Foreign object detection by frequency bandwidth comparison

Abstract

A wireless power transmitter and a method are provided, the methods being used to: determine the transmitter frequency bandwidth of the wireless power transmitter when no wireless power receiver is inductively coupled to the wireless power transmitter; determine the transmitter-receiver frequency bandwidth when the wireless power receiver is inductively coupled to the wireless power transmitter; compare the transmitter-receiver frequency bandwidth with the transmitter frequency bandwidth; and detect an intrusive object near the transmitting coil based on the comparison result of the transmitter-receiver frequency bandwidth and the transmitter frequency bandwidth.

Description

[0001] Priority Statement

[0002] This patent application claims priority to U.S. Provisional Patent Application No. 63 / 536,883, filed on September 6, 2023, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] This disclosure relates generally to wireless power transmission, and more specifically to object detection in multi-coil wireless power transmitters. Background Technology

[0004] Wireless power transfer systems can transfer power from one electronic device to another. More specifically, a transmitter in a transmitting device generates an electromagnetic field, and a receiver in a receiving device extracts power from that electromagnetic field. Qi is a widely adopted wireless charging standard and has been widely adopted across consumer mobile phone brands.

[0005] A Qi wireless system includes a transmitter and a receiver. The transmitter controls the power transmitted to the receiver based on feedback received from the receiver. The transmitter contains at least one coil, to which a receiver coil is coupled in a typical wireless system. In a multi-coil transmitter design, multiple overlapping transmit coils exist, allowing the receiver coil to be placed on any one of the coils. This provides spatial freedom for receiver placement, and proximity on the transmitter ensures power transmission. This contrasts with a single-coil transmitter, where the receiver coil is precisely aligned with a single transmit coil for power transmission.

[0006] One function of a transmitter is to detect the presence of a receiver on one of its coils. The Qi specification recommends two methods for receiver detection: analog ping and digital ping. One problem with these detection methods is distinguishing between the receiver and a receiver associated with a foreign object. Neither analog ping nor digital ping methods can accurately detect the presence of a foreign object, especially when the transmitter has a magnet. If a foreign object is not detected, it may cause the transmitter to mistake it for part of the receiver. This can lead to problems such as incorrect power loss calibration, and the foreign object will continue to receive power, resulting in overheating and wasted power. One method recommended in the Qi specification specifies that the receiver transmits a reference Q value acquired using a medium-power A1 (MP-A1) transmitter coil with 2mm spacers. The Q value is acquired at 100kHz and transmitted by the receiver to the transmitter during the calibration phase. The transmitter uses the reference value to detect the presence of a foreign object.

[0007] The reference Q value was first used in the design of the MPA1 transmitter and has been used ever since. One method for measuring Q is to use several receivers with different Q values ​​and attempt to fit a curve across the Q range using a new transmitter and its reference Q value. However, using this method, the measurement results become variable and potentially inaccurate depending on the receiver used, because Q depends on the ratio of the inductance L and resistance R values, and different receivers with the same Q but different L and R values ​​will provide different reference Q values ​​when placed on the transmitter. Furthermore, for low-Q transmitters or transmitters with magnets, the Q value is very low, which can make it difficult to detect foreign objects.

[0008] The method proposed in the Qi specification works well with transmitters that have transmitter characteristics similar to the originally proposed MPA1 transmitter. However, for newer transmitter topologies, the characteristics have changed, so the original Q method is not accurate enough to detect foreign objects. Some transmitters have low Q, while others have magnets embedded in the coil, thus significantly reducing the sensitivity of the Q method.

[0009] There is a need for a way to accurately detect the presence of foreign objects using a multi-coil wireless power transmitter without using a reference Q value sent by the receiver. Summary of the Invention

[0010] All aspects provide accurate detection of the presence of foreign objects using a wireless power transmitter with at least one transmitting coil.

[0011] Various aspects provide an apparatus comprising: a controller for a wireless power transmitter, the controller being configured to: determine the transmitter frequency bandwidth of the wireless power transmitter when no wireless power receiver is inductively coupled to the wireless power transmitter; determine the transmitter-receiver resonant frequency bandwidth when a wireless power receiver is inductively coupled to the wireless power transmitter; compare the transmitter-receiver resonant frequency bandwidth with the transmitter resonant frequency bandwidth; and detect an intrusive object near the transmitting coil based on the comparison result of the transmitter-receiver resonant frequency bandwidth and the transmitter resonant frequency bandwidth.

[0012] Various aspects provide the device as described in the preceding paragraph, wherein the transmitter frequency bandwidth is the frequency range in which the gain value differs from the peak value by approximately 3 dB, and wherein the transmitter-receiver frequency bandwidth is the frequency range in which the gain value differs from the peak value by approximately 3 dB.

[0013] Various parties have provided devices according to either of the preceding two paragraphs, wherein the controller is used to detect the foreign object based on the comparison result that the transmitter-receiver frequency bandwidth is higher than the transmitter frequency bandwidth.

[0014] Various parties have provided devices according to any of the first three paragraphs, wherein the controller includes an analog-to-digital converter for sampling the characteristics of the transmitting coil.

[0015] Various aspects provide the device as described in the preceding paragraph, wherein the characteristic is the transmitting coil voltage potential or the transmitting coil current.

[0016] Various parties have provided an apparatus according to any of the first five paragraphs, the apparatus including a data storage device electrically connected to the controller to store the transmitter frequency bandwidth.

[0017] Various aspects provide devices according to any of the preceding six paragraphs, wherein the controller is used to determine the transmitter frequency bandwidth and transmitter-receiver frequency bandwidth of a corresponding transmitter coil among a plurality of transmitter coils; compare the frequency bandwidth of the corresponding transmitter coil among the plurality of transmitter coils; and detect foreign objects based on the comparison results of the corresponding transmitter coil among the plurality of transmitter coils.

[0018] Various aspects provide devices according to any of the preceding seven paragraphs, wherein the controller of the wireless power transmitter is used to determine the transmitter frequency bandwidth of the wireless power transmitter when no wireless power receiver is inductively coupled to the wireless power transmitter.

[0019] According to one aspect, a method is provided, the method comprising: controlling a wireless power transmitter by: determining a transmitter frequency bandwidth of the wireless power transmitter when no wireless power receiver is inductively coupled to the wireless power transmitter; determining a transmitter-receiver resonant frequency bandwidth when a wireless power receiver is inductively coupled to the wireless power transmitter; comparing the transmitter-receiver resonant frequency bandwidth with the transmitter resonant frequency bandwidth; and detecting an intrusive object near a transmitting coil based on the comparison result of the transmitter-receiver resonant frequency bandwidth and the transmitter resonant frequency bandwidth.

[0020] Various aspects provide the method according to the preceding paragraph, wherein determining the transmitter frequency bandwidth includes determining a frequency range in which the gain value differs from the peak value by approximately 3 dB, and wherein determining the transmitter-receiver frequency bandwidth includes determining a frequency range in which the gain value differs from the peak value by approximately 3 dB.

[0021] Various aspects provide the method described in either of the first two paragraphs, wherein detecting an intrusive object includes detecting a transmitter-receiver frequency bandwidth higher than the transmitter frequency bandwidth.

[0022] Various aspects provide methods according to any of the first three paragraphs, including converting the characteristics of the wireless power transmitter from analog to digital.

[0023] The methods described in the first four paragraphs are provided in various aspects, wherein the characteristic is the transmitting coil voltage potential or the transmitting coil current.

[0024] Various aspects provide methods according to any of the first five paragraphs, including storing the transmitter frequency bandwidth.

[0025] Various aspects provide a method according to any of the first six paragraphs, the method comprising: determining a transmitter frequency bandwidth and a transmitter-receiver frequency bandwidth of a respective transmitter coil among a plurality of transmitter coils; comparing the frequency bandwidth of the respective transmitter coil among the plurality of transmitter coils; and detecting an intrusive object based on the comparison result of the frequency bandwidth of the respective transmitter coil among the plurality of transmitter coils.

[0026] One aspect provides a system comprising: a wireless power transmitter including: an energy storage circuit including a transmitting coil for inductive coupling to a receiving coil of a wireless power receiver; and a controller for the wireless power transmitter configured to: determine the transmitter frequency bandwidth of the wireless power transmitter when no wireless power receiver is inductively coupled to the wireless power transmitter; determine the transmitter-receiver frequency bandwidth when a wireless power receiver is inductively coupled to the wireless power transmitter; compare the transmitter-receiver resonant frequency bandwidth with the transmitter frequency bandwidth; and detect an intrusive object near the transmitting coil based on the comparison result of the transmitter-receiver frequency bandwidth and the transmitter resonant frequency bandwidth.

[0027] Various aspects provide a system according to the preceding paragraph, wherein the controller is used to determine the transmitter frequency bandwidth as the frequency range in which the gain value differs from the peak value by approximately 3 dB, and wherein the controller is used to determine the transmitter-receiver frequency bandwidth as the frequency range in which the gain value differs from the peak value by approximately 3 dB.

[0028] Various aspects provide a system according to either of the preceding two paragraphs, wherein the controller is used to detect an intruder based on the comparison result that the transmitter-receiver frequency bandwidth is higher than the transmitter frequency bandwidth.

[0029] Various aspects provide a system according to any of the first three paragraphs, wherein the controller includes an analog-to-digital converter to sample the characteristics of the transmitting coil.

[0030] Various aspects provide a system as described in any of the first four paragraphs, wherein the characteristic is the transmitting coil voltage potential or the transmitting coil current.

[0031] Various parties have provided a system according to any of the first five paragraphs, the system including a data storage device electrically connected to the controller to store the transmitter frequency bandwidth.

[0032] Various aspects provide a system according to any of the first six paragraphs, wherein the controller is used to determine the transmitter frequency bandwidth and transmitter-receiver frequency bandwidth for a respective transmitter coil among a plurality of transmitter coils; compare the frequency bandwidth of the respective transmitter coil among the plurality of transmitter coils; and detect foreign objects based on the comparison result of the frequency bandwidth of the respective transmitter coil among the plurality of transmitter coils.

[0033] Various aspects provide a system according to any of the preceding seven paragraphs, wherein the controller of the wireless power transmitter is used to: determine the transmitter frequency bandwidth of the wireless power transmitter when no wireless power receiver is inductively coupled to the wireless power transmitter. Attached Figure Description

[0034] The accompanying drawings illustrate examples of devices and methods for detecting the presence of foreign objects using a wireless power transmitter having one or more transmission coils.

[0035] Figure 1 This is a block diagram of a wireless power system.

[0036] Figure 2 This is a block diagram of a wireless power system configured to detect the presence of foreign objects.

[0037] Figure 3 yes Figure 1 and Figure 2 A schematic diagram of the section of the wireless power transmitter.

[0038] Figure 4 and Figure 5 A software algorithm for data collection and foreign object detection is shown.

[0039] Figure 6A and Figure 6B The simulated time-domain waveforms of coil voltage and bandwidth variations under transmitter-only conditions are shown.

[0040] Figure 7A and Figure 7B The simulated time-domain waveforms of coil voltage and bandwidth variations under transmitter and receiver conditions are shown.

[0041] Figure 8A and Figure 8B The simulated time-domain waveforms of coil voltage and bandwidth variations under conditions of transmitter and receiver with an external object are shown.

[0042] Figure 9A and Figure 9B They are shown respectively Figures 6A to 8A and Figures 6B to 8B The overlapping waveforms.

[0043] Figure 10A The coil voltage waveform is shown.

[0044] Figure 10B An example is shown near the transition between the AC signal on-time period and the data collection period. Figure 10A The graph shown is an enlarged version.

[0045] Figures 11 to 13 Experimental results for three different transmitter designs are shown.

[0046] Figure 14 It is a block diagram of a circuit that can be used to implement the various functions, operations, actions, processes and methods disclosed herein.

[0047] Figure 15 A flowchart is shown for a method of controlling a wireless power transmitter.

[0048] Figure 16 A block diagram of the controller for a wireless power transmitter is shown.

[0049] Reference numerals for any illustrated element appearing in multiple different figures have the same meaning in all figures, and any reference or discussion of any illustrated element in the context of any particular figure also applies to every other figure (if any) in which the same illustrated element is shown. Detailed Implementation

[0050] According to one aspect, a method is provided for detecting the presence or absence of a foreign object in a system using the system's frequency bandwidth. The system's frequency bandwidth can be defined as the frequency range where the gain differs from the peak value by 3 dB. The transmitter's frequency bandwidth can be defined as the frequency range where the gain differs from the peak value by approximately 3 dB. Therefore, the transmitter-receiver frequency bandwidth can be defined as the frequency range where the gain differs from the peak value by approximately 3 dB when the transmitter and receiver are magnetically coupled. As used herein, the term "frequency bandwidth" refers to the frequency range where the gain is less than a predetermined value of the peak value. For example, and as commonly used, a frequency bandwidth is determined where the gain is 3 dB lower than the peak value. The quality factor Q of a circuit is defined as the electrical energy stored in the circuit divided by the energy dissipated in one cycle. The transmitter's bandwidth is inversely proportional to Q and exhibits different characteristics in the presence of a foreign object. When the receiver is placed near the transmitter, the system's bandwidth decreases significantly compared to the bandwidth of the transmitter alone. However, when a foreign object is placed with the receiver, the system's bandwidth is much higher than the bandwidth of the transmitter alone. Due to these differences in system bandwidth, it is possible to accurately detect metallic foreign objects present alongside the receiver.

[0051] The response current-frequency curve of a resonant circuit provides the maximum current at the resonant frequency. The frequency bandwidth of a resonant circuit can be defined as the total number of cycles below and above the resonant frequency, for which the current is equal to or greater than 70.7% of its resonant value (20*log10(0.707)=3dB). The two frequencies at 0.707 of the maximum current in the curve are the half-power frequencies, i.e., where the gain differs from the peak value by 3dB. The half-power frequencies of a resonant circuit can also be referred to as the band frequency, critical frequency, or cutoff frequency.

[0052] Various aspects adapt to variations caused by placement and different types of receivers. The system bandwidth is defined as the ratio of the resonant frequency to Q. Compared to many existing Qi circuits, bandwidth measurement does not require additional circuitry. The transmitter can be driven by pulse width modulation (PWM) for a certain number of cycles and then turned off, at which point the transmitter's LC resonant energy storage circuit resonates at the resonant frequency, which depends on the inductance L and capacitance C values ​​of the transmitter and receiver, where the receiver is magnetically coupled to the transmitter due to its proximity. The attenuation rate depends on the resistance in the circuit. However, different receivers have different inductances and resistances depending on their coils. The presence of the receiver changes the transmitter's resonant frequency (as measured by itself) and the attenuation rate. Higher resistance in the circuit decreases Q, while higher inductance increases Q. The receiver inductance is reflected as a positive inductance value, which is added to the transmitter inductance. When viewed from the transmitter side, the receiver's resistance is also added to the transmitter resistance. When an additional inductor is present in the system, the resonant frequency decreases. However, when an external object is present, the resonant frequency increases, and Q decreases, thus increasing the system bandwidth compared to the independent bandwidth. As Q increases, the resonant frequency decreases and the bandwidth increases (B=F / Q). Specifically, the frequency bandwidth increases when an external object is present.

[0053] This method can be used with a variety of transmitter designs, where various inductance and resistance values ​​can be employed. This is likely due to variations in the coils or MOSFETs used in the inverter circuit.

[0054] Figure 1 A block diagram of a prior art wireless power system is shown. It includes a transmitter 102 and a receiver 104. The transmitter 102 may be powered by a direct current (DC) voltage source 112, while the receiver 104 is connected to a load 110. Power 116 is transmitted from the transmitter 102 to the receiver 104 through a set of coupling coils 114. Power transmission is effective when the coupling coils 114 are placed one on top of the other and aligned most closely.

[0055] The transmitter 102 can detect the presence of foreign objects in its vicinity. The wireless power system 100 also includes a plurality of transmission coils 106 associated with the transmitter 102. Figure 1One of the transmitting coils is shown in the diagram. A receiving coil 108 is also shown, which can be used (e.g., via inductive coupling) to transfer power 116 from transmitter 102 to receiver 104. When transmitting coil 106 is near receiving coil 108, transmitting coil 106 and receiving coil 108 can be coupled coil 114 (e.g., at least one of the transmitting coils 106 can be inductively coupled to receiving coil 108). Power 116 can be transferred from transmitter 102 to receiver 104 without a physical connection between transmitter 102 and receiver 104. Instead, a flux linkage is used to transfer power 116. Transmitter 102 can control the transferred power 116 by controlling the voltage potential amplitude, frequency, phase, and / or duty cycle supplied to transmitting coil 106.

[0056] Power transmission can be effective when one of the transmitting coils 106 is properly aligned with the receiving coil 108. Transmitter 102 uses one of the transmitting coils 106 with the strongest coupling to the receiving coil 108 to transmit power 116 to receiver 104. Transmitter 102 can detect the presence of receiving coil 108 individually, or together with other conductive foreign objects. Furthermore, if receiving coil 108 is detected, transmitter 102 can select one of the transmitting coils 106 (e.g., the one with the strongest coupling to receiving coil 108) to transmit power 116 to receiving coil 108, as will be discussed in more detail below.

[0057] Figure 2 yes Figure 1 A more detailed block diagram of the existing wireless power system 100, wherein Figure 2 Examples Figure 1 The illustrated transmitter 102, receiver 104, transmitter coil 106, receiver coil 108, voltage source 112, and load 110 are shown. Figure 2 The receiver 104 is shown to have a resonant energy storage circuit 230 formed by a receiving coil 108 and receiving capacitors Crec1 and Crec2. The output of the resonant energy storage circuit 230 passes through a diode bridge rectifier 206 to rectify the voltage. The output of the diode bridge rectifier 206 can be provided with a fixed voltage at the output load 110 by a buck converter or a low dropout (LDO) regulator (not shown).

[0058] At transmitter 102, the voltage across transmitter coil 106 can be connected to analog-to-digital converter (ADC) 238 of controller 226 using an operational amplifier biased with Vcc / 2, where Vcc represents the voltage supplied by H-bridge inverter 202. Controller 226 can be implemented using a dsPIC central processing unit or digital signal controller from Microchip Technology Incorporated of Chandler, Arizona, but is not limited to these. Controller 226 can provide pulse width modulator (PWM) pulses as control signals 240 to H-bridge inverter 202 at fixed or variable frequencies, depending on the topology of transmitter 102. Controller 226 can sample the coil voltage potential 222 across transmitter coil 106 in synchronization with the PWM signal of AC control signal 240 for Q calculation. Controller 226 can also use coil voltage potential 222 to measure resonant frequency. The ratio of resonant frequency to Q can provide the frequency bandwidth of system 100 in Hz.

[0059] like Figure 2 As illustrated, transmitter 102 includes an H-bridge inverter 202, a transmitter energy storage circuit 228 (including a transmitter coil 106 and a transmitter capacitor Crec1 connected in series between the transmitter coil 106 and the H-bridge inverter 202), one or more temperature sensors 218, and a controller 226. The H-bridge inverter 202 is electrically connected between a voltage source 112 and the transmitter energy storage circuit 228. As noted above, receiver 104 includes a resonant energy storage circuit 230 formed by a receiver coil 108 and receiver capacitors Crec1 and Crec2. Therefore, receiver 104 may include receiver capacitors Crec1 and Crec2, a diode bridge rectifier 206, and communication and voltage control circuitry 210. Receiver capacitor Crec1 may be connected in series between the receiver coil 108 and the diode bridge rectifier 206. Receiver capacitor Crec2 may be electrically coupled in parallel across the diode bridge rectifier 206. Diode bridge rectifier 206 can be configured to rectify the AC received signal 244 received from transmitter 102 to provide a DC power signal 246. Therefore, the output of resonant energy storage circuit 230 passes through diode bridge rectifier 206, which rectifies the AC received signal 244. Communication and voltage control circuit 210 can receive the DC power signal 246 and generate a load voltage potential 248 to load 110. As a non-limiting example, communication and voltage control circuit 210 may include a buck converter or low-dropout regulator (LDO) that provides a fixed load voltage potential 248 at output load 110. Communication and voltage control circuit 210 can be implemented in a controller (e.g., a microcontroller), but is not limited thereto.

[0060] The controller 226 of transmitter 102 may include a processor or processing core 220 electrically connected to one or more data storage devices (storage device 224). Various functions of controller 226 may be performed by processing core 220. Controller 226 also includes a coil voltage potential input 204 for receiving a coil voltage potential 222 and a coil current input 234 for receiving a coil current representation 232 indicating the current of transmitting coil 106. Controller 226 also includes an analog-to-digital converter (ADC 238) for sampling the coil current representation 232 at coil current input 234, the coil voltage potential 222 at coil voltage potential input 204, or both, and providing the sampled coil current representation 232 to processing core 220. Coil voltage potential 222 may be a scaled representation of the actual coil voltage potential, and / or coil current representation 232 may be a scaled representation of the actual coil current.

[0061] Controller 226 also includes a coil selection output 214 for providing one or more coil selection signals 216 to the transmitting coils 106. The coil selection signals 216 selectively control which of the transmitting coils 106 conducts the alternating current (AC) signal (AC signal 242) provided by the H-bridge inverter 202 to the transmitting energy storage circuit 228. Controller 226 also includes an AC control output 208 for providing one or more AC control signals 240 to the H-bridge inverter 202. The AC control signals 240 control the AC signal 242 applied by the H-bridge inverter 202 to the transmitting energy storage circuit 228. For example, when the H-bridge inverter 202 is electrically connected between the voltage source 112 and the transmitting energy storage circuit 228, controller 226 can selectively apply the AC control signals 240 to (e.g., by periodically reversing the input voltage Vin) convert the input voltage potential Vin (e.g., a DC voltage potential) provided by the voltage source 112 into a square wave AC signal 242. The potential Vcc of the square wave is approximately 1V.

[0062] When the receiver is inductively coupled to the transmitter, controller 226 uses measurements taken at transmitter 102 (e.g., coil current indicator 232 and / or coil voltage potential input 204) to calculate the expected Q-factor values ​​(Qt and Qtr). Controller 226 samples the coil voltage potential 222 and coil current indicator 232 of the transmitting coil 106. Controller 226 also drives AC control signal 240 at a fixed or variable frequency depending on the topology of transmitter 102. Controller 226 uses AC control signal 240 to drive H-bridge inverter 202 to deliver AC signal 242 to transmitting energy storage circuit 228 within a certain number of cycles of AC signal 242, and then disconnects AC control signal 240. AC control signal 240 may be a pulse-width modulated signal generated by controller 226. After the AC control signal 240 is disconnected, the transmitting energy storage circuit 228 can resonate at its resonant frequency according to the inductance and capacitance values ​​of the transmitting coil 106, receiving coil 108, transmitting capacitor Crec1, and receiving capacitors Crec2. The decay rate of the coil voltage potential 222 depends on the resistance in the transmitter 102. In the transmitter 102, the resistance can be in the transmitting coil 106, the inverter MOSFET RDSon, the capacitor ESR, and the PCB traces, but is not limited to these. In the receiver 104, the resistance can be in the receiving coil 108, the capacitor ESR, and the PCB traces, but is not limited to these. The presence of the receiver 104 changes the resonant frequency of the transmitting energy storage circuit 228 and the decay rate of the coil voltage potential 222 compared to the resonant frequency and decay rate without the receiver 104. The higher resistance in the transmitter 102 reduces the Q factor value of the transmitter 102, while the higher inductance of the transmitting coil 106 increases the Q factor value of the transmitter 102. When the transmitting coil 106 is inductively coupled to the receiving coil 108, the inductance of the receiving coil 108 manifests as a positive inductance at the transmitter 102, which is added to the inductance of the transmitting coil 106 (i.e., the effective inductance of the transmitting coil 106 increases when coupled to the receiving coil 108). From the transmitter 102's perspective, the resistance of the receiver 104 is also added to the transmitter 102's resistance (i.e., the effective resistance of the transmitter 102 increases in response to the resistance of the receiver 104 when coupled to the receiving coil 108). Even though the Q-factor value of the energy storage circuit 228 (which can be proportional to the ratio between the inductance of the transmitting coil 106 and the resistance of the transmitter 102) is monitored, it may still be difficult to determine whether the change in the Q-factor value of the energy storage circuit 228 is due to coupling with the receiver 104 or coupling with an external object. The coupling factor between the transmitter and receiver determines the Q-value, where the inductance L and resistance R are fixed. In cases of poor coupling, Q may increase, similar to when there is a foreign object.

[0063] Figure 3 yes Figure 1 and Figure 2 A schematic diagram of segment 300 of the existing wireless power transmitter 102. (See also:) Figure 2 and Figure 3 Section 300 includes a voltage source 112, an H-bridge inverter 202 (exemplified as including four switches Sa, Sb, Sc, and Sd), a transmitting capacitor Ctran, and the transmitting coils 106 (L1, L2, ..., LN) discussed above. The input terminals of the H-bridge inverter 202 are... Figure 3 The example is shown as an electrical connection to voltage source 112. An energy storage circuit voltage potential 308 exists. See also... Figure 3 Alternatively, the input of the H-bridge inverter 202 may be electrically connected to the output of a converter (not shown) (e.g., a DC-to-DC converter, such as a four-switch buck-boost converter (FSBBC), but not limited thereto).

[0064] In this example, transmitter 102 includes a metal-oxide-semiconductor field-effect transistor (MOSFET) H-bridge inverter 202, which is controlled by controller 226 (not shown). Transmitter energy storage circuit 228 (see...) Figure 2 ) by capacitor C tran The coil LN is formed by connecting to the output of the H-bridge inverter 202. The H-bridge inverter 202 includes four switches Sa to Sd, such as... Figure 2 As shown. Each switch can be a metal-oxide-semiconductor field-effect transistor (MOSFET) driven by a MOSFET driver. The MOSFET driver input is controlled by a PWM signal from controller 226 as AC control signal 240. In the positive half-cycle, switches Sa and Sd are turned on, while in the other half-cycle, Sb and Sc are turned on. For the selected topology, the operating frequency is fixed at 120kHz, but can be varied. The H-bridge inverter 202 applies an AC voltage across the emitter energy storage circuit 228 formed by capacitor C and coil inductance L (i.e., the inductance of the corresponding coils (i.e., coils 1 to 3)). Each coil inductance L contains a corresponding one of coil switches 302 (i.e., coil switches S1, S2, ..., SN), each coil switch being electrically connected in series with the corresponding emitter coil 106. This series switch SN, when closed in response to coil selection signal 216, places the corresponding coil in the emitter energy storage circuit 228. One coil is connected to the emitter energy storage circuit 228 at a time. The series switches S1 to SN for the corresponding transmitting coil 106 can be constructed from back-to-back MOSFETs to conduct bidirectional AC current in the transmitting energy storage circuit 228.

[0065] The number N of transmitting coils 106 and coil switches 302 can be any number (e.g., one, two, three, four, five, ten, twenty, but not limited to this). As noted above, coil switch 302 is an electrically controllable switch, enabling controller 226 to selectively open and close coil switch 302 via coil selection signal 216. By closing one coil switch of coil switch 302 associated with one of the transmitting coils 106, the associated transmitting coil in transmitting coil 106 is effectively placed in energy storage circuit 228. Figure 2 In some aspects, (e.g., by closing an associated coil switch in coil switch 302) one of the transmitting coils 106 is selected at a time. In some aspects, coil switch 302 may be a transistor (e.g., a back-to-back MOSFET for conducting bidirectional AC current in an energy storage circuit) having a gate electrically connected to coil selection signal 216. Therefore, coil selection signal 216 provided by controller 226 may include a signal bus configured to individually control coil switch 302.

[0066] The H-bridge inverter 202 also includes several electrically controllable switches (switches Sa, Sb, Sc, and Sd). Switches Sa, Sb, Sc, and Sd can be electrically controlled via an AC control signal 240 from controller 226 to generate an AC signal 242 across the first node 304 and the second node 306 of the H-bridge inverter 202. As a non-limiting example, switches Sa, Sb, Sc, and Sd can be transistors having the AC control signal 240 electrically connected to their gates. In some aspects, switches Sa, Sb, Sc, and Sd can be MOSFET transistors driven by MOSFET drivers. Controller 226 can disable or disconnect the AC signal 242 (i.e., provide a voltage potential configured to turn on the switch) by deasserting the AC control signal 240 at each of the switches Sa, Sb, Sc, and Sd. When the AC signal 242 is disabled, the first node 304 and the second node 306 can be in an electrically floating state. The controller 226 can drive the AC signal 242 alternately between: closing switches Sa and Sd while opening switches Sc and Sb; and opening switches Sa and Sd while closing switches Sc and Sb. Switches Sa, Sb, Sc, and Sd can be closed by asserting the corresponding AC control signal 240. The AC control signal 240 provided by the controller 226 may include a signal bus configured to control switches Sa, Sb, Sc, and Sd. In some embodiments, a single signal of the AC control signal 240 may control switches Sa and Sd, and another signal may control switches Sc and Sd. In some aspects, the AC control signal 240 may include four separate signals to control switches Sa, Sb, Sc, and Sd respectively. In some aspects, electrical coupling is present in the controller 226 ( Figure 2 The MOSFET driver input (not shown) of the MOSFET driver (not shown) between switches Sa, Sb, Sc, and Sd is controlled by an AC control signal 240, which can be provided by a pulse width modulation (PWM) output from the PWM output pin of controller 226, but is not limited thereto. When switches Sa and Sd are closed and switches Sb and Sc are open, the voltage potential across the first node 304 and the second node 306 can be Vin, resulting in a positive half-cycle of the AC signal 242. When switches Sa and Sd are open and switches Sb and Sc are closed, the voltage potential across the first node 304 and the second node 306 can be -Vin, resulting in a negative half-cycle of the AC signal 242. Thus, alternating between these two states, a square wave AC signal 242 is generated across the first node 304 and the second node 306. As a non-limiting example, the operating frequency (i.e., the switching frequency, which is in turn equal to the frequency of the AC signal 242) can be set to substantially 125 kHz. Therefore, the H-bridge inverter 202 spans the energy storage circuit 228 formed by the capacitance of the emitting capacitor and the inductance of the emitting coil 106. Figure 2 ) Apply AC signal 242.

[0067] The controller 226 periodically controls the wireless power transmitter 102 to perform object detection operations. During the time intervals between object detection operations, the wireless power transmitter 102 may operate in a low-power state (e.g., sleep mode or standby mode) to conserve power. The object detection operation includes data collection methods and data processing methods.

[0068] In the data collection method, controller 226 sets the number of coils to be equal to a first number. Each transmitting coil in transmitting coil 106 is associated with a specific number from a first number to a last number, such as... Figure 3 As illustrated. For example, transmitting coil L1 is associated with coil number = 1, transmitting coil L2 is associated with coil number = 2, and transmitting coil LN is associated with coil number = N. Similarly, each coil switch in coil switch 302 is associated with a number from the first number to the last number. For example, coil switch S1 is associated with coil number = 1, coil switch S2 is associated with coil number = 2, and coil switch SN is associated with coil number = N.

[0069] In the data collection method, controller 226 can also close one of the coil switches in coil switches 302 associated with the number of coils to electrically connect one of the transmitting coils 106 associated with the number of coils to H-bridge inverter 202. Controller 226 can control H-bridge inverter 202 to drive AC signal 242 to transmitting energy storage circuit 228. After applying AC signal 242 to energy storage circuit 228 (which can charge transmitting energy storage circuit 228), controller 226 can sample coil voltage potential 222 and coil current representation 232. Then, controller 226 can increment the number of coils and repeat the data collection method for each coil (i.e., unless the incrementing number of coils is greater than the final number, ...). Figure 3 In this case, the number of coils = N).

[0070] The controller 226 can also perform calibration of the transmitter 102. As previously mentioned, the inductance of the transmitting coil 106 can fluctuate in response to temperature fluctuations. Therefore, the controller 226 can take into account these fluctuations caused by temperature variations during object detection operations. For example, the controller 226 may be based on... Figure 2 Temperature sensor 218 provides temperature signal 236 to adjust the values ​​of minimum threshold Q-factor, expected uncoupled resonant frequency, and minimum threshold resonant frequency used during data processing and object detection methods. Furthermore, in some respects, the transmitting coils 106 may experience different temperatures from each other. Therefore, controller 226 can adjust the measured Q-factor and resonant frequency of the respective transmitting coils 106 based on the temperature difference to prevent the temperature difference between the transmitting coils 106 from affecting object detection and transmitting coil selection.

[0071] Furthermore, the inductance values ​​of the transmitting coil 106 may not be uniform. As a non-limiting example, due to manufacturing tolerances, the inductance value of the transmitting coil 106 may vary by approximately twenty percent (20%). Therefore, the controller 226 may perform calibration to normalize the differences between the inductance values ​​of the transmitting coil 106 to prevent these differences from affecting object detection and transmitting coil selection.

[0072] Figure 4 This illustrates a software algorithm used for data collection. The data collection routine is in... Figure 4 As shown in the diagram. For explanation, coil number 1 is considered the default 402, although it can start from any coil. PWM is enabled for 404 up to Np cycles. After Np cycles are completed, 406 is executed. Figure 2The ADC 238 samples the coil voltage at a very high rate (typically 1.6 MHz) 408, for example, approximately 20 times the expected resonant frequency, but not limited to this. Eight or more data points provide enough data to determine the peak. This ensures that several samples are available at each resonant frequency of 78 kHz. In the case of 1.6 MHz, twenty samples are available per cycle. Sample collection continues until a predefined number of samples N 410 is reached. In the case of N being 400, approximately twenty cycles of data are captured for post-processing. Data from each coil can be processed immediately after data collection, or it can be processed together with data from other coils. Once data from one coil has been collected, and after a delay 412, the next coil 414 is selected, and the above process is repeated until complete data from the coils 416 has been collected. The data includes the coil voltage sampled independently using the ADC channels. The coil voltage bandwidth signal can be used by a comparator inside the integrated circuit to determine the frequency by counting zero crossings. This can be a parallel path, where the coil voltage is also connected to the comparator and the ADC 238. Alternatively, the frequency can be determined from a given peak value (ADC data) given the number of samples between peaks and the sampling time. The comparator reference can be set to the operational amplifier's bias voltage. The coil voltage is a bipolar signal with a range of + / -VCC / 2 at the comparator terminals. The comparator supply voltage can be VCC (+3.3V) and ground (GND). The comparator input can be connected to a bias voltage of VCC / 2, allowing the coil voltage to be shifted within the comparator's range (from negative VCC / 2 to GND). The comparator output can be asserted when the comparator input is above the reference voltage, and vice versa. The comparator output is connected to a timer module, which can be a single-output capture-compare PWM timer (SCCP) module that starts the timer at the rising edge of the signal (i.e., when the comparator output is asserted) and stops the timer when the comparator output is asserted again (i.e., at a subsequent rising edge). The time elapsed between the two edges is used to determine the system's resonant frequency F. The resonant frequency and expected Q-factor values ​​(Qt and Qtr) are determined for each coil. The frequency bandwidth can be determined based on the determined resonant frequency.

[0073] Figure 5An algorithm for determining whether a foreign object has been detected is illustrated, where the algorithm is performed after data is collected from the coil. The coil voltage waveform is an exponentially decaying sine wave with a resonant frequency F. The algorithm finds the 502 peak by comparing the previous and next samples in a 3-point filter arrangement. At the peak, the previous and next values ​​are lower than the current value. If three consecutive ADC samples are taken relative to time n, and if Vn-1 is less than Vn and Vn-2, then Vn-1 is the peak of the sine wave. Positive peaks Vp and negative peaks Vp can be identified and stored in the array.

[0074] The expected Q-factor values ​​(Qt and Qtr) of the 504 can be determined from the peak values ​​of voltage or current, or both, using the following formulas:

[0075]

[0076] P N – The nth peak

[0077] P N+1 – The (n+1)th peak

[0078] The expected Q-factor values ​​(Qt and Qtr) can be based on a single calculation or the average of Q values ​​determined over several cycles. The average tends to mask the computational sensitivity to the determined values ​​and is preferred compared to individual values. The expected Q-factor values ​​(Qt and Qtr) of the coil and the F measurement 506 are completed and the values ​​are stored in an array. These measurements are typically performed once per board at the factory during the calibration phase, and the values ​​can be stored in non-volatile memory for future use.

[0079] The above data collection algorithm runs only on the transmitter (no receiver) and obtains the following information: 508

[0080] Qt – Transmitter Q value

[0081] Ft – Transmitter resonant frequency

[0082] Bt = Ft / Qt - Transmitter frequency bandwidth

[0083] These measurements are typically performed once per board at the factory during the calibration phase, and the values ​​are stored in non-volatile memory for future use.

[0084] A second set of readings is acquired as the receiver approaches the transmitter. This is done to check for foreign objects before proceeding to the power transfer phase. Whenever the receiver is placed near the transmitter, Figure 5 The algorithm is run by controller 226 and the following measurements are obtained:

[0085] Qtr - Combined transmitter-receiver Q value

[0086] Ftr-combined transmitter-receiver resonant frequency

[0087] Btr = Ftr / Qtr - Combined transmitter-receiver frequency bandwidth

[0088] The measured combined transmitter-receiver frequency bandwidth value Btr is compared with the transmitter frequency bandwidth Bt.510.

[0089] If Btr > Bt + threshold, controller 226 assumes or detects the presence of a foreign object (B12) in the system and does not provide power. If the value of Btr is less than Bt + threshold, controller 226 determines that no foreign object exists in the system and can provide power to receiver 104 via coupling coil 114. The threshold can be set based on the system's frequency bandwidth. For some transmitter designs, a typical figure is approximately 500 Hz. The threshold can be set during transmitter certification and interoperability testing. As a first step, receivers from a conformity testing system can be used to set the transmitter threshold. These receivers can be placed on transmitters with and without foreign objects and record the transmitter readings. Based on the readings, a threshold can be set between the two (foreign object and no foreign object) such that it is equidistant from both. This interval prevents false detections and missed detections.

[0090] Figure 6A and Figure 6B The simulated time-domain waveforms of the coil voltage and frequency bandwidth variation Bt are shown under the condition of transmitter only.

[0091] Figure 7A and Figure 7B The simulated time-domain waveforms of the coil voltage and frequency bandwidth variation Btr under transmitter and receiver conditions are shown.

[0092] Figure 8A and Figure 8B The simulated time-domain waveforms of the coil voltage and frequency bandwidth variation Btr under conditions of transmitter and receiver with an external object are shown.

[0093] Figure 9A and Figure 9B The following are simulated time-domain waveforms showing the changes in coil voltage and frequency bandwidth under different conditions: transmitter only (Figure 6), transmitter and receiver (Figure 6). Figure 7A and Figure 7B Transmitter and receiver with foreign objects ( Figure 8A and Figure 8B By using three waveforms on a single graph, changes in the time and frequency domains caused by the introduced foreign object can be observed.

[0094] Figure 10AThe coil voltage waveform is shown when there is no external object present. Note that the PWM is on for several cycles and then off. The resonant circuit resonates at its natural frequency, which can be seen from the voltage waveform. Figure 10A This is an example Figure 2 A graph 1000 is plotted against time for one of the following: AC control signal 240, coil voltage potential 222, and coil current representation 232 of the wireless power system 100. Graph 1000 illustrates that the AC control signal 240 is turned on during the AC signal on-time period 1002 and then turned off during the data collection time period 1004. As a non-limiting example, the controller (e.g., Figure 2 The controller 226 can execute during the data collection period 1004. Figure 4 Data collection methods and Figure 5 Foreign objects were detected and identified.

[0095] Figure 10B An example is shown near the transition between the AC signal on-time period 1002 and the data collection period 1004. Figure 10A A magnified version of the curve 1000. The AC control signal 240 is shown as oscillating during the on-time period 1002 and then remaining at a DC value during the data collection period 1004. The resonant circuit resonates at the resonant frequency fr during the data collection period 1004, as seen in both the coil voltage potential 222 and the coil current representation 232 (which is approximately ninety degrees out of phase with the coil voltage potential 222).

[0096] Figures 11 to 13 Experimental results for three different transmitter designs are shown. The system frequency bandwidth was calculated using several receivers (14) with different characteristics. The frequency bandwidth Bt of the transmitter alone was determined once, while other frequency bandwidths Btr (transmitter and receiver) and Btrf (transmitter, receiver and foreign object) were determined separately for each receiver with and without a foreign object. Figure 11 and Figure 12 The frequency bandwidth of a transmitter design with a magnet and a transmitting coil is shown, while Figure 13 The frequency bandwidth figures for transmitter designs without any magnets are shown. It is clear from the three transmitter designs that the presence of a foreign object in the system is evident, as the frequency bandwidth is higher in each case where a foreign object is present.

[0097] All aspects can provide accurate calculations of the frequency bandwidth values ​​for foreign object detection without requiring the transmitter to receive a reference Q or frequency value from the receiver. Reliable detection of foreign objects on the transmitter can be achieved in the presence of a receiver without implementing additional hardware.

[0098] Figure 14 This is a block diagram of circuitry 1400 that can be used in some respects to implement the various functions, operations, actions, processes, and / or methods disclosed herein. Circuitry 1400 includes one or more processors 1402 (sometimes referred to herein as "processor 1402") capable of being operatively coupled to one or more data storage devices (sometimes referred to herein as "storage device 1404"). Storage device 1404 includes machine-executable code 1406 stored thereon, and processor 1402 includes logic circuitry 1408. Machine-executable code 1406 includes information describing functional elements that can be implemented (e.g., executed by) logic circuitry 1408. Logic circuitry 1408 is adapted to implement (e.g., execute) the functional elements described by machine-executable code 1406. When executing the functional elements described by machine-executable code 1406, circuitry 1400 can be considered as dedicated hardware configured to execute the functional elements disclosed herein. In some respects, processor 1402 may execute the functional elements described by machine-executable code 1406 sequentially, concurrently (e.g., on one or more different hardware platforms), or in one or more parallel process flows.

[0099] When implemented by the logic circuitry 1408 of the processor 1402, the machine-executable code 1406 adapts the processor 1402 to perform the operations of the aspects disclosed herein. For example, the machine-executable code 1406 may adapt the processor 1402 to perform... Figure 4 Data collection methods 400 and / or Figure 5 At least some or all of the foreign object detection method 500. For example, machine-executable code 1406 may adapt processor 1402 to execute [a method targeting...]. Figure 2 The controller 226 discusses at least some or all of the operations. For example, machine-executable code 1406 may adapt processor 1402 to perform operations targeting... Figure 2 The processing core 220 performs at least some or all of the operations discussed herein. As a particular non-limiting example, machine-executable code 1406 may adapt processor 1402 to perform at least some of the object detection operations discussed herein.

[0100] Processor 1402 may include a general-purpose processor, special-purpose processor, central processing unit (CPU), microcontroller, programmable logic controller (PLC), digital signal processor (DSP), application-specific integrated circuit (ASIC), field-programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic unit, discrete hardware component, other programmable device, or any combination thereof, designed to perform the functions disclosed herein. A general-purpose computer including a processor is considered a special-purpose computer when it is configured to perform functional elements corresponding to machine-executable code 1406 (e.g., software code, firmware code, hardware code) associated with aspects of this disclosure. It should be noted that the general-purpose processor (also referred to herein as a host processor or simply host) may be a microprocessor, but in alternative embodiments, processor 1402 may include any conventional processor, controller, microcontroller, or state machine. Processor 1402 may also be implemented as a combination of computing devices, such as a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors combined with a DSP core, or any other such configuration.

[0101] In some aspects, storage device 1404 includes volatile data storage devices (e.g., random access memory (RAM)) and non-volatile data storage devices (e.g., flash memory, hard disk drive, solid-state drive, erasable programmable read-only memory (EPROM), but not limited thereto). In some aspects, processor 1402 and storage device 1404 may be implemented as a single device (e.g., semiconductor device product, system-on-a-chip (SoC), but not limited thereto). In some aspects, processor 1402 and storage device 1404 may be implemented as separate devices.

[0102] In some aspects, the machine-executable code 1406 may include computer-readable instructions (e.g., software code, firmware code). As a non-limiting example, the computer-readable instructions may be stored in storage device 1404, directly accessed by processor 1402, and executed by processor 1402 using at least logic circuitry 1408. Also as a non-limiting example, the computer-readable instructions may be stored on storage device 1404, transferred to a memory device (not shown) for execution, and executed by processor 1402 using at least logic circuitry 1408. Therefore, in some aspects, logic circuitry 1408 includes logic circuitry 1408 that can be configured electrically.

[0103] In some respects, machine-executable code 1406 may describe hardware (e.g., circuitry) to be implemented in logic circuitry 1408 to perform functional elements. This hardware can be described from any of a range of abstraction levels, from low-level transistor layout to high-level description languages. At high-level abstraction, hardware description languages ​​(HDLs), such as the IEEE standard hardware description language (HDL), can be used. As a non-limiting example, Verilog can be used. ™ SystemVerilog ™ Or Very Large Scale Integration (VLSI) Hardware Description Language (VHDL) ™ ).

[0104] HDL descriptions can be converted into descriptions at any of a variety of other levels of abstraction as needed. As a non-limiting example, a high-level description can be converted into a logic-level description such as Register Pass Language (RTL), Gate-level (GL) description, layout-level description, or mask-level description. As a non-limiting example, micro-operations to be performed by the hardware logic circuitry of logic circuitry 1408 (e.g., gates, flip-flops, registers, but not limited thereto) can be described in RTL, then converted into a GL description by a synthesis tool, and the GL description can be converted into a layout-level description by a placement and routing tool, which corresponds to the physical layout of the integrated circuit, discrete gate or transistor logic, discrete hardware components, or combinations thereof of the programmable logic device. Therefore, in some aspects, machine-executable code 1406 can include HDL, RTL, GL descriptions, mask-level descriptions, other hardware descriptions, or any combination thereof.

[0105] In the machine-executable code 1406, which includes aspects of a hardware description (at any level of abstraction), a system (not shown, but including storage device 1404) may be configured to implement the hardware description described by machine-executable code 1406. As a non-limiting example, processor 1402 may include a programmable logic device (e.g., an FPGA or PLC), and logic circuitry 1408 may be electrically controlled to implement circuitry corresponding to the hardware description as logic circuitry 1408. Again, by a non-limiting example, logic circuitry 1408 may include hardwired logic components manufactured by a manufacturing system (not shown, but including storage device 1404) according to the hardware description of machine-executable code 1406.

[0106] Regardless of whether the machine-executable code 1406 includes computer-readable instructions or a hardware description, the logic circuit 1408 is adapted to execute the functional elements described by the machine-executable code 1406 when implementing the functional elements of the machine-executable code 1406. It should be noted that although the hardware description may not directly describe the functional elements, it indirectly describes the functional elements that the hardware elements described by the hardware description can execute.

[0107] Figure 15 This is a flowchart illustrating a method for controlling a wireless power transmitter. When no wireless power receiver is inductively coupled to the wireless power transmitter, the transmitter frequency bandwidth 1502 of the wireless power transmitter is determined. When the wireless power receiver is inductively coupled to the wireless power transmitter, the transmitter-receiver frequency bandwidth 1504 is determined. The transmitter-receiver frequency bandwidth and the transmitter frequency bandwidth are compared 1506. According to one aspect, this comparison may show that the transmitter-receiver frequency bandwidth is higher than the transmitter frequency bandwidth. According to another aspect, this comparison may show that the transmitter-receiver frequency bandwidth has a higher threshold margin than the transmitter frequency bandwidth. An intrusive object 1508 is detected near the transmitting coil based on the comparison result of the transmitter-receiver frequency bandwidth and the transmitter frequency bandwidth.

[0108] Figure 16 A block diagram of the controller for the wireless power transmitter is shown. Transmitter bandwidth register 1602 and transmitter-receiver bandwidth register 1604 provide inputs to comparator 1606. The output of comparator 1606 is sent to detector 1608. When the wireless power receiver is not inductively coupled to the wireless power transmitter, the transmitter frequency bandwidth is determined and sent to transmitter bandwidth register 1602. When the wireless power receiver is inductively coupled to the wireless power transmitter, the combined transmitter-receiver frequency bandwidth is determined and sent to transmitter-receiver bandwidth register 1604. Comparator 1606 compares the transmitter-receiver frequency bandwidth with the transmitter frequency bandwidth. If the comparator determines that the combined transmitter-receiver frequency bandwidth is higher than the transmitter frequency bandwidth, the comparator sends an output to detector 1608 indicating the presence of a foreign object near the transmitter coil based on the comparison of the combined transmitter-receiver frequency bandwidth and the transmitter frequency bandwidth.

[0109] Although examples have been described above, other variations and examples may be made in accordance with this disclosure without departing from the substance and scope of these disclosed examples.

Claims

1. An apparatus, the apparatus comprising: The controller of the wireless power transmitter is used for: When the wireless power receiver is inductively coupled to the wireless power transmitter, the transmitter-receiver frequency bandwidth is determined; Compare the transmitter-receiver frequency bandwidth with the transmitter frequency bandwidth; and Foreign objects near the transmitting coil are detected based on the comparison between the transmitter-receiver frequency bandwidth and the transmitter frequency bandwidth.

2. The device of claim 1, wherein the transmitter frequency bandwidth is a frequency range in which the gain value differs from the peak value by approximately 3 dB, and wherein the transmitter-receiver frequency bandwidth is a frequency range in which the gain value differs from the peak value by approximately 3 dB.

3. The device according to any one of claims 1 to 2, wherein the controller is configured to detect the foreign object based on the comparison result that the transmitter-receiver frequency bandwidth is higher than the transmitter frequency bandwidth.

4. The device according to any one of claims 1 to 3, wherein the controller includes an analog-to-digital converter for sampling the characteristics of the transmitting coil.

5. The device according to claim 4, wherein the characteristic is a transmitting coil voltage potential or a transmitting coil current.

6. The device according to any one of claims 1 to 5, the device comprising a data storage device electrically connected to the controller to store the transmitter frequency bandwidth.

7. The device according to any one of claims 1 to 6, wherein the controller is configured to determine the transmitter frequency bandwidth and transmitter-receiver frequency bandwidth of a corresponding transmitter coil among a plurality of transmitter coils; compare the frequency bandwidths of the corresponding transmitter coils among the plurality of transmitter coils; and detect an intruder based on the comparison result of the corresponding transmitter coils among the plurality of transmitter coils.

8. The device according to any one of claims 1 to 7, wherein the controller of the wireless power transmitter is configured to determine the transmitter frequency bandwidth of the wireless power transmitter when no wireless power receiver is inductively coupled to the wireless power transmitter.

9. A method, the method comprising: Control the wireless power transmitter using the following methods: When no wireless power receiver is inductively coupled to the wireless power transmitter, determine the transmitter frequency bandwidth of the wireless power transmitter; When the wireless power receiver is inductively coupled to the wireless power transmitter, the transmitter-receiver frequency bandwidth is determined; Compare the transmitter-receiver frequency bandwidth with the transmitter frequency bandwidth; as well as Foreign objects near the transmitting coil are detected based on the comparison between the transmitter-receiver frequency bandwidth and the transmitter frequency bandwidth.

10. The method of claim 9, wherein determining the transmitter frequency bandwidth includes determining a frequency range in which the gain value differs from the peak value by approximately 3 dB, and wherein determining the transmitter-receiver frequency bandwidth includes determining a frequency range in which the gain value differs from the peak value by approximately 3 dB.

11. The method according to any one of claims 9 to 10, wherein detecting an intrusive object comprises detecting a transmitter-receiver frequency bandwidth higher than the transmitter frequency bandwidth.

12. The method according to any one of claims 9 to 11, the method comprising converting the characteristics of the wireless power transmitter from analog to digital.

13. The method of claim 12, wherein the characteristic is a transmitting coil voltage potential or a transmitting coil current.

14. The method according to any one of claims 9 to 13, the method comprising storing the transmitter frequency bandwidth.

15. The method of any one of claims 9 to 14, comprising: Determine the transmitter frequency bandwidth and transmitter-receiver frequency bandwidth of the corresponding transmitter coil among multiple transmitter coils; Compare the frequency bandwidths of the corresponding transmitting coils among the plurality of transmitting coils; And detect foreign objects based on the comparison results of the frequency bandwidth of the corresponding transmitting coils among multiple transmitting coils.

16. A system comprising: A wireless power transmitter, the wireless power transmitter comprising: Energy storage circuit, the energy storage circuit including a transmitting coil for inductive coupling to a receiving coil of a wireless power receiver; and The controller of the wireless power transmitter, the controller being configured to: When the wireless power receiver is inductively coupled to the wireless power transmitter, the transmitter-receiver frequency bandwidth is determined; Compare the transmitter-receiver frequency bandwidth with the transmitter frequency bandwidth; and Foreign objects near the transmitting coil are detected based on the comparison between the transmitter-receiver frequency bandwidth and the transmitter frequency bandwidth.

17. The system of claim 16, wherein the controller is configured to determine that the transmitter frequency bandwidth is a frequency range in which the gain value differs from the peak value by approximately 3 dB, and wherein the controller is configured to determine that the transmitter-receiver frequency bandwidth is a frequency range in which the gain value differs from the peak value by approximately 3 dB.

18. The system according to any one of claims 16 to 17, wherein the controller is configured to detect an intruder based on the comparison result, wherein the transmitter-receiver frequency bandwidth is higher than the transmitter frequency bandwidth.

19. The system according to any one of claims 16 to 18, wherein the controller includes an analog-to-digital converter for sampling the characteristics of the transmitting coil.

20. The system according to any one of claims 16 to 19, wherein the characteristic is a transmitting coil voltage potential or a transmitting coil current.

21. The system according to any one of claims 16 to 20, the system comprising a data storage device electrically connected to the controller to store the transmitter frequency bandwidth.

22. The system according to any one of claims 16 to 21, wherein the controller is configured to determine the transmitter frequency bandwidth and transmitter-receiver frequency bandwidth of a respective transmitter coil among a plurality of transmitter coils; compare the frequency bandwidths of the respective transmitter coils among the plurality of transmitter coils; and detect an intruder based on the comparison result of the frequency bandwidths of the respective transmitter coils among the plurality of transmitter coils.

23. The system according to any one of claims 16 to 22, wherein the controller of the wireless power transmitter is configured to determine the transmitter frequency bandwidth of the wireless power transmitter when no wireless power receiver is inductively coupled to the wireless power transmitter.

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