Switched-capacitor power ramping for soft switching
First Claim
1. A circuit for continuous soft-switching in a wireless power transmitter, the circuit comprising:
- a coil having a first terminal connected to a first-phase-output of an inverter and a second terminal connected to a second-phase-output of the inverter;
a first capacitor having a first terminal connected to the first terminal of the coil and a second terminal connected to the second terminal of the coil;
a second capacitor having a first terminal connected to the first terminal of the first capacitor;
a switch having a first terminal connected to a second terminal of the second capacitor and a second terminal connected to the second terminal of the first capacitor; and
a power ramp controller coupled to the switch, the power ramp controller configured to control the switch to provide soft switching of the inverter.
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Accused Products
Abstract
The present disclosure describes aspects of switched-capacitor power ramping for soft switching. In some aspects, a resonant circuit of a wireless power transmitter includes a portion of capacitance that is switchable. This portion of capacitance can be disconnected from the resonant circuit to detune the resonant circuit, which may affect voltage or current flow in the resonant circuit. For example, when ramping transmitted power up or down, detuning the resonant circuit may enable an inverter of the wireless power transmitter to continuously soft switch through the power ramping process. By so doing, hard switching of the inverter can be avoided and the inverter can be implemented with lower-power or less expensive components.
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Citations
30 Claims
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1. A circuit for continuous soft-switching in a wireless power transmitter, the circuit comprising:
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a coil having a first terminal connected to a first-phase-output of an inverter and a second terminal connected to a second-phase-output of the inverter; a first capacitor having a first terminal connected to the first terminal of the coil and a second terminal connected to the second terminal of the coil; a second capacitor having a first terminal connected to the first terminal of the first capacitor; a switch having a first terminal connected to a second terminal of the second capacitor and a second terminal connected to the second terminal of the first capacitor; and a power ramp controller coupled to the switch, the power ramp controller configured to control the switch to provide soft switching of the inverter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for initiating transmission of power by a wireless power transmitter, the method comprising:
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disconnecting, by a power ramp controller, one of at least two parallel capacitors of a resonant circuit of the wireless power transmitter; setting a frequency of an inverter of the wireless power transmitter to a first frequency; initiating, with the one of at least two parallel capacitors disconnected and the inverter operating at the first frequency, the transmission of the power to a wireless power receiver; increasing an amount of the power transmitted to the wireless power receiver until a phase angle of the power in the resonant circuit reaches a predefined threshold, the phase angle based on a voltage and a current of the resonant circuit; connecting, responsive to the phase angle reaching the predefined threshold, the one of at least two parallel capacitors of the resonant circuit of the wireless power transmitter; and setting the frequency of the inverter to a second frequency at which the transmission of the power continues. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. An apparatus for wireless power transmission, the apparatus comprising:
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an inverter configured to provide power by operating at two or more frequencies; a resonant circuit connected to the inverter, the resonant circuit comprising; a coil configured to transmit power to a wireless power receiver; a first capacitor connected in parallel with the coil; a second capacitor connected in parallel with the coil; and a switch interposed between a terminal of the second capacitor and a terminal of the coil; and a power ramp controller configured to; open the switch to disconnect the second capacitor from the coil; set an operating frequency of the inverter to a first frequency; initiate, with the second capacitor disconnected from the coil and the inverter operating at the first frequency, transmission of the power from the apparatus to the wireless power receiver; increase an amount of the power transmitted until a phase angle of the power in the resonant circuit is greater than 90 degrees, the phase angle based on a voltage and a current of the resonant circuit; set the operating frequency of the inverter to a second frequency; close the switch to connect the second capacitor in parallel with the coil; and transmit, with the second capacitor connected in parallel with the coil and the inverter operating at the second frequency, additional power from the apparatus to the wireless power receiver. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27)
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28. A circuit for continuous soft-switching in a wireless power transmitter, the circuit comprising:
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a coil having a first terminal connected to a first-phase-output of an inverter and a second terminal connected to a second-phase-output of the inverter; a first capacitor having a first terminal connected to the first terminal of the coil and a second terminal connected to the second terminal of the coil; switchable means for tuning the wireless power transmitter, the switchable means including a first terminal connected to the first terminal of the coil and a second terminal connected to the second terminal of the coil, the switchable means having a capacitance that is approximately three percent to twelve percent of a capacitance of the first capacitor; and control means for providing soft switching of the inverter while ramping power of the wireless power transmitter, the control means coupled to the switchable means. - View Dependent Claims (29, 30)
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Specification