Wireless power transfer system
First Claim
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1. A power inverter for driving a transmitter coil in an inductive power transfer system, wherein the power inverter is suitable for class ‘
- EF’
operation, is arranged to drive a load resistance, and comprises;
a switching device arranged between a power source and ground and arranged to switch at a switching frequency; and
a resonant network arranged in parallel with the switching device between the power source and ground, the resonant network having a resonant frequency which is a non-integer multiple of the switching frequency, such that, in operation, a substantially constant current passes through the load resistance.
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Abstract
A load-independent Class EF inverter may maintain ZVS operation, and produce a constant output current, rather than a constant output voltage, regardless of the load resistance. A constant output current allows the inverter to operate efficiently for a load range from zero resistance (short circuit) to a certain maximum load resistance, making the inverter more suitable as a coil driver for an IPT system. The resonant frequency of the resonant circuit may be tuned to a non-integer multiple of a switching frequency.
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Citations
20 Claims
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1. A power inverter for driving a transmitter coil in an inductive power transfer system, wherein the power inverter is suitable for class ‘
- EF’
operation, is arranged to drive a load resistance, and comprises;a switching device arranged between a power source and ground and arranged to switch at a switching frequency; and a resonant network arranged in parallel with the switching device between the power source and ground, the resonant network having a resonant frequency which is a non-integer multiple of the switching frequency, such that, in operation, a substantially constant current passes through the load resistance. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
- EF’
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11. A method of fabricating a power inverter for driving a transmitter coil in an inductive power transfer system, wherein the power inverter is suitable for class ‘
- EF’
operation, is arranged to drive a load resistance, and the method comprises;arranging a switching device between a power source and ground; arranging the switching device to switch at a switching frequency; arranging a resonant network in parallel with the switching device between the power source and ground; arranging the resonant network to have a resonant frequency which is a non-integer multiple of the switching frequency, such that, in operation, a substantially constant current passes through the load resistance. - View Dependent Claims (12)
- EF’
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13. A rectifier for receiving an AC signal from a receiver coil in an inductive power transfer system, wherein the rectifier is suitable for class ‘
- EF’
operation, is arranged to drive a load resistance, and comprises;a switching device arranged between a power source and the load resistance and arranged to switch at a switching frequency; and a resonant network having a resonant frequency which is a non-integer multiple of the switching frequency and arranged such that, in operation, a substantially constant current passes through the load resistance. - View Dependent Claims (14, 15)
- EF’
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16. An inductive power transfer system comprising a transmitter circuit and a receiver circuit, the transmitter circuit comprising a power inverter and the receiver circuit comprising a rectifier;
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wherein the power inverter is configured for driving a transmitter coil in the inductive power transfer system, wherein the power inverter is suitable for class ‘
EF’
operation, is arranged to drive a load resistance, and comprises;a switching device arranged between a power source and ground and arranged to switch at a first switching frequency; and a resonant network arranged in parallel with the switching device between the power source and ground, the resonant network having a resonant frequency which is a non-integer multiple of the first switching frequency, such that, in operation, a substantially constant current passes through the load resistance; and wherein the rectifier is configured for receiving an AC signal from a receiver coil in the inductive power transfer system, wherein the rectifier is suitable for class ‘
EF’
operation, is arranged to drive a load resistance, and comprises;a switching device arranged between a power source and the load resistance and arranged to switch at a second switching frequency; and a resonant network having a resonant frequency which is a non-integer multiple of the second switching frequency and arranged such that, in operation, a substantially constant current passes through the load resistance. - View Dependent Claims (17, 18)
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19. A method of fabricating a rectifier for receiving an AC signal from a receiver coil in an inductive power transfer system, wherein the rectifier is suitable for class ‘
- EF’
operation, is arranged to drive a load resistance, the method comprising;arranging a switching device between a power source and the load resistance; arranging the switching device to switch at a switching frequency; and arranging a resonant network having a resonant frequency which is a non-integer multiple of the switching frequency, such that, in operation, a substantially constant current passes through the load resistance. - View Dependent Claims (20)
- EF’
Specification