Bidirectional wireless power transmission

Abstract

A bidirectional wireless power transfer (WPT) system comprises a WPT resonator, a power transfer connection for coupling to a battery, a bidirectional power converter coupled to the WPT resonator and the power transfer connection, a communication interface for communicating with another bidirectional WPT system configured to be coupled to the WPT resonator, and a controller. The controller is configured to determine first, second, and third control parameters, control the bidirectional power converter based on the first and second control parameters, and communicate the third control parameter to another bidirectional WPT system. The controller may operate in a power-control mode when delivering power to a vehicle battery, and may operate in a voltage-control mode when delivering power from the vehicle battery to a load or grid.

Description

Technology Field

[0001] The present application relates to bidirectional wireless power transmission, and specifically, to bidirectional wireless power transmission between an electric vehicle and an external load or electric grid. Background Technology

[0002] Wireless Power Transfer (WPT) for charging the traction batteries of electric vehicles (EVs) has been standardized and is beginning to become available in the market. Plug-in or "wired" charging systems capable of bidirectional power transfer, such as Vehicle-to-Load (V2L) or Vehicle-to-Grid (V2G), generally known as V2X, are also available but have not yet been standardized. Among other things, the question of whether the conversion from the battery's DC voltage to the grid's AC voltage should be performed by the vehicle's on-board charger (OBC) or by an external power electronics system remains unresolved. Bidirectional wireless power transfer has been proposed and has been achieved in consumer electronic devices such as mobile phones.

[0003] Generally, in some embodiments, a bidirectional wireless power transfer (WPT) assembly comprises a WPT resonator, a power transfer connection for coupling to a battery, a bidirectional power converter coupled to the WPT resonator and the power transfer connection, a communication interface for communicating with another bidirectional WPT system configured to couple the WPT resonator, and a controller. The controller is configured to determine first, second, and third control parameters, control the bidirectional power converter based on the first and second control parameters, and communicate the third control parameter to the other bidirectional WPT system.

[0004] Generally, in some embodiments, a bidirectional wireless power transfer (WPT) controller includes an output section for providing control commands to a bidirectional power converter, an input section for receiving operation parameters and a target output value of the bidirectional power converter, and a communication interface for communicating with another bidirectional WPT system. The controller is configured to determine first, second, and third control parameters, communicate the first and second control parameters to the bidirectional power converter, and communicate the third control parameter to another bidirectional WPT system. The operation parameters include the output voltage and output power of the bidirectional power converter, and the target output value is selected from either the output power or the output voltage of the bidirectional power converter, the first control parameter is based on the output power, and the second and third parameters are based on either the output voltage or the output power selected as the target output value.

[0005] The implementations may include one or more of the following in any order or combination. A bidirectional WPT assembly is installed in a vehicle and configured to determine control parameters based on the output power of the bidirectional WPT assembly during a vehicle charging operation mode. A bidirectional WPT assembly is installed in a wireless electric vehicle charging station (WEVC) and configured to determine a first control parameter based on the output power and determine second and third control parameters based on the output voltage of the bidirectional WPT assembly during a V2x operation mode. The first control parameter includes a target phase shift between the current input and the voltage input of the bidirectional power converter. The controller includes a zero voltage switching (ZVS) controller that receives as input a first input parameter representing the power at the output of the bidirectional power converter and outputs the first control parameter. The first input parameter includes the product of the current and voltage measured at the output of the bidirectional power converter. The second control parameter includes the target duty cycle of the bidirectional power converter. The controller further includes a power controller that receives as input a second input parameter comprising the difference between a first input parameter and a third input parameter comprising a requested amount of power, and outputs a second control parameter. The ZVS controller further receives as input the second control parameter output from the power controller. The power controller further outputs a third control parameter, the third control parameter comprising a target coil current in a WPT resonator of another WPT assembly. The controller is further configured to generate an initial value of the third control parameter and to control whether the initial value of the third control parameter or the value output by the power controller is provided to the other WPT assembly. The controller is configured to generate an initial value of the third control parameter from a measured value of the current input to the bidirectional power converter and a minimum current value.The second control parameter includes the target duty cycle of the bidirectional power converter, and the third control parameter includes the target coil current in the WPT resonator of another WPT assembly, and the controller is configured to update the first control parameter more frequently than to update the second and third control parameters. The controller is configured to determine the second and third control parameters together. The controller is configured to determine the second and third control parameters independently of each other.

[0006] Generally, in some embodiments, a method for controlling a bidirectional wireless power transfer (WPT) assembly is disclosed. The method comprises determining first, second, and third control parameters for a bidirectional power converter coupled to a WPT resonator and a power transfer connection; controlling the bidirectional power converter based on the first and second control parameters; and communicating the third control parameter to another bidirectional WPT assembly.

[0007] The implementations may include one or more of the following in any order or combination. Determining a first control parameter includes determining a target phase shift between a current input and a voltage input in a bidirectional power converter based on a first input parameter representing power at the output of the bidirectional power converter. The first input parameter includes the product of the current and voltage measured at the output of the bidirectional power converter. Determining a second control parameter includes determining a target duty cycle of the bidirectional power converter based on a second input parameter including the difference between the first input parameter and a third input parameter including a requested amount of power. The second control parameter includes the target duty cycle of the bidirectional power converter, and the third control parameter includes a target coil current in a WPT resonator of another WPT assembly, and the method further includes updating the first control parameter more frequently than updating the second and third control parameters.

[0008] Various embodiments may include one or more of the aforementioned features in any combination. Brief explanation of the drawing

[0009] Figure 1 illustrates a wireless electric vehicle charging station and a vehicle. Figures 2, 3, 4, and 6 are block diagrams of wireless power transmission systems. Figure 5 is a flowchart illustrating an exemplary sequence of operations for control loops. Specific details for implementing the invention

[0010] Wireless power transfer (WPT) for charging electric vehicles is described in detail in patents such as U.S. Patent No. 8,933,594, titled “Wireless energy transfer for vehicles” and U.S. Patent No. 9,561,730, titled “Wireless power transmission in electric vehicles,” the entirety of which is incorporated herein by reference. As of the filing date of this application, wireless electric vehicle charging (WEVC) systems according to the SAE J2954 standard provide up to 22 kW of power at each charging station. Lower power levels, such as 11 kW and 7 kW, are commonly used due to their compatibility with residential and industrial electrical systems. At the same time, higher power levels are also used, particularly to charge heavier work vehicles such as buses or trucks, or to charge light work vehicles at higher rates, and proposals have been made to extend existing WEVC standards to such power levels. Lower power vehicles, such as scooters, golf carts, neighborhood electric vehicles (NEVs), or industrial vehicles such as forklifts and automated ground vehicles (AGVs), may also be charged using WPT, but standards for doing so do not currently exist, and some standards are under development. In this specification, any reference to "AC power," "DC power," or "AC" and "DC" alone should be understood to refer to power transmitted as electricity having a corresponding current waveform.

[0011] Wireless vehicle charging uses power converters on both sides of a WPT connection to convert 50 Hz or 60 Hz AC power from the grid into 85 kHz power (referred to as low frequency, LF, power) for conversion from current to magnetic field, for example, on the transmitter side, then from the LF magnetic field to LF current, and then into DC power within the vehicle to charge the battery. Wireless power transmission via electromagnetic fields essentially isolates the vehicle's electrical system from the grid, whereas wired charging solutions require isolation stages in the vehicle, at the external charger, or both. Sometimes, isolation is implemented within a power conversion stage, such as an isolation transformer, as part of a DC-DC converter. In some examples, as described in the application [Provisional Application No. 63 / 556601] concurrently pending with U.S. Patents No. 9,561,730 and No. 9,381,821, all of these are incorporated herein by reference, and various power converters or components of power converters are shared between wired and wireless charging systems.

[0012] Regarding bidirectional power transmission, the general assumption was that simply making each stage of power conversion itself bidirectional—for example, by using a switching rectifier rather than a diode bridge for AC-to-DC conversion—is sufficient to make the entire power transmission chain bidirectional. This disclosure discusses details of control logic for bidirectional systems, which are not necessarily identical for V2G and G2V operations, and may improve conventional G2V operations through additional control capabilities of the bidirectional system.

[0013] FIG. 1 illustrates an example of a parking facility (100) having wireless power transmission services. A vehicle (102) is parked on a WPT pad (104). Although illustrated as a car in FIG. 1, any type of vehicle, such as a golf cart, neighborhood electric vehicle, delivery van, bus, AGV, etc., can be charged in the same way. A WPT pad (106) inside the vehicle is connected to a power converter (108). The power converter (108) converts the power received by the pad (106) into a form suitable for charging the traction battery of a vehicle not illustrated. In some examples, the power converter (108) may be integrated with power converters used for plug-in charging of the vehicle, generally referred to as onboard chargers (OBCs), or other onboard vehicle components. The ground-side WPT pad (104) is illustrated as having an external power converter (110) connected to a power supply cable (112). The power supply cable (112) is, in turn, connected to a power converter (114). In some examples, the power converter (114) provides DC power through the cable (112), and the external power converter (110) includes inverters such as the multi-level inverter (MLI) described in U.S. Patent Applications No. 18 / 486,830 and No. 18 / 486,835, both of which were filed on October 13, 2023 and incorporated herein by reference. The inverters provide low-frequency (LF) power signals, such as 85 kHz signals used for wireless charging according to the SAE J2954 standard, to the pad (104) to convert them into magnetic fields for wireless power transmission. In other examples, the inverters included in the power converter (114) provide LF power signals through the cable (112), and the power converter (110) may be omitted or may provide only limited features such as impedance matching. The power converter (110) may also be integrated into the pad (104).In some examples, the pad (104) is referred to as the ground assembly resonator (GAR), and the combination of the GAR and the power converter (110) or any other ground-side electronics, whether integrated or separately housingd, is referred to as the ground assembly (GA). Similarly, the WPT pad (106) may be referred to as the vehicle assembly resonator (VAR), and the combination of the VAR and the power converter (108) or any other vehicle-side electronics, whether integrated or separately housingd, may be referred to as the vehicle assembly (VA). Each of the illustrated connections may be bidirectional so that vehicles may discharge power from their batteries to the power converter (114) in a V2x array.

[0014] FIG. 2 is a schematic diagram of exemplary components of a wireless power transmission system (200) as illustrated in FIG. 1. The wireless power transmission system (200) includes a base resonant circuit (e.g., GAR (206)) comprising a coil (204) having an inductance L1. The wireless power transmission system (200) further includes an electric vehicle resonant circuit (e.g., VAR (222)) comprising a coil (216) having an inductance L2. Implementations may use capacitively loaded conductor loops (e.g., multi-turn coils) that form a resonant structure capable of efficiently coupling energy from a primary structure (transmitter) to a secondary structure (receiver) through a magnetic or electromagnetic near-field when both the transmitter and receiver are tuned to a common resonant frequency. The coils may be used for the coil (216) and the coil (204). The use of resonant structures to couple energy may be referred to as "magnetically coupled resonance," "electromagnetically coupled resonance," or "resonance induction."

[0015] The power supply unit (208) supplies power P to the base power converter (236) to transmit energy to the electric vehicle. SThe base power converter (236) supplies power. The base power converter (236) may include circuits such as an AC-to-DC converter configured to convert power from standard grid-supply AC into DC power of an appropriate voltage level, and a DC-to-LF converter configured to convert DC power into LF power of an operating frequency suitable for wireless power transmission. The base power converter (236) supplies power P1 to a GAR (206) comprising a tuning capacitor C1 in series with a coil (204) to emit an electromagnetic field at the operating frequency. The series-tuned resonant circuit depicted for the GAR (206) should be interpreted as exemplary. In other implementations, the capacitor C1 may be coupled in parallel to the coil (204). In other implementations, tuning may be provided by several reactive elements of any combination of parallel or series topologies. The capacitor C1 may be provided to form a resonant circuit with the coil (204) that resonates substantially at the operating frequency. The coil (204) receives power P1 and wirelessly transmits power at a level sufficient to charge or power the electric vehicle. For example, the power level wirelessly provided by the coil (204) may be in kilowatts (kW) (e.g., any value from 1 kW to 500 kW, but actual levels may be higher or lower).

[0016] GAR (206) (including coil (204) and tuning capacitor C1) and VAR (222) (including coil (216) and tuning capacitor C2) may be tuned to substantially the same frequency. Coil (216) may be positioned within the near field of the base power transmission element, and vice versa, as further described below. Coil (204) and coil (216) may be coupled to each other so that power may be transmitted wirelessly from coil (204) to coil (216). Series capacitor C2 forms a resonant circuit with coil (216) that resonates substantially at the operating frequency. The series-tuned resonant circuit illustrated for VAR (222) should be interpreted as exemplary. In other implementations, capacitor C2 may be coupled in parallel to coil (216). In other implementations, VAR (222) may be formed of several reactive elements of any combination of parallel or series topologies. Element k (d) represents the mutual coupling coefficient arising from coil separation d. Equivalent resistances R eq,1 and R eq,2 Each represents losses that may be inherent in the coils (204 and 216) and tuning (anti-reactance) capacitors C1 and C2. The VAR (222), comprising the coil (216) and capacitor C2, receives power P2 and provides it to the electric vehicle power converter (238) of the electric vehicle charging system (214).

[0017] The electric vehicle power converter (238) may include, among other things, an LF-to-DC converter configured to convert power of the operating frequency back into DC power of the voltage level of a load (218) which may represent an electric vehicle battery unit. The electric vehicle power converter (238) converts the power P LDC Provides to the load (218).

[0018] The coil (216) and coil (204) as described throughout the disclosed embodiments may be referred to or configured as "conducting loops," and more specifically, as "multi-turn conducting loops" or coils. The base and electric vehicle power transmission elements (e.g., coil (204) and coil (216)) may also be referred to or configured as "magnetic" couplers in this specification. The term "coupler" is intended to refer to a component capable of wirelessly outputting or receiving energy to be coupled to another "coupler".

[0019] As discussed above, efficient energy transmission between a transmitter and a receiver occurs during matched or nearly matched resonance between them. However, even when the resonance between the transmitter and the receiver is not matched, energy may be transmitted at a lower efficiency.

[0020] FIG. 3 illustrates an exemplary bidirectional WPT system in more detail. The power converters of FIG. 2 are replaced by bidirectional switching inverters / rectifiers (336, 338), which may generally be referred to as inverters or rectifiers based on their mode of operation in a given situation. Control signals PWM1 through PWM8 control the switching of metal-oxide-semiconductor field-effect transistors (MOSFETs) Q1 through Q8 within the inverters / rectifiers (336, 338). Control methods are described later in this disclosure. In this example, impedance matching and filtering are provided by two inductors L3sA / B, L3dA / B and three capacitors C1sA / B, C2s, and C1dA / B on each side of the WPT coils L1s and L1d. This example assumes a DC input to the ground-side inverter / rectifier (336), denoted as VBUS. Such input may be provided, for example, by a bidirectional power factor correction (PFC) converter. The drawing shows the two values ​​used below, namely, the current I input to the vehicle-side inverter / rectifier (338) in charging (G2V) mode. 3d , and the voltage V across the input terminals of the same inverter / rectifier. acd Identify.

[0021] FIG. 4 illustrates the control logic used to operate the system of FIG. 3. The internal switches Q1 … Q8 of the inverter / rectifiers (336) are now illustrated. The control signals PWM1 to PWM4 for the ground-side switches are PWMs provided by the ground-side inverter controller (402). GA It is expressed as. VBUS from Fig. 3 is V grid Note that it is replaced by a bidirectional PFC (404) having its own controller (406). On the vehicle side, the inverter controller (408) is illustrated in more detail. The control signals for the ground-side switches, PWM5 to PWM5, are PWM VAIt is expressed as and provided by the modulator (410). The modulator receives input messages Φ from the corresponding controllers (412, 414). VA and β VA It receives. The modulator (410) also receives I of the inverter input current. acd,sense A synchronization signal based on measurements is received as an input. It is also noted that the Φ controller (412) is a zero voltage switching (ZVS) controller, and I is the current and voltage measured from the battery. batt,sense and V batt,sense The parameter P that is the product of batt It receives as its input. The β controller is P batt Wow, power command message P cmd Receives the difference as its input. P cmd represents the power that may be provided by an onboard charger (OBC) or another battery management system (BMS) and must be provided to the battery. In other words, the input to the β controller is the difference between the power supplied to the battery and the requested power.

[0022] As illustrated, the β controller (414) is coupled with the GA coil current controller (416) in the power controller (418). GA coil current command message I GA_cmd It is transmitted from the GA coil current controller to the GA via the WiFi link (420). Within the GA, the command processing unit (422) I GA_cmd The message V, which is transmitted to the PFC controller and indicates the voltage to be supplied to the GA inverter (e.g., inverter / rectifier (336)). bus_cmd The message and β transmitted to the GA inverter controller (402). GA_cmd Decompose into messages. The coil current is input voltage V according to Equation (1). bus and inverter duty cycle β GA is determined by:

[0023] Equation (1)

[0024] In Equation (1), X GA is the characteristic impedance on the GA side of the system. In both GA and VA, β and associated commands refer to the duty cycle of the inverter / rectifier. The symbol Φ and associated messages refer to the phase shift between the current input and the voltage input in the VA inverter / rectifier (338). By operating the switches of the inverter / rectifier in synchronization with the zero-crossing of the input current, the voltage can be made to lag or lead the current, thereby Φ VA Controls.

[0025] For grid-to-vehicle (G2V) mode (e.g., vehicle charging), it is desirable to operate in constant power mode. To this end, GA is operated to control the coil current as requested by VA, while VA is operated to control the rectifier duty cycle β. Both inverters / rectifiers operate as phase-shifted full-bridge devices, which allows all switches to operate with zero-voltage switching and enables losses to be shared equally. Φ VA Maintaining Φ at values ​​between 90°-β and 90° maintains zero voltage switching in the rectifier (338). Specifically, for any value of β, Φ = 90°-β represents the boundary where ZVS can be achieved. Φ VA Controlling it also helps increase the system's power output under weak coupling conditions.

[0026] As mentioned, I GA and β VA Together, they determine the power output of the system. The two controllers (414, 416) can be executed sequentially or simultaneously to implement power control. In some examples, β VA The control loop is I GA It can execute faster than a loop, which is β VA While the loop directly regulates the output power, I GAThis is because the control loop is limited by WiFi latency. In some examples, β VA The loop controls output power with a bandwidth between 5 Hz and 50 Hz, while I GA The loop has a bandwidth of less than 5 Hz. At the same time, Φ VA The control loop can operate at 500 Hz to ensure ZVS for good efficiency and maximum power output.

[0027] The flowchart of FIG. 5 illustrates an exemplary sequence of operations for control loops. Initially, in the first initial rectifier current phase (502) of startup, a power command (504) is received. This command is for a current mode of G2V and a requested power P batt and V batt This indicates that it will be delivered to the battery. Next, the VA rectifier input current I acd The value is increased (506), and the minimum value I ac-min It is compared with (508). During this loop, the GA current target I GA-ref The value of is, I acd Ga I ac-min It increases until it becomes less than (510).

[0028] I acd Ga I ac-min If it is greater than, the lower power phase (512) of the startup begins. In this phase, β VA and Φ VA is tuned together (514), and β VA is set to achieve the desired power output, and Φ VA is the ZVS boundary 90°-β VA It is set according to. During this phase, battery power P batt is Command P cmd It is compared with (516). If the difference is less than the threshold ε, the startup process, P cmdIt loops until the command changes, the output power deviates from the target for any other reason, or the charging process stops (518). When more power is needed, P batt Until β exceeds 3 kW (520) VA The command is adjusted, and at that point, it can exit the startup phase. In full-output operation, Φ VA is initially increased to increase the output power (522). As mentioned above, β VA and I GA,cmd is Φ VA These are updated at lower frequencies. Whenever it is time to update one or both of these (524), these parameters are updated at the output P batt Target P cmd It is tuned to match (526). Until instructed to stop charging (528), the output power P batt is target P cmd It is compared with (530). If the output power is maintained below the target by ε or drops, or if the target is updated, the tuning steps are repeated. If the output power drops below 3 kW (520), it re-enters the low-power phase of the startup. As long as the output power is within the threshold ε of the target, the system continues charging until it is instructed to stop, at which point charging is terminated.

[0029] FIG. 6 illustrates the control logic used to operate the system of FIG. 3 in vehicle-to-grid (V2G) mode. Specifically, details of the GA power controller (608), which was abstracted into a mathematical block (e.g., command processing unit (422)) in FIG. 4, are illustrated in more detail. This control block is largely a mirror image of the VA power controller (408) of FIG. 4, except that it operates in voltage control mode rather than power control mode. That is, P, the DC output power flowing from the inverter / rectifier (336) to the bidirectional PFC (404). busWhile providing input to the Φ controller (612) again, V bus × I bus The product of P bus It is not the bus voltage V bus Ga V bus,cmd It is compared with the target, and the difference is used as an input to the power controller (618). As shown in FIG. 4, the difference from the target is again used by the GA β controller (614) to determine the β for the duty cycle of the inverter (556). GA Used to set the value, and to request the coil current in VA (now operating as a power transmitter) by the GA-side VA coil current controller (616) I VA,cmd It is used to set the value of. The process of updating control commands in FIG. 6 may be essentially the same as that shown in FIG. 5, along with the change from power control to voltage control.

[0030] Bidirectional PFC (404) and the power system connected thereto—V in FIG. 6 grid As depicted—can be grid-connected or standalone. In grid-connected mode, for V2G operation, the PFC provides power to the grid at the frequency dictated by the grid connection. In standalone mode, for V2L (load), V2B (building), V2x, etc. operations, the PFC itself determines the voltage and sets the AC frequency for any loads connected to it. Unlike the vehicle charging scenario in Fig. 4, where battery power requirements are expected to be stable and predictable according to the battery charging curve, grids in V2G situations or other loads in V2x modes may cause unpredictable spikes or drops in demand. Φ GA Controlling allows for a rapid response to demand changes in PFC, and β GA or I VAThe required amount of power can be reduced through adjustment. Additionally, the capacitor bank (604) provides a buffer to some extent to maintain the required output voltage during the response time of the vehicle charging system to deliver the transition time required by the relatively slow WiFi connection (420) and the requested power increases.

[0031] FIG. 6 also illustrates a coupling check block (630) corresponding to the coupling check (430) on the vehicle side of FIG. 4. The coupling check may verify that the two WPT systems are aligned with each other by comparing the current passing through one of the inductors with the current provided to the transmitting coil on the other side. In some cases, the coupling check may be performed by the same system (VA or GA) in both G2V and V2G / x modes. In other cases, measurements may be performed on one side, but calculations are performed on the other side. For example, measurements may be performed on the vehicle side during G2V and on the ground side during V2G, but calculations are performed by the vehicle in both cases.

[0032] The various exemplary logic blocks, modules, circuits, and methods described in connection with the examples disclosed above may be implemented as electronic hardware, computer software, or a combination of both. To clearly exemplify this interchangeability between hardware and software, various exemplary components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or as software depends on the design constraints imposed on the overall system and the specific application. While the described functionality may be implemented in various ways for each specific application, such decisions regarding implementation should not be interpreted as causing a deviation from the scope of the described modes.

[0033] The various exemplary blocks, modules, and circuits described in connection with the disclosed controllers may be implemented or performed by a general-purpose hardware processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose hardware processor may be a microprocessor, but alternatively, the hardware processor may be any conventional processor, controller, microcontroller, or state machine. The hardware processor may also be implemented as a combination of computing devices.

[0034] The steps and functions of the method described above may be implemented directly in hardware, in a software module executed by a hardware processor, or in a combination of both. If implemented in software, the functions may be stored or transmitted as one or more instructions or codes on a type of non-transient computer-readable medium. The software module may reside in random access memory (RAM), flash memory, read-only memory (ROM), or any other form of storage medium known in the art. The storage medium is coupled to the hardware processor so that the hardware processor can read information from the storage medium and write information to the storage medium. In other examples, the storage medium may be integrated into the hardware processor. The hardware processor and the storage medium may reside in an ASIC.

[0035] Unless the context indicates otherwise, the items and terms depicted in the accompanying drawings may represent one or more items or terms, and thus, references to a single or multiple forms of items and terms may be made interchangeably in this described description. Although the subject matter has been described in language specific to structural features or methodological operations, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or operations described above, including that the configurations in which the features are arranged or the order in which the operations are performed are not necessarily limited. For example, while the context of the above description is wireless charging of electric vehicles, these techniques may be used in other situations where it is desirable to distribute power between various sources and loads.

[0036] Many implementations have been described. Nevertheless, additional modifications may be made without departing from the scope of the concepts described herein, and accordingly, it will be understood that other embodiments are within the scope of the following claims.

Claims

Claim 1 A bidirectional wireless power transmission (WPT) assembly comprising: a WPT resonator; a power transmission connection for coupling to a battery; a bidirectional power converter coupled to the WPT resonator and the power transmission connection; a communication interface for communicating with another bidirectional WPT assembly configured to be coupled to the WPT resonator; and a controller, wherein the controller determines control parameters including first, second, and third control parameters, controls the bidirectional power converter based on the first and second control parameters, and is configured to communicate the third control parameter to the other bidirectional WPT assembly. Claim 2 A bidirectional wireless power transmission (WPT) assembly according to claim 1, wherein the bidirectional WPT assembly is installed in a vehicle and configured to determine the control parameters based on the output power of the bidirectional WPT assembly during a vehicle charging operation mode. Claim 3 A bidirectional wireless power transmission (WPT) assembly according to claim 1, wherein the bidirectional WPT assembly is a component of a wireless electric vehicle charging station (WEVC) and is configured to determine the first control parameter based on output power during a V2x operation mode; and to determine the second and third control parameters based on the output voltage of the bidirectional WPT assembly. Claim 4 A bidirectional wireless power transmission (WPT) assembly according to claim 1, wherein the first control parameter includes a target phase shift between the current input and the voltage input in the bidirectional power converter. Claim 5 In claim 4, the bidirectional wireless power transmission (WPT) assembly comprises a zero voltage switching (ZVS) controller that receives as input a first input parameter representing power at the output of the bidirectional power converter and outputs the first control parameter. Claim 6 In claim 5, the bidirectional wireless power transmission (WPT) assembly, wherein the first input parameter comprises the product of the current and voltage measured at the output of the bidirectional power converter. Claim 7 In claim 5, the bidirectional wireless power transmission (WPT) assembly, wherein the second control parameter includes the target duty cycle of the bidirectional power converter. Claim 8 A bidirectional wireless power transmission (WPT) assembly according to claim 7, wherein the controller further comprises a power controller that receives as input a second input parameter including the difference between the first input parameter and a third input parameter including a requested amount of power, and outputs the second control parameter. Claim 9 In claim 8, the bidirectional wireless power transmission (WPT) assembly further receives the second control parameter output from the power controller as an input. Claim 10 In claim 8, the power controller further outputs the third control parameter, and the third control parameter includes a target coil current in a WPT resonator of another WPT assembly, in a bidirectional wireless power transmission (WPT) assembly. Claim 11 A bidirectional wireless power transmission (WPT) assembly, wherein, in paragraph 10, the controller is further configured to generate an initial value of the third control parameter and to control whether the initial value of the third control parameter or the value output by the power controller is provided to another WPT assembly. Claim 12 In claim 11, a bidirectional wireless power transmission (WPT) assembly configured such that the controller generates the initial value of the third control parameter from the measured value of the current input to the bidirectional power converter and the minimum current value. Claim 13 In paragraph 4, the second control parameter includes a target duty cycle of the bidirectional power converter; the third control parameter includes a target coil current in a WPT resonator of another WPT assembly; and the controller is configured to update the first control parameter more frequently than to update the second and third control parameters, a bidirectional wireless power transmission (WPT) assembly. Claim 14 A bidirectional wireless power transmission (WPT) assembly according to claim 1, wherein the controller is configured to determine the second and third control parameters together. Claim 15 A bidirectional wireless power transmission (WPT) assembly according to claim 1, wherein the controller is configured to determine the second and third control parameters independently of each other. Claim 16 A method for controlling a bidirectional wireless power transmission (WPT) assembly, comprising: determining first, second, and third control parameters for a bidirectional power converter coupled to a WPT resonator and a power transmission connection; controlling the bidirectional power converter based on the first and second control parameters; and communicating the third control parameter to another bidirectional WPT assembly. Claim 17 A method for controlling a bidirectional wireless power transmission (WPT) assembly, wherein the step of determining the first control parameter comprises determining a target phase shift between a current input and a voltage input in the bidirectional power converter based on a first input parameter representing power at the output of the bidirectional power converter. Claim 18 A method for controlling a bidirectional wireless power transmission (WPT) assembly according to claim 17, wherein the first input parameter comprises the product of the current and voltage measured at the output of the bidirectional power converter. Claim 19 A method for controlling a bidirectional wireless power transmission (WPT) assembly, wherein the step of determining the second control parameter comprises determining the target duty cycle of the bidirectional power converter based on the second input parameter, which includes the difference between the first input parameter and the third input parameter, which includes the requested amount of power. Claim 20 A method for controlling a bidirectional wireless power transmission (WPT) assembly, wherein, in claim 16, the second control parameter comprises a target duty cycle of the bidirectional power converter, the third control parameter comprises a target coil current in a WPT resonator of another WPT assembly, and the method further comprises the step of updating the first control parameter more frequently than the second and third control parameters are updated. Claim 21 A bidirectional wireless power transfer (WPT) controller comprising: an output portion for providing control commands to a bidirectional power converter; an input portion for receiving operation parameters and a target output value of the bidirectional power converter; and a communication interface for communicating with another bidirectional WPT assembly, wherein the controller is configured to determine first, second, and third control parameters; communicate the first and second control parameters to the bidirectional power converter; and communicate the third control parameter to the other bidirectional WPT assembly; wherein the operation parameters include an output voltage and an output power of the bidirectional power converter; wherein the target output value is selected from either the output power or the output voltage of the bidirectional power converter; wherein the first control parameter is based on the output power; and wherein the second and third control parameters are based on either the output voltage or the output power selected as the target output value.

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