual inductance is no longer zero, and it exhibits a monotonically changing characteristic with the offset. This provides a physical basis for extracting location information.

[0032] Furthermore, based on Figure 1 The coupling mechanism shown in this embodiment provides the circuit topology of a wireless power transmission system with forehead band position detection function as follows: Figure 3 As shown, it includes a transmitter and a receiver. The transmitter includes a DC power supply. (Current is expressed as) ), high-frequency inverter (composed of MOSFETs S1 to S4 connected together, the inverter output current is expressed as...) ), primary-side compensation network and transmitting coil (Its current is expressed as) The transmitter also includes control circuitry, comprising a current sensor, a DSP controller, and a PWM drive circuit. The current sensor is used to detect the inverter output current. The current is input to the DSP controller, which then extracts the inverter's output current. The DSP controller determines the lateral offset position based on the phase difference between the phase difference and the drive voltage signal, and the relationship between the calibrated phase difference and the offset displacement. The DSP controller is also used to control the PWM drive circuit to drive the high-frequency inverter.

[0033] The receiver includes a receiving coil. (Current is expressed as) ), secondary side compensation network (whose output current is expressed as ), rectifier and filter circuit (including a full-bridge rectifier consisting of diodes D1 to D4 connected together and filter capacitors) and load resistance (Its current is expressed as) Voltage is expressed as Transmitting coil and receiving coil The mutual induction between them is represented as .

[0034] In a preferred embodiment, both the primary-side compensation network and the secondary-side compensation network adopt LCC-type compensation networks, i.e., the system uses a dual-LCC topology. The primary-side compensation network includes a primary-side compensation inductor. Primary-side parallel compensation capacitor series compensation capacitor with primary side The secondary-side compensation network includes the secondary-side compensation inductor. (i.e., integrated inductor), secondary-side parallel compensation capacitor series compensation capacitor with primary side .

[0035] Due to the secondary compensation inductor With transmitting coil There is mutual inductance coupling. This allows the geometric position information of the secondary side to be mapped to the input impedance characteristics of the primary side in real time. When the receiver experiences a positional shift, the system's equivalent reflected impedance changes accordingly, leading to an increase in the inverter's output current. The phase difference between the driving voltage signal and the phase difference changes. By introducing a zero-crossing detection-based phase detection circuit on the primary side, the DSP controller can accurately extract the change characteristics of this phase difference, thereby achieving real-time estimation of the lateral offset position. Finally, the position feedback data is transmitted to the vehicle-mounted terminal using the system's inherent wireless communication link to guide the vehicle in position correction.

[0036] Figure 3 The equivalent circuit of the system shown is as follows Figure 4 As shown, where This is the system's AC input voltage (i.e., the inverter output voltage). This is the system's AC output voltage (i.e., the rectifier input voltage). This is an equivalent AC load.

[0037] The system's compensation network parameters satisfy the following resonance condition:

[0038] ,

[0039] in, This is the system's operating angular frequency.

[0040] System AC input voltage It can be represented as:

[0041] ,

[0042] in, This refers to the period when the voltage is positive. This refers to the period when the voltage is negative. Indicates the start time of a cycle. This represents the zero-crossing point in a period. It indicates the end time of a cycle.

[0043] According to KVL's law, the system can be expressed by the following equation:

[0044] ,

[0045] The current in each part can then be expressed as:

[0046] .

[0047] In actual operation, the square wave voltage output by the inverter contains abundant harmonic components, which can lead to current... The waveform is distorted near the zero-crossing point, introducing static detection error. To improve positioning accuracy, this invention establishes a precise time-domain model of the system. Precise correspondence helps improve the accuracy of position detection. Because... It contains a large number of harmonics, which can affect the zero-crossing time and thus the position determination. Therefore, further analysis is needed. The time-domain expression is obtained to get a more accurate zero-crossing point. Based on the above equation, , and The time-domain expression can be approximated as:

[0048] ,

[0049] in, , They represent and The phase.

[0050] Figure 5 The simplified LCC model of the harmonic components shown can be described by differential equations:

[0051] ,

[0052] in, Indicates capacitance The voltage.

[0053] After the system stabilizes, Because it has symmetry, we can obtain:

[0054] .

[0055] The time-domain expression is transformed into:

[0056] ,

[0057] in ( Moment )for:

[0058] .

[0059] Based on the previous analysis, it can be seen that the system only operates when... and When the two variables are offset in the X direction, their mutual inductance changes in a one-to-one correspondence.

[0060] The calculated zero-crossing points are determined by the same set of mutual inductances, forming a correspondence between position, mutual inductance, and the phase difference between the zero-crossing points. A dual-channel zero-crossing comparator is used to convert the drive voltage and inverter current signals into square wave signals synchronized with the zero-crossing points. The rising edge of the square wave precisely marks the zero-crossing moment of the sinusoidal signal. The two square waves are then input into an XOR gate, and the duration of the high-level output directly corresponds to the time interval between the two zero-crossing points. This can be converted into phase difference:

[0061] ,

[0062] Therefore, the offset position of the receiver can be deduced from the detected phase difference, thus realizing position detection.

[0063] In summary, the wireless power transmission system with position detection function provided in this embodiment of the invention improves the system's power density and compactness by integrating the secondary-side compensation inductor and the receiving coil into the same magnetic core. Utilizing the monotonic change in the mutual inductance between the integrated inductor and the transmitting coil during lateral offset, the offset position can be deduced in real time simply by detecting the phase difference between the inverter output current and the driving voltage on the primary side, eliminating the need for additional sensors or switching devices and significantly reducing hardware costs. Simultaneously, by establishing a precise time-domain model analysis, the detection variable (the phase difference between the inverter output current and the driving voltage) and the phase difference acquisition method are determined, improving the phase difference detection accuracy. This system meets the alignment accuracy requirements for wireless charging and is suitable for scenarios such as electric vehicles and industrial robots, achieving low-cost and highly reliable alignment guidance.

[0064] The effectiveness of the present invention will be verified by experiments below. An 11kW output power system was built for the experiment, and the system parameters are shown in Table 1.

[0065] Table 1 System Parameters

[0066]

[0067] When the X-axis shifts, mutual inductance and The theoretical value (sim) and the measured value (test) are as follows: Figure 6 As shown, each offset position has a different set of mutual inductance values. Substituting these values ​​into the position-mutual inductance-zero-crossing phase difference model, we can obtain the correspondence between position and phase difference, as follows: Figure 7 As shown. From Figure 7 As can be seen, the DSP controller can reverse-map the corresponding position by detecting the phase difference. Due to the large phase change amplitude, the system position detection can achieve high accuracy.

[0068] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A wireless power transmission system with position detection function, characterized in that: The coupling mechanism it employs includes a transmitting mechanism and a receiving mechanism, wherein the transmitting mechanism is equipped with a transmitting coil. The receiving mechanism includes a hierarchically arranged integrated inductor. Receiver coil The integrated inductor The integrated inductor is the compensation inductor in the secondary-side compensation network. Using the receiving coil The transmitting coil when facing directly Decoupled coil structure.

2. The wireless power transmission system with position detection function according to claim 1, characterized in that: The system also includes a current sensor and a DSP controller, the latter used to extract the output current of the primary-side inverter. The phase difference between the phase difference and the driving voltage signal is used to determine the lateral offset position based on the calibrated relationship between the phase difference and the offset displacement.

3. The wireless power transmission system with position detection function according to claim 2, characterized in that, The DSP controller extracts the output current from the primary-side inverter. The specific process of the phase difference between the driving voltage signal and the driving voltage signal is as follows: A dual-channel zero-crossing comparator is used to combine the drive voltage signal and the primary-side inverter output current. It is converted into a square wave signal synchronized with the zero-crossing point, and the rising edge of the square wave marks the zero-crossing time of the sine signal; The two square waves are then input into an XOR gate, and the duration of the high-level output directly corresponds to the time interval between the two zero-crossing points. ; Time interval Converted to phase difference.

4. The wireless power transmission system with position detection function according to claim 3, characterized in that, pass The relationship will be the time interval Converted to phase difference , This represents the system's operating angular frequency.

5. The wireless power transmission system with position detection function according to any one of claims 1 to 4, characterized in that: The transmitting coil and the receiving coil Rectangular coils are used in all cases.

6. The wireless power transmission system with position detection function according to claim 5, characterized in that: The integrated inductor A bipolar DD-type coil, decoupled from the rectangular coil, is used. The arrangement direction of the two D-type coils of the bipolar DD-type coil is consistent with the offset direction to be detected.

7. The wireless power transmission system with position detection function according to claim 6, characterized in that: The system includes a transmitter; the transmitter includes a DC power supply. High-frequency inverter, primary-side compensation network and the transmitting coil .

8. The wireless power transmission system with position detection function according to claim 7, characterized in that: The system includes a receiver; the receiver includes the receiving coil. Secondary-side compensation network, rectifier filter circuit and load resistor .

9. The wireless power transmission system with position detection function according to claim 8, characterized in that: Both the primary-side compensation network and the secondary-side compensation network adopt LCC-type compensation networks.

10. The wireless power transmission system with position detection function according to claim 9, characterized in that, Primary inverter output current The time-domain expression is: ， in, The primary-side compensation inductor in the primary-side compensation network is... This is the inverter output voltage. For the receiving coil The current, The output current of the secondary-side compensation network is... For the integrated inductor With the transmitting coil Mutual intuition between them For the transmitting coil and the receiving coil Mutual intuition between them This refers to the period when the voltage is positive. This refers to the period when the voltage is negative. Indicates the start time of a cycle. This represents the zero-crossing point in a period. Indicates the end time of a cycle. , They represent and The phase.

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