High efficiency power converting apparatus
A system includes a transmitter circuit coupled to an input power source, a transmitter coil coupled to the transmitter circuit, a receiver coil magnetically coupled to the transmitter coil, a rectifier coupled to the receiver coil and configured to convert an alternating current voltage into a direct current voltage, and a high efficiency power converter comprising a first stage and a second stage connected in cascade between the rectifier and a battery, wherein the first stage is configured to charge the battery, and the second stage is configured to provide isolation between the first stage and the battery.
1. A system comprising:
a transmitter circuit coupled to an input power source;
a transmitter coil coupled to the transmitter circuit;
a receiver coil magnetically coupled to the transmitter coil;
a rectifier coupled to the receiver coil and configured to convert an alternating current voltage into a direct current voltage; and
a high efficiency power converter comprising a first stage and a second stage connected in cascade between the rectifier and a battery, wherein the first stage is configured to charge the battery, and the second stage is configured to provide isolation between the first stage and the battery.
2. The system of claim 1 , wherein:
the first stage is a step-down power converter configured to operate in multiple modes for charging the battery; and
the second stage is an isolation switch configured to provide the isolation between the first stage and the battery.
3. The system of claim 1 , wherein:
the first stage of the high efficiency power converter is configured to operate in a current control mode to charge the battery when an output voltage of the system is less than a predetermined voltage threshold.
4. The system of claim 3 , wherein:
the first stage of the high efficiency power converter is configured to operate in a voltage control mode to charge the battery when the output voltage of the system is greater than the predetermined voltage threshold.
5. The system of claim 1 , wherein the first stage is implemented as a hybrid converter comprising:
a first switch, a capacitor and a second switch connected in series between an output of the rectifier and an output filter comprising an inductor and a capacitor;
a third switch connected between a common node of the first switch and the capacitor, and a common node of the second switch and the output filter; and
a fourth switch connected between a common node of the capacitor and the second switch, and ground.
6. The system of claim 1 , wherein the first stage is implemented as a buck-boost converter comprising:
a first switch and a second switch connected in series between an output of the rectifier and ground;
a third switch and a fourth switch connected in series between an output of the first stage and ground; and
an inductor coupled between a common node of the first switch and the second switch, and a common node of the third switch and the fourth switch.
7. The system of claim 1 , further comprising:
a power converter coupled between the input power source and the transmitter circuit.
8. A method comprising:
detecting an output voltage of a high efficiency power converter, wherein the high efficiency power converter comprises a first stage and a second stage connected in cascade;
applying a current control mode to the first stage and configuring an output current of the first stage within a predetermined current range when the output voltage is less than a predetermined output voltage threshold; and
applying a voltage control mode to the first stage and configuring an output voltage of the first stage within a predetermined voltage range when the output voltage is greater than the predetermined output voltage threshold.
9. The method of claim 8 , wherein:
the first stage is a step-down power converter configured to operate in various operating modes for charging a battery connected to the high efficiency power converter; and
the second stage is a charge pump converter configured as a voltage divider.
10. The method of claim 8 , wherein:
the first stage is a step-down power converter configured to operate in various operating modes for charging a battery connected to the high efficiency power converter; and
the second stage is an isolation switch.
11. The method of claim 8 , wherein:
the high efficiency power converter is connected to a receiver coil through a rectifier.
12. The method of claim 11 , wherein:
the receiver coil comprises a first coil and a second coil connected in series; and
the rectifier comprises a first diode and a second diode, and wherein:
the first diode and the first coil are connected in series;
the second diode and the second coil are connected in series; and
a common node of the first diode and the second diode is connected to an input of the high efficiency power converter.
13. The method of claim 8 , wherein:
the first stage is a four-switch buck-boost power converter connected to a rectifier; and
the second stage is a charge pump converter.
14. The method of claim 13 , further comprising:
configuring the four-switch buck-boost power converter to operate in a buck converter mode when an output voltage of the rectifier is greater than a first rectifier output voltage threshold;
configuring the charge pump converter to operate in a bypassing mode when the output voltage of the rectifier is less than the first rectifier output voltage threshold and greater than a second rectifier output voltage threshold; and
configuring the four-switch buck-boost power converter to operate in a boost converter mode when the output voltage of the rectifier is less than the second rectifier output voltage threshold.
15. The method of claim 8 , further comprising:
configuring the high efficiency power converter to charge a battery connected to a receiver of a wireless power transfer system.
16. The method of claim 8 , wherein:
the predetermined current range has a current resolution of less than 400 mA; and
the predetermined voltage range has a voltage resolution of less than 40 mV.
17. A system comprising:
a receiver coil configured to be magnetically coupled to a transmitter coil;
a rectifier connected to the receiver coil; and
a high efficiency converter connected between the rectifier and a battery, wherein the high efficiency converter comprises a first stage and a second stage connected in cascade, and wherein the first stage configured to operate in various operating modes for charging the battery and the second stage configured to provide isolation between the first stage and the battery.
18. The system of claim 17 , wherein:
the receiver coil comprises a first coil and a second coil connected in series; and
the rectifier is a center tapped rectifier connected to the first coil and the second coil.
19. The system of claim 17 , wherein:
the first stage is a step-down power converter configured to operate in either a voltage control mode or a current control mode for charging the battery; and
the second stage is a charge pump power converter configured to function as a voltage divider.
20. The system of claim 17 , wherein:
the first stage is a four-switch buck-boost power converter connected to a rectifier; and
the second stage is an isolation switch.