Microprocessor controlled class E driver
A charger including a class E power driver, a frequency-shift keying (“FSK”) module, and a processor. The processor can receive data relating to the operation of the class E power driver and can control the class E power driver based on the received data relating to the operation of the class E power driver. The processor can additionally control the FSK module to modulate the natural frequency of the class E power transformer to thereby allow the simultaneous recharging of an implantable device and the transmission of data to the implantable device. The processor can additionally compensate for propagation delays by adjusting switching times.
1. A charger comprising:
a charging coil magnetically coupleable with an implantable device to recharge the implantable device;
a class E driver electrically connected to the charging coil, wherein the class E driver comprises:
a switching circuit, wherein the switching circuit is switched by application of a first voltage to the switching circuit; and
a current sensor positioned to sense a current passing through the charging coil; and
a processor electrically connected to the class E driver to receive data indicative of the current passing through the charging coil and electrically connected to the class E driver to control the switching circuit via the application of the first voltage to the switching circuit, wherein the processor is controllable according to stored instructions to receive data indicative of the current passing through the charging coil and control the switching circuit in response to the received data to adjust a drive frequency of the class E driver based on a combination of a zero crossing current time and a compensation factor.
2. The charger of claim 1 , wherein the compensation factor mitigates an effect of propagation delays.
3. The charger of claim 2 , wherein the propagation delays comprise a difference between a zero crossing current time and a sensed zero crossing current time.
4. The charger of claim 3 , wherein the propagation delays further comprise: a processing time; and a turn-on time of the switching circuit.
5. The charger of claim 1 , wherein the switching circuit comprises a transistor.
6. The charger of claim 5 , wherein the transistor comprises a MOSFET.
7. The charger of claim 1 , wherein the current sensor is in series with the charging coil.
8. The charger of claim 1 , wherein the current sensor generates an output indicative of the sensed current passing through the charging coil.
9. The charger of claim 8 , wherein the output of the current sensor is buffered and squared before being provided to the processor.
10. The charger of claim 9 , wherein controlling the switching circuit comprises optimizing an on transition of the switching circuit.
11. The charger of claim 10 , wherein controlling the switching circuit further comprises optimizing an off transition of the switching circuit.
12. The charger of claim 11 , wherein each of the on transition of the switching circuit and the off transition of the switching circuit are independently controlled.
13. The charger of claim 1 , wherein controlling the switching circuit based on a combination of the zero crossing current time and the compensation factor comprises switching the switching circuit on before receipt of a signal indicative of the zero crossing current time.
14. The charger of claim 1 , wherein the processor is configured to determine the compensation factor.
15. The charger of claim 14 , wherein the processor is configured to determine the compensation factor based on a table comprising a plurality of frequencies for controlling the switching circuit.
16. The charger of claim 15 , wherein the processor is configured to receive a signal indicative of a measured parameter; and select one of the plurality of frequencies for controlling the switching circuit.
17. The charger of claim 16 , wherein the measured parameter comprises a voltage of the switching circuit.
18. The charger of claim 14 , wherein the processor is configured to determine the compensation factor based on a table comprising a plurality of durations of time for which the switching circuit is closed.
19. The charger of claim 18 wherein the processor is configured to receive a signal indicative of a measured parameter; and select one of the plurality of durations of time for controlling the switching circuit.
20. The charger of claim 19 , wherein the measured parameter comprises a voltage of the switching circuit.