Abstract: A high performance kilowatt-scale large air-gap multi-modular capacitive wireless power transfer (WPT) system is provided for electric vehicle (EV) charging. In one particular implementation, the multi-modular system achieves high power transfer while maintaining fringing electric fields within prescribed safety limits. The fringing fields are reduced using near-field phased-array field-focusing techniques, wherein the adjacent modules of the multi-modular system are out-phased with respect to one another. The inter-module interactions in this multi-modular system can be modeled, and an approach to eliminate these interactions in a practical EV charging environment is provided. To illustrate one example implementation, a prototype 1.2-kW 6.78-MHz 12-cm air-gap multi-modular capacitive WPT system comprising two 600-W modules is provided. This prototype system achieves 21.2 kW/m2 power transfer density and a peak efficiency of 89.8%.

Abstract: Systems and method herein provide for energy buffering. In one embodiment, a system includes an energy buffer comprising at least two energy storage elements. Each energy storage element is operable to buffer electrical energy. The system also includes a switch module operable to charge a first of the at least two energy storage elements while discharging a second of the at least two energy storage elements, and to discharge the first energy storage element while charging the second energy storage element after charging the first energy storage element. The switched charging of the energy storage elements compensates voltage variations between the energy storage elements to increase available electrical energy from the energy buffer.

Abstract: Capacitive wireless power transfer systems are provided. In one embodiment, for example, the system comprises two pair of coupled conducting plates; a first matching network coupled to the first pair of conducting plates; and a second matching network coupled to the second pair of conducting plates. At least one of the first and second matching networks comprises an inductor having inductance value selected based on at least one parasitic capacitance value of the capacitive wireless power transfer system. In another embodiment, a method of designing a capacitive wireless power transfer system is provided comprising determining a parasitic capacitance value of a capacitive wireless power transfer system and determining an inductance value of an inductor of at least one of the first and second matching network having a value selected based on at least one parasitic capacitance value of the capacitive wireless power transfer system.

Abstract: A high performance kilowatt-scale large air-gap multi-modular capacitive wireless power transfer (WPT) system is provided for electric vehicle (EV) charging. In one particular implementation, the multi-modular system achieves high power transfer while maintaining fringing electric fields within prescribed safety limits. The fringing fields are reduced using near-field phased-array field-focusing techniques, wherein the adjacent modules of the multi-modular system are out-phased with respect to one another. The inter-module interactions in this multi-modular system can be modeled, and an approach to eliminate these interactions in a practical EV charging environment is provided. To illustrate one example implementation, a prototype 1.2-kW 6.78-MHz 12-cm air-gap multi-modular capacitive WPT system comprising two 600-W modules is provided. This prototype system achieves 21.2 kW/m2 power transfer density and a peak efficiency of 89.8%.

Abstract: Described herein are power conversion systems and related techniques which utilize a coupled split path (CSP) circuit architecture. The CSP structure combines switches, capacitors and magnetic elements in such a way that power is processed in multiple coupled split paths in a variety of voltage domains. These techniques are well suited for power conversion applications that have one or more input/output ports that have a wide voltage range, or if the application is interfacing with the ac line voltage and requires power-factor correction.

Abstract: A systematic procedure for the synthesis of hybrid feedforward control architectures for pulse-width modulated (PWM) switching converters is provided. In this hybrid feedforward control architecture selected converter variables are sensed and utilized in a particular way based on the converter open-loop characteristics to determine the duty-cycle needed to achieve a control objective. Compared to standard feedback control techniques, advantages can include simpler controller implementation, more convenient sensing, and improved static and dynamic regulation. An example systematic procedure for developing hybrid feedforward controllers is illustrated by first considering a previously known example of hybrid feedforward control: hybrid feedforward control of a boost power factor correction (PFC) rectifier operating in discontinuous conduction mode (DCM).

Abstract: Capacitive wireless power transfer systems are provided. In one embodiment, for example, the system comprises two pair of coupled conducting plates; a first matching network coupled to the first pair of conducting plates; and a second matching network coupled to the second pair of conducting plates. At least one of the first and second matching networks comprises an inductor having inductance value selected based on at least one parasitic capacitance value of the capacitive wireless power transfer system. In another embodiment, a method of designing a capacitive wireless power transfer system is provided comprising determining a parasitic capacitance value of a capacitive wireless power transfer system and determining an inductance value of an inductor of at least one of the first and second matching network having a value selected based on at least one parasitic capacitance value of the capacitive wireless power transfer system.

Abstract: In one implementation, an analytical approach to determining an improved and/or optimal design of a matching network in a capacitive or inductive WPT system is provided. In one implementation, for example, a framework is provided to enable stage(s) of the network to simultaneously provide gain and compensation. The multistage matching network efficiency can be improved and/or optimized, such as by using the method of Lagrange multipliers, resulting in the optimum distribution of gain and compensation among the L-section stages.

Abstract: An active variable reactance rectifier circuit is provided. In one example implementation, the circuit includes an active variable reactance rectifier circuit input port and an active variable reactance rectifier circuit output port adapted to couple to a load. A power splitter circuit includes a power splitter circuit input port coupled to the active variable reactance rectifier circuit input port, a first power splitter circuit output port and a second power splitter circuit output port. A first rectifier circuit includes a first rectifier circuit input port and a first rectifier circuit output port. The first rectifier circuit input port is coupled to the first power splitter circuit output port. A second rectifier circuit includes a second rectifier circuit input port and a second rectifier circuit output port. The second rectifier circuit input port is coupled to the second power splitter circuit output port.

Abstract: Described herein are power conversion systems and related techniques which utilize a coupled split path (CSP) circuit architecture. The CSP structure combines switches, capacitors and magnetic elements in such a way that power is processed in multiple coupled split paths in a variety of voltage domains. These techniques are well suited for power conversion applications that have one or more input/output ports that have a wide voltage range, or if the application is interfacing with the ac line voltage and requires power-factor correction.

Abstract: A capacitive wireless power transfer (WPT) architecture that provides for dynamic (i.e., in motion) and/or stationary power transfer is provided. In various implementations, for example, the capacitive WPT architecture can achieve high power transfer levels at high efficiencies while maintaining fringing field strengths within acceptable safety limits. In one implementation, for example, a multi-module capacitive wireless power transfer system provides a capacitive charging system, such as for, but not limited to, charging electric vehicles (EV). In another implementation, a capacitive wireless power transfer module is provided. The module, for example, comprises a plurality of first coupling plates adapted to be coupled to a power source via an inverter; a plurality of second coupling plates adapted to be coupled to a load and to the plurality of first coupling plates for receiving wireless power and a matching network adapted to provide reactive compensation and gain.

Abstract: Multistage matching networks and analytical frameworks for improving and/or optimizing the networks is provided. In one example, a framework relaxes the resistive constraint on the input and load impedances of the stages of a multistage matching network and allows them to be complex. Based on this framework, the design of multistage matching networks can be improved or optimized, such as using a method of Lagrange multipliers. A design optimization approach, for example, can be used to predict an optimum distribution of gains and impedance characteristics among the stages of a multistage matching network. The efficiency of matching networks designed using this example approach is compared with a conventional design approach, and it is shown that significant efficiency improvements are possible.

Abstract: A heterogeneous energy storage device and a method for controlling a heterogeneous energy storage device are provided. In one implementation, a heterogeneous energy storage device is provided. The heterogeneous energy storage device includes a first energy storage device, a second energy storage device and a capacitive device. The first energy storage device has a first energy capacity and a first power to energy ratio (P/E). The second energy storage device has a second total energy capacity and a second P/E ratio different from the first P/E ratio. The capacitive device is coupled in series with the first energy storage device, wherein the second energy storage device is coupled in parallel with the series combination of the capacitive device and the first energy storage device. In another implementation, a method of controlling a heterogeneous energy storage device including a first energy storage device and a second energy storage device is provided.

Abstract: A stacked switched capacitor (SSC) energy buffer circuit includes a switching network and a plurality of energy storage capacitors. The switching network need operate at only a relatively low switching frequency and can take advantage of soft charging of the energy storage capacitors to reduce loss. Thus, efficiency of the SSC energy buffer circuit can be extremely high compared with the efficiency of other energy buffer circuits. Since circuits utilizing the SSC energy buffer architecture need not utilize electrolytic capacitors, circuits utilizing the SSC energy buffer architecture overcome limitations of energy buffers utilizing electrolytic capacitors. Circuits utilizing the SSC energy buffer architecture (without electrolytic capacitors) can achieve an effective energy density characteristic comparable to energy buffers utilizing electrolytic capacitors.

Abstract: SSC energy buffer circuit includes a switching network and a plurality of energy storage capacitors. The switching network may operate at a relatively low switching frequency and can take advantage of soft charging of the energy storage capacitors to reduce loss. Efficiency of the SSC energy buffer circuit can be extremely high compared with the efficiency of other energy buffer circuits. The SSC energy buffer architecture exhibits losses that scale with the amount of energy buffered, such that a relatively high efficiency can be achieved across a desired operating range. Improvements in SSC energy buffer circuits include, in various implementations, the use of ground reference gate drive, the elimination of a separate precharge circuit through control of at least a portion of the switches of the SSC energy buffer circuit, and/or optimized ratio of capacitance values of two or more capacitors in an SSC energy buffer circuit.

Abstract: An impedance control resonant power converter (converter) operated at a fixed switching frequency includes an impedance control network (ICN) coupled between two or more inverters operated at a fixed duty ratio with a phase shift between them and one or more rectifiers. The phase shift is used to control output power or compensate for variations in input or output voltage. The converter operates at fixed frequency yet achieves simultaneous zero voltage switching (ZVS) and zero or near zero current switching (ZCS) across a wide operating range. Output power may be controlled by: (1) changing phase shift between inverters; or (2) adjusting phase shift between inverters depending upon input and/or output voltages so that an admittance presented to the inverters is conductive and then turning the converter on and off at a frequency lower than the converter switching frequency to control output power below a value set by the phase shift.

Abstract: A control architecture that overcomes limitations of conventional ac-dc converters and enables bidirectional active and reactive power processing is provided. In one implementation, for example, this may be achieved through the use of unrectified sensed ac signals in the generation of the control commands for the converter. This control architecture, in this example implementation, eliminates or at least reduces zero crossing distortions in the ac current of the converter even with relatively low bandwidth controllers. The concept can be applied to different power stage topologies.

Abstract: A circuit includes a reconfigurable rectifier, a voltage balancer, and a pair of converters. The reconfigurable rectifier includes an ac input port and three output ports. In a first configuration, the reconfigurable rectifier can deliver power at a first output port and, in a second configuration, to at least a second output port. The voltage balancer includes first and second ports coupled to second and third output ports of the reconfigurable rectifier and is configured to balance received voltage at the first and second ports. The first converter has an input coupled to the first port of the voltage balancer and an output at which a first converted voltage signal is provided. The second converter has an input coupled to the second port of the voltage balancer and an output at which a second converted voltage signal is provided.

Abstract: A capacitive wireless power transfer (WPT) architecture that provides for dynamic (i.e., in motion) and/or stationary power transfer is provided. In various implementations, for example, the capacitive WPT architecture can achieve high power transfer levels at high efficiencies while maintaining fringing field strengths within acceptable safety limits. In one implementation, for example, a multi-module capacitive wireless power transfer system provides a capacitive charging system, such as for, but not limited to, charging electric vehicles (EV). In another implementation, a capacitive wireless power transfer module is provided. The module, for example, comprises a plurality of first coupling plates adapted to be coupled to a power source via an inverter; a plurality of second coupling plates adapted to be coupled to a load and to the plurality of first coupling plates for receiving wireless power and a matching network adapted to provide reactive compensation and gain.

Abstract: Described herein are power conversion systems and related techniques which utilize a coupled split path (CSP) circuit architecture. The CSP structure combines switches, capacitors and magnetic elements in such a way that power is processed in multiple coupled split paths in a variety of voltage domains. These techniques are well suited for power conversion applications that have one or more input/output ports that have a wide voltage range, or if the application is interfacing with the ac line voltage and requires power-factor correction.