Systems and methods for object detection

Abstract

A system and method for object detection are provided. The system includes at least one coil, a small signal generator, a small signal receiver, and a processor. The small signal generator includes a digital-to-analog converter circuit with programmable impedance. The small signal generator is configured to: select an output impedance for the digital-to-analog converter circuit for capacitive sensing or RFID tag detection; generate a small signal based on the output impedance; and provide the small signal to the coil. The small signal receiver receives the small signal and a response signal associated with the small signal and measures the response signal to generate a measured signal. The processor compares the measured signal with one or more reference signals and performs capacitive sensing and / or RFID tag detection based on the comparison.

Description

[0001] Information about divisional applications

[0002] This application is a divisional application. The parent application is an invention patent application filed on March 25, 2019, with application number 201910226454.3 and the title of invention being “System and Method for Object Detection.”

[0003] CROSS-REFERENCE TO RELATED APPLICATIONS

[0004] This application claims the benefit of and priority to U.S. Provisional Application No. 62 / 659,020, filed April 17, 2018, which is incorporated herein by reference in its entirety. Technical Field

[0005] The present invention generally relates to systems and methods for object detection, including but not limited to systems and methods for object detection for wireless power transmitter and receiver units. Background Art

[0006] The wireless charging system includes a wireless power transmitter unit and one or more wireless power receiver units. When a wireless power receiver unit is in proximity to the wireless power transmitter unit, the wireless transmitter unit determines whether to transmit power to the wireless power receiver unit without user interaction.

[0007] Before power transfer begins, the wireless power transmitter unit discovers the wireless power receiver unit without waking up the wireless power receiver unit or initiating digital communication with the wireless power receiver unit. The wireless power transmitter unit uses a power inverter circuit to perform several acoustic pulse signals to excite the coil of the wireless charging system and measures the response from the coil and determines whether the power receiver unit is present in the field based on the measured values.

[0008] Additionally, if a foreign object (e.g., metal, RFID tag) is present in the field, the power transmitter unit can potentially increase the temperature of the foreign object placed in the field. The power transmitter unit needs to respond to the detection result (i.e., terminate power transfer if a foreign object is detected) to avoid overheating the foreign object. Summary of the Invention

[0009] In one aspect, the present application provides a wireless power transmitter device comprising: at least one coil; a small signal generator comprising a digital-to-analog converter circuit having a programmable impedance, wherein the small signal generator is configured to: select an output impedance for the digital-to-analog circuit for capacitive sensing or radio frequency identification (RFID) tag detection; generate a small signal based on the output impedance; and provide the small signal to the coil; and a small signal receiver configured to: receive the small signal and a response signal associated with the small signal; measure the response signal to generate a measured signal; and a processor configured to: compare the measured signal with one or more reference signals; and perform capacitive sensing and / or detect the RFID tag based on the comparison.

[0010] In another aspect, the present application provides a wireless power transmitter device comprising: a first coil configured for power transmission and low-frequency noise measurement; a second coil configured for high-frequency noise measurement; a small signal receiver configured to: select one of the first coil or the second coil according to a frequency range for noise measurement; receive a noise signal at the selected coil; and provide a noise distribution of the noise signal, the noise distribution comprising a spectral distribution.

[0011] In another aspect, the present application provides a method for performing wireless power receiver detection and alignment, comprising: selecting an impedance for a digital-to-analog circuit for wireless power receiver detection and alignment, a small signal generator comprising a digital-to-analog converter circuit having a programmable impedance; providing a small signal to a coil of a wireless power transmitter device through the small signal generator; receiving the small signal and a response signal associated with the small signal; comparing the response signal with one or more reference signals; and performing wireless power receiver detection and alignment based on the comparison. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Various objects, aspects, features and advantages of the present invention will become more apparent and better understood by referring to the detailed description taken in conjunction with the accompanying drawings, in which like reference numerals identify corresponding elements throughout. In the drawings, like reference numerals generally indicate identical, functionally similar and / or structurally similar elements.

[0013] Figure 1 is an overall schematic block diagram of a power transmitter unit including an object detection system according to some embodiments;

[0014] Figure 2 According to some embodiments, Figure 1 An overall schematic block diagram of a dual coil circuit of an object detection system as described in ; and

[0015] Figure 3 is a flow diagram of operations for providing object detection in accordance with some embodiments.

[0016] The details of various embodiments of the methods and systems are set forth in the accompanying drawings and the description below. DETAILED DESCRIPTION

[0017] Before turning to a detailed description of the features of the exemplary embodiments, it should be understood that the present application is not limited to the details or methods set forth in the description or illustrated in the drawings. It should also be understood that the terminology is for descriptive purposes only and should not be regarded as limiting.

[0018] Referring generally to the drawings, systems and methods for providing object detection are shown in accordance with various exemplary embodiments.

[0019] According to some embodiments, the systems and methods allow for a much wider swept frequency range (i.e., from 10 KHz to 100 MHz) than the swept frequency range of conventional object detection systems (i.e., 100 kHz to 500 KHz) to improve detection sensitivity and enable detection of high resonant frequency foreign objects (e.g., RFID tags).

[0020] According to some embodiments, the systems and methods incorporate capacitive detection (eg, human body) and high resonant frequency foreign object detection not possible with conventional object detection systems.

[0021] According to some embodiments, the systems and methods can measure background noise spectra (ie, noise spectra from several kilohertz to several megahertz), which is not possible with conventional object detection systems.

[0022] According to some embodiments, systems and methods excite coils with low power, low distortion sine waves, minimizing harmonics of the excitation signal to improve measurement sensitivity. In some embodiments, harmonics of the excitation square wave associated with conventional systems degrade measurement accuracy.

[0023] Because the system and method do not require activation of a transmitter power inverter (which has low output impedance and consumes a large amount of quiescent power) to energize the coil and do not require a boost converter (which consumes a large amount of quiescent current and requires a long wake-up time) to provide power to the circuit, the system and method achieve much lower power consumption and much shorter detection time than conventional methods.

[0024] According to some embodiments, the impedance of the excitation coil of the system and method is different depending on the presence of different types of foreign objects in the field. According to some embodiments, when the source impedance of the excitation signal is significantly greater or less than the impedance of the excitation coil, the amplitude of the response signal (e.g., the received signal) may be too small, which is difficult to measure. According to some embodiments, the system and method can control the source impedance of the excitation signal to match the impedance of the system's excitation coil for different detection operations to improve detection sensitivity.

[0025] According to some embodiments, systems and methods can control the excitation amplitude to avoid turning on the diode of an external object (e.g., a wireless power receiver unit or a foreign object) to improve measurement accuracy. The power generated by the transmitter power inverter unit associated with object detection operations of conventional systems can easily turn on the diode of the external wireless power receiver due to its uncontrollable output impedance, which reduces measurement accuracy.

[0026] In some embodiments, the systems and methods include one or more circuits configured to excite the primary or secondary coil of a power transmitter unit with a small programmable signal. According to some embodiments, the small programmable signal enables the system to be a linear system. The systems and methods use a low-power excitation signal to reduce power consumption and improve measurement accuracy and speed.

[0027] In some embodiments, the systems and methods may be employed to perform one or more of the following detection operations:

[0028] 1) Detecting a "friend" wireless power receiver unit with or without waking it up and performing digital communication;

[0029] 2) Perform alignment tests for power transmitter and receiver units to improve power transfer efficiency;

[0030] 3) Detection of foreign objects (e.g., metal) to improve power transfer efficiency and avoid temperature rise;

[0031] 4) Detect low-power rated foreign objects (i.e., RFID tags) before power is transferred to avoid damaging the low-power rated foreign objects;

[0032] 5) Detecting human touch for safety reasons;

[0033] 6) performing built-in self-test to reduce test time and test costs (e.g., one or more circuits may test whether the primary coil is properly connected and whether the components of the primary coil have the correct values); or

[0034] 7) Measure the background noise spectrum of the system (for example, noise analysis can be used for system diagnostics and other high-precision circuit operating frequency selection).

[0035] Some embodiments relate to a system for detecting an object. The system includes a first coil, a second coil, and one or more circuits. The one or more circuits are configured to: receive a command for a detection operation to be performed; select an output impedance of a signal generator based at least in part on the operation to be performed; select one of the first coil or the second coil; transmit a small signal to the selected coil; generate a small signal at one or more frequencies; receive and measure a response signal at one or more signal frequencies; determine the coil impedance at one or more frequencies, or determine the background noise of the system at one or more frequencies, or determine the capacitance of the coil; compare these values ​​(i.e., coil impedance, noise spectrum, coil capacitance) with reference values ​​stored in a database; determine whether a target receiver unit or a foreign object is present in the field; determine the type of object present in the field; measure the coupling coefficient (distance) between the coil and the object based on real-time measured values; determine whether human tissue is touching the coil; determine the distance between the human and the unit based on the measured capacitance; and determine whether the coil is properly connected to the system.

[0036] Some embodiments relate to a device for detecting an object. The device includes a first coil, a second coil, and one or more circuits. The one or more circuits are configured to: receive a command for a detection operation to be performed; select an output impedance of a signal generator based at least in part on the operation to be performed; select one of the first coil or the second coil; transmit a small signal to the selected coil; generate a small signal at one or more frequencies; receive and measure a response signal at one or more signal frequencies; determine the coil impedance at one or more frequencies, or determine the background noise of the system at one or more frequencies, or determine the capacitance of the coil; compare these values ​​(i.e., coil impedance, noise spectrum, coil capacitance) with reference values ​​stored in a database; determine whether a target receiver unit or a foreign object is present in the field; determine the type of object present in the field; measure the coupling coefficient (distance) between the coil and the object based on real-time measured values; determine whether human tissue is touching the coil; determine the distance between the human and the unit based on the measured capacitance; and determine whether the coil is properly connected to the device.

[0037] Some embodiments relate to a wireless power transmitter unit for detecting an object. The wireless power transmitter unit includes a first coil, a second coil, and one or more circuits. The one or more circuits are configured to: receive a command for a detection operation to be performed; select an output impedance of a signal generator based at least in part on the operation to be performed; select one of the first coil or the second coil; transmit a small signal to the selected coil; generate a small signal at one or more frequencies; receive and measure a response signal at one or more signal frequencies; determine the coil impedance at one or more frequencies, or determine the background noise of the system at one or more frequencies, or determine the capacitance of the coil; compare these values ​​(i.e., coil impedance, noise spectrum, coil capacitance) with reference values ​​stored in a database; determine whether a target receiver unit or a foreign object is present in the field; determine the type of object present in the field; measure the coupling coefficient (distance) between the coil and the object based on real-time measured values; determine whether human tissue is touching the coil; determine the distance between the human and the unit based on the measured capacitance; and determine whether the coil is properly connected to the wireless power transmitter unit.

[0038] Some embodiments relate to a method for detecting an object. The method includes a first coil, a second coil, and one or more circuits. The one or more circuits are configured to: receive a command for a detection operation to be performed; select an output impedance of a signal generator based at least in part on the operation to be performed; select one of the first coil or the second coil; transmit a small signal to the selected coil; generate a small signal at one or more frequencies; receive and measure a response signal at one or more signal frequencies; determine the coil impedance at one or more frequencies, or determine the background noise of the system at one or more frequencies, or determine the capacitance of the coil; compare these values ​​(i.e., coil impedance, noise spectrum, coil capacitance) with reference values ​​stored in a database; determine whether a target receiver unit or a foreign object is present in the field; determine the type of object present in the field; measure the coupling coefficient (distance) between the coil and the object based on real-time measured values; determine whether human tissue is touching the coil; determine the distance between the human and the unit based on the measured capacitance; and determine whether the coil is properly connected.

[0039] refer to Figure 1 According to some embodiments, the wireless power transmitter unit 90 includes a power inverter 92, a processor 101, and an object detection system 100. According to some embodiments, the power inverter 92 is used to generate AC power by alternating its output between ground and power. The AC power is transmitted to the power receiver unit via the primary coil 102. According to some embodiments, the wireless power transmitter unit 90 may be a smartphone, tablet computer, laptop computer, or wireless charging base station. The processor 101 is used to control the power inverter 92, the object detection system 100, and other analog or digital components in the wireless power transmission unit 90.

[0040] According to some embodiments, object detection system 100 performs object detection for wireless power transmitter unit 90. In some embodiments, object detection system 100 includes primary coil 102, secondary coil 118, small signal generator 108, digital synthesizer 116, and small signal receiver 134. In some embodiments, processor 101, small signal generator 108, digital synthesizer 116, and small signal receiver 134 can be implemented in hardware, software, firmware, or a combination of hardware, software, and firmware. In some embodiments, object detection system 100 can also be used as a standalone device without the main power inverter unit 92 or other components associated with power transmitter device 90.

[0041] In some embodiments, processor 101 controls object detection system 100 via a firmware program. In some embodiments, processor 101 receives instructions from a user interface or an application associated with wireless power receiver unit 90. In some embodiments, processor 101 includes a list of object types for object detection system 100 to detect from which objects can be selected. In some embodiments, processor 101 can be part of or integrated with wireless power transmitter unit 90.

[0042] In some embodiments, the digital synthesizer 116 receives signals from the processor 101 indicating one or more operations to be performed by the object detection system 100, such as detecting one or more types of objects, performing a built-in self-test, detecting human touch, and measuring the system's background noise spectrum. In some embodiments, the digital synthesizer 116 is programmed to generate a control signal (e.g., a digital code) for the small signal generator 108, causing the small signal generator 108 to generate a small signal (e.g., a sine wave with a small amplitude) at a desired frequency. In some embodiments, the digital synthesizer 116 generates the control signal based at least in part on the type of object to be detected or the detection operation to be performed. In some embodiments, the digital synthesizer 116 transmits the control signal to the positive resistive digital-to-analog converter (RDACP) 112 and the negative resistive digital-to-analog converter (RDACN) 114 of the small signal generator 108. In some embodiments, the digital synthesizer 116 generates the control signal to select a frequency within a frequency range of 10 kHz to 100 MHz with a 10 kHz resolution. In some embodiments, the signal frequency and other parameters associated with the signallet are selected based on the application or detection operation of the object detection system 100 (eg, the type of object to be detected).

[0043] In some embodiments, the small signal generator 108 includes an RDACP 112, an RDACN 114, high-voltage switches S1, S2, S3, S4, and an optional overvoltage (OV) protection circuit 115. In some embodiments, the small signal generator 108 provides a low-power sinusoidal signal to the coils 102 and / or 104 via switches S1-4 for object detection. In some embodiments, the RDACP 112 and RDACN 114 are RDACs with programmable output impedance. In some embodiments, the RDACP 112 and RDACN 114 can be programmed to a desired output impedance (e.g., 10Ω-100KΩ).

[0044] According to some embodiments, the OV protection circuit 115 is optional. When one or more of the switches S1, S2, S3, and S4 are connected to the coils 102 and / or 104 (e.g., the switches are turned on), the OV protection circuit 115 is used to protect the RDACP 112 and RDACN 114 from overvoltage damage. According to some embodiments, a high voltage signal (e.g., a signal having a voltage exceeding the rated voltage of the RDACN 114 or RDACP 112) can be generated by the power inverter 92 or received from the primary coil 102 or the secondary coil 104. In some embodiments, the OV protection circuit 115 uses an input / output (IO) device (e.g., a device having a 12V rated voltage) to clamp the output to approximately 1V.

[0045] In some embodiments, RDACP 112 and RDACN 114 receive control signals from processor 101 to set a desired output impedance for small signal generator 108. In some embodiments, the output impedance of RDACP 112 and RDACN 114 is selected based on the detection operation to be performed.

[0046] In some embodiments, RDACP 112 and RDACN 114 are programmed with the same impedance. In some embodiments, RDACP 112 and RDACN 114 are programmed with different impedances. In some embodiments, RDACP 112 is an RDAC with a positive output. In some embodiments, RDACN 114 is an RDAC with a negative output. In some embodiments, RDACN 114 and RDACP 112 generate differential signals, common-mode signals, and single-ended signals. In some embodiments, RDACN 114 and RDACP 112 can generate a differential signal comprising two signals with opposite phases (e.g., a 180-degree phase difference). In some embodiments, RDACN 114 and RDACP 112 can generate a common-mode signal comprising two signals with the same phase (e.g., a 0-degree phase difference). In some embodiments, RDACN 114 and RDACP 112 can generate any other type of signal comprising two signals with a programmable phase difference (e.g., a 0-180-degree phase difference). In some embodiments, object detection system 100 can generate a single-ended signal using either RDACN 114 or RDACP 112. In some embodiments, when RDACN 114 is used to generate a single-ended signal, RDACP 112 is grounded or floating. Similarly, when RDACP 112 is used to generate a single-ended signal, RDACN 114 is grounded or floating.

[0047] In some embodiments, primary coil 102 is a larger coil than secondary coil 118. In some embodiments, primary coil 102 is configured to transmit power (e.g., a square wave signal with a source impedance less than 1 generated by inverter 92) and an object detection test signal (e.g., a small signal generated by small signal generator 108). In some embodiments, the self-resonant frequency of secondary coil 118 is higher than the self-resonant frequency of primary coil 102. In some embodiments, secondary coil 118 is optional for object detection system 100. In some embodiments, secondary coil 118 is a small coil and is configured to transmit the object detection test signal and not the power signal. In some embodiments, small signal generator 108 provides a small signal to primary coil 102 at a low frequency (e.g., 10 kHz-10 MHz) for low-frequency object detection. In some embodiments, small signal generator 108 provides a small signal to secondary coil 118 at a high frequency (e.g., 1 MHz-100 MHz) for high-frequency object detection.

[0048] Switches S1-S4 are controlled to select one of the primary coil 102 and the secondary coil 118 for receiving a small signal from the small signal generator 108. In some embodiments, the primary coil 102 is connected to the RDACP 112 via the chip pin 104 (e.g., pin AC1) and the switch S1. In some embodiments, the primary coil 102 is connected to the RDACN 114 via the chip pin 106 (e.g., pin AC2) and the switch S3. In some embodiments, when switches S1 and S3 are connected (e.g., turned on), the primary coil 102 receives a small signal from the small signal generator 108 for object detection. In some embodiments, when switches S1 and S3 are disconnected (e.g., closed), the primary coil 102 is disconnected from the small signal generator 108 and is not used for object detection.

[0049] In some embodiments, secondary coil 118 is connected to RDACP 112 via chip pin 120 (e.g., pin HF_DET1) and switch S2. In some embodiments, secondary coil 108 is connected to RDACN 114 via chip pin 122 (e.g., pin HF_DET2) and switch S4. In some embodiments, when switches S2 and S4 are connected (e.g., turned on), secondary coil 118 receives a small signal from small signal generator 108 and is used to detect an object. In some embodiments, when switches S2 and S4 are disconnected (e.g., closed), secondary coil 118 is disconnected from small signal generator 108 and is not used to detect an object.

[0050] Small signal receiver 134 includes spectrum analyzer 124, differential amplifier 130, multiplexer 132, peak detector 136, digital-to-analog converter (ADC) 138, optional overvoltage protection circuit 140, and switches S5, S6, S7, S8, S9, and S10. In some embodiments, small signal receiver 134 receives a response signal from primary coil 102 or secondary coil 118, and a small signal from small signal generator 108. In some embodiments, spectrum analyzer 124 measures the response signal and generates a first measured signal 150. In some embodiments, differential amplifier 130 measures the response signal and generates a second measured signal 151. In some embodiments, the peak signal of first measured signal 150 and / or second measured signal 151 is determined by peak detector 136 and output to ADC 138. In some embodiments, peak signal 152 is digitized by ADC 138. In some embodiments, the output digital data of ADC 138 is transmitted to digital processor 101. The digital processor 101 compares the received digital data 153 with one or more detection references stored in its database detection system and determines whether a foreign object or a target power receiver unit is present in the field. Based on the comparison, the digital processor 101 determines the coupling coefficient between the object and the wireless power transmitter unit 90. In some embodiments, the detection references can be determined based on one or more laboratory tests and / or production tests. In some embodiments, each of the one or more reference signals is associated with an object. In some embodiments, switches S5, S6, S7, and S8 are used to connect the primary coil 102 and the secondary coil 118 to the small signal receiver 134.

[0051] In some embodiments, an optional OV protection circuit 140 is used to protect spectrum analyzer 124 and differential amplifier 130 from overvoltage damage when one or more of high-voltage switches S5, S6, S7, and S8 are connected to primary coil 102 or secondary coil 118 (e.g., turned on). According to some embodiments, a high-voltage signal (e.g., a signal having a voltage exceeding the rated voltage of spectrum analyzer 124 or differential amplifier 130) can be generated by power inverter 92 or received from the primary coil or secondary coil. In some embodiments, OV protection circuit 140 uses an IO device (12-V rated voltage) to fix the output close to 1V.

[0052] In some embodiments, switches S9 and S10 are optional and are used to perform self-calibration before measurement. In some embodiments, switches S9 and S10 are connected between the small signal generator 108 and the small signal receiver 134. In some embodiments, switch S9 is connected between RDACP 112 and the positive input 142 of the spectrum analyzer 124 and the differential amplifier 130. In some embodiments, switch S10 is connected between RDACN 114 and the negative input 144 of the spectrum analyzer 124 and the differential amplifier 130. In some embodiments, the small signal generator 108 generates a small signal and transmits the small signal to the small signal receiver 134 for calibration before measurement. Through such calibration, some non-idealities during circuit manufacturing, such as offset, mismatch, and circuit nonlinearity, can be eliminated.

[0053] In some embodiments, the primary coil 102 is connected to the small signal receiver 134 via switches S5 and S7. In some embodiments, the secondary coil 118 is connected to the small signal receiver 134 via switches S6 and S8. In some embodiments, only one of the primary coil 102 or the secondary coil 118 is used for object detection. In some embodiments, the selection of the primary coil 102 or the secondary coil 118 is based on the object type of the object being detected by the system. For example, according to some embodiments, for metal and wireless power receiver (WPC) receiver detection, the system 100 (via the processor 101) enables the primary coil 102 by opening switches S1, S3, S5, and S7 and closing switches S2, S4, S6, and S8. For example, according to some embodiments, for high resonant frequency object detection, the system 100 (via the processor 101) enables the secondary coil 118 by closing switches S1, S3, S5, and S7 and opening switches S2, S4, S6, and S8. For example, according to some embodiments, for background noise measurement, system 100 (via processor 101 ) may use primary coil 102 (eg, for measuring low frequency noise) or secondary coil 118 (eg, for measuring high frequency noise).

[0054] In some embodiments, when primary coil 102 is used for detection, at least one of switches S1 and S5 or switches S3 and S7 is connected. Similarly, according to some embodiments, when secondary coil 118 is used for detection, at least one of switches S2 and S6 or switches S4 and S8 is connected. In some embodiments, according to some embodiments, only one of primary coil 102 or secondary coil 118 is connected to both small signal generator 108 and small signal receiver 134 for detection.

[0055] In some embodiments, spectrum analyzer 124 provides a first measured signal 150 to multiplexer 132. According to some embodiments, spectrum analyzer 124 can be configured to operate in differential mode or single-ended mode. According to some embodiments, for differential mode, the amplitude of first measured signal 150 is equal to the amplitude of the voltage difference between positive input 142 and negative input 144 at a desired frequency. According to some embodiments, for single-ended mode, the amplitude of first measured signal 150 is equal to the amplitude of the voltage difference between one of the inputs (one of 142 and 144) and common-mode voltage VCM at a desired frequency. In some embodiments, spectrum analyzer 124 measures the signal spectrum of the response signal from primary coil 102 or secondary coil 118. In some embodiments, spectrum analyzer 124 includes mixer 126 and bandpass filter 128. In some embodiments, spectrum analyzer 124 is configured to measure the signal amplitude of the response signal at one or more desired frequencies. According to some embodiments, the desired frequency is controlled by the frequencies of switches CK2 and CK2B, which are generated by digital frequency synthesizer 116. In some embodiments, narrowband filter 128 is configured to filter out undesired frequency components from the mixed signal.

[0056] In some embodiments, differential amplifier 130 provides a second measured signal 151 to multiplexer 132. According to some embodiments, differential amplifier 130 can be configured in differential mode or single-ended mode. According to some embodiments, in differential input mode, differential amplifier 130 amplifies the differential voltage from primary coil 102 or secondary coil 118 and outputs second measured voltage 151 to multiplexer 134. According to some embodiments, in single-ended mode, differential amplifier 130 amplifies the difference between the single-ended voltage and the common-mode voltage from primary coil 102 or secondary coil 118 and outputs second measured voltage 151 to multiplexer 134. In some embodiments, differential amplifier 130 provides built-in low-pass / high-pass, band-pass, and all-pass functions.

[0057] In some embodiments, second measured signal 151 is noisier than first measured signal 150 because mixer 126 selects desired frequency components of the input signal (e.g., signal inputs at 142 and 144) and narrowband filter 128 rejects undesired frequency components of the input signal. In some embodiments, spectrum analyzer 124 is slower in providing a measured signal than differential amplifier 130 due to the increased complexity of signal processing (e.g., noise filtering operations).

[0058] In some embodiments, multiplexer 132 is configured to select one of first measured signal 150 provided by spectrum analyzer 124 or second measured signal 151 provided by differential amplifier 130. In some embodiments, multiplexer 132 selects the measured signal based on the detection operation (e.g., the type of object to be detected) and the environment of object detection system 100 (e.g., if the environment is noisy, spectrum analyzer output 150 is selected). In some embodiments, multiplexer 132 outputs the selected measured signal to peak detector 136.

[0059] In some embodiments, peak detector 136 determines the voltage envelope (e.g., amplitude) of the selected measured signal from multiplexer 132. In some embodiments, peak detector 136 has a variety of programmable attenuation frequencies ranging from 10 Hz to 100 kHz. In some embodiments, the attenuation frequency can also be selected as the automatic tracking frequency of small signal generator 108. In some embodiments, the attenuation frequency is controlled by signals at switches CK1 and CK1b, which are generated by digital synthesizer 124. According to some embodiments, a higher attenuation frequency results in faster measurement speed, while a lower attenuation frequency results in better measurement accuracy. According to some embodiments, an optimized attenuation bandwidth can be selected through a programmable attenuation bandwidth or automatic tracking function embedded in peak detector 136. According to some embodiments, the optimized attenuation bandwidth is determined by the frequency of the small signal selected to excite primary coil 102 or secondary coil 118. According to some embodiments, the use of peak detector 136 significantly relaxes the sampling speed of ADC 138, which significantly reduces power consumption.

[0060] According to some embodiments, by stimulating at one or more frequencies and measuring the response, the object detection system 100 can measure the impedance, capacitance, and background noise of the primary coil 102 or the secondary coil 118. According to some embodiments, the impedance of the primary coil 102 or the secondary coil 118 is associated with the type of object to be detected and the coupling coefficient (distance) between the wireless power transmitter unit 90 and the object to be detected. According to some embodiments, the capacitance of the primary coil 102 or the secondary coil 118 is associated with the human touch of the wireless power transmitter unit 90 and the distance between the human and the wireless power transmitter unit 90. According to some embodiments, the background noise is associated with the operating environment of the object detection system 100, for example, the operation of adjacent circuits and systems.

[0061] In some embodiments, the object detection system 100 can be configured for capacitive sensing. When the object detection system 100 is used for capacitive sensing, the digital frequency synthesizer 116 controls the small signal generator 108 to generate a single-ended sine wave signal at a desired frequency (e.g., 10 MHz). In some embodiments, the RDACP 112 or RDACN 114 is programmed with an output impedance of 1 kΩ. In some embodiments, switches S2 and S6 are connected, and switches S1, S3, S4, S5, S7, S8, S9, and S10 are disconnected. In some embodiments, the secondary coil 118 is used for object detection. In some embodiments, the small signal receiver 134 receives the single-ended signal and transmits the measured data 153 to the processor 101. In some embodiments, the processor 101 determines the measured capacitance value or a sudden change in the measured capacitance value based on the real-time measured data 153. In some embodiments, the measured capacitance or the change in the measured capacitance is compared with a reference value to detect a human hand touch and determine the distance between the human hand and the wireless power transmitter unit 90. In some embodiments, the reference capacitance value is associated with one or more laboratory measurements or factory calibrations.

[0062] In some embodiments, the object detection system 100 can be configured for metal detection. In some embodiments, when the object detection system 100 is used for metal detection, the digital frequency synthesizer 116 controls the small signal generator 108 to generate a differential sine wave signal at a desired frequency. In some embodiments, RDACP 112 and RDACN 114 are programmed with an output impedance of 1 kΩ. In some embodiments, switches S1, S3, S5, and S7 are connected, and switches S2, S4, S6, S8, S9, and S10 are disconnected. In some embodiments, the primary coil 102 is used for metal detection. In some embodiments, the small signal receiver 134 receives the differential signal from the primary coil 102 and transmits measured data 153 to the processor 101. In some embodiments, the excitation and measurement described above are repeated at one or more frequencies of the sine wave generated by the small signal generator 108. In some embodiments, the frequency of the sine wave ranges from 10 kHz to 2 MHz, with 10 kHz frequency steps (e.g., 10 kHz, 20 kHz, 1.9 MHz, 2 MHz). In some embodiments, the processor 101 determines the measured impedance of the primary coil 102 relative to frequency (e.g., a frequency response). In some embodiments, the measured frequency response is compared to a reference frequency response to determine whether an object (e.g., a key, a coin, etc.) is present in the field. In some embodiments, the reference frequency response is associated with one or more laboratory measurements or a factory calibration.

[0063] In some embodiments, the object detection system 100 can be configured for power receiver detection and alignment testing. In some embodiments, when the object detection system 100 is used for power receiver detection, the digital frequency synthesizer 116 controls the small signal generator 108 to generate a differential sine wave signal at the desired frequency. In some embodiments, RDACP 112 and RDACN 114 are programmed with an output impedance of 50Ω. In some embodiments, switches S1, S3, S5, and S7 are connected, and switches S2, S4, S6, S8, S9, and S10 are disconnected. In some embodiments, the primary coil 102 is used for power receiver detection and alignment testing. In some embodiments, the small signal receiver 134 receives the differential signal from the primary coil 102 and transmits the measured data to the processor 101. In some embodiments, the above-described excitation and measurement are repeated at one or more frequencies of the sine wave generated by the small signal generator 108. In some embodiments, the frequency sweep range of the sine wave is from 10 kHz to 2 MHz with a frequency step of 10 kHz (e.g., 10 kHz, 20 kHz, . . . 1.9 MHz, 2 MHz). In some embodiments, processor 101 determines the measured impedance of the coil relative to the frequency (e.g., frequency response). In some embodiments, the measured frequency response is compared to a reference frequency response to determine whether a WPC receiver is present in the field and the coupling coefficient (e.g., alignment coefficient) between the power beaming unit and the receiver. In some embodiments, the reference frequency response is associated with one or more laboratory measurements or factory calibrations.

[0064] In some embodiments, the object detection system 100 can be configured for built-in self-test (BIST). In some embodiments, when the object detection system 100 is configured for built-in self-test (BIST), the digital frequency synthesizer 116 controls the small signal generator 108 to generate a differential sine wave signal at a desired frequency. In some embodiments, RDACP 112 and RDACN 114 are programmed with a 50Ω output impedance. In some embodiments, switches S1, S3, S5, and S7 are connected, and switches S2, S4, S6, S8, S9, and S10 are disconnected. In some embodiments, the impedance of the primary coil 102 is measured. In some embodiments, the small signal receiver 134 receives the differential signal from the primary coil 102 and transmits the measured data to the processor 101. In some embodiments, the above-described excitation and measurement are repeated at one or more frequencies of the sine wave generated by the small signal generator 108. In some embodiments, the frequency of the sine wave ranges from 10 kHz to 2 MHz, with 10 kHz frequency steps (e.g., 10 kHz, 20 kHz, 1.9 MHz, 2 MHz). In some embodiments, the processor 101 determines the measured impedance of the primary coil 102 relative to frequency (e.g., a frequency response). In some embodiments, the measured frequency response is compared to a reference frequency response to determine whether the primary coil 102 is properly connected. In some embodiments, the reference frequency response is associated with the values ​​of the components used in the coil.

[0065] In some embodiments, the object detection system 100 can be configured for noise spectrum measurement. In some embodiments, when the object detection system 100 is used for noise spectrum measurement, the small signal generator 108 is turned off by opening switches S1, S2, S3, S4, S9, and S10. In some embodiments, when the object detection system 100 uses the primary coil 102 to measure noise, switches S5 and S7 are connected, and switches S1, S2, S3, S4, S6, S8, S9, and S10 are disconnected. In some embodiments, when the object detection system 100 uses the primary coil 118 to measure noise, switches S6 and S8 are connected, and switches S1, S2, S3, S4, S5, S7, S9, and S10 are disconnected. In some embodiments, a spectrum analyzer 124 can be used to analyze the noise signal. Noise measurements can be used for system diagnostics.

[0066] In some embodiments, object detection system 100 can be configured for self-calibration and reference measurement. In some embodiments, when object detection system 100 is used for self-calibration and reference measurement, switches S9 and S10 are connected, and switches S1, S2, S3, S4, S5, S6, S7, and S8 are disconnected. In some embodiments, small signal generator 108 generates a small signal and transmits the small signal to small signal receiver 134 via connections S9 and S10. In some embodiments, object detection system 100 performs reference measurement / self-calibration before actual measurement, so that offset and gain errors due to IC process variations can be extracted and removed.

[0067] refer to Figure 2 , according to some embodiments, a dual coil circuit 200 for use in object detection system 100 is shown. According to some embodiments, dual coil circuit 200 is used to detect foreign objects 206. According to some embodiments, dual coil circuit 200 includes a first coil 202 and a second coil 204. In some embodiments, first coil 202 (e.g., a 1uH coil) is smaller than second coil 204 (e.g., a 10uH coil). In some embodiments, first coil 202 and second coil 204 are connected in parallel. In some embodiments, first coil 202 is used to generate a high-frequency signal to detect foreign objects 206. In some embodiments, second coil 204 is used to generate a low-frequency signal to detect foreign objects 206. In some embodiments, second coil 204 is also used to transmit wireless power to a wireless receiver. In some embodiments, dual coil circuit 200 is connected to chip pins 104 and 106 of wireless transmitter unit 90, and chip pins 120 and 122 are not used. According to some embodiments, the dual coil configuration reduces the number of chip pins used in wireless transmitter unit 90, which reduces the cost and size of wireless transmitter unit 90.

[0068] refer to Figure 3 , a flow chart 300 illustrating the operation of an object detection system for detecting nearby objects in a wireless charging system according to some embodiments. In some embodiments, the object detection system can be implemented in hardware, software, firmware, or a combination of hardware, software, and firmware.

[0069] In operation 301, according to some embodiments, an object detection system receives one or more commands indicative of operations to be performed by the object detection system. In some embodiments, the one or more commands are input by a user. In some embodiments, the one or more commands are programmed into the object detection system. For example, according to some embodiments, the wireless power transmitter system includes a list of detection operations arranged in an order to be performed by the object detection system.

[0070] In operation 302, a frequency sweep range and a frequency sweep step are applied to the object detection system. In some embodiments, the frequency sweep range is input by a user. In some embodiments, the frequency sweep range is determined by the object detection system based on the detection operation to be performed.

[0071] At operation 304, one or more output impedance values ​​are applied to the object detection system. In some embodiments, the one or more output impedance values ​​are input by a user. In some embodiments, the one or more output impedance values ​​are determined by the system based on the detection operation to be performed.

[0072] At operation 306, according to some embodiments, one or more object detection signals are generated by the object detection system using one or more output impedance values ​​and at one or more frequencies. According to some embodiments, the one or more object detection signals are sinusoidal signals.

[0073] In operation 308, according to some embodiments, the object detection system energizes the coils using one or more object detection signals. In some embodiments, the object detection system selects whether to energize the first coil or the second coil based on the frequency of the object detection signal. In some embodiments, the object detection system selects whether to energize the first coil or the second coil based on the type of detection operation. In some embodiments, the object detection system selects whether to energize the first coil or the second coil based on user input. According to some embodiments, the coils are selected by connecting and / or disconnecting one or more switches in the object detection system.

[0074] At operation 310 , the object detection system receives one or more response signals or one or more background noise signals from the selected coils, according to some embodiments.

[0075] In operation 312, according to some embodiments, the object detection system measures one or more response signals and one or more background noise signals. According to some embodiments, the one or more response signals and one or more background noise signals may be measured via a differential amplification operation or a spectrum analysis operation. According to some embodiments, the amplitude of the output of the differential amplification operation or the spectrum analysis operation is obtained via a peak detector. According to some embodiments, the output of the peak detector is digitized using an analog-to-digital converter. According to some embodiments, the output data of the analog-to-digital converter is transmitted to a processor of the wireless charging system.

[0076] In operation 314, the object detection system compares the measured data with reference data stored in a database and determines whether the target receiver unit or foreign object is present in the field. According to some embodiments, the object detection system may also determine the type of object present in the field based on the comparison. According to some embodiments, the object detection system may also measure the coupling coefficient (distance) between the wireless power transmitter system and the object based on the measured value. According to some embodiments, the object detection system may also determine whether human tissue is touching the wireless power transmitter system based on the comparison. Based on the capacitance measured in real time, the object detection system may also determine the distance between the human and the wireless power transmitter system.

[0077] While the present disclosure may refer to one or more "users," such "users" may refer to devices associated with the users, e.g., consistent with the terms "user" and "multi-users" often used in the context of MU-MIMO environments. While the examples of communication systems described above may include devices and access points operating according to IEEE 802.11, 3GPP, or LTE standards, it should be understood that embodiments of the described systems and methods may operate according to other standards and utilize wireless communication devices other than devices implemented as devices and base stations. For example, communication interfaces associated with cellular networks, satellite communications, vehicular communication networks, 802.11, and other non-802.11 wireless networks may utilize the systems and methods described herein to achieve improved overall capacitance and / or link quality without departing from the scope of the systems and methods described herein.

[0078] It should be noted that certain sections of the present disclosure may refer to terms such as "first" and "second" in connection with devices, arrays, directions, etc., for the purpose of identifying or distinguishing one from another or from others. These terms are not intended to relate only to entities (e.g., a first device and a second device) in time or order, although in some cases, these entities may include such relationships. These terms also do not limit the number of possible entities (e.g., devices) that can operate within a system or environment.

[0079] It should be understood that the system described above can provide multiple components in any one or each of those components, and these components can be provided on a standalone machine or, in some embodiments, on multiple machines in a distributed system. In addition, the system and method described above can be provided as one or more computer-readable programs or executable instructions implemented on or in one or more articles of manufacture. The article of manufacture can be a floppy disk, hard disk, CD-ROM, flash memory card, PROM, RAM, ROM, or magnetic tape. In general, the computer-readable program can be implemented in any programming language, for example, LISP, PERL, C, C++, C#, PROLOG, or in any bytecode language such as JAVA. The software program or executable instructions can be stored as object code on or in one or more articles of manufacture.

[0080] Although the foregoing written description of the methods and systems enables one skilled in the art to make and use various embodiments of the methods and systems, those skilled in the art will understand and appreciate that there are variations, combinations, and equivalents of the specific embodiments, methods, and examples herein. Therefore, the present methods and systems should not be limited to the embodiments, methods, and examples described above, but rather to all embodiments and methods within the scope and spirit of the invention.

Claims

1. A method for performing wireless power receiver detection and alignment, the method being used in a wireless power transmitter device (90), the wireless power transmitter device (90) comprising at least one coil (102, 118, 202, 204), a small signal generator (108) comprising a digital-to-analog converter circuit (112, 114, 138) having programmable impedance, a small signal receiver (134), and a processor (101), the method comprising: selecting, by the processor (101), an impedance for the digital-to-analog converter circuit (112, 114, 138) for wireless power receiver detection and alignment; generating a small signal at one or more frequencies using the selected impedance by the small signal generator (108); Providing the small signal to the at least one coil (102, 118, 202, 204) through the small signal generator (108); receiving the small signal and a response signal associated with the small signal by the small signal receiver (134), wherein the response signal is received from the at least one coil (102, 118) and the small signal is received from the small signal generator (108); measuring capacitance of the at least one coil at the one or more frequencies to obtain a measurement; comparing, by the processor, one or more of the measured values ​​with one or more reference values ​​stored in a database; determining whether an object is present in the field of the at least one coil based on the comparison; as well as A distance between the wireless power transmitter device and the object is determined based on the comparison. 2 . The method of claim 1 , further comprising generating one or more control signals for generating the small signal.

3. The method of claim 2, further comprising providing the one or more control signals to a first resistive digital-to-analog converter (RDAC) and a second RDAC (112, 114) of the digital-to-analog converter circuit (112, 114, 138).

4. The method of claim 3, further comprising programming the first and second RDACs (112, 114) to 50Ω impedance. The method of claim 4 , wherein the small signal is generated based at least in part on the one or more control signals and the programmed impedance. The method of claim 1 , wherein generating the small signal comprises generating a sinusoidal signal. The method of claim 1 , wherein generating the small signal comprises generating a differential sine wave signal at a desired frequency. The method of claim 1 , wherein generating the small signal comprises generating a plurality of differential sine wave signals at different frequencies.

9. The method of claim 1 , wherein performing wireless power receiver detection and alignment further comprises one or more of: comparing, by the processor (101), the measured frequency response with a reference frequency response; determining a type of object present in the field of the at least one coil (102, 118, 202, 204) based on the comparison; determining a distance between the at least one coil and the object based on real-time measurements; determining whether human tissue touches the at least one coil; determining a distance between the human and the at least one coil based on the measured capacitance; or A determination is made as to whether the at least one coil is properly connected to the wireless power transmitter device.

10. A system for performing wireless power receiver detection and alignment, the system comprising: A wireless power transmitter device (90) comprising at least one coil (102, 118, 202, 204), a small signal generator (108) comprising a digital-to-analog converter circuit (112, 114, 138) with programmable impedance, a small signal receiver (134), and a processor (101), wherein: The processor (101) is configured to select an impedance for the digital-to-analog converter circuit (112, 114, 138) for wireless power receiver detection and alignment; The small signal generator (108) is configured to generate a small signal at one or more frequencies using the selected impedance; The small signal generator (108) is configured to provide the small signal to the at least one coil (102, 118, 202, 204); The small signal receiver (134) is configured to receive the small signal and a response signal associated with the small signal, wherein the response signal is received from the at least one coil (102, 118) and the small signal is received from the small signal generator (108); and The processor (101) is further configured to: measuring capacitance of the at least one coil at the one or more frequencies to obtain a measurement; comparing one or more of the measured values ​​with one or more reference values ​​stored in a database; determining whether an object is present in the field of the at least one coil based on the comparison; and A distance between the wireless power transmitter device and the object is determined based on the comparison.

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