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

Abstract

To provide methods and systems for low power excitation in wireless power systems.SOLUTION: Disclosed herein are systems and methods for low power excitation of wireless power transmitters configured to transmit high power. The exemplary systems and methods include disabling a power factor correction circuit of the transmitter, and adjusting one or more variable impedance components of the impedance network to obtain a minimum attainable impedance. The variable impedance components can be configured to operate between the minimum attainable impedance and a maximum attainable impedance. The systems and methods can include adjusting a phase shift angle associated with one or more transistors of the inverter and driving the transmitter such that the transmitter resonator coil generates a magnetic flux density less than or equal to a field safety threshold.SELECTED DRAWING: None

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority under and the benefit of U.S. Provisional Patent Application No. 62 / 773,518, filed November 30, 2018, entitled “Systems and methods fwor low power excitation in high power wireless power systems,” the entire contents of which are incorporated herein by reference.

[0002] The following disclosure relates to methods and systems for low power excitation in wireless power systems, and more particularly, to methods and systems for low power excitation of high power wireless power transmitters. [Background technology]

[0003] A wireless power system can include one or more wireless power transmitters configured to transmit power via an oscillating electromagnetic field to one or more wireless power receivers. The wireless power receivers can be coupled to one or more batteries such that the received power is used to charge the batteries. Wireless power systems can be configured to power a variety of electronic devices (such as phones, laptops, medical equipment, vehicles, robots, etc.). Summary of the Invention [Means for solving the problem]

[0004] Wireless power systems may be specially configured to transmit power in a particular power, current, and / or voltage range. This is because some electronic components used in wireless power systems for 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 transfer (e.g., on the order of hundreds to thousands of watts). Thus, such transistors will fail or be damaged when operated outside their power range. In another example, some electronic components, such as power factor correction (PFC) circuits, are beneficial in high power systems but may result in inefficiencies in low power ranges. Thus, it is not useful to use certain components when trying to achieve high efficiency power transfer (e.g., greater than 90% from source to load).

[0005] In some cases, configuring a wireless power system to operate in a particular power range (e.g., low power) can be difficult when the same wireless power system has previously been configured to operate in a significantly different power range (e.g., high power). Thus, it may be beneficial for a wireless power system to operate in different power ranges (or "modes") and / or to switch between modes. Furthermore, it may be beneficial for the wireless power system to do so without a significant loss in efficiency and / or significant additional 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., set at several thousand watts) to charge a large capacity battery (e.g., a vehicle battery) and, in some circumstances, to operate in a "low power mode" (e.g., less than 10 watts) to perform certain functions, e.g., positioning between the wireless power transmitter and receiver coils, as further described herein. The "high power mode" may also be referred to herein as a "wireless power transmission mode" or "WPT mode."

[0006] In one aspect, the 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 can include disabling a power factor correction circuit coupled proximate to an 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 can be configured to operate between a minimum achievable impedance and a maximum achievable impedance. The method can include adjusting a phase shift angle associated with one or more transistors of the inverter to drive the transmitter such that the transmitter resonator coil generates a magnetic flux density below a market safety threshold.

[0007] Various embodiments of the example method can include one or more of the following features.

[0008] The wireless power transmitter can be configured to transmit high power at an operating frequency between 80 kHz and 90 kHz. The wireless power transmitter can be configured to transmit power at a power level between 500 W and 20,000 W. Powering the transmitter can be performed from a fixed low voltage source. Powering the transmitter can include powering the transmitter at 30V or less. Powering the transmitter can include powering the transmitter at 50W or less. The market safety threshold can be between 10 microtesla and 15 microtesla.

[0009] Adjusting the phase shift angle may include adjusting the phase shift angle between 0 degrees and 180 degrees such that the magnetic flux density is below a market safety threshold. Adjusting the phase shift angle may include adjusting the phase shift such that a current in the transmitter resonator coil is below a current limit. The current limit may be based on a market safety threshold. Driving the transmitter may include driving the transmitter such that a current in the transmitter resonator coil is below a current limit. The current limit may be based on a market 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 current in one or more measurement coils, where the measurement coils may be separate from the transmitter resonator coil, and providing a signal representative of the magnetic flux density to a controller coupled to the transmitter. Prior to driving the transmitter, the method may include receiving a signal indicative of a presence of a vehicle having a receiver resonator coil near the transmitter resonator coil. The method may include receiving a signal indicative of a presence of a vehicle having a receiver resonator coil near the transmitter resonator coil.

[0010] In another aspect, the disclosure may feature a system for low power excitation 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 excitation, and a low voltage source coupled to an output of the power factor correction circuit and configured to drive the transmitter such that a resonator coil of the transmitter generates a magnetic flux density below a market safety threshold during low power excitation. The system may include an inverter coupled to an 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 excitation, and 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. The variable impedance component may be configured to operate between a minimum achievable impedance and a maximum achievable impedance.

[0011] Various embodiments of the example system can include one or more of the following features.

[0012] The wireless power transmitter can be configured to transmit high power at an operating frequency between 80 kHz and 90 kHz. The wireless power transmitter can be configured to transmit power at a power level between 500 W and 20,000 W. The wireless power transmitter can be configured to output power at or below 50 W during low power excitation. The market safety threshold can be between 10 microtesla and 15 microtesla. The system can include a current sensor coupled to the transmitter resonator coil and configured to provide a signal representative of a current characteristic to a controller of the transmitter. The controller can be operably coupled to at least one of (i) the at least two transistors, or (ii) the at least one variable impedance component. The low power voltage source can be configured to drive the transmitter during low power operation such that the current in the transmitter resonator coil is at or below a current limit. The current limit can be based on a market safety threshold.

[0013] In another aspect, the disclosure features a method for low power excitation of a high power wireless power transmitter. The transmitter can 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 can 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 can be configured to operate between the minimum achievable impedance and the maximum achievable impedance and drive the transmitter such that the transmitter resonator coil generates a magnetic flux density below a market safety threshold.

[0014] Various embodiments of the example method can include one or more of the following features.

[0015] The market safety threshold may be between 10 microtesla and 15 microtesla. Driving the transmitter may include driving the transmitter such that a current in the transmitter resonator coil is at or below a current limit, where the current limit is based on the market safety threshold. The current limit may be 2 amps. The current limit may be 355 milliamps. 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 current in one or more sense coils, the sense coils being separate 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 indicative of a presence of a vehicle having a receiver resonator coil near the transmitter resonator coil.

[0016] In another aspect, the disclosure features a method for low power excitation of a wireless power transmitter configured to transmit high power. The transmitter can 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 can include configuring a power factor correction circuit to output a minimum bus voltage, where the power factor correction circuit is proximately coupled to an input of the inverter. The method can include adjusting one or more variable impedance components of the impedance network to obtain a minimum achievable impedance, where the variable impedance components can be configured to operate between the minimum achievable impedance and the maximum achievable impedance, and adjusting a phase shift angle associated with one or more transistors of the inverter such that the transmitter resonator coil generates a magnetic flux density below a market safety threshold.

[0017] Various embodiments of the example method can include one or more of the following features.

[0018] The minimum bus voltage can be about 380V. The market safety threshold can be between 10 microtesla and 15 microtesla. Adjusting the phase shift angle can include adjusting the phase shift such that a current in the transmitter resonator coil is at or below a current limit, the current limit being based on the market safety threshold. The current limit can be 2 amps. The current limit can be 355 milliamps. The method can include determining a magnetic flux density by determining an induced voltage or induced current in one or more measurement coils, the coils being separate from the transmitter resonator coil. Adjusting the phase shift angle can include adjusting the phase shift angle based on the determined magnetic flux.

[0019] 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, the transmitter including 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 can include disabling a power factor correction circuit coupled proximate to the input of the inverter and tuning one or more variable impedance components of the impedance network to obtain a minimum achievable impedance, the variable impedance components configured to operate between the minimum achievable impedance and a maximum achievable impedance. The method can include driving the transmitter such that the transmitter resonator coil generates a magnetic flux density below a market safety threshold.

[0020] Various embodiments of the example method can include one or more of the following features.

[0021] A phase shift angle associated with one or more transistors of the inverter can be fixed. Driving the transmitter can be performed by a variable low voltage source. Driving the transmitter can include driving the transmitter with a voltage between 1V and 10V. The market safety threshold can be between 10μTesla and 15 microTesla. Adjusting the phase shift angle can include adjusting the phase shift such that a current in the transmitter resonator coil is at or below a current limit, where the current limit is based on the market safety threshold. The current limit can be 2 amps. The current limit can be 355 milliamps. The method can include determining a magnetic flux density by determining an induced voltage or induced current in one or more measurement coils, the coils being separate from the transmitter resonator coil. Driving the transmitter can include driving the transmitter based on the determined magnetic flux. The present invention provides, for example, the following items. (Item 1) 1. A method for low power excitation of a wireless power transmitter configured to transmit high power, the transmitter including an inverter coupled to an input of an impedance network and a transmitter resonator coil coupled to an output of the impedance network; disabling a power factor correction circuit coupled proximate to an input of the inverter; adjusting one or more variable impedance components of the impedance network to obtain a minimum achievable impedance, the variable impedance components being configured to operate between a minimum achievable impedance and a maximum achievable impedance; adjusting a phase shift angle associated with one or more transistors of the inverter; driving the transmitter such that the transmitter resonator coil produces a magnetic flux density below a market safety threshold; The method includes: (Item 2) Item 14. The method of item 1, wherein the wireless power transmitter is configured to transmit high power at an operating frequency between 80 kHz and 90 kHz. (Item 3) Item 14. The method of item 1, wherein the wireless power transmitter is configured to transmit power at a power level between 500W and 20,000W. (Item 4) 2. The method of claim 1, wherein driving the transmitter is performed by a fixed low voltage source. (Item 5) 2. The method of claim 1, wherein driving the transmitter includes driving the transmitter at 30V or less. (Item 6) 2. The method of claim 1, wherein driving the transmitter includes driving the transmitter at 50 W or less. (Item 7) 2. The method of claim 1, wherein the market safety threshold is between 10 microTesla and 15 microTesla. (Item 8) Adjusting the phase shift angle adjusting the phase shift angle between 0 degrees and 180 degrees so that the magnetic flux density is below the market safety threshold; The method according to item 1, comprising: (Item 9) Adjusting the phase shift angle adjusting the phase shift such that a current in the transmitter resonator coil is below a current limit, the current limit being based on a market safety threshold. The method according to item 1, comprising: (Item 10) Driving the transmitter driving the transmitter such that a current in the transmitter resonator coil is below a current limit, the current limit being based on a market safety threshold. The method according to item 1, comprising: (Item 11) 11. The method of claim 10, wherein the current limit is 2 amps. (Item 12) determining the magnetic flux density based on an induced voltage or current in one or more measurement coils, the measurement coils being separate from the transmitter resonator coil; providing a signal representative of the magnetic flux density to a controller connected to the transmitter; The method of claim 1, further comprising: (Item 13) Prior to driving the transmitter, receiving a signal indicative of a presence of a vehicle having the receiver resonator coil in the vicinity of the transmitter resonator coil; The method of claim 1, further comprising: (Item 14) 1. A system for low power excitation of a wireless power transmitter configured to transmit high power, comprising: a power factor correction circuit configured to be enabled during high power transmission and disabled during low power excitation; a low voltage source coupled to an output of the power factor correction circuit and configured to drive the transmitter such that a resonator coil of the transmitter produces a magnetic flux density below a market safety threshold during low power excitation; an inverter coupled to an 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 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, the variable impedance component configured to operate between the minimum achievable impedance and a maximum achievable impedance; A system including: (Item 15) Item 15. The system of item 14, wherein the wireless power transmitter is configured to transmit high power at an operating frequency between 80 kHz and 90 kHz. (Item 16) Item 15. The system of item 14, wherein the wireless power transmitter is configured to transmit power at a power level between 500W and 20,000W. (Item 17) Item 15. The system of item 14, wherein the wireless power transmitter is configured to output power at or below 50 W during low power excitation. (Item 18) 15. The system of claim 14, wherein the market safety threshold is between 10 microTesla and 15 microTesla. (Item 19) a current sensor coupled to the transmitter resonator coil and configured to provide a signal representative of a current characteristic to a controller of the transmitter, the controller being operatively coupled to at least one of (i) the at least two transistors or (ii) the at least one variable impedance component; Item 14. The system of item 13, further comprising: (Item 20) Item 14. The system of item 13, wherein the low-power voltage source is configured to drive the transmitter during low-power operation such that a current in the transmitter resonator coil is below a current limit, the current limit being based on the market safety threshold. [Brief description of the drawings]

[0022] [Figure 1A] FIG. 1A is a block diagram of an example wireless power system. [Figure 1B] FIG. 1B is a diagram of a vehicle having an exemplary receiver resonator coil disposed over a transmitter resonator coil. [Diagram 2] 2A, 2B, 2C, and 2D are diagrams of an exemplary coil configuration. [Diagram 3] FIG. 3 is a schematic diagram of a portion of an example wireless power transmitter configured for low-power excitation (LPE). [Figure 4A] FIG. 4A is a schematic diagram of an exemplary wireless power transmitter configured for low power excitation. [Figure 4B] FIG. 4B is a flowchart of an example method for low power excitation of the example wireless power transmitter of FIG. 4A. [Figure 5A] FIG. 5A is a schematic diagram of an exemplary wireless power transmitter configured for low power excitation. [Figure 5B] FIG. 5B is a flowchart of an example method for low power excitation of the example wireless power transmitter of FIG. 5A. [Figure 5C] FIG. 5C is a plot of transmitter coil current (in amperes) as a function of inverter phase shift angle (in degrees). [Figure 6A] FIG. 6A is a schematic diagram of an exemplary wireless power transmitter configured for low power excitation. [Figure 6B]FIG. 6B is a flowchart of an example method for low power excitation of the example wireless power transmitter of FIG. 6A. [Figure 7A] FIG. 7A is a schematic diagram of an exemplary wireless power transmitter configured for low power excitation. [Figure 7B] FIG. 7B is a flowchart of an example method for low power excitation of the example wireless power transmitter of FIG. 7A. [Figure 8] FIG. 8 is a flow chart illustrating an exemplary series of steps for performing wireless power transfer from a transmitter to a receiver, including vehicle positioning. [Figure 9] FIG. 9 is a block diagram of an example computer system that can be used in implementing the systems and methods described herein. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Disclosed herein are exemplary embodiments of systems and methods for low power excitation (LPE) in wireless power systems, particularly high power wireless power systems that include a high power wireless power transmitter.

[0024] Wireless Power Systems FIG. 1A is a block diagram of an exemplary wireless power system 100. The system 100 includes a wireless power transmitter 102 and a wireless power receiver 104. In the transmitter 104, a power source 105 (e.g., AC mains, a battery, etc.) supplies power to an inverter 108. Additional components may include a power factor correction (PFC) circuit 106 prior to the inverter stage 108. The inverter 108 drives a transmitter resonator coil and capacitive component 112 ("resonator") through an impedance matching network 110 (including fixed and / or adjustable network components). The resonator 112 generates an oscillating magnetic field that induces a current and / or voltage in a receiver resonator 114. The received energy is supplied to a rectifier 118 through an impedance matching network 116 (including fixed and / or adjustable network components). Finally, the rectified power is supplied to a load 120 (e.g., one or more batteries in an electric or hybrid vehicle). In some embodiments, the battery voltage level may 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 wireless power system 100. For example, common battery voltage ranges for electric vehicles include 0-280V, 0-350V, 0-420V, etc.

[0025] In some embodiments, one or more components of the transmitter 102 may be coupled to a controller 122, which may include a communications module (e.g., Wi-Fi, wireless, Bluetooth, in-band signaling, etc.). In some embodiments, one or more components of the transmitter 102 may be coupled to one or more sensors 124 (e.g., current sensors, voltage sensors, power sensors, temperature sensors, fault sensors, etc.). The controller 122 and the sensors 124 may be operatively coupled to control portions of the transmitter 102 based on feedback signals from the sensors 124.

[0026] In some embodiments, one or more components of the receiver 104 may be coupled to a controller 126, which may include a communications module (e.g., Wi-Fi, wireless, Bluetooth, in-band signaling, etc.). In some embodiments, one or more components of the transmitter 104 may be coupled to one or more sensors 128 (e.g., current sensors, voltage sensors, power sensors, temperature sensors, fault sensors, etc.). The controller 126 and the sensors 128 may be operatively coupled to control portions of the transmitter 102 based on feedback signals from the sensors 124.

[0027] Examples of wireless power systems can be found in U.S. Patent Application Publication No. 2010 / 0141042, published June 10, 2010, entitled "Wireless energy transfer systems," and U.S. Patent Application Publication No. 2012 / 0112535, published May 10, 2012, entitled "Wireless energy transfer for vehicles," both of which are incorporated by reference in their entireties herein.

[0028] In some embodiments, the exemplary impedance matching network 110, 118 may include one or more variable impedance components. The one or more variable impedance components may be referred to herein together as a “tunable matching network” (TMN). The TMN may be used in adjusting the impedance (e.g., including reactance) of the wireless power transmitter 102 and / or the receiver 104. In some embodiments, the tunable matching network 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 the receiver 104 may change dynamically. In such applications, impedance matching may be required between the receiver resonator coil (at 114) and the load 120, and between the transmitter resonator coil (at 112) and the power source 105 to prevent unnecessary energy loss and excess heat. The impedance experienced by the resonator coil 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 of the wireless power system 100, the impedance seen by the power source 105 may vary significantly due to changes in the load 120 (e.g., a battery or battery charging circuit) receiving power and changes in coupling between the transmitter 102 and the receiver 104 (e.g., caused by changes in the relative positions of the transmitter and receiver resonator coils). Similarly, the impedance seen by the receiver resonator 114 may also change dynamically due to changes in the load 120 from which it is receiving power. In addition, the desired impedance match for the receiver resonator 114 may be different for different coupling and / or power source conditions. Thus, for example, a power transfer system that transmits and / or receives power via highly resonant wireless power transfer may need to configure or modify the impedance matching network 110, 116 to maintain efficient power transfer.One or more components of the TMN can be configured to exhibit 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 a particular point in the power transfer (e.g., at the beginning of the power transfer). Examples of tunable matching networks can be found in U.S. Patent Application Publication No. 2017 / 0217325, published August 3, 2017, entitled "Controlling wireless power transfer systems," and U.S. Patent Application Publication No. 2017 / 0229917, published August 10, 2017, entitled "PWM capacitor control," both of which are incorporated herein by reference in their entireties.

[0029] A high-power wireless power transmitter can be configured to transmit wireless power in applications such as powering and / or charging batteries in vehicles, industrial machines, robots, or electronic devices that rely on high power. For purposes of explanation, the following disclosure focuses on wireless power transmission for vehicles. However, it is understood that any one or more of the embodiments described herein may be applied to other applications in which wireless power may be utilized.

[0030] Low Power Excitation (LPE) Overview As used herein, "low power excitation" can include driving a wireless power transmitter with a relatively low power, current, and / or voltage. As discussed above, low power excitation can be particularly challenging in wireless power transmitters configured to operate at high powers (e.g., 500 W to 20,000 W or more).

[0031] In an exemplary embodiment, a vehicle having a wireless power receiver 104 can be positioned on a wireless power transmitter 102 using low power excitation of a high power transmitter (see FIG. 8 and the section below entitled "Vehicle Positioning"). In particular, proper placement of the receiver resonator coil on the transmitter resonator coil can be important to maximize the transmit power to the receiver 104 and / or maximize the efficiency of power transfer. An example vehicle positioning system and method is described in "Relative position determination and vehicle guidance," published on March 1, 2018. No. 2018 / 0056800, entitled "Methods and apparatus for positioning a vehicle using foreign object detection," issued on October 29, 2019; U.S. Patent No. 10,343,535, entitled "Wireless power antenna alignment adjustment system for vehicles," issued on July 9, 2019; and U.S. Patent No. 10,090,885, entitled "Antenna alignment and vehicle guidance for wireless charging of electric vehicles," issued on October 2, 2018, each of which is incorporated by reference in its entirety.

[0032] 1B illustrates a vehicle 150 having an exemplary receiver resonator coil 204 disposed on a transmitter resonator coil 202. In a wireless power transfer (WPT) mode, the transmitter resonator coil 202 is typically energized with high power (e.g., on the order of thousands of watts) for the purpose of transmitting power via an electromagnetic field to the receiver coil 204 and ultimately charging the battery of the vehicle 150. In a low power excitation (LPE) mode, the transmitter resonator coil 202 can be energized with low power (e.g., on the order of a 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.

[0033] In some embodiments, the wireless power transmitter 102 may be in the LPE mode before entering the wireless power transfer (WPT) mode. For example, when the vehicle 150 is guided to a desired parking position, the transmitter 102 may switch from the LPE mode to the WPT mode to begin charging the battery of the vehicle 150. In some embodiments, if the vehicle 150 is moved during the WPT mode, the transmitter 102 may enter the LPE mode (e.g., interrupt the WPT mode) to determine whether the vehicle 150 (and thus the receiver 104) should be repositioned relative to the transmitter 102. For example, the vehicle 150 and receiver 104 may be moved if the vehicle 150 is being held down by cargo in the trunk or a passenger sitting in the vehicle 150. Additional examples are shown in FIG. 8 and described in the following section under the heading "Vehicle Positioning."

[0034] In some embodiments, the electromagnetic field generated by the wireless power transmitter 102 may be exposed to its environment, including humans, animals, etc., before the wireless power receiver 104 is placed on or near the transmitter 102. In some embodiments, the receiver may be placed on or near the transmitter 102, but power transmission may not begin before the receiver 102 is aligned with the transmitter 102. In such cases, the wireless power transmitter 102 may be driven such that the magnetic flux density generated by the transmitter resonator coil 202 is below a market safety threshold, e.g., less than 10 microTesla, less than 25 microTesla, less than 50 microTesla, etc. In some embodiments, the market safety threshold is between 10 and 15 microTesla. This market safety threshold may be determined based on limitations on electromagnetic field exposure to the human body and / or electromagnetic compatibility (EMC) concerns.

[0035] In some embodiments, the magnetic flux density may be determined at a surface of the transmitter resonator coil 202 facing the receiver resonator coil 204. For example, the magnetic flux density may be determined at a surface 152 of the packaging of the transmitter resonator coil 202. For example, the transmitter resonator coil 202 may be packaged or housed in a material (e.g., a non-conductive material including plastic, rubber, etc.) to protect electronic components from the environment and / or provide safety to humans and animals. In some embodiments, the magnetic flux density may be determined at a particular distance and / or angle from the transmitter resonator coil 202 or the surface 152 of its packaging. In some embodiments, the transmitter 102 may be driven such that the current in the transmitter resonator coil 202 is limited to 2 amps or less, 1 amp or less, or less than 1 amp or less to meet market safety thresholds. In some embodiments, the current in the transmitter resonator coil 202 may be limited to 325 milliamps rms + / - 9% or less (e.g., 295-355 milliamps rms + / - 9% or less) to meet market safety thresholds. RMS In some embodiments, the transmitter 102 may be driven at a low power in the range of 1 W to 50 W.

[0036] In the LPE mode, the receiver resonator coil 204, or another coil disposed 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 or tuned to the pickup coil) can determine the strength of the magnetic field to determine whether the receiver resonator coil 204 is in a position of sufficiently high coupling with respect to the transmitter resonator coil 202, thereby allowing efficient power transfer and / or maximum power delivery.

[0037] 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 position of high coupling is achieved when the coupling between the receiver resonator coil 204 and the transmitter resonator coil 202 is high enough (e.g., greater than 90% efficiency from power source to battery) to allow efficient high power transfer to the vehicle's battery. In other examples, the strength of the electromagnetic field in combination with the known geometry of the wireless power system and / or pickup coil can be used to further determine whether a position of high coupling is a safe position (e.g., for EMF exposure, equipment operation, etc.) for the transmitter 102 to transfer power. 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 a vehicle or vehicle user to a desired relative position (whether or not such a position is also a relative maximum coupling position) based on safety, efficiency, coupling, or other system parameters.

[0038] In some embodiments, one or more sensing coils (e.g., 2, 3, 4, 6, 8, or more) can 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 can be coupled to a processor configured to determine the magnetic flux density at the sensing coil or the relative magnetic flux density between two or more sensing coils. A received voltage and / or compensation current (e.g., shorted directly or via another element such as an inductor, capacitor, or resistor) can be used to determine the location of the relative magnetic flux density (e.g., with respect to the surface of the resonator coil). In some embodiments, multiple coils can 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 positioned coils are sufficiently distributed with respect to the transmitter resonator coil 204.

[0039] 2A-2D show example sensing coil geometries for an example wireless power receiver resonator coil 204. Examples may include two coils 206 in a "four" series of loops (see FIG. 2A) or four coils 208 in a cloverleaf pattern with the sensing coils in alternating directions (see FIG. 2B). In other examples, an odd or even number of multiple coils may be used. FIG. 2C shows an example of a single coil 210 concentric with the receiver resonator coil 204. FIG. 2D shows multiple coils 212 distributed with respect to the receiver resonator coil 204. It is understood that separate coils or multiple coils can be arranged to provide additional geometric information of 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, positioning of one or more coils may provide specific information about the location of the magnetic flux density. The example coil configurations provided herein are not intended to be limiting, and it is understood that other coil configurations are within the scope of the present disclosure.

[0040] In some embodiments, any one or more of the following parameters of the transmitter 102 can be included and / or adjusted to achieve a current of 2 amps or less in the transmitter resonator coil 202 and / or to achieve an electromagnetic field generated by the transmitter coil 202 that is below market safety thresholds:

[0041] Drive voltage. In various embodiments, the 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 the transmitter 102 may be configured to apply a voltage of about 5V to the input of the matching network 110 after the inverter 108. This may generate a similar voltage at the 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 is understood that other types of voltage sources can be used to drive the transmitter 102. In some embodiments, the voltage source may be switched in or out of the transmitter 102 or may be a fixed part of the transmitter's circuitry. In some embodiments, the inverter 108 and / or the PFC circuit 106 may be configured to drive the transmitter 102 to generate a low voltage.

[0042] Drive Current. In various embodiments, the drive current of the transmitter 102 can be adjusted by varying the drive voltage and determining the current in the transmitter 102 (e.g., via a feedback mechanism such as a current sensor). In some embodiments, the transmitter 102 can include a drive current mechanism for generating the drive current (see, e.g., FIG. 3). FIG. 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 can (i) be disconnected from the inverter 108 via a switch 304 and (ii) be driven by a current source 306 to generate a coil current of less than 2 amps.

[0043] TMN Impedance. In various embodiments, the TMN (as part of the matching network 110) in the transmitter 102 may be tuned so that it presents a particular impedance. The TMN can be tuned to present an impedance between a minimum achievable impedance and a maximum achievable impedance. In particular, the components of the TMN may be tuned to present a minimum impedance (e.g., minimum inductive reactance or minimum positive reactance) achievable by a particular TMN to the drive circuit of the transmitter 102. The drive circuit may include components of the transmitter 102, including the inverter 108, the PFC circuit 106, and / or any other drive circuit (e.g., one or more LPE circuit components described herein) prior to the matching network 110 in the power path. In some embodiments, the minimum achievable impedance is pre-determined for a particular wireless power system 100 based on the particular specifications of the components selected in the TMN. In some embodiments, the controller 122 of the wireless power transmitter 102 may determine the minimum achievable impedance of the TMN. For example, the controller 122 may send a signal to a tunable component with a setting to achieve a particular impedance.

[0044] 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 such that the switch is fully open to present the maximum capacitive (e.g., negative) reactance achievable by the particular TMN, thereby reducing the impedance of the branch with the TMN (see, e.g., the upper and / or lower branches of component 406). When the TMN FET is fully open for the entire switching cycle, the effective capacitive reactance of the TMN is at a minimum value (in other words, the most negative value). The capacitive reactance sums with the inductive reactance of a fixed inductor in series with the TMN to result in the minimum impedance achievable in the X3 branch. Achieving a low or minimum impedance can have the effect of minimizing the variation of coil current in the transmitter resonator coil 202 over 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 tuning the TMN for minimum inductive reactance may include minimizing the amount of control required to produce a desired current level in the transmitter resonator coil.

[0045] Phase Shift Angle of the Inverter. 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 (e.g., see generator 422) of the controller 122 can be configured to control gate drivers (e.g., see driver 418) coupled to the transistors of the inverter 108 to generate a desired phase shift angle. The phase shift of the inverter can include application of 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. For a phase shift angle of 0 degrees, the output voltage of the inverter is zero because the output is shorted by either (i) transistors Q1 and Q3 being turned on simultaneously or (ii) transistors Q2 and Q4 being turned on simultaneously.

[0046] The phase shift angle may depend on the components and parameters of a particular wireless power system, including the DC voltage bus, the particular impedance matching, etc. In some embodiments, the phase shift angle may be defined by two rules. Specifically, in the first rule, when the phase angle is at zero (0) degrees, the coil current may be at or near the maximum level achievable by a particular transmitter 102, and when the phase angle is at 180 degrees, the coil current may be zero or near zero. In the second rule (opposite of the first rule), when the phase angle is 180 degrees, the coil current may be at or near the maximum level achievable by a particular transmitter 102, and when the phase angle is at zero (0) degrees, the coil current may be zero or near zero. For example, using the second rule, when the phase shift angle is about 5 degrees, the coil current may be at a low level. In some embodiments, a combination of duty cycle and inverter phase angle may be varied to improve switching behavior, thereby reducing ringing, reducing harmonics, increasing or decreasing body diode conduction, and / or reducing switching losses, etc.

[0047] Pulse Width Modulation (PWM). In some embodiments, a PWM generator (see, e.g., generator 422) of the controller 122 can adjust the pulse width or duty cycle of one or more transistors of the inverter 108 to achieve a desired voltage level at the transmitter resonator coil 202.

[0048] Power Factor Correction (PFC). The PFC circuit 106 operates at a specific bus voltage V BUS , may be enabled or disabled or adjusted to generate The following is the driving voltage V BUS (V) and peak inductor current I s1 (A PEAK ) and the root mean square coil current I s1 (A RMS ) are exemplary values. [Table 1]

[0049] In some embodiments, the voltage of the transmitter resonator coil 202, one or more electromagnetic field sensors, or one or more sensing coils can be used to measure the electromagnetic field level of the electromagnetic field from the transmitter resonator coil 202 and can be provided to a control system (see, e.g., control systems 412, 506, 604, 708). The voltage feedback can be used to adjust one or more of the transmitter components and / or parameters (e.g., power, voltage, and / or current) to set the desired electromagnetic field level. For example, the transmitter 102 can include a current sensor (see, e.g., current sensor 416) configured to determine one or more characteristics of the current in the transmitter 102 (e.g., level, frequency, phase, etc.). The current readings are provided as feedback to the control system (e.g., control systems 412, 506, 604, 708) and can be used to adjust one or more of the transmitter components and / or parameters as described above. This feedback mechanism can be used alone or in combination with other sensors, such as current sensors and / or voltage sensors.

[0050] In the following description, for clarity and conciseness, the system for low power excitation and the corresponding method are described together. For example, the system for low power excitation 400 is discussed together with the method for low power excitation 450. It should be noted that the order of steps of each method described herein is intended to describe example embodiments and may be performed or accomplished in another order or combination to achieve a desired output.

[0051] LPE - First Exemplary Embodiment FIG. 4A is a schematic diagram of an exemplary wireless power transmitter 400 including a low power excitation (LPE) circuit 402. FIG. 4B is a flow chart of an exemplary method 450 for low power excitation of the wireless power transmitter 400. In this exemplary embodiment, the LPE circuit 402 includes a variable voltage source 404, a diode D1, and relays 408a, 408b. The exemplary variable voltage source 404 can be coupled in parallel between the PFC circuit 106 and the inverter 108. The PFC circuit 106 can receive power directly or indirectly from a power source (e.g., an AC power source, a battery, etc.) and provide the necessary power correction to the wireless power transmitter 400 during a wireless power transfer (WPT) mode. As described above, during a WPT mode, the wireless power transmitter 400 can operate at a significantly higher power, voltage, and / or current level compared to operation during an LPE mode. It should be noted 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 a gate driver 418. The gate driver 418 can receive PWM signals PWM1, PWM2, PWM3, and PWM4 generated by a PWM generator 422. The PWM generator 422 can receive control signals, e.g., signals representing the phase shift angles of the PWM signals, from a digital controller 424.

[0052] The exemplary variable voltage source 404 can be coupled in series with a diode D1 to block strong currents so that during wireless power transfer (WPT) mode, the variable voltage source 404 is not compromised by significant power, current, and / or voltage from the PFC circuit 106. The diode D1 and the relay allow current flow in one direction, which can be beneficial to enable the voltage source 404 in driving the transmitter 102. The relay can be used to power down the inverter bias and other power electronics of the transmitter 102. During the 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 electronics power controller (SEPC) 410). In this exemplary embodiment, in the 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 send a signal to the relay 408b to open and switch the variable voltage source 404 to avoid harm to the power source 404 and / or avoid open inefficiencies in the power path driving the wireless power transfer.

[0053] Referring to step 452 of the method 450, in the 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., the SEPC 410) can send a control signal to the relays 408a, 408b to open the circuit so that the PFC circuit 106 is disconnected (and therefore cannot drive the transmitter 400). In some embodiments, the SEPC 410 can communicate with a zero voltage switching (ZVS) error generation module 414. In the WPT mode, the ZVS error generation module 414 is a protection mechanism that generates a flag and disables power transfer if the phase angle between the inverter output voltage and current is less than 12 degrees. This error is intended to protect the system from lossy operation of semiconductors that may cause failures. In the LPE mode, the voltage-current (VI) phase seen by the inverter 108 is expected to be below the threshold for ZVS detection, so the ZVS error generation can be disabled. In LPE mode, this condition is tolerable because the power handled by the inverter 108 is very small, and therefore the switching losses are not disruptive.

[0054] The SEPC 410 can receive the signal I1s_ref directly or indirectly from the current sensor 416. The signal I1s_ref is a reference signal based on the current measurement I1 by the sensor 416 coupled (e.g., in series, parallel, inductively, etc.) with the transmitter resonator coil 202.

[0055] In step 454, the impedance of one or more variable impedance components (e.g., TMN reactance) 406 of the impedance network may be adjusted to obtain the minimum inductive reactance that a particular TMN component can achieve. For example, an upper branch component labeled "X3sa_minΩ-X3sa_maxΩ" and / or a lower branch component labeled "X3sb_minΩ-X3sb_maxΩ" may be adjusted to obtain a desired impedance (e.g., minimum reactance). The TMN components 406 may be adjusted by one or more components (e.g., adjustable X3S controller 420, SEPC 410, etc.) of the control system 412. For example, the adjustable components 406 may be adjusted by the controller 420 receiving a signal (e.g., signal "LPE on / off") from the SEPC 410, and may adjust the components 406 to achieve the minimum reactance during the LPE mode (e.g., when the SEPC 410 disables the PFC circuit 106 and enables the variable voltage source 404).

[0056] In step 456, the variable voltage source 404 drives the transmitter 400 such that the current in the transmitter resonator coil 202 is within a target current range for the LPE mode. To do so, the SEPC 410 can send one or more signals to close the relay 408b and enable the variable voltage source 404. In this embodiment, the inverter is enabled to convert 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 to indicate whether the current is within a target range (e.g., less than 1 A, less than 3 A, less than 5 A, etc.) for the LPE mode.

[0057] LPE - Second Exemplary Embodiment 5A is a schematic diagram of an exemplary wireless power transmitter 500 including a low power excitation (LPE) circuit 502. FIG. 5B is a flow chart of an exemplary method 550 for low power excitation of the transmitter 500. Specifically, the system 502 includes a fixed low voltage source 504 coupled in series with a diode D1. In this embodiment, the fixed low voltage source 504 may be on (operable) during both the LPE mode and the WPT mode. In some embodiments, the fixed low voltage source 504 is hardware implemented in the circuitry of the transmitter 500.

[0058] At 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 when entering LPE mode. Note that, as described above, in LPE mode, the ZVS error generation 414 may be disabled.

[0059] In step 554, the impedance of one or more variable impedance components (e.g., TMN reactance) 406 can be adjusted to obtain the minimum reactance (e.g., minimum inductive reactance) that a particular TMN component 406 can achieve. For example, an upper branch component labeled "X3sa_minΩ-X3sa_maxΩ" and / or a lower branch component labeled "X3sb_minΩ-X3sb_maxΩ" can be adjusted to obtain a desired impedance (e.g., minimum reactance). The TMN components 406 can be adjusted by one or more components of the control system 506 (e.g., digital controller 424, adjustable 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 can have the effect of minimizing the variation of current in the transmitter resonator coil 202 over the coupling range of the resonator coil. 1B, the coupling range can 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 can include receiving a signal from the sensor 416 representative of a current characteristic (e.g., level, phase, frequency). The signal can be provided to the control system 506 to ascertain the current characteristic of the coil 202.

[0060] In step 556, remaining variations in the coil current can be minimized by adjusting the phase shift angle of a pulse width modulation (PWM) signal for 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 506. Specifically, the digital controller 424 can send a signal θinv_ps to a PWM generator 422 to generate specific PWM signals PWM1, PWM2, PWM3, PWM4 for the gate driver 418. The driver 418 can then drive gates G1, G2, G3, G4 corresponding to respective transistors Q1, Q2, Q3, Q4 of the inverter 108.

[0061] In some embodiments, the phase shift angle can be adjusted between 0 and 180 degrees so that the magnetic flux density is below the market safety threshold. This includes adjusting the phase shift angle to adjust the current level to achieve a magnetic flux density below the market safety threshold. In particular, with reference to FIG. 5C, the relationship between the coil current and the phase shift angle is approximately linear and monotonic. This relationship can be used to determine the coil current and / or magnetic flux density to provide negative feedback to the controller to adjust the phase shift angle to eliminate disturbances in the transmitter coil current. It should be noted 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:

number

[0062] In some embodiments, the voltage source 504 can drive the transmitter at 30 V or less. For example, a 1 A output can be achieved using a fixed voltage level of about 12 V generated by the voltage source 504. RMS To obtain an approximate coil current of , the inverter phase shift angle can be adjusted by the control system 506 to about 60 degrees.

[0063] LPE - Third Exemplary Embodiment 6A is a schematic diagram of an example wireless power transmitter 600 configured for low power excitation. FIG 6B is a flow chart of an example method 650 for low power excitation of the transmitter 600.

[0064] In step 652 of the method 650, the PFC circuit 106 determines whether the bus voltage V BUS The PFC circuit 106 can be configured to drive the transmitter at a minimum voltage V BUS_min and maximum voltage V BUS_max In some embodiments, during the LPE mode, the bus voltage V BUS is 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 (e.g., the digital controller 424) may send a signal to the PFC circuit 106 to adjust the voltage to a minimum bus voltage V BUS_min Note that, as noted above, in LPE mode, ZVS error generation 414 can be disabled.

[0065] In step 654, the impedance of one or more variable impedance components (e.g., TMN reactance) 406 may be adjusted to obtain the minimum reactance (e.g., minimum inductive reactance) that a particular TMN component 406 can achieve. For example, an upper branch component labeled "X3sa_minΩ-X3sa_maxΩ" and / or a lower branch component labeled "X3sb_minΩ-X3sb_maxΩ" may be adjusted to obtain a desired impedance (e.g., minimum reactance). The TMN components 406 may be adjusted by one or more components of the control system 604 (e.g., digital controller 424, adjustable X3S controller 420, SEPC 410, etc.). For example, controller 420 may receive a signal X3s_min from 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 over the coupling range of the resonator coil.

[0066] In step 656, the remaining variation in the coil current can be minimized by adjusting the phase shift of a pulse width modulation (PWM) signal input to each transistor 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 gates G1, G2, G3, G4 corresponding to the respective transistors Q1, Q2, Q3, Q4 of the inverter 108. For example, at a voltage level of about 380V generated by the PFC circuit 106, 1A can be generated. RMS In order to generate a coil current approximately equal to 1000 Hz, the inverter phase shift angle can be adjusted by the controller 604 to less than about 5 degrees.

[0067] LPE - Fourth Exemplary Embodiment 7A is a schematic diagram of an example wireless power transmitter 700 including a low power excitation (LPE) circuit 702. FIG. 7B is a flow chart of an example method 750 for low power excitation of the transmitter 700. The LPE circuit 702 includes a variable low voltage source 704 coupled in series with a diode D1. The LPE circuit 702 is coupled in parallel between the PFC circuit 106 and the inverter 108. The variable low voltage source 704 receives the bus voltage V from the digital controller 424. BUS The controller 424 is configured to receive a signal representing the level of V for the voltage source 704 to output 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 voltage source 704 to ensure that the PFC circuit 106 is disabled before or at the same time as the voltage source 704 turns 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.

[0068] At step 752, during the 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 send a signal to the PFC circuit 106 to enable or disable the PFC circuit 106. For example, during the WPT mode, the PFC circuit 106 is enabled. Note that, as described above, during the LPE mode, the ZVS error generation 414 can be disabled.

[0069] 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 that a particular TMN can achieve. In this example, the upper branch components labeled "X3sa_minΩ-X3sa_maxΩ" and / or the lower branch components labeled "X3sb_minΩ-X3sb_maxΩ" can be adjusted to obtain a desired impedance (e.g., minimum reactance). The TMN components 406 can be adjusted by one or more components of the control system 412 (e.g., tunable X3S controller 420, SEPC 410, etc.).

[0070] In step 756, the variable low voltage source 704 is configured to drive the transmitter 700 such that the transmitter resonator coil 202 generates a magnetic field whose magnitude is below the market safety threshold. In some embodiments, the voltage source 704 can drive the transmitter 700 with a voltage between about 4V and 5V. For example, 1A at a fixed phase shift angle. RMS The voltage level of the variable low voltage supply is adjusted to between about 4V and 5V to generate a coil current of approximately

[0071] Vehicle positioning The low power excitation components, systems, and methods disclosed herein can form part of the wireless power system 100 that performs various other performance and safety verifications before, during, or after wireless power transmission.

[0072] 8 is a flowchart 800 illustrating an example of a series of steps that may be performed in the wireless power system 100 before and / or during wireless power transfer. In step 802, a communication link is established between the wireless power transmitter 102 and the wireless power receiver 104. The link may be established, for example, via a Wi-Fi network or communication protocol, via a Bluetooth connection, or more generally, via any link, connection, or communication protocol that allows the transmitter 102 and receiver 104 to communicate.

[0073] Next, in step 804, a system processor (e.g., any of the processors disclosed herein or another processor in communication with a processor disclosed herein) determines the relative position of the wireless power receiver 104 and / or a class associated with the relative position of the receiver using any of the methods disclosed herein. The system processor then generates a signal including information regarding the relative position and / or class of the receiver and transmits the signal to another processor, controller, or display interface.

[0074] In optional step 806, the system (i.e., the system processor or another processor, circuitry, or controller) may use information from the transmitted signal to provide vehicle guidance information to a vehicle operator or an automated driving system. In some embodiments, this step may include displaying an indicator on a vehicle display unit to provide the guidance information.

[0075] Next, in step 808, the system determines whether alignment is complete based on the relative position or class 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 particular class. If alignment is not achieved, control returns to step 804; if alignment is achieved, control passes to step 810.

[0076] At optional step 810, the system performs additional environmental and safety checks. These may include, for example, foreign object checks, living organism checks, vehicle / receiver movement checks, and monitoring / checks of various other safety systems and operating parameters. If all checks and systems are satisfied, then at step 812, power transfer from the wireless power transmitter 102 to the wireless power receiver 104 begins.

[0077] After a period of time has elapsed, wireless power transmission may optionally be interrupted at step 814. Various criteria and / or signals may lead to the interruption of power transmission. In some embodiments, for example, power transmission may be interrupted periodically 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 the capacitance of the vehicle / receiver, and / or a change in the position of the vehicle / receiver. In some embodiments, power transmission may also be interrupted when certain system operation / performance parameters, such as the voltage and / or current induced in the wireless power receiver, change.

[0078] After power transfer is 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 the environmental and safety checks are passed in step 810, control eventually returns to step 812 and power transfer resumes.

[0079] Hardware and Software Implementation FIG. 9 is a block diagram of an exemplary computer system 900 that can be used in implementing the systems and methods described herein. A general purpose computer, a network appliance, a mobile device, or other electronic system may also include at least a portion of the system 900. The system 900 includes a processor 910, a memory 920, a storage device 930, and an input / output device 940. Each of the components 910, 920, 930, and 940 may be interconnected, for example, using a system bus 950. The processor 910 may process instructions for execution within the system 900. In some implementations, the processor 910 is a single-threaded processor. In some implementations, the processor 910 is a multi-threaded processor. The processor 910 may process instructions stored in the memory 920 or the storage device 930.

[0080] 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 examples, some or all of the above data can be stored on a personal computing device, in data storage hosted on one or more centralized computing devices, or via cloud-based storage. In some examples, some data is stored in one place and other data is stored in another place. In some examples, quantum computing can be used. In some examples, functional programming languages ​​can be used. In some examples, electrical memory, such as flash-based memory, can be used.

[0081] The storage device 930 can provide mass storage for the system 900. In some implementations, the storage device 930 is a non-transitory computer-readable medium. In various different implementations, the storage device 930 can 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 to the system 900. In some implementations, the input / output device 940 can include one or more of 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, a 4G wireless modem, etc. In some implementations, the input / output device can include a driver device configured to receive input data and send output data to other input / output devices, e.g., a keyboard, a printer, and a display device 960. In some examples, mobile computing devices, mobile communication devices, and other devices can be used.

[0082] In some implementations, at least some of the above approaches may be realized by instructions that, when executed, cause one or more processing devices to perform the processes and functions described above. Such instructions may include, for example, interpreted instructions such as script instructions, executable code, or other instructions stored on a non-transitory computer-readable medium. The storage device 930 may be implemented in a distributed manner over a network, such as a server farm or a set of widely distributed servers, or may be implemented in a single computing device.

[0083] Although an exemplary processing system is illustrated in FIG. 9, embodiments of the subject matter, functional operations and processes described herein can be implemented in other types of digital electronic circuitry, computer software or firmware embodied in a tangible manner, computer hardware including the structures disclosed herein and their structural equivalents, or one or more combinations thereof. Embodiments of the subject matter described herein can be implemented as one or more modules of one or more computer programs, i.e., computer program instructions encoded on a tangible, non-volatile program carrier for execution by or control of the operation of a data processing device. Alternatively, or in addition, the program instructions can be encoded into an artificially generated transmitted signal, such as a machine-generated electrical, optical or electromagnetic signal generated to encode information for transmission to an appropriate receiver device for execution by a data processing device. The computer storage medium can be a machine-readable storage device, a machine-readable storage medium substrate, a random or sequential access memory device, or one or more combinations thereof.

[0084] The term "data processing apparatus" encompasses all kinds of apparatus, devices and machines for processing data, including, by way of example, a programmable processor, computer, or multiple processors or computers. A processing system may include special purpose 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 include code that creates an execution environment for a given computer program, such as code that constitutes a processor firmware, a protocol stack, a database management system, an operating system, or one or more combinations thereof.

[0085] 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 programming language, including compiled or interpreted, or declarative or procedural languages, and it may be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program may correspond to a file in a file system, but that is not required. 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 that program, or in multiple cooperating files (e.g., a file that stores one or more modules, subprograms, or multiple pieces of code). A computer program may be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a communication network.

[0086] The processes and logic flows described herein can be performed by one or more programmable computers executing one or more computer programs to perform functions by manipulating input data to generate output. The processes and logic flows can also be performed by special purpose logic circuitry, such as an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit), and an apparatus can also be implemented as a special purpose circuit.

[0087] A computer suitable for executing a computer program may include, by way of example, a general-purpose or special-purpose microprocessor or both, or any other type of central processing unit. Typically, the central processing unit receives instructions and data from a read-only memory or a random access memory or both. A computer generally includes a central processing unit for executing or accomplishing instructions, and one or more memory devices for storing instructions and data. Typically, a computer also includes or is operatively coupled to one or more mass storage devices, such as magnetic disks, magneto-optical disks, or optical disks, for storing data, for receiving data therefrom, transferring data thereto, or both. However, a computer need not include such devices. Furthermore, a computer may be incorporated into another device, such as 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), to name just a few.

[0088] Computer-readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media and memory devices, including, by way of example, semiconductor storage 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.

[0089] An embodiment of the subject matter described herein 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 having a graphical user interface or a web browser that allows a user to interact with an implementation of the subject matter described herein, 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 communications network. Examples of communications networks include local area networks ("LANs") and wide area networks ("WANs"), e.g., the Internet.

[0090] A computing system may include clients and servers. Clients and servers 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.

[0091] While this specification contains many specific implementation details, these should not be construed as limitations on the scope of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments. Certain features described herein in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable subcombination. Furthermore, although features may be described above as working in a particular combination and initially claimed as such, one or more features from the claimed combination may in some cases be deleted from the combination, and the claimed combination may be directed to a subcombination or a variation of the subcombination.

[0092] Similarly, while operations are depicted in a particular order in the figures, this should not be understood as requiring such operations to be performed in the particular order or sequence shown, or to perform all of the operations illustrated, in order to achieve desirable results. In certain environments, multitasking and parallel processing may be advantageous. Furthermore, the separation of various system components in the above embodiments should not be understood as requiring such separation in all embodiments, and it should be understood that the program components and systems described may typically be integrated together in a single software product or packaged into multiple software products.

[0093] Particular embodiments of the 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 different orders and still achieve desirable results. By way of example, the methods depicted in the accompanying figures do not necessarily require the particular order shown, or sequential order, to achieve desirable results. In certain implementations, multitasking and parallel processing may be advantageous. Other steps or stages may be provided, or steps or stages may be deleted, from the processes described. Accordingly, other implementations are within the scope of the following claims.

[0094] term Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.

[0095] As used in this specification and in the claims, the term "approximately," 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 can be plus or minus 20%, 10%, 5%, 3%, 1%, 0.1%, or less than 0.1%.

[0096] As used herein and in the claims, the indefinite articles "a" and "an" shall be understood to mean "at least one" unless expressly indicated otherwise. As used herein and in the claims, the phrase "and / or" shall be understood to mean "either or both" of the conjoint elements, i.e., elements that are jointly present in some cases and disjunctively present in other cases. Multiple elements listed with "and / or" shall be interpreted in the same manner (i.e., "one or more" of the conjoint elements). Other elements, whether related or unrelated to the elements specifically identified, may optionally be present other than the elements identified in the "and / or" clause. Thus, by way of example and not of limitation, a reference to "A and / or B," when used in conjunction with open-ended language such as "comprising," may refer in one embodiment to only A (optionally including elements other than B), in another embodiment to only B (optionally including elements other than A), and in yet another embodiment to both A and B (optionally including other elements), and so forth.

[0097] When used in the specification and claims, "or" shall be understood to have the same meaning as "and / or" as defined above. For example, when separating items in a list, "or" or "and / or" shall be interpreted as inclusive, i.e., including at least one, but also more than one, of a number or list of elements, and optionally additional items not in the list. Only terms clearly indicating the contrary, such as "only one of," or "exactly one of," or, when used in the claims, the term "consisting of," shall refer to the inclusion of exactly one element of a number or list of elements. When used generally, the term "or" shall only be interpreted as indicating exclusive alternatives (i.e., "either or but not both") when preceded by terms of exclusivity, such as "either," "one of," "only one of," or "exactly one of,". "Consisting essentially of," when used in the claims, shall have its ordinary meaning as used in the field of patent law.

[0098] As used in this specification and claims, the phrase "at least one" referring to a list of one or more elements should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each element specifically listed within the list of elements, nor excluding any combination of elements in the list of elements. This definition also allows that elements other than the elements specifically identified within the list of elements to which the phrase "at least one" refers may optionally be present, whether related or unrelated to the elements specifically identified. Thus, by way of example and not limitation, "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 in one embodiment to at least one and optionally more A and no B (and optionally including elements other than B), in another embodiment to at least one and optionally more B and no A (and optionally including elements other than A), in yet another embodiment to at least one and optionally more A and at least one and optionally more B (and optionally including other elements), etc.

[0099] The words "including," "comprising," "having," "containing," "involving" and variations thereof are intended to be inclusive of the items listed thereafter and additional items.

[0100] The use of ordinal terms such as "first," "second," "third," etc. to modify claim elements in a claim does not, by itself, imply any priority, precedence, or ordering of one claim element relative to another, or the temporal order in which method operations are performed. Ordinal terms are used solely as labels to distinguish one claim element having a particular name from another element having the same name (other than the use of ordinal terms) to distinguish claim elements.

Claims

1. 1. A wireless power transmitter configured to transmit high power to a wireless power receiver, the transmitter comprising: A DC voltage bus; an inverter including at least two transistors, the inverter having an input coupled to the DC voltage bus; at least one variable impedance component coupled to an output of the inverter; a resonator coil configured to generate a magnetic flux density; At least one controller wherein the at least one controller comprises: determining whether the transmitter is aligned with the receiver; in response to determining that the transmitter is not aligned with the receiver, operating the transmitter in a low power excitation (LPE) mode; adjusting at least one of a voltage level of the DC voltage bus, a phase shift angle associated with at least one transistor of the inverter, or an impedance of the at least one variable impedance component during the LPE mode such that the magnetic flux density generated by the resonator coil is below a market safety threshold; 4. A wireless power transmitter configured to:

2. 10. The wireless power transmitter of claim 1, further comprising a power factor correction (PFC) circuit having an output coupled to the DC voltage bus.

3. 3. The wireless power transmitter of claim 2, further comprising a low voltage source coupled to the DC voltage bus, and during the LPE mode, regulating the voltage level of the DC voltage bus includes disabling the PFC circuitry and providing DC power from the low voltage source to the DC voltage bus.

4. The wireless power transmitter of claim 3 , wherein the low-voltage source is one of a variable low-voltage source or a fixed low-voltage source.

5. 3. The wireless power transmitter of claim 2, wherein during the LPE mode, regulating the voltage level of the DC voltage bus includes controlling the PFC circuit to output a minimum bus voltage, the PFC circuit being configured to output a bus voltage between the minimum bus voltage and a maximum bus voltage.

6. 10. The wireless power transmitter of claim 1, wherein the at least one controller is further configured to operate the transmitter in a wireless power transfer (WPT) mode in response to determining that the transmitter is aligned with the receiver.

7. 7. The wireless power transmitter of claim 6, wherein the transmitter is configured to transmit power at a power level between 500 W and 20,000 W in the WPT mode.

8. 10. The wireless power transmitter of claim 1, wherein the transmitter is configured to transmit power at a power level between 1 W and 50 W in the LPE mode.

9. The wireless power transmitter of claim 1 , wherein determining whether the transmitter is aligned with the receiver includes performing at least one of an environmental check or a safety check.

10. (i) a controller operatively coupled to at least one of the at least two transistors or (ii) the at least one variable impedance component; a current sensor coupled to the resonator coil; 13. The wireless power transmitter of claim 1, further comprising: a current sensor configured to provide a signal representative of at least one characteristic of a current in the resonator coil to the controller, the at least one characteristic including a level, a phase, and / or a frequency of the current in the resonator coil.

11. 1. A method for low power excitation of a wireless power transmitter configured to transmit high power to a wireless power receiver, the transmitter including a DC voltage bus, an inverter having an input coupled to the DC voltage bus, the inverter including at least two transistors, at least one variable impedance component coupled to an output of the inverter, and a resonator coil configured to generate a magnetic flux density, the method comprising: determining whether the transmitter is aligned with the receiver; in response to determining that the transmitter is not aligned with the receiver, operating the transmitter in a low power excitation (LPE) mode; adjusting at least one of a voltage level of the DC voltage bus, a phase shift angle associated with at least one transistor of the inverter, or an impedance of the at least one variable impedance component during the LPE mode such that the magnetic flux density generated by the resonator coil is below a market safety threshold; A method comprising:

12. The method of claim 11 , wherein the transmitter includes a power factor correction (PFC) circuit having an output coupled to the DC voltage bus.

13. 13. The method of claim 12, wherein the transmitter includes a low voltage source coupled to the DC voltage bus, and during the LPE mode, regulating the voltage level of the DC voltage bus includes disabling the PFC circuitry and providing DC power from the low voltage source to the DC voltage bus.

14. The method of claim 13 , wherein the low voltage supply is one of a variable low voltage supply and a fixed low voltage supply.

15. 13. The method of claim 12, wherein during the LPE mode, regulating the voltage level of the DC voltage bus includes controlling the PFC circuit to output a minimum bus voltage, the PFC circuit being configured to output a bus voltage between the minimum bus voltage and a maximum bus voltage.

16. The method of claim 11 , further comprising, in response to determining that the transmitter is aligned with the receiver, operating the transmitter in a wireless power transfer (WPT) mode.

17. 17. The method of claim 16, wherein the transmitter is configured to transmit power in the WPT mode at a power level between 500 W and 20,000 W.

18. The method of claim 11 , wherein the transmitter is configured to transmit power in the LPE mode at a power level between 1 W and 50 W.

19. The transmitter includes a controller operatively coupled to at least one of (i) the at least two transistors or (ii) the at least one variable impedance component, and a current sensor coupled to the resonator coil, and the method further comprises: providing a signal indicative of at least one characteristic of the current in the resonator coil to the controller via the current sensor; 12. The method of claim 11, further comprising: wherein the at least one characteristic comprises a level, a phase, and / or a frequency of the current in the resonator coil.

20. The method of claim 11 , wherein determining whether the transmitter is aligned with the receiver includes performing at least one of an environmental check or a safety check.

21. The wireless power transmitter of claim 1 , wherein the transmitter is configured to operate in the LPE mode when the receiver is present.

22. The method of claim 11 , wherein the transmitter is configured to operate in the LPE mode when the receiver is present.

Images