INDUCTIVE POWER TRANSMITTER

• US 20170279313A1
• Filed: 08/13/2015
• Published: 09/28/2017
• Est. Priority Date: 08/21/2014
• Status: Abandoned Application

• Current Assignee: Apple Inc.
• Original Assignee: PowerbyProxi Limited (Apple Inc.)
• Inventors: HU, Aiguo, TIAN, Jianlong
• Application Number:
  US15/505,336
• Publication Number:
  US 20170279313A1
• Time in Patent Office: Days
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02M 1/0058 by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826
• CPC Class Codes: H02M 7/4818 with means for adaptation of resonance frequency, e.g. by modification of capacitance or inductance of resonance circuits
• CPC Class Codes: H02M 7/53803 with automatic control of output voltage or current
• CPC Class Codes: H02M 7/53835 of the parallel type
• CPC Class Codes: H02M 7/53846 Control circuits
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

An inductive power transmitter comprising: at least two switching elements connected across a resonant circuit, the resonant circuit including an inductance and a capacitance; wherein the transmitter is configured to adjust the value of the capacitance based on a desired operating frequency.

Claims

1. An inductive power transmitter comprising:

at least two switching elements connected across a resonant circuit, the resonant circuit including an inductance and a capacitance;

wherein the transmitter is configured to adjust the value of the capacitance based on a desired operating frequency.

2. The transmitter in claim 1 wherein the capacitance comprises a voltage-controlled variable capacitor.

3. The transmitter in claim 2 wherein the capacitance comprises a passive voltage-controlled variable capacitor.

4. The transmitter in claim 2 wherein the capacitance comprises two capacitors in series and a diode in parallel with a first of the capacitors.

5. The transmitter in claim 4 configured to receive a positive DC voltage at the positive terminal of the diode to adjust the value of the capacitance.

6. The transmitter in claim 5 configured to receive the positive DC voltage at a resistor connected the positive terminal of the diode.

7. The transmitter in claim 5 wherein the DC voltage is substantially inversely proportion to the operating frequency.

8. The transmitter in claim 1 wherein the at least two switching elements comprise an autonomous push pull inverter or a current fed push pull resonant inverter.

9. The transmitter in claim 1 wherein the inductance is in parallel with the capacitance

10. An inductive power transfer system comprising:

an inductive power transmitter, and

a phase locked loop configured to control the operating frequency of the transmitter.

11. The system in claim 10 wherein the transmitter comprises at least two switching elements connected across a resonant circuit, the resonant circuit including an inductance and a capacitance, wherein the transmitter is configured to adjust the value of the capacitance based on a desired operating frequency, wherein the phase locked loop is configured to adjust the value of the capacitance and wherein the inductance is a transmitter coil for inductive power transfer.

12. The system in claim 10 further comprising a voltage attenuator and a comparator between an output side of the transmitter and the phase locked loop and an inverting voltage amplifier between an input side of the transmitter and the phase locked loop.

13. The system in claim 12 wherein the inverting voltage amplifier includes a current amplifier, and a voltage amplifier and inverter.

14. The system in claim 13 wherein the current amplifier includes an adjustable precision shunt regulator.

15. The system in claim 10 wherein the transmitter is configured as a voltage controlled oscillator.

16. The system in claim 10 further comprising an inductive power receiver having a resonant frequency, wherein the operating frequency of the transmitter is substantially controlled to the receiver resonant frequency.

17. The system in claim 16 wherein the receiver resonant frequency is selected from a predetermined set of frequencies, determined based on a receiver identifier, or determined directly from the receiver.