Systems and methods for low power excitation in high power wireless power systems

Abstract

Disclosed herein are systems and methods for low-power activation of a wireless power transmitter configured to transmit high power. Exemplary systems and methods include disabling a power factor correction circuit of the transmitter and adjusting one or more variable impedance components of an impedance network to obtain a minimum achievable impedance. The variable impedance components can be configured to operate between the minimum achievable impedance and a maximum achievable impedance. The systems and methods can include adjusting a phase shift angle associated with one or more transistors of an inverter and driving the transmitter so that a transmitter resonator coil generates a magnetic flux density less than or equal to a field safety threshold.

Description

[0001] This application is a divisional application of the patent application with the same name with application number 201980081010.3 filed on November 27, 2019.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application No. 62 / 773,518, filed on November 30, 2018, entitled “System and Method for Low-Power Excitation in a High-Power Wireless Power System,” the entire contents of which are incorporated herein by reference. Technical Field

[0004] The following disclosure is directed to methods and systems for low power excitation in wireless systems, and more particularly, to methods and systems for low power excitation of high power wireless power transmitters. Background Art

[0005] A wireless power system may include one or more wireless power transmitters configured to transmit power to one or more wireless power receivers via an oscillating electromagnetic field. The wireless power receivers may be coupled to one or more batteries so that the received power is used to charge the batteries. The wireless power system may be configured to power various electronic devices (e.g., phones, laptops, medical devices, vehicles, robots, etc.). Summary of the Invention

[0006] Wireless power systems can be specifically configured to transmit power within a specific power, current, and / or voltage range. This is because some electronic components used in wireless power systems in one power range may not be suitable or optimized for operation in another power range. For example, transistors used to drive wireless power transmitters at low power (e.g., on the order of milliwatts to tens of watts) are typically not configured to handle higher levels of current or voltage to achieve higher levels of power transmission (e.g., on the order of hundreds of watts to thousands of watts). Therefore, if such transistors are operated outside of their power range, they will fail or be damaged. In another example, some electronic components (e.g., power factor correction (PFC) circuits) may be beneficial in higher power systems, but may cause inefficiencies in lower power ranges. Therefore, when striving to achieve high power transmission (e.g., greater than 90% from power source to load), it is useless to use certain components.

[0007] In some cases, it may be challenging to configure a wireless power system to operate in a particular power range (e.g., low power) where the same wireless power system has previously been configured to operate in a significantly different power range (e.g., high power). Therefore, it may be beneficial for a wireless power system to operate in different power ranges (or “modes”) and / or switch between modes. Further, it may be beneficial for the wireless power system to do so without significantly losing efficiency and / or significantly increasing cost or physical volume (e.g., due to additional or different electronic components). For example, it may be useful to operate a wireless power system in a “high power mode” (e.g., configured for several kilowatts) for charging a large capacity battery (e.g., a vehicle battery), and in some cases, in a “low power mode” (e.g., less than 10 watts) for certain functions (e.g., positioned between a wireless power transmitter and a receiver coil), as further described herein. “High power mode” may also be referred to herein as a “wireless power transmission mode” or “WPT mode.”

[0008] In one aspect, the present disclosure features a method for low-power excitation of a wireless power transmitter configured to transmit high power. The transmitter includes an inverter coupled to an input of an impedance network and a transmitter resonator coil coupled to an output of the impedance network. The method may include: disabling a power factor correction circuit coupled to the input of the inverter; and adjusting one or more variable impedance components of the impedance network to obtain a minimum achievable impedance. The variable impedance components may be configured to operate between the minimum achievable impedance and a maximum achievable impedance. The method may include: adjusting a phase shift angle associated with one or more transistors of the inverter; and driving the transmitter so that the transmitter resonator coil generates a magnetic flux density less than or equal to a field safety threshold.

[0009] Various embodiments of the example method may include one or more of the following features.

[0010] The wireless power transmitter may be configured to transmit high power at an operating frequency between 80 kHz and 90 kHz. The wireless power transmitter may be configured to transmit power at a power level between 500 W and 20,000 W. Driving the transmitter may be performed by a fixed low voltage source. Driving the transmitter may include driving the transmitter at a voltage of 30 V or less. Driving the transmitter may include driving the transmitter at a power of 50 W or less. The field safety threshold may be between 10 microteslas and 15 microteslas.

[0011] Adjusting the phase shift angle may include adjusting the phase shift angle between 0 degrees and 180 degrees so that the magnetic flux density is less than or equal to a field safety threshold. Adjusting the phase shift angle may include adjusting the phase shift so that a current in the transmitter resonator coil is less than or equal to a current limit. The current limit may be based on the field safety threshold. Driving the transmitter may include driving the transmitter so that a current in the transmitter resonator coil is less than or equal to a current limit. The current limit may be based on the field safety threshold. The current limit may be 2 amps. The current limit may be 355 milliamps. The method may include determining the magnetic flux density based on an induced voltage or an induced current in one or more measurement coils, wherein the measurement coils may be separate from the transmitter resonator coil; and providing a signal representing the magnetic flux density to a controller coupled to the transmitter. Prior to driving the transmitter, the method may include receiving a signal indicating the presence of a vehicle having a receiver resonator coil in proximity to the transmitter resonator coil. The method may include receiving a signal indicating the presence of a vehicle having a receiver resonator coil in proximity to the transmitter resonator coil.

[0012] In another aspect, the present disclosure may feature a system for low-power activation of a wireless power transmitter configured to transmit high power. The system may include: a power factor correction circuit configured to be enabled during high-power transmission and disabled during low-power activation; and a low-voltage source coupled to an output of the power factor correction circuit and configured to drive the transmitter such that, during low-power activation, a resonator coil of the transmitter generates a magnetic flux density less than or equal to a field safety threshold. The system may include: an inverter coupled to the output of the low-voltage source and including at least two transistors, the transistors configured to be controlled such that a phase shift angle of each transistor is adjustable during low-power activation; and at least one variable impedance component coupled to the output of the inverter and configured to be adjusted to obtain a minimum achievable impedance during low-power activation. The variable impedance component may be configured to operate between the minimum achievable impedance and a maximum achievable impedance.

[0013] Various embodiments of the exemplary system may include one or more of the following features.

[0014] The wireless power transmitter may be configured to transmit high power at an operating frequency between 80 kHz and 90 kHz. The wireless power transmitter may be configured to transmit power at a power level between 500 W and 20,000 W. The wireless power transmitter may be configured to output power at 50 W or less during low-power excitation. The field safety threshold may be between 10 microteslas and 15 microteslas. The system may include a current sensor coupled to the transmitter resonator coil and configured to provide a signal representing a current characteristic to a controller of the transmitter. The controller may be operably coupled to at least one of: (i) at least two transistors or (ii) at least one variable impedance component. The low-power voltage source may be configured to drive the transmitter such that, during low-power operation, the current in the transmitter resonator coil is less than or equal to a current limit. The current limit may be based on the field safety threshold.

[0015] In another aspect, the present disclosure features a method for low-power excitation of a high-power wireless power transmitter. The transmitter may include an inverter coupled to an input of an impedance network and a transmitter resonator coil coupled to an output of the impedance network. The method may include disconnecting a power factor correction circuit from the input of the inverter; and adjusting one or more variable impedance components of the impedance network to obtain a minimum achievable impedance. The variable impedance components may be configured to operate between the minimum achievable impedance and a maximum achievable impedance; and driving the transmitter such that the transmitter resonator coil generates a magnetic flux density less than or equal to a field safety threshold.

[0016] Various embodiments of the example method may include one or more of the following features.

[0017] The field safety threshold may be between 10 microteslas and 15 microteslas. Driving the transmitter may include driving the transmitter so that a current in the transmitter resonator coil is less than or equal to a current limit, wherein the current limit is based on the field safety threshold. The current limit may be 2 amps. The current limit may be 355 milliamperes. The method may include determining a current in the transmitter resonator coil; and adjusting a voltage source of the transmitter based on the determined current. The method may include determining a magnetic flux density by determining an induced voltage or an induced current in one or more sensing coils, wherein the sensing coils are separated from the transmitter resonator coil. Driving the transmitter may include driving the transmitter based on the determined magnetic flux. The method may include receiving a signal indicating the presence of a vehicle having a receiver resonator coil in proximity to the transmitter resonator coil.

[0018] In another aspect, the present disclosure features a method for low-power excitation of a wireless power transmitter configured to transmit high power. The transmitter may include an inverter coupled to an input of an impedance network and a transmitter resonator coil coupled to an output of the impedance network. The method may include configuring a power factor correction circuit to output a minimum bus voltage, wherein the power factor correction circuit is coupled near the input of the inverter. The method may include: adjusting one or more variable impedance components of the impedance network to obtain a minimum achievable impedance, wherein the variable impedance components may be configured to operate between the minimum achievable impedance and a maximum achievable impedance; and adjusting a phase shift angle associated with one or more transistors of the inverter so that the transmitter resonator coil generates a magnetic flux density less than or equal to a field safety threshold.

[0019] Various embodiments of the example method may include one or more of the following features.

[0020] The minimum bus voltage may be approximately 380V. The field safety threshold may be between 10 microteslas and 15 microteslas. Adjusting the phase shift angle may include adjusting the phase shift so that a current in the transmitter resonator coil is less than or equal to a current limit, the current limit being based on the field safety threshold. The current limit may be 2 amps. The current limit may be 355 milliamperes. The method may include determining a magnetic flux density by determining an induced voltage or an induced current in one or more measurement coils, wherein the coils are separate from the transmitter resonator coil. Adjusting the phase shift angle may include adjusting the phase shift angle based on the determined magnetic flux density.

[0021] In another aspect, the disclosure features a method for low-power excitation of a wireless power transmitter configured to transmit high power at low power, wherein the transmitter includes an inverter coupled to an input of an impedance network and a transmitter resonator coil coupled to an output of the impedance network. The method may include: disabling a power factor correction circuit coupled to the input of the inverter; and adjusting one or more variable impedance components of the impedance network to obtain a minimum achievable impedance, wherein the variable impedance components are configured to operate between the minimum achievable impedance and a maximum achievable impedance. The method may include driving the transmitter so that the transmitter resonator coil generates a magnetic flux density less than or equal to a field safety threshold.

[0022] Various embodiments of the example method may include one or more of the following features.

[0023] A phase shift angle associated with one or more transistors of the inverter may be fixed. Driving the transmitter may be performed by a variable low voltage source. Driving the transmitter may include driving the transmitter with a voltage between 1V and 10V. The field safety threshold may be between 10 microteslas and 15 microteslas. Adjusting the phase shift angle may include adjusting the phase shift such that a current in the transmitter resonator coil is less than or equal to a current limit, wherein the current limit is based on the field safety threshold. The current limit may be 2 amps. The current limit may be 355 milliamperes. The method may include determining a magnetic flux density by determining an induced voltage or an induced current in one or more measurement coils, the coils being separate from the transmitter resonator coil. Driving the transmitter may include driving the transmitter based on the determined magnetic flux density. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1A is a block diagram of an exemplary wireless power system. Figure 1B is a diagram of a vehicle with an exemplary receiver resonator coil positioned above a transmitter resonator coil.

[0025] Figures 2A to 2D is a diagram of an exemplary coil configuration.

[0026] Figure 3 is a schematic diagram of a portion of an exemplary wireless power transmitter configured for low power excitation (LPE).

[0027] Figure 4A is a schematic diagram of an exemplary wireless power transmitter configured for low power excitation. Figure 4B is used for Figure 4A Flowchart of an exemplary method of low-power excitation of an exemplary wireless power transmitter.

[0028] Figure 5A is a schematic diagram of an exemplary wireless power transmitter configured for low power excitation. Figure 5B is used for Figure 5A Flowchart of an exemplary method of low-power excitation of an exemplary wireless power transmitter. Figure 5C is a graph of transmitter coil current (in amperes) as a function of inverter phase shift angle (in degrees).

[0029] Figure 6A is a schematic diagram of an exemplary wireless power transmitter configured for low power excitation. Figure 6B is used for Figure 6A Flowchart of an exemplary method of low-power excitation of an exemplary wireless power transmitter.

[0030] Figure 7A is a schematic diagram of an exemplary wireless power transmitter configured for low power excitation. Figure 7B is used for Figure 7AFlowchart of an exemplary method of low-power excitation of an exemplary wireless power transmitter.

[0031] Figure 8 is a flow chart illustrating a series of example steps for performing wireless power transmission from a transmitter to a receiver, including vehicle positioning.

[0032] Figure 9 is a block diagram of an example computer system that can be used to implement the systems and methods described herein. DETAILED DESCRIPTION

[0033] Disclosed herein are exemplary embodiments of systems and methods for low power excitation (LPE) in wireless power systems, and particularly in high power wireless power systems including high power wireless power transmitters.

[0034] Wireless Power Systems

[0035] Figure 1A is a block diagram of an exemplary wireless power system 100. System 100 includes a wireless power transmitter 102 and a wireless power receiver 104. In transmitter 104, a power source 105 (e.g., AC mains, battery, etc.) provides power to an inverter 108. Additional components may include a power factor correction (PFC) circuit 106 prior to inverter stage 108. Inverter 108 drives a transmitter resonator coil and capacitive component 112 ("resonator") via an impedance matching network 110 (including fixed and / or tunable network components). Resonator 112 generates an oscillating magnetic field that induces current and / or voltage in a receiver resonator 114. The received energy is provided to a rectifier 118 via an impedance matching network 116 (including fixed and / or tunable network components). Ultimately, the rectified power is provided to a load 120 (e.g., one or more batteries of an electric or hybrid vehicle). In some embodiments, the battery voltage level can affect various parameters (e.g., impedance) of wireless power system 100. Thus, the battery voltage level may be received, determined, or measured to be provided as an input to other portions of the wireless power system 100. For example, typical battery voltage ranges for electric vehicles include 0-280V, 0-350V, 0-420V, and the like.

[0036] In some embodiments, one or more components of transmitter 102 may be coupled to a controller 122, which may include a communication module (e.g., Wi-Fi, radio, Bluetooth, in-band signaling mechanism, etc.). In some embodiments, one or more components of transmitter 102 may be coupled to one or more sensors 124 (e.g., current sensor, voltage sensor, power sensor, temperature sensor, fault sensor, etc.). Controller 122 and sensors 124 may be operatively coupled to a control portion of transmitter 102 based on feedback signals from sensors 124.

[0037] In some embodiments, one or more components of the receiver 104 can be coupled to a controller 126, which can include a communication module (e.g., Wi-Fi, radio, Bluetooth, in-band signaling mechanism, etc.). In some embodiments, one or more components of the transmitter 104 can be coupled to one or more sensors 128 (e.g., current sensor, voltage sensor, power sensor, temperature sensor, fault sensor, etc.). The controller 126 and sensors 128 can be operatively coupled to a control portion of the transmitter 102 based on feedback signals from the sensors 124.

[0038] Examples of wireless power systems can be found in U.S. patent application publication No. 2010 / 0141042, published on June 10, 2010, and entitled “Wireless Energy Transfer System,” and U.S. patent application publication No. 2012 / 0112535, published on May 10, 2012, and entitled “Wireless Energy Transfer for Vehicles,” both of which are incorporated herein by reference in their entirety.

[0039] In some embodiments, the exemplary impedance matching networks 110, 118 may include one or more variable impedance components. The one or more variable impedance components may be collectively referred to herein as a "tunable matching network" (TMN). The TMN may be used to adjust the impedance (e.g., including reactance) of the wireless power transmitter 102 and / or receiver 104. In some embodiments, the (multiple) tunable matching network(s) may be referred to as a "tunable reactance circuit." In some applications (e.g., wireless power transmission), the impedance seen by the wireless power transmitter 102 and receiver 104 may change dynamically. In such applications, impedance matching between the receiver resonator coil (114) and the load 120 and the transmitter resonator coil (112) and the power source 105 may be required to prevent unnecessary energy loss and excess heat. The impedance seen by the resonator coils may be dynamic, in which case a dynamic impedance matching network may be provided to match the changing impedance to improve the performance (e.g., efficiency, power delivery, etc.) of the system 100. In the case of the power source 105 in the wireless power system 100, the impedance seen by the power source 105 can be highly variable due to changes in the load 120 receiving power (e.g., a battery or battery charging circuit) and changes in the coupling between the transmitter 102 and the receiver 104 (e.g., caused by changes in the relative positions of the transmitter and receiver resonant coils). Similarly, the impedance seen by the receiver resonator 114 can also dynamically change due to changes in the load 120 receiving power. Furthermore, the desired impedance matching for the receiver resonator 114 can be different for different coupling conditions and / or power supply conditions. Thus, power transmission systems transmitting and / or receiving power via, for example, highly resonant wireless power transmission, may need to configure or modify the impedance matching networks 110, 116 to maintain efficient power transmission. One or more components of the TMN can be configured to present an impedance between the minimum and maximum impedance achievable by the particular component. In various embodiments, the achievable impedance can depend on the operating frequency of the wireless power system 100 (e.g., 80 kHz to 90 kHz). This can be performed continuously, intermittently, or at certain points in the power transmission (e.g., at the beginning of the power transmission). Examples of tunable matching networks can be found in U.S. Patent Application Publication No. 2017 / 0217325, published on August 3, 2017, and entitled "Controlling a Wireless Power Transfer System," and U.S. Patent Application Publication No. 2017 / 0229917, published on August 10, 2017, and entitled "PWM Capacitor Control," both of which are hereby incorporated by reference in their entirety.

[0040] A high-power wireless power transmitter can be configured to transmit wireless power in applications such as powering and / or charging batteries for vehicles, industrial machines, robots, or electronic devices that rely on high power. For illustrative purposes, the following disclosure focuses on wireless power transmission for vehicles. However, it should be understood that any one or more of the embodiments described herein can be applied to other applications where wireless power can be utilized.

[0041] Low Power Excitation (LPE) Overview

[0042] As used herein, "low power excitation" may include driving a wireless power transmitter at relatively low power, current, and / or voltage. As discussed above, low power excitation may be particularly challenging in wireless power transmitters configured to operate at high power (e.g., 500 W to 20,000 W or more).

[0043] In an exemplary embodiment, low power excitation of a high power transmitter may be used in positioning a vehicle having a wireless power receiver 104 over a wireless power transmitter 102 (see FIG. Figure 8 and the section below having the title “Vehicle Positioning”). In particular, it may be important to appropriately position the receiver resonator coil above the transmitter resonator coil for maximizing the transmit power of the receiver 104 and / or maximizing the efficiency of the maximized power transmission. Examples of vehicle positioning systems and methods can be found in U.S. Patent Application Publication No. 2018 / 0056800, published on March 1, 2018, and entitled “Relative Position Determination and Vehicle Guidance in a Wireless Power Transfer System”; U.S. Patent No. 10,461,587, published on October 29, 2019, and entitled “Method and Apparatus for Positioning a Vehicle Using Foreign Object Detection”; U.S. Patent No. 10,343,535, published on July 9, 2019, and entitled “Wireless Power Antenna Alignment Adjustment System for a Vehicle”; and U.S. Patent No. 10,090,885, published on October 2, 2018, and entitled “Antenna Alignment and Vehicle Guidance for Wireless Charging of Electric Vehicles”; the entire contents of each of which are incorporated herein by reference.

[0044] Figure 1BThe vehicle 150 is shown with an exemplary receiver resonator coil 204 positioned above the transmitter resonator coil 202. In wireless power transmission (WPT) mode, the transmitter resonator coil 202 is typically energized at high power (e.g., on the order of several kilowatts) for the purpose of transmitting power to the receiver coil 204 via an electromagnetic field, ultimately charging the battery of the vehicle 150. In low power excitation (LPE) mode, the transmitter resonator coil 202 can be excited at low power (e.g., on the order of one watt or tens of watts), thereby generating a low-energy magnetic field. As discussed herein, in various embodiments, this low-energy magnetic field can be used for vehicle positioning or alignment.

[0045] In some embodiments, the wireless power transmitter 102 may be in LPE mode before being in wireless power transmission (WPT) mode. For example, once the vehicle 150 is guided to a desired parking location, the transmitter 102 may switch from LPE mode to WPT mode to begin charging the battery of the vehicle 150. In some embodiments, if the vehicle 150 moves during WPT mode, the transmitter 102 may enter LPE mode (e.g., interrupting WPT mode) to determine whether the vehicle 150 (and therefore the receiver 104) should be repositioned relative to the transmitter 102. For example, if the vehicle 150 is weighed down by cargo in the trunk or passengers sitting in the vehicle 150, the vehicle 150 and receiver 104 may be moved. Additional examples are provided in Figure 8 and described in the following section with the title "Vehicle Positioning".

[0046] In some embodiments, the field generated by the wireless power transmitter 102 may be exposed to its environment (including people, animals, etc.) before the wireless power receiver 104 is positioned above or near the transmitter 102. In some embodiments, the receiver may be positioned above or near the transmitter 102, but power transmission may not be initiated until the receiver 104 is aligned with the transmitter 102. In such a case, the wireless power transmitter 102 may be driven such that the magnetic flux density generated by the transmitter resonator coil 202 is less than or equal to a field safety threshold, e.g., less than 10 microteslas, less than 25 microteslas, less than 50 microteslas, etc. In some embodiments, the field safety threshold is between 10-15 microteslas. The field safety threshold may be determined based on limitations on field exposure to people and / or electromagnetic compatibility (EMC) issues.

[0047] In some embodiments, the magnetic flux density can be determined at the surface of the transmitter resonator coil 202 that faces the receiver resonator coil 204. For example, the magnetic flux density can be determined at the surface 152 of the packaging of the transmitter resonator coil 202. For example, the transmitter resonator coil 202 can be encapsulated or contained in a material (e.g., a non-conductive material including plastic, rubber, etc.) to protect electronic components from the environment and / or provide safety for humans or animals. In some embodiments, the magnetic flux density can be determined at a specified distance and / or angle from the surface 152 of the transmitter resonator coil 202 or its packaging. In some embodiments, to meet a field safety threshold, the transmitter 102 can be driven such that the current in the transmitter resonator coil 202 is limited to less than or equal to 2 amps, less than or equal to 1 amp, or less. In some embodiments, to meet a field safety threshold, the transmitter 102 can be driven such that the current in the transmitter resonator coil 202 is limited to less than or equal to 325 milliamps rms + / - 9% (e.g., less than a value between 295-355 milliamps rms). In some embodiments, transmitter 102 may be driven with low power in the range of 1 W to 50 W.

[0048] In LPE mode, the receiver resonator coil 204, or another coil positioned on or near the receiver resonator coil 204, can “pick up” the low-energy magnetic field generated by the transmitter resonator coil 202. In some embodiments, by picking up the magnetic field, the wireless power system 100 (or a device coupled to or coordinated with the pickup coil) can determine the strength of the field to determine whether the receiver resonator coil 204 is in a sufficiently high coupling position relative to the transmitter resonator coil 202 to achieve efficient power transmission and / or maximum power delivery.

[0049] In some embodiments, by determining the coupling between the transmitter resonator coil 202 and the receiver resonator coil 204, the system can determine whether the receiver resonator coil 204 is optimally positioned relative to the transmitter resonator coil 202. In some cases, a high coupling position can be achieved when the coupling between the receiver resonator coil 204 and the transmitter resonator coil 202 is high enough to achieve efficient high-power transmission to the vehicle's battery (e.g., with greater than 90% efficiency from the power source to the battery). In other examples, the strength of the field, combined with the known geometry of the wireless power system and / or the pickup coil, can be used to further determine whether the high coupling position is a safe position for the transmitter 102 to transmit power (e.g., for EMF exposure, device operation, etc.). In some embodiments, the current in the transmitter resonator coil 202 can be determined and, in some cases, maintained at a constant level for a range of coupling positions. In some cases, the determination of coupling is simplified by maintaining a constant current in the transmitter resonator coil 202 (e.g., by keeping a variable of the coil current constant). Using such information, system 100 (or a separate positioning system) can inform and / or guide the vehicle or the user of the vehicle to a desired relative position based on safety, efficiency, coupling, or any other system parameter (whether such position is also a relative maximum coupling position).

[0050] In some embodiments, one or more sensing coils (e.g., 2, 3, 4, 6, 8, or more) may be positioned on or near the vehicle 150 and / or receiver 104 to pick up the magnetic flux generated by the transmitter 102. The sensing coils may be coupled to a processor configured to determine the magnetic flux density at the sensing coils or the relative magnetic flux density between two or more sensing coils. The received voltage and / or the compensated current (e.g., shorted directly or through another element such as an inductor, capacitor, or resistor) may be used to determine the location of the relative magnetic flux density (e.g., relative to the surface of the resonator coil). In some embodiments, multiple coils may be sized, shaped, positioned, oriented, and / or connected to each other to generate a voltage and / or compensation current close to 0V or 0A, respectively, to determine whether such located coils are sufficiently distributed relative to the transmitter resonator coil 204.

[0051] Figures 2A to 2D An exemplary sensing coil geometry is shown relative to an exemplary wireless power receiver resonator coil 204. Examples may include two (2) coils 206 in a "figure 8" series of loops (see Figure 2A ) or four (4) coils 208 in a cloverleaf pattern, wherein the sensing coils are in alternating directions (see Figure 2B ). Other examples may use odd or even numbers of multiple coils. Figure 2CAn example of a single coil 210 is shown that is concentric with the receiver resonator coil 204 . Figure 2D 204. It will be appreciated that individual coils or multiple coils may be positioned to provide additional geometric information about the magnetic flux density for positioning and / or other purposes. For example, the use of multiple coils (e.g., coils 206, 208, 212) may provide specific information about the location of the magnetic flux density compared to a single coil. In another example, the positioning of one or more coils may provide specific information about the location of the magnetic flux density. It will also be appreciated that the examples of coil configurations provided herein are not intended to be limiting, and that other coil configurations are within the scope of the present invention.

[0052] In some embodiments, to achieve a current less than or equal to 2 amps in the transmitter resonator coil 202 and / or to achieve an electromagnetic field less than or equal to a field safety threshold generated by the transmitter coil 202, any one or more of the following parameters of the transmitter 102 may be included and / or adjusted:

[0053] Drive Voltage. In various embodiments, transmitter 102 may include a drive circuit configured to generate a relatively low voltage (e.g., less than 20V, less than 10V, less than 5V, etc.). For example, the drive circuit of transmitter 102 may be configured to apply a voltage of approximately 5V at the input of matching network 110 after inverter 108. This may generate a similar voltage at transmitter resonator coil 202. In some embodiments, the drive circuit includes one or more of a fixed voltage source, a variable voltage source, a DC-DC converter, a flyback converter, or a low dropout (LDO) regulator with a reference voltage. It should be understood that other types of voltage sources may be used to drive transmitter 102. In some embodiments, the voltage source may be switched on and off at transmitter 102 or may be a fixed part of the transmitter's circuitry. In some embodiments, inverter 108 and / or PFC circuit 106 may be configured to drive transmitter 102 to generate the low voltage.

[0054] Drive Current. In various embodiments, the drive current of transmitter 102 can be adjusted by varying the drive voltage and determining the current in transmitter 102 (e.g., via a feedback mechanism such as a current sensor). In some embodiments, transmitter 102 may include a drive current mechanism to generate the drive current (see, e.g., Figure 3 ). Figure 3 is a schematic diagram of a portion 300 of a wireless power transmitter 102 configured for low power excitation. In this embodiment, the transmitter resonator coil 202 may be disconnected from the inverter 108 via a switch 304 and (ii) driven by a current source 306 to produce a coil current of less than 2 amps.

[0055] TMN Impedance. In various embodiments, the TMN in transmitter 102 (as part of matching network 110) can be tuned so that it presents a specific impedance. The TMN can be tuned to present an impedance between a minimum achievable impedance and a maximum achievable impedance. Specifically, the components of the TMN can be tuned to present the minimum impedance (e.g., minimum inductive reactance or minimum positive reactance) achievable by the specific TMN to the driver circuit of transmitter 102. The driver circuit can include components of transmitter 102 in the power path before matching network 110, including inverter 108, PFC circuit 106, and / or any other driver circuit (e.g., one or more LPE circuit components as described herein). In some embodiments, the minimum achievable impedance is predetermined for a particular wireless power system 100 based on the specific specifications of the components selected in the TMN. In some embodiments, the controller 122 of the wireless power transmitter 102 can determine the minimum achievable impedance of the TMN. For example, the controller 122 can send a signal to the adjustable components with settings to achieve the specific impedance.

[0056] In some embodiments, to achieve a desired impedance, one or more switches (e.g., field-effect transistors (FETs), metal-oxide-semiconductor FETs (MOSFETs), etc.) of the TMN can be adjusted so that the switches are fully off and present the maximum capacitive (e.g., negative) reactance achievable by a particular TMN, thereby reducing the impedance of the branch having the TMN (see, for example, the upper and / or lower branches of component 406). When the TMN FETs are fully off throughout the switching cycle, the effective capacitive reactance of the TMN will be at its minimum value (in other words, at its most negative value). When the capacitive reactance is summed with the inductive reactance of the fixed inductor in series with the TMN, it results in the minimum achievable impedance for the X3 branch. Achieving a low or minimum impedance can have the effect of minimizing the variation of the coil current in the transmitter resonator coil 202 within the coupling range of the resonator coil. As discussed above, the coupling range can be based on one or more positions of the receiver resonator coil 204 relative to the transmitter resonator coil 202. Another advantage of adjusting the TMN to achieve minimum inductive reactance can include minimizing the amount of control required to produce a desired current level in the transmitter resonator coil.

[0057] Inverter Phase Shift Angle. The phase shift angle of the inverter 108 of the transmitter 102 can be adjusted by a controller 122 coupled to the inverter 108. Specifically, a pulse width modulation (PWM) generator (see, e.g., generator 422) of the controller 122 can be configured to control the gate drivers (see, e.g., driver 418) of the transistors coupled to the inverter 108 to produce a desired phase shift angle. The inverter phase shift can include applying a controllable delay between the complementary PWM pair (e.g., signals PWM1 and PWM2) driving transistors Q1 and Q2 and the complementary PWM pair (e.g., signals PWM3 and PWM4) driving transistors Q3 and Q4. The delay can range from 0 to 180 degrees. When the phase shift angle is 0 degrees, the inverter output voltage is zero because the output is short-circuited due to either (i) transistors Q1 and Q3 being on simultaneously or (ii) transistors Q2 and Q4 being on simultaneously.

[0058] The phase shift angle may depend on the specific wireless power system components and parameters, including the DC voltage bus, specific impedance matching, etc. In some embodiments, the phase shift angle may be defined by two conventions. Specifically, in a first convention, when the phase angle is at zero (0) degrees, the coil current may be at or near its maximum level achievable by a specific transmitter 102, and when the phase angle is at 180 degrees, the coil current may be at or near zero. In a second convention (the opposite of the first convention), when the phase angle is at 180 degrees, the coil current may be at or near its maximum level achievable by a specific transmitter 102, and when the phase angle is at zero (0) degrees, the coil current may be at or near zero. For example, using the second convention, if the phase shift angle is approximately 5 degrees, the coil current may be at a low level. In some embodiments, the combination of duty cycle and inverter phase angle may be varied to improve switching behavior and thereby reduce ringing, reduce harmonics, increase or reduce body diode conduction and / or reduce switching losses, etc.

[0059] Pulse Width Modulation (PWM). In some embodiments, a PWM generator (see, e.g., generator 422) of the controller 122 may adjust the pulse width or duty cycle in one or more transistors of the inverter 108 to achieve a desired voltage level in the transmitter resonator coil 202.

[0060] Power Factor Correction (PFC). The PFC circuit 106 can be enabled or disabled or adjusted to produce a specific bus voltage V BUS .

[0061] The following are the driving voltages V BUS (V) and peak coil current I sl (A PEAK ) and the RMS coil current I sl (A RMS ) are:

[0062]

[0063] Table 1. Example values for drive voltage and transmitter resonator coil current.

[0064] In some embodiments, the voltage on the transmitter resonator coil 202, one or more field sensors, or one or more sensing coils can be used to measure the field level of the electromagnetic field from the transmitter resonator coil 202 and can be fed into a control system (see, e.g., control systems 412, 506, 604, 708). Voltage feedback can be used to adjust one or more of the transmitter's components and / or parameters (e.g., power, voltage, and / or current) to set the desired field level. For example, the transmitter 102 can include a current sensor (see, e.g., current sensor 416) configured to determine one or more current characteristics (e.g., level, frequency, phase, etc.) in the transmitter 102. The current reading can be provided as feedback to the control system (e.g., control system 412, 506, 604, 708) and used to adjust one or more transmitter components and / or parameters, as described above. This feedback mechanism can be used alone or in combination with other sensors (e.g., current sensors and / or voltage sensors).

[0065] In the following description, for the sake of clarity and simplicity, the system for low-power excitation and the corresponding method are discussed together. For example, the system 400 for low-power excitation and the method 450 for low-power excitation are discussed together. Note that the order of the steps of each method described herein is intended to illustrate exemplary embodiments and can be performed or executed in another order or combination to achieve the desired output.

[0066] LPE—First Exemplary Embodiment

[0067] Figure 4A is a schematic diagram of an exemplary wireless power transmitter 400 including a low power excitation (LPE) circuit 402 . Figure 4BFIG4 is a flow chart of an exemplary method 450 for low power excitation of a wireless power transmitter 400. In the exemplary embodiment, the low power energizing circuit 402 includes a variable voltage source 404, a diode D1, and relays 408a and 408b. The exemplary variable voltage source 404 may be coupled in parallel between the PFC circuit 106 and the inverter 108. The PFC circuit 106 may receive power directly or indirectly from a power source (e.g., an AC power mains, a battery, etc.) and provide the required power correction for the wireless power transmitter 400 during wireless power transfer (WPT) mode. As discussed above, during WPT mode, the wireless power transmitter 400 may operate at significantly higher power, voltage, and / or current levels than during operation in the low power energizing mode. Note that in the WPT mode, the gates G1, G2, G3, and G4 of the transistors Q1, Q2, Q3, and Q4 of the inverter 108 are driven by the gate driver 418. The gate driver 418 may receive PWM signals PWM1, PWM2, PWM3, PWM4 generated by a PWM generator 422. The PWM generator 422 may receive a control signal from a digital controller 424, such as a signal indicating a phase shift angle of the PWM signal.

[0068] The exemplary variable voltage source 404 can be coupled in series with a diode D1 to block high currents so that during wireless power transfer (WPT) mode, the variable voltage source 404 is not damaged by the active power, current, and / or voltage from the PFC circuit 106. The diode D1 and the relay can allow current to flow in one direction and can be useful in enabling the voltage source 404 in driving the transmitter 102. The relay can be used to de-energize the inverter bias and other power electronics of the transmitter 102. During WPT mode, the PFC circuit 106 can be enabled (e.g., turned on) by one or more components of the control system 412 (e.g., the source electronic power controller (SEPC) 410). In the exemplary embodiment, in WPT mode, the control system 412 can also send a signal to the relay 408a to close the circuit between the PFC circuit 106 and the inverter 108. It should be noted that in WPT mode, the control system 412 may signal the relay 408b to open in order to disconnect the variable voltage source 404 to avoid damage to the power source 404 and / or avoid disconnect inefficiencies in the power path driving the wireless power transmission.

[0069] Referring to step 452 of method 450, in LPE mode, the PFC circuit 106 can be disconnected from the inverter 108. For example, one or more components of the control system 412 (e.g., SEPC 410) can send a control signal to relays 408a, 408b to open the circuit, causing the PFC circuit 106 to be disconnected (and therefore unable to drive the transmitter 400). In some embodiments, the SEPC 410 can communicate with a zero voltage switching (ZVS) error generation module 414. In WPT mode, the ZVS error generation module 414 is a protection mechanism that generates a flag and disables power transmission if the phase angle between the inverter output voltage and current falls below 12 degrees. This error is intended to protect the system from damaging operation of semiconductors that could cause failures. In LPE mode, ZVS error generation can be disabled because the voltage-current (V1) phase seen by the inverter 108 is expected to be below the threshold for ZVS detection. In LPE mode, this condition is acceptable because the power handled by the inverter 108 is very small, so the switching losses are not destructive.

[0070] The SEPC 410 may directly or indirectly receive a signal I1s_ref from a current sensor 416. The signal I1s_ref is a reference signal based on a current measurement I1s made by the sensor 416 coupled to the transmitter resonator coil 202 (eg, serially, shunt, inductively, etc.).

[0071] In step 454, the impedance of one or more variable impedance components (e.g., reactance of the TMN) 406 of the impedance network can be adjusted to achieve the minimum inductive reactance that can be achieved for a particular TMN component. For example, the upper branch component labeled "X3sa_minΩ-X3sa_maxΩ" and / or the lower branch component labeled "X3sb_minΩ-X3sb_maxΩ" can be adjusted to achieve the desired impedance (e.g., minimum reactance). The TMN component 406 can be adjusted by one or more components of the control system 412 (e.g., tunable X3S controller 420, SEPC 410, etc.). For example, the tunable component 406 can be adjusted by the controller 420, which receives a signal (e.g., signal "LPE ON / OFF") from the SEPC 410 to adjust the component 406 to achieve the minimum reactance during the LPE mode (e.g., when the SEPC 410 has disabled the PFC circuit 106 and enabled the variable voltage source 404).

[0072] In step 456, the variable voltage source 404 drives the transmitter 400 so that the current in the transmitter resonator coil 202 is within the target current range for the LPE mode. To do so, the SEPC 410 may send one or more signals to close the relay 408b and enable the variable voltage source 404. In this embodiment, the inverter is capable of converting a constant (DC) voltage to a high-frequency oscillating (AC) voltage. In some embodiments, the method 450 includes receiving, by the SEPC 410, a current signal from the sensor 416 indicating whether the current is within the target range for the LPE mode (e.g., less than 1A, less than 3A, less than 5A, etc.).

[0073] LPE-Second Exemplary Embodiment

[0074] Figure 5A is a schematic diagram of an exemplary wireless power transmitter 500 including a low power excitation (LPE) circuit 502 . Figure 5B 5 is a flow chart of an exemplary method 550 for low-power excitation of transmitter 500. Specifically, system 502 includes a fixed low-voltage source 504 coupled in series with diode D1. In this embodiment, fixed low-voltage source 504 can be turned on (operable) during both LPE mode and WPT mode. In some embodiments, fixed low-voltage source 504 is hardwired into the circuitry of transmitter 500.

[0075] In step 552 of method 550, in LPE mode, the PFC circuit 106 is disabled. For example, one or more components of the control system 506 (e.g., the digital controller 424) may send a signal to enable or disable the PFC circuit 106 upon entering LPE mode. Note that, as described above, in LPE mode, the ZVS error generation 414 may be disabled.

[0076] In step 554, the impedance 406 of one or more variable impedance components 406 (e.g., the reactance of the TMN) may be adjusted to obtain a minimum reactance (e.g., minimum inductive reactance) that can be achieved for a particular TMN component 406. For example, the upper branch component labeled "X3sa_minΩ-X3sa_maxΩ" and / or the lower branch component labeled "X3sb_minΩ-X3sb_maxΩ" may be adjusted to obtain a desired impedance (e.g., minimum reactance). The TMN component 406 may be adjusted by one or more components of the control system 506 (e.g., the digital controller 424, the tunable X3S controller 420, the SEPC 410, etc.). For example, the controller 420 may receive a signal X3s_min from the digital controller 424 indicating that the reactance should be adjusted to the minimum achievable reactance. This may have the effect of minimizing the variation of the current in the transmitter resonator coil 202 within the coupling range of the resonator coil. Reference Figure 1B The coupling range may be based on one or more positions of the receiver resonator coil 204 relative to the transmitter resonator coil 202. In some embodiments, the method 550 may include receiving a signal representing a current characteristic (e.g., level, phase, frequency) from the sensor 416. The signal may be provided to the control system 506 for confirming the current characteristic in the coil 202.

[0077] In step 556, any remaining variation in the coil current can be minimized by adjusting the phase shift angle of the pulse width modulation (PWM) signals for the transistors of the inverter 108. The PWM signals can be provided to the inverter 108 by one or more components of the control system 506. Specifically, the digital controller 424 can send a signal θinv_ps to the PWM generator 422 to generate specific PWM signals PWM1, PWM2, PWM3, PWM4 for the gate drivers 418. The drivers 418 can then drive the gates G1, G2, G3, G4 corresponding to the respective transistors Q1, Q2, Q3, Q4 of the inverter 108.

[0078] In some embodiments, the phase shift angle can be adjusted between 0 degrees and 180 degrees so that the magnetic flux density is less than or equal to the field safety threshold. This can include adjusting the phase shift angle to adjust the current level to achieve a magnetic flux density at or below the field safety threshold. Specifically, with reference to Figure 5C , the relationship between the coil current and the phase shift angle is approximately linear and monotonic. Using this relationship, by determining the coil current and / or magnetic flux density, negative feedback can be provided to the controller to adjust the phase shift angle to suppress interference in the transmitter coil current. Note that the transmitter coil current can be based on the voltage induced in the loop near the transmitter resonator coil 202. The coil current can be determined by the following relationship:

[0079]

[0080] In some embodiments, source 504 can drive the emitter at a voltage of 30 V or less. For example, to obtain 1 A using a fixed voltage level of approximately 12 V generated by source 504 RMS The inverter phase shift angle can be adjusted by the control system 506 to about 60 degrees based on the approximate coil current.

[0081] LPE-Third Exemplary Embodiment

[0082] Figure 6A is a schematic diagram of an exemplary wireless power transmitter 600 configured for low power excitation. Figure 6B is a flow chart of an exemplary method 650 for low power excitation of transmitter 600.

[0083] In step 652 of method 650 , the PFC circuit 106 may be configured to BUS The PFC circuit 106 can be configured to output a minimum voltage V BUS_min With the maximum voltage V BUS_max In some embodiments, during LPE mode, the bus voltage V bus = equal to the minimum bus voltage V that a particular PFC circuit 106 is configured to output bus_min For example, one or more components of the controller 604 (eg, the digital controller 424) may send a signal to the PFC circuit 106 to adjust the voltage to the minimum bus voltage V BUS_min Note that, as described above, in LPE mode, ZVS error generation 414 may be disabled.

[0084] In step 654, the impedance of one or more variable impedance components (e.g., reactance of the TMN) 406 can be adjusted to obtain the minimum reactance (e.g., minimum inductive reactance) achievable for a particular TMN component 406. For example, the upper branch component labeled "X3sa_minΩ-X3sa_maxΩ" and / or the lower branch component labeled "X3sb_minΩ-X3sb_maxΩ" can be adjusted to obtain the desired impedance (e.g., minimum reactance). The TMN component 406 can be adjusted by one or more components of the control system 604 (e.g., digital controller 424, tunable X3S controller 420, SEPC 410, etc.). For example, the controller 420 can receive a signal X3s_min from the digital controller 424 indicating that the reactance should be adjusted to the minimum achievable reactance. This has the effect of minimizing the variation in coil current within the coupling range of the resonant coil.

[0085] In step 656, any remaining variation in the coil current can be minimized by adjusting the phase shift of the pulse width modulation (PWM) signal input to each of the transistors of the inverter 108. The PWM signal can be provided to the inverter 108 by one or more components of the control system 604. Specifically, the digital controller 424 can send a signal to the PWM generator 422 to generate specific PWM signals PWM1, PWM2, PWM3, PWM4 for the gate driver 418. The driver 418 can then drive the gates G1, G2, G3, G4 corresponding to the respective transistors Q1, Q2, Q3, Q4 of the inverter 108. For example, in order to generate approximately 1A at a voltage level of approximately 380V as generated by the PFC circuit 106, the gate driver 418 can generate a specific PWM signal PWM1, PWM2, PWM3, PWM4 for the gate driver 418. The gate driver 418 can then drive the gates G1, G2, G3, G4 corresponding to the respective transistors Q1, Q2, Q3, Q4 of the inverter 108. For example, in order to generate approximately 1A at a voltage level of approximately 380V as generated by the PFC circuit 106, the gate driver 418 can generate a specific PWM signal PWM1, PWM2, PWM3, PWM4 for the gate driver 418. RMS The inverter phase shift angle can be adjusted by the controller 604 to be less than about 5 degrees based on the approximate coil current.

[0086] LPE-Fourth Exemplary Embodiment

[0087] Figure 7A is a schematic diagram of an example wireless power transmitter 700 including a low power excitation (LPE) circuit 702 . Figure 7B 7 is a flow chart of an exemplary method 750 for low power excitation of transmitter 700. LPE circuit 702 includes a variable low voltage source 704 coupled in series with diode D1. LPE circuit 702 is coupled in parallel between PFC circuit 106 and inverter 108. Variable low voltage source 704 is configured to receive a signal representing bus voltage V from digital controller 424. BUS The controller 424 may determine the V output of the source 704 during the LPE mode. BUS In some embodiments, the controller 424 can be configured to time the signals to the PFC circuit 106 and the power source 704 to ensure that the PFC circuit 106 is disabled before or at the same time as the voltage source 704 is turned on. Note that in this embodiment, the phase shift of the PWM signals (e.g., PWM1, PWM2, PWM3, PWM4) input to each of the transistors Q1, Q2, Q3, Q4 of the inverter 108 can be fixed.

[0088] In step 752, during LPE mode, the PFC circuit 106 is disabled. In some embodiments, one or more components of the control system 708 (e.g., the digital controller 424) are configured to transmit a signal to the PFC circuit 106 to enable or disable the PFC circuit 106. For example, during WPT mode, the PFC circuit 106 is enabled. Note that, as described above, in LPE mode, the ZVS error generation 414 can be disabled.

[0089] In step 754, the impedance of one or more variable impedance components (e.g., reactance of the TMN) 406 of the impedance network can be adjusted to obtain the minimum inductive reactance achievable for a particular TMN component. In this example, the upper branch component labeled "X3sa_minΩ-X3sa_maxΩ" and / or the lower branch component labeled "X3sb_minΩ-X3sb_maxΩ" can be adjusted to obtain the desired impedance (e.g., minimum reactance). The TMN component 406 can be adjusted by one or more components of the control system 412 (e.g., tunable X3S controller 420, SEPC 410, etc.).

[0090] In step 756, the variable low voltage source 704 is configured to drive the transmitter 700 so that the transmitter resonator coil 202 generates a magnetic field having an amplitude less than or equal to the field safety threshold. In some embodiments, the source 704 can drive the transmitter 700 with a voltage between approximately 4V and 5V. For example, to generate 1A at a fixed phase shift angle, RMSThe voltage level of the variable low voltage source is adjusted to between approximately 4V and 5V to obtain the approximate coil current.

[0091] Vehicle Positioning

[0092] The low power excitation components, systems, and methods disclosed herein may form part of a wireless power system 100 that implements various other performance and safety verifications before, during, or after wireless power transmission.

[0093] Figure 8 FIG8 is a flow chart 800 illustrating one example of a series of steps that may be performed in the wireless power system 100 before and / or during wireless power transmission. In step 802, a communication link is established between the wireless power transmitter 102 and the wireless power receiver 104. The link may be, for example, over a Wi-Fi network or communication protocol, The connection may be established over a link, or more generally over any link, connection, or communication protocol over which the transmitter 102 and receiver 104 may communicate.

[0094] Next, in step 804, a system processor (e.g., any of the processors disclosed herein or another processor in communication with the processors disclosed herein) uses any of the methods disclosed herein to determine the relative position of the wireless power receiver 104 and / or a classification associated with the relative position of the receiver. The system processor then generates a signal including information about the relative position and / or classification of the receiver and transmits the signal to another processor, a controller, or a display interface.

[0095] In optional step 806, the system (i.e., the system processor or another processor, circuit or controller) can use the information from the transmitted signal to provide vehicle guidance information to the vehicle operator or autonomous driving system. In some embodiments, this step can include displaying an indicator on a vehicle display unit to provide guidance information.

[0096] Next, in step 808, the system determines whether alignment is complete based on the relative position or classification of the relative position of the wireless power receiver 104, i.e., whether the wireless power receiver 104 is within a predetermined distance of the wireless power transmitter 102, or whether the wireless power receiver 104 is assigned to a specific classification. If alignment is not achieved, control returns to step 804; if alignment is achieved, control passes to step 810.

[0097] In optional step 810, the system performs additional environmental and safety checks. These may include, for example, checking for foreign objects, checking for living bodies, checking for vehicle / receiver motion, and monitoring / checking various other safety systems and operating parameters. If all checks and systems are met, then in step 812, power transfer from the wireless power transmitter 102 to the wireless power receiver 104 is initiated.

[0098] After a period of time has elapsed, wireless power transmission may optionally be interrupted at step 814. Various criteria and / or signals may cause the interruption of power transmission. In some embodiments, for example, power transmission may be periodically interrupted to perform additional system checks. In certain embodiments, power transmission may be interrupted when a system sensor generates a signal indicating an irregular event, such as unexpected acceleration of the vehicle / receiver, a change in capacitance of the vehicle / receiver, and / or a change in position of the vehicle receiver. In some embodiments, power transmission may also be interrupted when certain system operating / performance parameters, such as voltage and / or current induced in the wireless power receiver, change.

[0099] After power transmission has been interrupted, control returns to step 804 to perform an alignment check to ensure that the wireless power transmitter 102 and receiver 104 remain aligned. If aligned, and if the environmental and safety checks pass in step 810, control eventually returns to step 812 and power transmission is restarted.

[0100] Hardware and software implementation

[0101] Figure 9 9 is a block diagram of an example computer system 900 that can be used to implement the systems and methods described herein. A general-purpose computer, network device, mobile device, or other electronic system may also include at least a portion of system 900. System 900 includes a processor 910, memory 920, storage device 930, and input / output device 940. Each of components 910, 920, 930, and 940 can be interconnected, for example, using a system bus 950. Processor 910 is capable of processing instructions for execution within system 900. In some embodiments, processor 910 is a single-threaded processor. In some embodiments, processor 910 is a multi-threaded processor. Processor 910 is capable of processing instructions stored in memory 920 or storage device 930.

[0102] Memory 920 stores information within system 900. In some implementations, memory 920 is a non-transitory computer-readable medium. In some implementations, memory 920 is a volatile memory unit. In some implementations, memory 920 is a non-volatile memory unit. In some instances, some or all of the above data may be stored on a personal computing device, in a data storage device hosted on one or more centralized computing devices, or via a cloud-based storage device. In some instances, some data is stored in one location and other data is stored in another location. In some instances, quantum computing may be used. In some instances, functional programming languages may be used. In some instances, electronic storage such as flash-based memory may be used.

[0103] The storage device 930 can provide mass storage for the system 900. In some implementations, the storage device 930 is a non-temporary computer-readable medium. In various implementations, the storage device 930 may include, for example, a hard disk device, an optical disk device, a solid-state drive, a flash drive, or some other mass storage device. For example, the storage device can store long-term data (e.g., database data, file system data, etc.). The input / output device 940 provides input / output operations for the system 900. In some implementations, the input / output device 940 may include one or more of the following: a network interface device (e.g., an Ethernet card), a serial communication device (e.g., an RS-232 port), and / or a wireless interface device (e.g., an 802.11 card, a 3G wireless modem, or a 4G wireless modem). In some embodiments, the input / output device may include a drive device configured to receive input data and send output data (e.g., a keyboard, a printer, and a display device 960) to other input / output devices. In some instances, a mobile computing device, a mobile communication device, and other devices may be used.

[0104] In some implementations, at least a portion of the above methods may be implemented by instructions that, upon execution, cause one or more processing devices to perform the above processes and functions. Such instructions may include, for example, interpreted instructions such as script instructions, or executable code, or other instructions stored in a non-transitory computer-readable medium. Storage device 930 may be implemented in a distributed manner via a network (such as a server farm or a group of widely distributed servers), or may be implemented in a single computing device.

[0105] Despite Figure 9While example processing systems have been described herein, the functional operations and processes described herein may be implemented in other types of digital electronic circuits, tangibly embodied computer software or firmware, computer hardware, structures disclosed herein and their structural equivalents, or a combination of one or more thereof. The embodiments of the subject matter described herein may be implemented as one or more computer programs (i.e., one or more modules of computer program instructions encoded on a tangible, non-volatile program carrier) for execution by a data processing apparatus or for controlling the operation of the data processing apparatus. Alternatively or in addition, the program instructions may be encoded on an artificially generated propagated signal, e.g., a machine-generated electrical, optical, or electromagnetic signal, generated to encode information for transmission to a suitable receiver device for execution by a data processing apparatus. The computer storage medium may be a machine-readable storage device, a machine-readable storage substrate, a random or serial access memory device, or a combination of one or more thereof.

[0106] The term "system" may encompass all kinds of equipment, devices, and machines for processing data, including, for example, a programmable processor, a computer, or multiple processors or computers. A processing system may include specialized logic circuitry, such as an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit). In addition to hardware, a processing system may also include code that creates an execution environment for the computer program in question, such as code constituting processor firmware, a protocol stack, a database management system, an operating system, or a combination of one or more of these.

[0107] A computer program (which may also be referred to or described as a program, software, software application, module, software module, script, or code) may be written in any form of programming language, including compiled or interpreted languages, or declarative or procedural languages, and it may be deployed in any form, including as a standalone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program may, but need not, correspond to a file in a file system. A program may be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, subroutines, or portions of code). A computer program may be deployed to execute on one or more computers located at one site or distributed across multiple sites and interconnected by a communications network.

[0108] The processes and logic flows described in this specification can be performed by one or more programmable computers executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows can also be performed by, and devices can be implemented as, special purpose logic circuitry, such as an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit).

[0109] For example, a computer suitable for executing a computer program may include a general or special purpose microprocessor or both, or any other type of central processing unit. Typically, the central processing unit will receive instructions and data from a read-only memory or random access memory or both. A computer typically includes a central processing unit for executing or performing instructions and one or more memory devices for storing instructions and data. Typically, a computer will also include one or more large-capacity storage devices (e.g., magnetic disks, magneto-optical disks, or optical disks) for storing data, or be operably coupled to receive data from one or more large-capacity storage devices (e.g., magnetic disks, magneto-optical disks, or optical disks), or transfer data to one or more large-capacity storage devices (e.g., magnetic disks, magneto-optical disks, or optical disks) or both. However, a computer does not need to have such a device. In addition, a computer can be embedded in another device, for example, a mobile phone, a personal digital assistant (PDA), a mobile audio or video player, a game console, a global positioning system (GPS) receiver, or a portable storage device (e.g., a universal serial bus (USB) flash drive).

[0110] Computer-readable media suitable for storing computer program instructions and data include all forms of nonvolatile memory, media, and storage devices, including, for example, semiconductor memory devices, such as EPROM, EEPROM, and flash memory devices; magnetic disks, such as internal hard disks or removable disks; magneto-optical disks; and CD-ROM and DVD-ROM disks. The processor and memory can be supplemented by, or incorporated in, special purpose logic circuitry.

[0111] Embodiments of the subject matter described in this specification may be implemented in a computing system that includes a back-end component (e.g., as a data server), or includes a middleware component (e.g., an application server), or includes a front-end component (e.g., a client computer with a graphical user interface or a web browser through which a user can interact with an implementation of the subject matter described in this specification), or any combination of one or more such back-end, middleware, or front-end components. The components of the system may be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include local area networks ("LANs") and wide area networks ("WANs"), such as the Internet.

[0112] A computing system may include clients and servers. A client and server are generally remote from each other and typically interact through a communication network. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other.

[0113] Although this specification contains many specific implementation details, these details should not be interpreted as limiting the scope of the claims, but should be interpreted as descriptions of features that may be specific to a particular embodiment. Certain features described in the context of a separate embodiment in this specification may also be implemented in combination in a single embodiment. On the contrary, the various features described in the context of a single embodiment may also be implemented in multiple embodiments individually or in any suitable sub-combination. In addition, although features may be described above as working in certain combinations and even initially required, one or more features from the required combination may be removed from the combination in some cases, and the required combination may be for a variant of a sub-combination or sub-combination.

[0114] Similarly, although operations are depicted in a particular order in the accompanying drawings, this should not be understood as requiring that such operations be performed in the particular order shown or in sequence, or that all illustrated operations be performed to achieve the desired results. In some cases, multitasking and parallel processing can be advantageous. Moreover, the partitioning of various system components in the embodiments described above should not be understood as requiring such partitioning in all embodiments, and it should be understood that the described program components and systems can generally be combined into a single software product or compressed into multiple software products.

[0115] Certain embodiments of the present subject matter have been described. Other embodiments are within the scope of the following claims. For example, the actions recited in the claims can be performed in a different order and still achieve the desired results. As an example, the processes depicted in the accompanying figures do not necessarily require the particular order or sequential order shown to achieve the desired results. In certain embodiments, multitasking and parallel processing may be advantageous. Additional steps or stages may be provided, or steps or stages may be eliminated from the described processes. Therefore, other implementations are within the scope of the following claims.

[0116] the term

[0117] The phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

[0118] As used in this specification and claims, the term "about," the phrase "approximately equal to," and other similar phrases (e.g., "X has a value of approximately Y" or "X is approximately equal to Y") should be understood to mean that one value (X) is within a predetermined range of another value (Y). Unless otherwise specified, the predetermined range may be ±20%, 10%, 5%, 3%, 1%, 0.1%, or less than 0.1%.

[0119] The indefinite articles "a" and "an" used in the specification and claims should be understood to mean "at least one" unless expressly stated otherwise. The phrase "and / or" used in the specification and claims should be understood to mean "either or both" of the elements so combined, that is, elements that exist in combination in some cases and separately in other cases. Multiple elements listed with "and / or" should be interpreted in the same way, that is, "one or more" of the elements so combined. In addition to the elements specifically identified by the "and / or" clause, other elements may optionally be present, whether related or unrelated to those specifically identified. Therefore, as a non-limiting example, when used in conjunction with open language (such as, "comprising"), a reference to "A and / or B" may refer to only A (optionally including elements other than B) in one embodiment; in another embodiment, only B (optionally including elements other than A); in yet another embodiment, both A and B (optionally including other elements); and so on.

[0120] As used in this specification and claims, "or" should be understood to have the same meaning as "and / or" as defined above. For example, when separating the items in a list, "or" or "and / or" should be interpreted as inclusive, i.e., including at least one of a plurality of elements or a list of elements, but also including more than one, and optionally other unlisted items. Only clearly indicate opposite terms (such as, "only one" or "just one"), or when used in the claims, "consisting of ... " will refer to including just one element in a plurality of elements or a list of elements. Usually, when before an exclusive term, the term "or" used should only be interpreted to indicate exclusive alternatives (i.e., "one or another but not both"), such as, "... or ...", "one in ...", "only one" or "just one". When used in the claims, "consisting essentially of ... " should have its ordinary meaning as used in the field of patent law.

[0121] As used in this specification and claims, the phrase "at least one" with reference to a list of one or more elements should be understood to mean at least one element selected from any one or more elements in the list of elements, but not necessarily including at least one of each and every element specifically listed in the list of elements, and not excluding any combination of elements in the list of elements. This definition also allows for the optional presence of elements other than the elements specifically identified within the list of elements to which the phrase "at least one" refers, whether related or unrelated to those specifically identified elements. Thus, as a non-limiting example, "at least one of A and B" (or equivalently, "at least one of A or B," or equivalently, "at least one of A and / or B") can refer to at least one (optionally including more than one) A in one embodiment, without B (and optionally including elements other than B); in another embodiment, to at least one (optionally including more than one) B in the absence of A (and optionally including elements other than A); in yet another embodiment, to at least one (optionally including more than one) A and at least one (optionally including more than one) B (and optionally including other elements); and so on.

[0122] The use of "including," "comprising," "having," "containing," "involving," and variations thereof, is meant to encompass the items listed thereafter as well as additional items.

[0123] The use of ordinal terms (such as "first," "second," "third," etc.) in the claims to modify claim elements does not in itself imply any priority, precedence, or order of one claim element over another, or the temporal order of performing the acts of the method. Formal terms are used only as markers to distinguish one claim element having a certain name from another element having the same name (but for the use of formal terms) to distinguish the claim elements.

Claims

1. A system for low-power excitation of a wireless power transmitter configured to transmit high power, the system comprising: an inverter comprising at least two transistors configured to be controlled such that a phase shift angle associated with at least one of the transistors is adjustable during low power excitation; at least one variable impedance component coupled to an output of the inverter and configured to be adjusted to obtain a minimum achievable impedance during low power excitation, wherein the at least one variable impedance component is configured to operate between the minimum achievable impedance and a maximum achievable impedance; and The resonator coil of the transmitter is configured to generate a magnetic flux density less than or equal to a field safety threshold during low power excitation.

2. The system according to claim 1, further comprising: A power factor correction circuit is configured to drive the transmitter at a minimum bus voltage during low power excitation, wherein the power factor correction circuit is configured to output a bus voltage between the minimum bus voltage and a maximum bus voltage.

3. The system according to claim 1, further comprising: A power factor correction circuit and a low voltage source coupled to an output of the power factor correction circuit, the low voltage source configured to drive the transmitter during low power excitation.

4. The system according to claim 3, wherein: The power factor correction circuit is disabled during low power excitation.

5. The system according to claim 3, wherein: The low voltage source is one of a variable low voltage source or a fixed low voltage source.

6. The system according to claim 3, wherein: The low voltage source is configured to drive the transmitter such that during low power excitation, a current in the resonator coil is less than or equal to a current limit, wherein the current limit is based on the field safety threshold.

7. The system according to claim 6, further comprising: a controller operably coupled to at least one of: (i) the at least two transistors or (ii) the at least one variable impedance component; as well as A current sensor is coupled to the resonator coil and configured to provide a signal representative of at least one characteristic of the current in the resonator coil to the controller.

8. The system according to claim 7, wherein: The at least one characteristic comprises a level, a phase and / or a frequency of the current in the resonator coil.

9. The system according to claim 1, wherein: The wireless power transmitter is configured to output power at 50 W or less during low power excitation.

10. The system according to claim 1, wherein: The field safety threshold is between 10 microteslas and 15 microteslas.

11. A method for low power excitation of a wireless power transmitter configured to transmit high power, the transmitter comprising an inverter coupled to an input of an impedance network and a transmitter resonator coil coupled to an output of the impedance network, the method comprising: adjusting one or more variable impedance components of the impedance network to obtain a minimum achievable impedance, wherein the variable impedance components are configured to operate between the minimum achievable impedance and a maximum achievable impedance; adjusting a phase shift angle associated with one or more transistors of the inverter; and The transmitter is driven such that the transmitter resonator coil generates a magnetic flux density less than or equal to a field safety threshold.

12. The method according to claim 11, wherein The transmitter includes a power factor correction circuit configured to output a bus voltage between a minimum bus voltage and a maximum bus voltage.

13. The method according to claim 12, wherein: Driving the transmitter such that the transmitter resonator coil generates the magnetic flux density less than or equal to the field safety threshold includes driving the transmitter at the minimum bus voltage via the power factor correction circuit.

14. The method according to claim 12, wherein: The transmitter also includes a low voltage source coupled to the output of the power factor correction circuit.

15. The method according to claim 14, wherein The low voltage source is one of a variable low voltage source or a fixed low voltage source.

16. The method according to claim 14, wherein Driving the transmitter such that the transmitter resonator coil generates the magnetic flux density that is less than or equal to the field safety threshold includes driving the transmitter via the low voltage source.

17. The method of claim 16, driving the transmitter via the low voltage source comprises disabling the power factor correction circuit.

18. The method according to claim 16, wherein Driving the transmitter via the low voltage source includes driving the transmitter such that, during low power excitation, a current in the resonator coil is less than or equal to a current limit, wherein the current limit is based on the field safety threshold.

19. The method according to claim 18, wherein The transmitter includes: a controller operably coupled to at least one of: (i) the one or more transistors of the inverter or (ii) the one or more variable impedance components of the impedance network; and a current sensor coupled to the resonator coil.

20. The method according to claim 19, further comprising: A signal representative of at least one characteristic of the current in the resonator coil is provided to the controller via the current sensor, the at least one characteristic including a level, a phase and / or a frequency of the current in the resonator coil.

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