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, wherein the charging coil is configured to generate a magnetic field having a frequency and to magnetically couple with an implantable device to recharge the implantable device;
a class E driver electrically connected to the charging coil; and
an FSK module coupled to the class E driver and configured to modulate a natural frequency of the class E driver and configured to modulate the frequency of the magnetic field among at least three frequencies.
2. The charger of claim 1 , wherein the at least three frequencies comprise a first frequency, a second frequency, and a third frequency, and wherein the third frequency is the highest frequency and the second frequency is the lowest frequency.
3. The charger of claim 2 , further comprising a processor electrically connected to the FSK module and configured to control the FSK module.
4. The charger of claim 3 , wherein the processor is configured to selectively operate the charger in either a data non-transmitting state or in a data transmitting state.
5. The charger of claim 4 , wherein a carrier signal has the first frequency when the charger operates in the data non-transmitting state.
6. The charger of claim 5 , wherein the processor controls the FSK module to modulate the carrier signal between the second frequency and the third frequency when the charger operates in the data transmitting state.
7. The charger of claim 6 , wherein the FSK module comprises two capacitors and two transistors.
8. The charger of claim 7 , wherein the two capacitors and the two transistors of the FSK module are electrically connected such that the two capacitors can be selectively included within a circuit by the FSK module.
9. The charger of claim 8 , wherein the processor is configured to control the two transistors of the FSK module to selectively include the two capacitors within the circuit by the FSK module.
10. The charger of claim 9 , wherein the selective inclusion of the two capacitors within the circuit of the FSK modulates the frequency of the magnetic field between the first, second, and third frequencies.
11. A method of communicating with an implantable device during charging of the implantable device, the method comprising:
generating a charging signal with a charging coil by driving the charging coil with a class E driver, wherein the class E driver drives the charging coil at an initial, first frequency; and
transmitting data by modulating a natural frequency of the class E driver such that the class E driver drives the charging coil at a second frequency that is lower than the first frequency and at a third frequency that is higher than the first frequency.
12. The method of claim 11 , further comprising generating binary transmission data during the charging of the implantable device, wherein the transmission data is the transmitted data.
13. The method of claim 12 , wherein modulating the frequency of the charging signal between the second frequency and the third frequency transmits the binary transmission data.
14. The method of claim 11 , wherein the frequency of the charging signal is modulated by an FSK module.
15. The method of claim 14 , wherein the FSK module comprises two capacitors and two transistors.
16. The method of claim 15 , wherein the two capacitors and the two transistors of the FSK module are electrically connected such that the two capacitors can be selectively included within a circuit of by the FSK module to thereby modulate the frequency of the charging signal.
17. A method of controlling a charger comprising:
setting an initial frequency of a drive signal, wherein the frequency of the drive signal is set by a processor, and wherein the drive signal controls opening and closing of a switch;
driving a charging coil according to the drive signal to create a magnetic coupling between a charger and an implantable device, wherein the magnetic coupling charges the implantable device;
sensing a voltage at the switch at a first time;
based on the voltage at the switch at the first time, retrieving a value identifying a second frequency; and
changing the frequency of the drive signal.
18. The method of claim 17 , wherein changing the frequency of the drive signal comprises changing the frequency of the drive signal from the first frequency to the second frequency.
19. The method of claim 17 , comprising retrieving one or several frequency limits, wherein the frequency limits provide an upper and lower bound to a range of acceptable frequencies of the drive signal.
20. The method of claim 19 , comprising comparing the second frequency to the one or several frequency limits.
21. The method of claim 20 , wherein changing the frequency of the drive signal comprises changing the frequency of the drive signal from the first frequency to the one of the one or several frequency limits if the second frequency exceeds the one of the one or several frequency limits.
22. The method of claim 20 , wherein changing the frequency of the drive signal comprises changing the frequency of the drive signal from the first frequency to the second frequency if the second frequency does not exceed the one or several frequency limits.
23. The method of claim 17 , wherein the changing of the frequency of the drive signal mitigates an effect of a propagation delay.
24. The method of claim 23 , wherein the frequency of the drive signal can be adjusted multiple times to mitigate the effect of the propagation delay.