Filter for improved driver circuit efficiency and method of operation
First Claim
1. A wireless power transmitter apparatus, comprising:
- a transmit coil configured to generate a magnetic field for wirelessly transferring power to one or more receiver devices to power or charge respective loads of the one or more receiver devices, a resistive part of an impedance presented to the transmit coil varying over a range of real impedance values in response to changes in positioning or presence of the one or more receiver devices within the magnetic field;
a driver circuit electrically connected to the transmit coil and comprising;
a first choke inductor electrically connected between a first node and a voltage source;
a switch electrically connected between the first node and a ground reference;
a shunt capacitor electrically connected in to the first node and electrically connected in parallel with the switch; and
a second inductor electrically connected to the first node; and
a passive filter circuit electrically connected between the driver circuit and the transmit coil, the passive filter circuit comprising one or more inductors or capacitors having fixed values selected that transform the impedance presented by the transmit coil to the passive filter circuit to a second impedance that is presented to the driver circuit, the second impedance transformed to one of a range of complex impedance values falling along a contoured line or half circuit when plotted in a complex number coordinate system, the transformed second impedance maintaining an efficiency of the driver circuit within 20% of a maximum efficiency value of the driver circuit irrespective of changes in the positioning or presence of the one or more receiver devices within the magnetic field.
1 Assignment
0 Petitions
Accused Products
Abstract
This disclosure provides systems, methods and apparatus for increasing the efficiency of an amplifier when driven by a variable load. In one aspect a transmitter device is provided. The transmitter device includes a driver circuit characterized by an efficiency. The driver circuit is electrically connected to a transmit circuit characterized by an impedance. The transmitter device further includes a filter circuit electrically connected to the driver circuit and configured to modify the impedance to maintain the efficiency of the driver circuit at a level that is within 20% of a maximum efficiency of the driver circuit. The impedance is characterized by a complex impedance value that is within a range defined by a real first impedance value and a second real impedance value. A ratio of the first real impedance value to the second real impedance value is at least two to one.
33 Citations
54 Claims
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1. A wireless power transmitter apparatus, comprising:
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a transmit coil configured to generate a magnetic field for wirelessly transferring power to one or more receiver devices to power or charge respective loads of the one or more receiver devices, a resistive part of an impedance presented to the transmit coil varying over a range of real impedance values in response to changes in positioning or presence of the one or more receiver devices within the magnetic field; a driver circuit electrically connected to the transmit coil and comprising; a first choke inductor electrically connected between a first node and a voltage source; a switch electrically connected between the first node and a ground reference; a shunt capacitor electrically connected in to the first node and electrically connected in parallel with the switch; and a second inductor electrically connected to the first node; and a passive filter circuit electrically connected between the driver circuit and the transmit coil, the passive filter circuit comprising one or more inductors or capacitors having fixed values selected that transform the impedance presented by the transmit coil to the passive filter circuit to a second impedance that is presented to the driver circuit, the second impedance transformed to one of a range of complex impedance values falling along a contoured line or half circuit when plotted in a complex number coordinate system, the transformed second impedance maintaining an efficiency of the driver circuit within 20% of a maximum efficiency value of the driver circuit irrespective of changes in the positioning or presence of the one or more receiver devices within the magnetic field. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A transmitter device, comprising:
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a transmit coil configured to generate a magnetic field for wirelessly transferring power to one or more receiver devices to power or charge respective loads of the one or more receiver devices, a resistive part of an impedance presented to the transmit coil varying over a range of real impedance values in response to changes in positioning or presence of the one or more receiver devices within the magnetic field; a class E driver circuit comprising a switch; and a passive filter circuit electrically connected between the driver circuit and the transmit coil, the passive filter circuit comprising one or more reactive elements including a capacitor and an inductor having fixed values and configured to transform the impedance presented by the transmit coil to the class E driver circuit to one of a range of complex impedance values falling along a contoured line or half circuit when plotted in a complex number coordinate system, the transformed impedance maintaining an efficiency level of the class E driver circuit within 20% of a maximum efficiency of the driver circuit, irrespective of the changes in the positioning or presence of the one or more receiver devices within the magnetic field. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A transmitter device, comprising:
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means for generating a magnetic field for wirelessly transferring power to one or more receiver devices to power or charge respective loads of the one or more receiver devices, a resistive part of an impedance presented to the means for generating a magnetic field varying over a range of real impedance values in response to changes in positioning or presence of the one or more receiver devices within the magnetic field; means for driving comprising a switch; and means for passive filtering, the means for passive filtering being electrically connected between the means for driving and the means for generating, the means for passive filtering comprising one or more reactive elements including a capacitor and an inductor having fixed values, and configured to transform the impedance presented by the means for generating a magnetic field to the means for driving to one of a range of complex impedance values falling along a contoured line or half circuit when plotted in a complex number coordinate system, the transformed impedance maintaining an efficiency level of the means for driving within 20% of a maximum efficiency of the means for driving, irrespective of the changes in the positioning or presence of the one or more receiver devices within the magnetic field. - View Dependent Claims (27, 28, 29, 30, 31)
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32. A method for filtering a transmit signal, comprising:
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generating a magnetic field for wirelessly transferring power to one or more receiver devices to power or charge respective loads of the one or more receiver devices, via a transmit coil, a resistive part of an impedance presented to the transmit coil varying over a range of real impedance values in response to changes in positioning or presence of the one or more receiver devices within the magnetic field; driving a signal using a class E driver circuit comprising a switch; providing the signal to the transmit coil; and transforming the impedance presented by the transmit coil to the driver circuit using a passive filter circuit electrically connected between the driver circuit and the transmit coil, the passive filter circuit comprising one or more reactive elements including a capacitor and an inductor having fixed values and configured to transform the impedance presented by the transmit coil to the driver circuit to one of a range of complex impedance values falling along a contoured line or half circuit when plotted in a complex number coordinate system, the transformed impedance maintaining an efficiency level of the class E driver circuit within 20% of a maximum efficiency of the driver circuit, irrespective of the changes in the positioning or presence of the one or more receiver devices within the magnetic field. - View Dependent Claims (33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43)
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44. A method for designing a power transmitter apparatus, the method comprising:
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selecting characteristics of at least two elements of a group of elements including; a class E driver circuit comprising a switch, a passive filter circuit configured to transform an impedance presented to the class E driver circuit as a resistive part of an impedance presented to a transmit coil varies over a range of real impedance values in response to changes in positioning or presence of one or more receiver devices within a magnetic field generated by the transmit coil, the transformed impedance in a range of complex impedance values falling along a contoured line or half circuit when plotted in a complex number coordinate system, and an impedance shifting element; and determining, based on the selected characteristics of the at least two elements, a characteristic of a non-selected element such that the transformed impedance maintains an efficiency level of the class E driver circuit within 20% of a maximum efficiency of the driver circuit, irrespective of the changes in the positioning or presence of the one or more receiver devices within the magnetic field. - View Dependent Claims (45, 46, 47, 48, 49, 50, 51, 52, 53, 54)
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Specification