Coil driven switched capacitor and controller for wired and inductive charging
A coil driven switched capacitor (CDSC) converter can include at least one input coil that receives input power; first and second cascades of one or more CDSC cells, an input of each cascade being coupled to the at least one coil, and an output of each cascade being coupled to an output bus of the CDSC converter. The at least one input coil can include a first inductor coupled between a wired input power source and the first cascade of one or more CDSC cells and a second inductor coupled between the wired input power source and the second cascade of one or more CDSC cells. The at least one input coil can further include a wireless power receiver coil.
1 . A coil driven switched capacitor (CDSC) converter comprising:
at least one input coil configured to receive input power;
a first cascade of two or more CDSC cells, an input of the first cascade being coupled to a first terminal of the at least one input coil, and an output of the first cascade being coupled to an output bus of the CDSC converter; and
a second cascade of two or more CDSC cells coupled to a second terminal of the at least one input coil and an output of the second cascade being coupled to the output bus of the CDSC converter.
2 . The CDSC converter of claim 1 wherein the at least one input coil comprises a first inductor coupled between a wired input power source and the first cascade of one or more CDSC cells and a second inductor coupled between the wired input power source and the second cascade of one or more CDSC cells.
3 . The CDSC converter of claim 2 wherein the at least one input coil further comprises a wireless power receiver coil.
4 . The CDSC converter of claim 1 wherein the at least one input coil further comprises a wireless power receiver coil.
5 . The CDSC converter of claim 1 wherein each CDSC cell comprises:
a flying capacitor having a first terminal coupled to an input terminal of the CDSC cell and a second terminal;
a top switch having a first terminal coupled to the input terminal of the CDSC cell and the first terminal of the flying capacitor and a second terminal coupled to a first output terminal of the CDSC cell, thereby allowing the top switch to selectively couple the first terminal of the flying capacitor to the first output terminal of the CDSC cell;
a middle switch having a first terminal coupled to a second output terminal of the CDSC cell and a second terminal coupled to the second terminal of the flying capacitor, thereby allowing the middle switch to selectively couple the second terminal of the flying capacitor to the second output terminal of the CDSC cell; and
a bottom switch having a first terminal coupled to the second terminal of the flying capacitor and the second terminal of the middle switch and a second terminal coupled to ground, thereby allowing the bottom switch to selectively couple the second terminal of the flying capacitor to ground.
6 . The CDSC converter of claim 5 wherein:
the first cascade of one or more CDSC cells further comprises:
a first upstream CDSC cell having its input terminal coupled to a first rectifier and its first output terminal coupled to the output bus; and
a first downstream CDSC cell having its input terminal coupled to a second output terminal of the first upstream CDSC cell and its first and second output terminals coupled to the output bus; and
the second cascade of one or more CDSC cells further comprises:
a second upstream CDSC cell having its input terminal coupled to a second rectifier and its first output terminal coupled to the output bus; and
a second downstream CDSC cell having its input terminal coupled to a second output terminal of the second upstream CDSC cell and its first and second output terminals coupled to the output bus.
7 . The CDSC converter of claim 6 wherein the first and second cascades of CDSC cells each further comprise one or more intermediate CDSC cells, with each intermediate CDSC cell having its input terminal coupled to an immediately upstream CDSC cell, its first output terminal coupled to the output bus, and its second output terminal coupled to an immediately downstream CDSC cell.
8 . The CDSC converter of claim 7 wherein each CDSC cell further comprises:
a diode having its anode coupled to the second terminal of the flying capacitor and its cathode coupled to a terminal of the input coil.
9 . The CDSC converter of claim 5 further comprising control circuitry that selectively alternates each CDSC cell among a P mode, an S mode, and a float mode to convert received input power to a desired voltage on the output bus, wherein:
in the P mode the flying capacitor of the CDSC cell is connected in parallel with the first output terminal of the CDSC cell;
in the S mode the flying capacitor of the CDSC cell is connected in series with the second output terminal of the CDSC cell; and
in the float mode the flying capacitor of the CDSC cell is disconnected from the first and second output terminals of the CDSC cell.
10 . The CDSC converter of claim 9 wherein the control circuitry sequences switching of switching devices of each cascade of CDSC cells to achieve zero voltage switching.
11 . The CDSC converter of claim 9 wherein the control circuitry sequences switching a cascade of CDSC cells undergoing a P mode to S mode transition to achieve zero voltage switching by:
simultaneously turning off top and bottom switches of the cascade of CDSC cells undergoing a P mode to S mode transition;
turning off a low side switch of a rectifier coupled to the cascade of CDSC cells undergoing a P mode to S mode transition;
turning on a high side switch of a rectifier coupled to the cascade of CDSC cells undergoing a P mode to S mode transition; and
turning on middle switches of all CDSC cells in the cascade from upstream to downstream, upon middle switches' body diode conduction.
12 . The CDSC converter of claim 9 wherein the control circuitry sequences switching a cascade of CDSC cells undergoing an S mode to P mode transition to achieve zero voltage switching by:
turning off a middle switch of a most downstream CDSC cell in the cascade of CDSC cells undergoing an S mode to Pmode transition;
turning on a bottom switch of the most downstream CDSC cell upon its body diode conduction, and then turning on a top switch of the most downstream CDSC cell;
turning off a middle switch of an adjacent upstream CDSC cell;
turning on a bottom switch of the adjacent upstream RDSC cell upon its body diode conduction, and then turning on a top switch of the adjacent upstream RDSC cell; and
turning off a high side switch and turning on a low side switch of a rectifier corresponding to the cascade of CDSC cells undergoing a S mode to P mode transition.
13 . The CDSC converter of claim 9 wherein the control circuitry sequences switching a cascade of CDSC cells undergoing an S mode to P mode transition to achieve zero voltage switching by:
simultaneously turning off a middle switch of each CDSC cell in the cascade of CDSC cells undergoing an S mode to P mode transition, and off a high side switch of a rectifier corresponding to the same cascade of CDSC cells;
waiting for current through the input coil to discharge the voltage on a second terminal of each flying capacitor through an auxiliary diode of each CDSC cell in the cascade;
upon completion of discharging the voltage on second terminals of all flying capacitors, simultaneously turning on a bottom switch and a top switch of each CDSC cell in the cascade of CDSC cells undergoing an S mode to P mode transition; and
turning on a low side switch of a rectifier corresponding to the cascade of CDSC cells undergoing an S mode to P mode transition.
14 . The CDSC converter of claim 9 wherein the control circuitry varies a conversion ratio of the CDSC converter to produce discrete conversion ratios by selectively actively operating a first subset of CDSC cells of a CDSC cascade and selectively forcing a second subset of CDSC cells of the CDSC cascade into P mode.
15 . The CDSC converter of claim 9 wherein the control circuitry varies a conversion ratio of the CDSC converter to produce continuous conversion ratios by selectively actively operating a first subset of CDSC cells of a CDSC cascade, selectively operating at least one CDSC cell of the CDSC cascade with a variable duty cycle alternating between active operation and forced P mode, and selectively forcing a second subset of CDSC cells of the CDSC cascade into P mode.
16 . The CDSC converter of claim 9 wherein the control circuitry varies a conversion ratio of the CDSC converter to produce continuous conversion ratios by selectively operating a first subset of CDSC cells of a CDSC cascade with a first variable duty cycle alternating between active operation and forced P mode, selectively operating a second subset of CDSC cells of the CDSC cascade with a second variable duty cycle greater than the first variable duty cycle and alternating between active operation and forced P mode, and selectively forcing a third subset of CDSC cells of the CDSC cascade into P mode.
17 . The CDSC converter of claim 9 wherein the control circuitry operates the CDSC cells to produce three voltage levels in each switching period to control inductor current.
18 . The CDSC converter of claim 17 wherein one of the three voltage levels is a medium voltage close to an input voltage of the CDSC converter, one of the voltage levels is a low voltage that is lower than the input voltage, and one of the voltage levels is a high voltage that is higher than the input voltage.
19 . The CDSC converter of claim 18 wherein the control circuitry controls the inductor current to achieve boundary conduction mode operation.
20 . The CDSC converter of claim 18 wherein the control circuitry operates the CDSC cells responsive to a peak current signal to trigger voltage level switching from the low voltage to the medium voltage and operates the CDSC cells responsive to a dual-role ramp signal to trigger voltage level switching from the medium voltage to the high voltage so as to force coil current to cross below zero at an end of each switching period.
21 . The CDSC converter of claim 20 wherein the dual-role ramp signal is used as a switching period timer and an inductor current threshold.
22 . The CDSC converter of claim 21 wherein the control circuitry generates the dual-role ramp signal so that an amplitude and a slope of the dual-role ramp signal change with input and output voltage to keep the switching period constant.
23 . The CDSC converter of claim 22 wherein the control circuitry generates the dual-role ramp signal so that the amplitude and slope of the dual-role ramp signal are proportional to an amplitude and slope of a current through the input coil.
24 . A wireless power receiver comprising:
a wireless power receiver coil configured to have an AC receiver input voltage induced thereacross by a wireless power transmitter;
a first rectifier having an input coupled to a first terminal of the wireless power receiver coil;
a second rectifier having an input coupled to a second terminal of the wireless power receiver coil;
a first cascade of two or more rectifier driven switched capacitor (RDSC) cells coupled between an output of the first rectifier and an output bus, each RDSC cell comprising a flying capacitor and a plurality of associated switching devices; and
a second cascade of two or more RDSC cells coupled between an output of the second rectifier and the output bus; each RDSC cell comprising a flying capacitor and a plurality of associated switching devices;
whereby the first and second cascades of RDSC cells allow selecting a voltage or current conversion ratio to reduce losses.
25 . The wireless power receiver of claim 24 wherein for each RDSC cell:
the flying capacitor has a first terminal coupled to an input terminal of the RDSC cell and a second terminal; and
the plurality of switching devices include:
a top switch having a first terminal coupled to the input terminal of the RDSC cell and the first terminal of the flying capacitor and a second terminal coupled to a first output terminal of the RDSC cell, thereby allowing the top switch to selectively couple first terminal of the flying capacitor to the first output terminal of the RDSC cell;
a middle switch having a first terminal coupled to a second output terminal of the RDSC cell and a second terminal coupled to the second terminal of the flying capacitor, thereby allowing the middle switch to selectively couple the second terminal of the flying capacitor to the second output terminal of the RDSC cell; and
a bottom switch having a first terminal coupled to the second terminal of the flying capacitor and the second terminal of the middle switch and a second terminal coupled to ground, thereby allowing the bottom switch to selectively couple the second terminal of the flying capacitor to ground.
26 . The wireless power receiver of claim 25 wherein each RDSC cell further comprises: a diode having its anode coupled to the second terminal of the flying capacitor and its cathode coupled to the wireless power receiver coil.
27 . The wireless power receiver of claim 25 wherein:
the first cascade of one or more RDSC cells further comprises:
a first upstream RDSC cell having its input terminal coupled to the first rectifier and its first output terminal coupled to the output bus; and
a first downstream RDSC cell having its input terminal coupled to the second output terminal of the first upstream RDSC cell and its first and second output terminals coupled to the output bus; and
the second cascade of one or more RDSC cells further comprises:
a second upstream RDSC cell having its input terminal coupled to the second rectifier and its first output terminal coupled to the output bus; and
a second downstream RDSC cell having its input terminal coupled to the second output terminal of the second upstream RDSC cell and its first and second output terminals coupled to the output bus.
28 . The wireless power receiver of claim 27 wherein the first and second cascades of RDSC cells each further comprise one or more intermediate RDSC cells, with each intermediate RDSC cell having its input terminal coupled to an immediately upstream RDSC cell, its first output terminal coupled to the output bus, and its second output terminal coupled to an immediately downstream RDSC cell.
29 . The wireless power receiver of claim 24 further comprising control circuitry that:
operates the first cascade of one or more RDSC cells in a series mode when the AC receiver input current is in a positive half cycle and in a parallel mode when the AC receiver input current is in a negative half cycle; and
operates the second cascade of one or more RDSC cells in a series mode when the AC receiver input current is in a negative half cycle and in a parallel mode when the AC receiver input current is in a positive half cycle.
30 . The wireless power receiver of claim 29 wherein the control circuitry sequences switching of switching devices of each cascade of RDSC cells to achieve zero voltage switching.
31 . The wireless power receiver of claim 24 further comprising control circuitry that operates to communicate data to the wireless power transmitter by amplitude shift keying.
32 . The wireless power receiver of claim 31 further comprising controllable load circuitry coupled to at least one of the output of the first rectifier and the output of the second rectifier.
33 . The wireless power receiver of claim 31 wherein the control circuitry operates the first and second cascades of one or more RDSC cells to simultaneously alternate between a first conversion ratio and a second conversion ratio.
34 . The wireless power receiver of claim 31 wherein the control circuitry operates the first and second cascades of one or more RDSC cells to respectively alternate between a first conversion ratio and a second conversion ratio, wherein the cascades of one or more RDSC cells operate at two or more conversion ratios on the same switching cycle.