High-power resonant inverter system for wireless power transfer and method to operate the same

Abstract

Disclosed is a high-power resonant inverter system (100) for wireless power transfer. The system (100) includes a control block (102) that generates control input signals. A synchronous gate driving arrangement (104), isolated from the main power circuit, operates a series-parallel configuration of plurality of switching elements (106). The series connection of switching elements increases voltage handling capability, while the parallel connection increases current handling capability. Furthermore, a voltage balancing network (108) evenly distributes voltage stress across the plurality of switching elements (106). Additionally, a resonant tank circuit (110) is coupled to the voltage balancing network (108) for efficient wireless power transfer.

Description

HIGH-POWER RESONANT INVERTER SYSTEM FOR WIRELESS POWER TRANSFER AND METHOD TO OPERATE THE SAMETECHNICAL FIELD

[0001] The present invention relates generally to resonant inverter circuits for wireless power transfer. More specifically, the invention relates to a high-power resonant inverter system for efficient wireless charging of electric vehicles (EVs) and a method to operate the same.BACKGROUND

[0002] Various resonant coupling systems are used to wirelessly power devices like laptops, smartphones, robot vacuums, and vehicles across short distances. Non- resonant inductive coupling methods are inefficient over greater distances due to resistive losses in the primary coil. Resonant coupling, where the secondary coil is capacitively loaded to form a resonant circuit driven at its resonant frequency, can significantly improve power transfer efficiency over a few times the coil diameter range.

[0003] Resonant wireless charging systems (WCS) employ AC-DC conversion, DC-AC high-frequency inversion, magnetic resonant coupling, and a final AC-DC stage to charge batteries. The DC-AC high-frequency inverter stage is critical for high power transfer with low losses.

[0004] While resonant inverters reduce switching losses by operating at zerovoltage crossing points, existing topologies face limitations in scaling to high power levels. Issues like high transient voltages during start-up and limited gate driver current handling restrict the maximum operating power capabilities of these circuits. Therefore, in the light of the foregoing discussion, there exists a need to overcome the aforementioned drawbacks.SUMMARY

[0005] The present disclosure provides a high-power resonant inverter system for wireless power transfer to increase voltage and current handling capability while evenly distributing voltage stress, thereby improving efficiency and reliability. Further, the present disclosure provides a method of operating a high-power resonant inverter for wireless power transfer to balance voltage stress across switching elements and transfer power wirelessly efficiently, thereby enhancing overall system performance. Advantageous features and additional implementations are set out in the appended dependent claims.

[0006] One or more objectives of the present disclosure is achieved by the solutions provided in the enclosed independent claims. Advantageous implementations of the present disclosure are further defined in the dependent claims.

[0007] In one aspect, the present disclosure provides a high-power resonant inverter system for wireless power transfer. The high-power resonant inverter system comprises a control block configured to generate control input signals. Further, the high-power resonant inverter system comprises a synchronous gate driving arrangement coupled to receive the control input signals from the control block. The gate driving arrangement is configured to operate a plurality of switching elements. The gate driving arrangement is isolated from a main power circuit of the high-power resonant inverter. Further, the high-power resonant inverter system comprises the plurality of switching elements arranged in a series-parallel configuration. A series connection of switching elements increases voltage handling capability. A parallel connection of switching elements increases current handling capability. Further, the high-power resonant inverter system comprises a voltage-balancing network coupled across the plurality of switching elements. The voltage-balancing network is configured to evenly distribute voltage stress. Further, the high-power resonant inverter system comprises a resonant tank circuit coupled to the voltage balancing network for efficient wireless power transfer.

[0008] The high-power resonant inverter system of the present disclosure offers several key advantages over conventional resonant inverter topologies. By arranging the switching elements in a series-parallel configuration, the inverter canhandle significantly higher voltages through the series connection, while also supporting higher currents via the parallel connection. The increased voltage and current rating allow the inverter to operate reliably at the high-power levels required for wireless charging of electric vehicles and unmanned aerial vehicles. Moreover, the voltage balancing network coupled across the series-connected switching elements ensures an even distribution of voltage stress, preventing any single switch from experiencing excessive voltage stress that could lead to failure. The synchronous gate driving arrangement isolated from the main power circuit further enhances the inverter's robustness by preventing any coupling that could disrupt the gate driving signals. Further, coupling with the resonant tank circuit enables efficient wireless power transfer, the inverter system overcomes the limitations of existing resonant inverters by providing a unique combination of high voltage and current capability, balanced voltage distribution, isolated reliable gate driving, and resonant power transfer - making the inverter system of the present disclosure ideally suited for high power wireless charging applications previously unattainable with conventional inverter designs.

[0009] In another aspect, the present disclosure provides a method of operating a high-power resonant inverter for wireless power transfer. The method comprises generating control input signals from a control block. Further, the method comprises receiving the control input signals at an isolated gate driving arrangement decoupled from a main power circuit of the resonant inverter. Further, the method comprises driving a plurality of switching elements arranged in a series-parallel configuration using the isolated gate driving arrangement, wherein the seriesparallel configuration increases voltage and current handling capability. Further, the method comprises balancing voltage stress across the plurality of switching elements using a voltage-balancing network coupled across the switching elements. Further, the method comprises transferring power wirelessly via a resonant tank circuit coupled to the voltage balancing network.

[0010] The method achieves all the advantages and technical effects of the high-power resonant inverter system of the present disclosure.

[0011] It is to be appreciated that all the aforementioned implementation forms can be combined. All steps which are performed by the various entities described in the present application as well as the functionalities described to be performed by the various entities are intended to mean that the respective entity is adapted to or configured to perform the respective steps and functionalities. Even if, in the following description of specific embodiments, a specific functionality or step to be performed by external entities is not reflected in the description of a specific detailed element of that entity which performs that specific step or functionality, it should be clear for a skilled person that these methods and functionalities can be implemented in respective software or hardware elements, or any kind of combination thereof. It will be appreciated that features of the present disclosure are susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the appended claims.

[0012] Additional aspects, advantages, features and objects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative implementations construed in conjunction with the appended claims that follow.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein:FIG. 1 is a block diagram illustrating a high-power resonant inverter system, in accordance with an embodiment of the present disclosure;FIG. 2 is a block diagram illustrating a gate driving arrangement, in accordance with an embodiment of the present disclosure;FIG. 3 is a flowchart of a method of operating a high-power resonant inverter for wireless power transfer, in accordance with an embodiment of the present disclosure; andFIG. 4 is a block diagram of the working implementation of the high-power resonant inverter system, in accordance with an embodiment of the present disclosure.DETAILED DESCRIPTION OF EMBODIMENTS

[0014] The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognize that other embodiments for carrying out or practising the present disclosure are also possible.

[0015] As used throughout this disclosure, the word “may” is used in a permissive sense (i.e., meaning having the potential to), rather than the mandatory sense (i.e., meaning must). Similarly, the words “include”, “including”, and “includes” mean including but not limited to.

[0016] The phrases “at least one”, “one or more”, and “and / or” are open- ended expressions that are both conjunctive and disjunctive in operation. For example, each of the expressions “at least one of A, B and C”, “at least one of A, B, or C”, “one or more of A, B, and C”, “one or more of A, B, or C” and “A, B, and / or C” means A alone, B alone, C alone, A and B together, A and C together, B and C together, or A, B and C together.

[0017] The term “a” or “an” entity refers to one or more of that entity. As such, the terms “a” (or “an”), “one or more” and “at least one” can be used interchangeably herein. It is also to be noted that the terms “comprising”, “including”, and “having” can be used interchangeably.

[0018] Throughout the description and claims of this specification, the words "comprise", "include", "have", and "contain" and variations of these words, for example "comprising" and "comprises", mean "including but not limited to", and do not exclude other components, items, integers, or steps not explicitly disclosed also to be present. Moreover, the singular encompasses the plural unlessthe context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

[0019] The present subject matter may have a variety of modifications and may be embodied in a variety of forms, and specific embodiments will be described in more detail with reference to the drawings. It should be understood, however, that the embodiments of the present subject matter are not intended to be limited to the specific forms, but include all modifications, equivalents, and alternatives falling within the spirit and scope of the present subject matter.

[0020] FIG. 1 is a block diagram illustrating a high-power resonant inverter system, in accordance with an embodiment of the present disclosure. With reference to FIG. 1, there is shown a block diagram that includes a high-power resonant inverter system 100. The high-power resonant inverter system 100 includes a control block 102 operatively coupled with a synchronous gate driving arrangement 104. There is further shown that the synchronous gate driving arrangement 104 is operatively coupled to the plurality of switching elements 106. Further, a voltage balancing network 108 is coupled across the plurality of switching elements 106. Further, a resonant tank circuit 110 is coupled to the voltage balancing network 108. The term high-power resonant inverter refers to an inverter circuit that is capable of converting direct current (DC) power into alternating current (AC) power at high power levels, utilizing resonant techniques.

[0021] Throughout the present disclosure, the control block 102 refers to a functional unit that is responsible for generating signals to operate the high-power resonant inverter system 100. The control input signals refers to the various electrical and electronic signals that are received by the control block 102 and used to influence and direct operation of the high-power resonant inverter system 100.

[0022] The high-power resonant inverter system 100 comprises the control block 102 that is configured to generate control input signals. The control block 102 is configured to regulate and control the operation of the high-power resonantinverter system 100. By generating the control input signals, the control block 102 ensures proper functioning and efficient operation of the high-power resonant inverter system 100, allowing for effective wireless power transfer.

[0023] Further, the synchronous gate driving arrangement 104 refers to a configuration that enables the synchronized control of multiple gate driving signals for a plurality of switching elements 106 in a main power circuit. The synchronous gate driving arrangement 104 provides the necessary gate driving signals to control the operation of the plurality of switching elements 106.

[0024] The switching elements refer to electronic components that can be selectively turned on or off to control the flow of current in a circuit. In an implementation, the switching elements may include a Metal-Oxide- Semiconductor Field-Effect Transistor (MOSFET). The main power circuit refers to the primary circuitry or pathway through which high-power electrical energy is transmitted to the high-power resonant inverter system 100. The high-power resonant inverter system 100 comprises the synchronous gate driving arrangement 104 that receives control input signals from the control block 102. The synchronous gate driving arrangement 104 operates the plurality of switching elements 106. In an implementation, the synchronous gate driving arrangement 104 is isolated from the main power circuit of the high-power resonant inverter system 100. The isolation of the synchronous gate driving arrangement 104 from the main power circuit is implemented to ensure reliable and safe operation of the high-power resonant inverter system 100. By isolating the synchronous gate driving arrangement 104, any potential disturbances or fluctuations in the main power circuit are prevented from affecting the operation of the plurality of switching elements 106 that further helps to maintain the stability and efficiency of the wireless power transfer process. The isolation of the synchronous gate driving arrangement 104 from the main power circuit enables accurate synchronization and timing of the gate pulses, ensuring efficient power transfer. Additionally, the isolation helps to protect the synchronous gate driving arrangement 104 from highvoltage and current stresses present in the main power circuit, enhancing the overall reliability and longevity of the high-power resonant inverter system 100.

[0025] Throughout the present disclosure, the term “series-parallel configuration” refers to a combination of switching (electrical) components that are connected in both series and parallel arrangements, allowing for increased flexibility and improved performance. In an implementation, "series connection" refers to a configuration in which switching components are connected one after another, such that the same current flows through each switching component. In another implementation, "parallel connection" refers to a configuration in which switching components are connected side by side, such that the same voltage is applied across each switching component.

[0026] The high-power resonant inverter system 100, comprises the plurality of switching elements 106 arranged in the series-parallel configuration, wherein voltage handling capability is increased by the series connection of switching elements, and current handling capability is increased by the parallel connection of switching elements. In an implementation, the "plurality of switching elements" refers to a collection or group of multiple electronic (switching) components that are capable of controlling the flow of electrical current or signals in a circuit. In an embodiment, the plurality of switching elements 106 are connected in both series and parallel combinations.

[0027] In an implementation, the "voltage handling capability" refers to the maximum voltage that the switching component can withstand without experiencing damage or failure. In another implementation, the "current handling capability" refers to the maximum current that the switching component can carry without exceeding its specified limits. The series connection of the plurality of switching elements 106 increases the voltage handling capability, while the parallel connection of the plurality of switching elements 106 increases the current handling capability. The series-parallel configuration is employed to enhance the overall power rating of the high-power resonant inverter system 100. By increasing the voltage handling capability through the series connection, the system can handlehigher voltages without compromising its functionality. Similarly, the parallel connection increases the current handling capability, allowing the system to handle larger currents without being overloaded. The series-parallel configuration of switching elements in the high-power resonant inverter system enables the system to handle higher voltages, which is crucial for efficient wireless power transfer and enhances the current handling capability, ensuring that the system can deliver sufficient power without being limited by current constraints. Overall, the seriesparallel configuration improves the performance and reliability of the high-power resonant inverter system 100 for wireless power transfer applications.

[0028] In an embodiment, a plurality of parallel-connected switching element sets, each parallel-connected switching element set comprising two or more switching elements coupled in parallel between a common drain node and a common source node. In an implementation, the "common drain node" refers to a node in a field-effect transistor (FET) circuit that serves as both the input and output terminal for the drain current, allowing the drain voltage to be controlled by the gate voltage. In another implementation, the "common source node" refers to a node in a FET circuit that serves as both the input and output terminal for the source current, enabling the source voltage to be regulated by the gate voltage. The high-power resonant inverter system 100 achieves parallel topology by connecting two or more switching elements in parallel between the common drain node and the common source node. The parallel configuration allows the current to be divided between the parallel switching elements (MOSFETs), increasing the current handling capacity. By distributing the current between multiple parallel-connected switching elements, the high-power resonant inverter system 100 can handle higher power levels.

[0029] In such an embodiment, the plurality of parallel-connected switching element sets is coupled in series to form the series-parallel configuration, wherein the common drain nodes of the parallel-connected sets are coupled together in series, and the common source nodes of the parallel-connected sets are coupled together in series. The high-power resonant inverter system 100 achieves a series-parallel configuration by coupling the plurality of parallel-connected switching element sets in series. The common drain nodes of the parallel-connected sets are also coupled together in series, as well as the common source nodes of the parallel- connected sets. The series-parallel configuration is implemented to divide the current between two parallel switching elements (MOSFETs) in the parallel topology of the resonant inverter. By doing so, both the voltage and current handling capacity of the high-power resonant inverter system 100 are increased. The series-parallel configuration of the plurality of switching elements 106 in the high-power resonant inverter system 100 allows for improved current distribution and increased voltage and current handling capacity.

[0030] Throughout the present disclosure, the "voltage balancing network" refers to an arrangement of switching components designed to distribute or equalize the voltage levels across multiple electrical circuits or devices. Further, "voltage stress" refers to the amount of electrical pressure or strain experienced by the switching component due to the applied voltage, which can potentially lead to performance degradation or failure if not properly managed.

[0031] The high-power resonant inverter system 100 further comprises the voltage balancing network 108 that is coupled across the plurality of switching elements 106. The voltage balancing network 108 is configured to evenly distribute voltage stress. The voltage balancing network 108 is designed to evenly distribute the voltage stress across the plurality of switching elements 106 (MOSFETs) in the high-power resonant inverter system 100. The voltage stress is evenly distributed by connecting resistors or capacitors between drain node and source node of the MOSFETs. The voltage balancing network 108 is implemented to address the need for evenly distributing the voltage stress across the MOSFETs in the high-power resonant inverter system 100. By balancing the voltage stress, voltage balancing network 108 helps prevent MOSFET failure and enables reliable operation at high input voltages. Balancing the voltage stress is required for achieving efficient wireless power transfer. The implementation of the voltage balancing network 108 in the high-power resonant inverter system 100 increases the voltage and currenthandling capacity of the high-power resonant inverter system 100 by utilizing the series-parallel configuration of the plurality of switching elements 106 (MOSFETs). Additionally, the voltage balancing network 108 ensures that the voltage stress is evenly distributed across the MOSFETs, preventing any individual MOSFET from being subjected to excessive stress, and thereby, promoting the longevity and reliability of the high-power resonant inverter system 100.

[0032] In an embodiment, the voltage balancing network 108 comprises one or more resistors coupled across the plurality of switching elements. In an implementation, the "resistors" refer to passive electronic components that impede the flow of electric current in a circuit, thereby providing resistance to the flow of electrical energy. In the high-power resonant inverter system 100, one or more resistors are connected across the plurality of switching elements 106. One or more resistors are connected by placing resistors in parallel with the MOSFETs in the parallel topology or in series with the MOSFETs in the series topology. The resistors are connected across the drain and source of the MOSFETs to balance the voltage stress. The purpose of coupling one or more resistors across the switching elements in the high-power resonant inverter system 100 is to, in the parallel topology, divide the current between two parallel MOSFETs allows for better current handling capacity, and, in the series topology, balance the voltage stress between the resistors connected across the MOSFETs ensures reliable operation, particularly at high input voltages.

[0033] In another embodiment, the voltage balancing network 108 comprises one or more capacitors coupled across the plurality of switching elements 106. In an implementation, the term "capacitors" refers to electronic components that store electrical energy in an electric field, consisting of two conductive plates separated by an insulating material known as a dielectric. In the high-power resonant inverter system 100, one or more capacitors are connected across the plurality of switching elements 106. One or more capacitors are connected by placing capacitors in parallel with the MOSFETs in the parallel topology or in series with the MOSFETs in the series topology. By coupling the capacitors across theswitching elements, both the voltage and current capabilities are enhanced. The coupling of capacitors across the switching elements in the high-power resonant inverter system 100 allows for increased voltage and current handling capacity, enabling the high-power resonant inverter system 100 to handle higher power levels. Additionally, the parallel topology divides the current between the parallel MOSFETs, distributing the load.

[0034] In an embodiment, the voltage balancing network 108 comprises a topology-based resistive divider coupled across the plurality of switching elements 106. In an implementation, the term "topology-based resistive divider" refers to a configuration or arrangement of resistive elements that are interconnected in a specific manner to divide an electrical signal into smaller fractions, where the division ratio is determined by the resistive values and the interconnection scheme employed. The high-power resonant inverter system 100 achieves voltage balancing by utilizing a resistive divider topology. The resistive divider topology is connected across the series-connected switching elements of the high-power resonant inverter system 100. The purpose of employing the resistive divider topology is to evenly balance the voltage stress across the MOSFETs in the high- power resonant inverter system 100, ensuring reliable operation of the circuit, particularly when subjected to high input voltages. By implementing the resistive divider topology, the high-power resonant inverter system 100 is able to effectively distribute the voltage stress across the MOSFETs, preventing MOSFET failure and enables the circuit to handle high input voltages with increased reliability and efficiency.

[0035] In an embodiment, a controlled input voltage source is configured to provide a ramped input voltage to the high-power resonant inverter system 100, wherein the ramped input voltage increases from a low startup level to a high operating level to mitigate voltage transients during startup. In an implementation, the "controlled input voltage source" refers to a voltage source that can be regulated or adjusted to provide a specific voltage level as required for a particular application. The "ramped input voltage" refers to a voltage that increases ordecreases gradually over time, rather than instantaneously changing from one level to another. The "low startup level" refers to a voltage level that is initially lower than the normal operating level, used during the startup phase of the high-power resonant inverter system 100. The "high operating level" refers to a voltage level that is higher than the startup level and is maintained during the normal operation of the high-power resonant inverter system 100. The "voltage transients" refers to sudden and temporary changes in voltage, caused by switching events or disturbances in the high-power resonant inverter system 100. The high-power resonant inverter system 100 achieves a controlled input voltage by utilizing a delayed DC ramp voltage. Initially, a low constant DC voltage (ranging from 12- 48V) is applied to kick-start the high-power resonant inverter system 100. Once a resonant AC output reaches a steady state, the input DC voltage is gradually ramped up to a higher voltage, for example, 250V. The gradual increase in voltage prevents any transient voltage that could potentially damage the plurality of switching elements 106 (MOSFETs). The purpose of providing the ramped input voltage is to mitigate voltage transients during startup. By starting with a low voltage and gradually increasing it to the desired operating level, the high-power resonant inverter system 100 ensures that the MOSFETs are not subjected to sudden voltage spikes or surges that could lead to damage. The technical effect of implementing a ramped input voltage is the prevention of switching element (MOSFET) damage caused by voltage transients, ensuring reliable and safe operation, thereby allowing for the high-power transfer capability of the high-power resonant inverter system 100 without compromising the integrity of the plurality of switching elements 106.

[0036] Throughout the present disclosure, the "resonant tank circuit" refers to an electrical circuit consisting of an inductor and a capacitor connected in parallel, which exhibits resonance at a specific frequency due to the energy exchange between the inductor and the capacitor.

[0037] The high-power resonant inverter system 100 comprises the resonant tank circuit 110 that is coupled to the voltage balancing network 108 in order to enable efficient wireless power transfer. In an embodiment, the resonanttank circuit 110 comprises an inductor and a capacitor connected parallelly. In an implementation, the "inductor" refers to a passive electronic component that stores energy in a magnetic field when an electric current flows through it, typically consisting of a coil of wire wound around a core. The resonant tank circuit is a critical component of the high-power resonant inverter system 100, responsible for enabling efficient wireless power transfer. The resonant tank circuit 110 comprises the inductor and the capacitor connected in parallel. The parallel connection of the inductor and the capacitor form a resonant LC circuit, which exhibits resonant behaviour at a specific resonant frequency determined by the values of the inductor and the capacitor. The resonant frequency is given by the equation: f_res = 1 / (2irV(LC)), where: f_ res is the resonant frequency, L is the inductance value, and C is the capacitance value.

[0038] When the high-power resonant inverter system 100 operates at or near the resonant frequency, the resonant tank circuit 110 enables magnetic resonance, facilitating efficient DC (Direct Current) to HFAC (High-frequence Alternative Current) power conversion with low switching loss.

[0039] At resonance, the resonant LC circuit presents a high impedance to the inverter output, allowing for efficient voltage gain and power transfer to a wireless charging receiver coil coupled to a transmitter coil of the resonant tank circuit 110. The parallel connection of the inductor and the capacitor at resonance, enables maximum reactive power compensation and unity power factor operation thereby maximizing both, efficiency and power handling capacity of the high- power resonant inverter system 100. The resonant LC circuit exhibits resonant behaviour, which is essential for efficient wireless power transfer through magnetic resonant coupling. The inductor in the resonant tank circuit is implemented using a high-frequency, low-loss inductor design optimized for the operating frequency and power levels. The capacitor is a high-voltage, low-loss ceramic or film capacitor capable of handling the high currents and voltages present in the resonant tank. The values of the inductor and capacitor are carefully selected to achieve the desired resonant frequency and impedance matching for optimal power transfer to thewireless charging coil. Additionally, the resonant tank circuit 110 may include additional components or topologies to improve performance, such as series or parallel resonant compensation networks, or variable tuning capabilities to compensate for changes in the wireless charging environment.

[0040] By incorporating the parallel-connected inductor and capacitor in the resonant tank circuit 110, the high-power resonant inverter system 100 can efficiently transfer power to the wireless charging coil through magnetic resonant coupling, enabling wireless charging of electric vehicles (EVs) and unmanned aerial vehicles (UAVs) with high power levels and efficiency.

[0041] In an implementation, the input voltage is ramped up (controlled) to the required value (high operating level) for high amplitude output resonance. The controlling of the input voltage allows for control of the power output of the resonant tank circuit 110. A resonant output waveform changes in response to a controlled ramp waveform of the input voltage. The ramping -up of the input voltage is done to achieve high amplitude output resonance, which is essential for high power wireless power transfer. By controlling the power output of the resonant tank circuit 110, the high-power resonant inverter system 100 ensures optimal energy transfer during the wireless charging process. The high-power resonant inverter system 100 with the resonant tank circuit 110 and voltage balancing network 108 enables efficient wireless power transfer. The high-power resonant inverter system 100 provides a significant increase in the resonant output voltage, which is advantageous for fast wireless charging of electric vehicles (EVs) and other high- power, high-frequency applications.

[0042] FIG. 2 is a block diagram illustrating a gate driving arrangement, in accordance with an embodiment of the present disclosure. With reference to FIG. 2, there is shown a block diagram 200 that includes the synchronous gate driving arrangement 104. The synchronous gate driving arrangement 104 includes an isolation circuit 202, an external low-voltage gate supply 204, and a trigger circuit 206. There is further shown that the isolation circuit 202 is operatively coupled to the trigger circuit 206 and the external low -voltage gate supply 204.

[0043] The synchronous gate driving arrangement 104 in the high-power resonant inverter system 100 is achieved by replacing the conventional triggering circuit with a particular arrangement of capacitors and resistors, along with a Zener diode to prevent reverse bias from gate to source. The synchronous gate driving arrangement 104 is necessary to ensure reliable operation of the plurality of switching elements 106 arrangement in zero voltage switching (ZVS) operation. By triggering the MOSFETs simultaneously, the plurality of switching elements 106 can operate efficiently and effectively. The synchronous gate driving arrangement 104 allows for the proper division of current between the parallel MOSFETs in the parallel resonant inverter. The synchronous gate driving arrangement 104 also enables synchronized triggering and isolated gate power supply, which is decoupled from the power circuit.

[0044] In an embodiment, the isolation circuit 202 is coupled to receive the control input signals from the control block 102. In an implementation, the "isolation circuit" refers to a circuit that provides electrical separation between two or more components, preventing the flow of electrical current between them while allowing the transmission of signals or power through means such as optocouplers, transformers, or capacitive coupling. The high-power resonant inverter system 100 incorporates an isolation circuit 202 that is connected to receive the control input signals from the control block 102. The isolation circuit 202 ensures that the trigger circuit 206, responsible for controlling the gate of the MOSFET and the current through the Zener, operates independently from the power circuit during high input voltage operation. The inclusion of the isolation circuit 202 in the high-power resonant inverter system 100 allows for the independent operation of the trigger circuit 206, ensuring that the gate of the MOSFET and the current through the Zener are controlled separately from the power circuit.

[0045] In an embodiment, the isolation circuit 202 is coupled to the external low-voltage gate supply 204 and the trigger circuit 206. The "external low-voltage gate supply" refers to an external power source that provides a low voltage level to drive the gate of a semiconductor device, such as a transistor or a thyristor. Theexternal low-voltage gate supply 204 is configured to supply a low DC voltage level, typically in the range of 5V to 20V, to the isolation circuit 202. The low DC voltage level is used by the isolation circuit 202 and the trigger circuit 206 to generate properly timed and isolated gate driving signals for the plurality of switching elements 106. The external low-voltage gate supply 204 isolates the synchronous gate driving arrangement 104 from the high voltages present in the main power circuit, preventing any interference or coupling that could disrupt the gate signals. By using the external low-voltage gate supply 204, the gate driving signals can be optimized for the specific voltage levels required to reliably turn on and off the plurality of switching elements 106, improving the overall efficiency and performance of the high-power resonant inverter system 100.

[0046] In an embodiment, the trigger circuit 206 is configured to generate gate driving signals. In an implementation, the "trigger circuit" refers to a circuitry or device that initiates or activates a specific action or function in response to a predetermined condition or event. In such an implementation, the "gate driving signals" refers to electrical signals that are applied to the gate terminal of a semiconductor device, such as a MOSFET or IGBT, to control its operation or switching behaviour. In another implementation, the trigger circuit 206 may comprise one or more trigger circuits.

[0047] The trigger circuit 206 is designed to receive input signals from the isolation circuit 202. Upon receiving the input signals, the trigger circuit 206 generates precisely timed gate driving signals with the appropriate voltage levels to turn on and off the plurality of switching elements 106.

[0048] The gate driving signals generated by the trigger circuit 206 have specific characteristics as required by the plurality of switching elements 106, such as, the gate driving signals have voltage amplitudes compatible with the gate-source voltage ratings of the plurality of switching elements 106, typically within the range of the external low-voltage gate supply 204 (e.g., 5V to 20V). The gate driving signals are precisely timed and synchronized to ensure that the plurality of switching elements 106 turn on and off at the correct instances, maintaining thedesired switching sequence and preventing any shoot-through or cross-conduction issues. The trigger circuit 206 incorporates isolation techniques, such as optocouplers or transformer coupling, to maintain electrical isolation between the gate driving signals and the high-voltage power circuit, preventing any potential feedback or interference. The trigger circuit 206 is designed to provide sufficient current drive capability to quickly charge and discharge the gate capacitances of the plurality of switching elements 106, ensuring efficient and reliable switching transitions. In some embodiments, the trigger circuit 206 may include protection features, such as desaturation detection or active clamping, to safeguard the plurality of switching elements 106 from over-voltage or over-current conditions. By generating properly timed and isolated gate driving signals, the trigger circuit 206 helps in the operation of the high-power resonant inverter system 100, enabling efficient and reliable switching of the plurality of switching elements 106 while maintaining the necessary isolation from the high-voltage power circuit.

[0049] FIG. 3 is a flowchart of a method of operating a high-power resonant inverter for wireless power transfer, in accordance with an embodiment of the present disclosure. FIG. 3 is explained in conjunction with elements from FIGs. 1 and 2. With reference FIG. 3, there is shown a flowchart of a method 300. The method 300 is executed in the high-power resonant inverter system 100 (shown in FIG. 1). The method 300 may include steps 302 to 310.

[0050] At step 302, the method 300 comprises generating control input signals from the control block 102. The control block 102 is configured to regulate and control the operation of the high-power resonant inverter system 100. By generating the control input signals, the control block 102 ensures proper functioning and efficient operation of the high-power resonant inverter system 100, allowing for effective wireless power transfer.

[0051] At step 304, the method 300 comprises receiving the control input signals at the synchronous gate driving arrangement 104 decoupled from the main power circuit of the resonant inverter.

[0052] At step 306, the method 300 comprises driving the plurality of switching elements 106 arranged in a series-parallel configuration using the synchronous gate driving arrangement 104, wherein the series-parallel configuration increases voltage and current handling capability. The series connection of the plurality of switching elements 106 increases the voltage handling capability, while the parallel connection of the plurality of switching elements 106 increases the current handling capability.

[0053] In an embodiment, the method 300 further comprises receiving the control input signals at the isolation circuit 202. The isolation circuit 202 ensures that the control input signals are electrically isolated from the main power circuit of the high-power resonant inverter system 100, preventing high-voltage transients from interfering with the control signals and ensuring the safe operation of the control block 102. Further, the external low-voltage gate supply 204 provides an isolated gate voltage to the gate driving circuits. The external low-voltage gate supply 204 powers the gate driving circuits while maintaining isolation from the main power circuit. The isolated gate voltage ensures that the gate driving circuits can operate correctly without being affected by the high-voltage stresses of the main power circuit. Further, the trigger circuit 206 coupled to the isolation circuit 202 generates the necessary gate driving signals. The trigger circuit 206 converts the control input signals into precise gate signals that are used to drive the plurality of switching elements 106. The trigger circuit 206 ensures that the plurality of switching elements 106 operates synchronously and efficiently, according to the control input signals.

[0054] In another embodiment, the series-parallel configuration of the plurality of switching elements 106 comprises arranging the plurality of switching elements 106 in parallel-connected sets with each set having two or more parallel- connected switching elements; and connecting the plurality of parallel-connected switching element sets in series to form the series-parallel configuration. The seriesparallel configuration is employed to enhance the overall performance of the high- power resonant inverter system 100. By increasing the voltage handling capabilitythrough the series connection, the system can handle higher voltages without compromising its functionality. Similarly, the parallel connection increases the current handling capability, allowing the high-power resonant inverter system 100 to handle larger currents without being overloaded.

[0055] At step 308, the method 300 comprises balancing voltage stress across the plurality of switching elements 106 using the voltage balancing network 108 coupled across the plurality of switching elements 106. The voltage balancing network 108 is designed to evenly distribute the voltage stress across the plurality of switching elements 106 (MOSFETs) in the high-power resonant inverter system 100. The voltage stress is evenly distributed by connecting resistors or capacitors between drain node and source node of the MOSFETs. The voltage balancing network 108 is implemented to address the need for evenly distributing the voltage stress across the MOSFETs in the high-power resonant inverter system 100. By balancing the voltage stress, voltage balancing network 108 helps prevent MOSFET failure and enables reliable operation at high input voltages.

[0056] At step 310, the method 300 comprises transferring power wirelessly via the resonant tank circuit 110 coupled to the voltage balancing network 108. The resonant tank circuit 110 comprises the inductor and the capacitor connected in parallel. The parallel connection of the inductor and the capacitor form a resonant LC circuit, which exhibits resonant behaviour at a specific resonant frequency determined by the values of the inductor and the capacitor. When the high-power resonant inverter system 100 operates at or near the resonant frequency, the resonant tank circuit 110 enables magnetic resonance, facilitating efficient DC to HF AC power conversion with low switching loss. By incorporating the parallel- connected inductor and capacitor in the resonant tank circuit 110, the high-power resonant inverter system 100 can efficiently transfer power to the wireless charging receiver coil through magnetic resonant coupling, enabling wireless charging of electric vehicles (EVs) and unmanned aerial vehicles (UAVs) with high power levels and efficiency.

[0057] In an implementation, the method 300 may further comprise shutting down the high-power resonant inverter system 100. The shutting down of the high- power resonant inverter system 100 comprises steps such as, the input DC voltage provided by the controlled input voltage source 402 is ramped down to a low level, (for example 48V DC), in a similar manner as it was ramped up during startup to mitigate voltage transients. Subsequently, the external low-voltage gate supply 204 supplying power to the gate driving circuits is disconnected and turned off, effectively halting the operation of the plurality of switching elements 106 and shutting down the high-power resonant inverter system 100. The controlled shutdown procedure ensures a safe and controlled transition of the high-power resonant inverter system 100 from its operating state to a de-energized state, preventing potential damage to components due to abrupt voltage or current changes.

[0058] FIG. 4 is a block diagram of the working implementation of the high- power resonant inverter system, in accordance with an embodiment of the present disclosure. FIG. 4 is explained in conjunction with elements from FIGs. 1 and 2. With reference FIG. 4, there is shown a block diagram 400 of the high-power resonant inverter system 100 designed for efficient wireless charging of electric vehicles (EVs) and unmanned aerial vehicles (UAVs).

[0059] The input to the inverter system is the input voltage provided through the controlled input voltage source 402. The controlled input voltage source 402 provides a controlled ramping of the input DC voltage, starting from the low voltage level and gradually increasing to the desired high operating voltage. The ramping approach helps mitigate voltage transients during the startup phase of the high-power resonant inverter system 100, preventing potential damage to the plurality of switching elements 106.

[0060] The control block 102, fed with the input voltage, generates the control input signals that govern the operation of the high-power resonant inverter system 100. These control input signals are fed into the isolation circuit 202, whichprovides electrical isolation between the control circuitry and the main power circuit of the high-power resonant inverter system 100.

[0061] The isolation circuit 202 is coupled to two separate trigger circuits (206A and 206B). The two separate trigger circuits (206A and 206B) receive the isolated control input signals from the isolation circuit 202 and the external low- voltage gate supply 204. The external low-voltage gate supply provides the stable, low-voltage DC source (typically 5V to 20V) required for generating the gate driving signals for the plurality of switching elements 106.

[0062] Each trigger circuit (206A and 206B) is responsible for generating the precisely timed gate driving signals necessary to control the switching behaviour of a respective set of switching elements (106A and 106B).

[0063] Choke inductors (404A and 404B) are included in the high-power resonant inverter system 100, used for filtering or smoothing purposes to minimize any high-frequency noise or ripple in the input currents.

[0064] The plurality of switching elements 106 are the core power switching components of the high-power resonant inverter system 100. The plurality of switching elements 106 consists of multiple MOSFETs (Metal-Oxide- Semiconductor Field-Effect Transistors) arranged in the series-parallel configuration. The series-parallel configuration combines the advantages of both series and parallel connections, allowing the high-power resonant inverter system 100 to handle high voltages (through the series connection) and high currents (through the parallel connection).

[0065] The first trigger circuit 206A generates the gate driving signals for the first set of plurality of switching elements 106A, while the second trigger circuit 206B generates the gate driving signals for the second set of plurality of switching elements 106B. The parallel operation of the set of switching elements (106A and 106B) further increases the overall current handling capability of the high-power resonant inverter system 100.

[0066] Associated with each set of switching elements (106A and 106B) is the voltage balancing circuits (108A and 108B). The voltage balancing circuits (108A and 108B) are designed to evenly distribute the voltage stress across the series-connected MOSFETs within each set of switching elements (106A and 106B). The voltage balancing circuits (108A and 108B) employ techniques such as resistive or capacitive voltage dividers or topology-based balancing methods to ensure that no single MOSFET experiences excessive voltage stress, which could lead to failure.

[0067] The output of the plurality of switching elements 106 is coupled to the resonant tank circuit 110, that comprises the capacitor 408 and the inductor 410 connected in parallel. The parallel LC circuit of the resonant tank circuit 110 exhibits resonant behaviour at the resonant frequency determined by the values of the inductor 410 and the capacitor 408. When the inverter operates at or near the resonant frequency, the resonant tank circuit 110 facilitates efficient wireless power transfer to the receiver charging coil through magnetic resonant coupling.

[0068] The high-power resonant inverter system 100 offers several significant advantages over conventional inverter topologies, making it exceptionally well-suited for demanding wireless power transfer applications such as charging electric vehicles (EVs) and unmanned aerial vehicles (UAVs). Its unique series-parallel configuration of switching elements enables unparalleled voltage and current handling capabilities, allowing the high-power resonant inverter system 100 to operate reliably at the high-power levels required for these applications. The voltage balancing network 108 ensures even distribution of voltage stress across the series-connected switching elements, preventing excessive stress on any single component and enhancing overall system reliability.

[0069] Furthermore, the synchronous gate driving arrangement 104, isolated from the main power circuit, provides robust and interference-free operation, ensuring precise control of the plurality of switching elements 106 crucial for efficient resonant operation. The controlled input voltage ramping feature mitigates potentially damaging voltage transients during startup, furtherimproving system robustness and longevity. Coupled with the resonant tank circuit 110 optimized for efficient wireless power transfer, the high-power resonant inverter system 100 offers a powerful combination of high-power capability, balanced voltage distribution, isolated gate driving, and resonant wireless charging - making it a game-changing solution for high-power wireless charging applications that were previously unattainable with conventional inverter designs.

[0070] Modifications to embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as "including", "comprising", "incorporating", "have", "is" used to describe and claim the present disclosure are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural. The word "exemplary" is used herein to mean "serving as an example, instance or illustration". Any embodiment described as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments and / or to exclude the incorporation of features from other embodiments. The word "optionally" is used herein to mean "is provided in some embodiments and not provided in other embodiments" . It is appreciated that certain features of the present disclosure, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the present disclosure, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable combination or as suitable in any other described embodiment of the disclosure.

Claims

We Claim:

1. A high-power resonant inverter system (100) for wireless power transfer, comprising: a control block (102) configured to generate control input signals; a synchronous gate driving arrangement (104) coupled to receive the control input signals from the control block (102), wherein the synchronous gate driving arrangement (104) is configured to operate a plurality of switching elements (106), and wherein the synchronous gate driving arrangement (104) is isolated from a main power circuit of the high-power resonant inverter system (100); the plurality of switching elements (106) arranged in a series-parallel configuration, wherein a series connection of switching elements increases voltage handling capability; and a parallel connection of switching elements increases current handling capability; a voltage balancing network (108) coupled across the plurality of switching elements (106), wherein the voltage balancing network (108) is configured to evenly distribute voltage stress; and a resonant tank circuit (110) coupled to the voltage balancing network (108) for efficient wireless power transfer.

2. The high-power resonant inverter system (100) as claimed in claim 1, comprises a controlled input voltage source configured to provide a ramped input voltage to the high-power resonant inverter system (100), wherein the ramped input voltage increases from a low startup level to a high operating level to mitigate voltage transients during startup.

3. The high-power resonant inverter system (100) as claimed in claim 1, wherein the synchronous gate driving arrangement (104) comprises: an isolation circuit (202) coupled to receive the control input signals from the control block (102); an external low-voltage gate supply (204) coupled to the isolation circuit (202); anda trigger circuit (206) coupled to the isolation circuit (202), wherein the trigger circuit (206) is configured to generate gate driving signals.

4. The high-power resonant inverter system (100) of claim 1, wherein the series-parallel configuration of the plurality of switching elements (106) comprises: a plurality of parallel-connected switching element sets, each parallel-connected set comprising two or more switching elements coupled in parallel between a common drain node and a common source node; and the plurality of parallel-connected switching element sets are coupled in series to form the series-parallel configuration, wherein the common drain nodes of the parallel -connected sets are coupled together in series, and the common source nodes of the parallel-connected sets are coupled together in series.

5. The high-power resonant inverter system (100) of claim 1, wherein the voltage balancing network (108) comprises at least one of: one or more resistors coupled across the plurality of switching elements (106); and one or more capacitors coupled across the plurality of switching elements (106).

6. The high-power resonant inverter system (100) of claim 1, wherein the voltage balancing network (108) comprises a topology-based resistive divider coupled across the plurality of switching elements (106).

7. The high-power resonant inverter system (100) of claim 1, wherein the resonant tank circuit (HO) comprises an inductor and a capacitor connected parallelly.

8. A method (300) of operating a high-power resonant inverter for wireless power transfer, the method (300) comprising: generating control input signals from a control block (102); receiving the control input signals at a synchronous gate driving arrangement (104) decoupled from a main power circuit of the high-power resonant inverter system (100);driving a plurality of switching elements (106) arranged in a series-parallel configuration using the synchronous gate driving arrangement (104), wherein the series-parallel configuration increases voltage and current handling capability; balancing voltage stress across the plurality of switching elements (106) using a voltage balancing network (108) coupled across the plurality of switching elements (106); and transferring power wirelessly via a resonant tank circuit (110) coupled to the voltage balancing network (108).

9. The method (300) of claim 8, wherein driving the plurality of switching elements (106) comprises: receiving the control input signals at an isolation circuit (202); supplying an isolated gate voltage from an external low-voltage gate supply (204); and generating gate driving signals at a trigger circuit (206) coupled to the isolation circuit (202).

10. The method (300) of claim 8, wherein the series-parallel configuration of the plurality of switching elements (106) comprises: arranging the plurality of switching elements (106) in parallel-connected sets with each set having two or more parallel-connected switching elements; and connecting the two or more parallel-connected switching element sets in series to form the series-parallel configuration.

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