Phase shift clock for digital LLC converter
The techniques of this disclosure may digitally generate a driver signal with a period (or frequency) at a finer resolution than can be achieved by simply counting clock cycles of a system clock. The driver signal may be configured to trigger based on single output clock signal that may be phase-shifted relative to the master system clock. A clock phase shift circuit may increment the phase shift of the output clock signal to any fraction relative to the master system clock. A driver signal generated based on the phase-shifted output clock may achieve the high resolution in frequency desirable when controlling some pulse-width modulated circuits, such as an LLC converter.
1. A system comprising:
a single, input clock, wherein the single, input clock defines a master input clock frequency;
a clock phase shift circuit, configured to:
output a second clock signal wherein a second clock signal frequency is approximately the same frequency as the master input clock frequency, and
increment a phase shift of the second clock signal relative to the single, input clock, wherein the clock phase shift circuit increments the phase shift in response to a capacitor charge current amperage level; and
a control unit configured to:
receive the second clock signal,
generate a driver signal at a predetermined frequency,
wherein the phase shift of the second clock signal relative to the master input clock sets a fractional part of a frequency ratio between the master input clock frequency and the predetermined frequency, and
wherein the predetermined frequency of the driver signal comprises an integer part generated by counting clock cycles and the fractional part generated by shifting the phase of the second clock signal.
2. The system of claim 1 , wherein the integer part comprises a multiple of the single, input clock generated by counting clock cycles of the second clock signal.
3. The system of claim 1 , wherein the second clock signal contains no discontinuities or short pulses when the phase shift exceeds multiples of 360 degrees.
4. The system of claim 1 , wherein the clock phase shift circuit increments the phase shift based on a phase control word.
5. The system of claim 1 , wherein the clock phase shift circuit is further configured to increment the phase during times when there is no time event and stop incrementing the phase during times where there is a time event.
6. The system of claim 1 , wherein the increment of the phase shift of the second clock signal increases relative to the single, input clock.
7. The system of claim 1 , wherein the driver signal is an LLC half-bridge driver signal.
8. The system of claim 7 , wherein the control unit is further configured to generate a driver signal comprising a high-side gate driver signal and a low-side gate driver signal.
9. The system of claim 8 , wherein the high-side gate driver signal is an ultra-high voltage (UHV) signal.
10. The system of claim 8 , wherein the driver signal is compatible to drive the LLC half-bridge, wherein the LLC half-bridge includes gallium nitride (GaN) components.
11. The system of claim 1 , wherein the driver signal further comprises a dead time signal, wherein the dead time signal is substantially synchronized to the second clock signal.
12. The system of claim 1 , wherein the control unit is further configured to generate a level shifter signal, wherein the level shifter signal is substantially synchronized to the second clock signal.
13. The system of claim 1 , further comprising an LLC converter, wherein the LLC converter is configured to receive the driver signal.
14. The system of claim 13 , wherein the LLC converter comprises a piezo transformer.
15. The system of claim 13 , wherein the LLC converter comprises a high-side switch and a low-side switch.
16. The system of claim 15 , wherein the high-side switch is an ultra-high voltage (UHV) switch.
17. The system of claim 15 , wherein the high-side switch and the low-side switch comprise gallium nitride (GaN).
18. The system of claim 13 , wherein the LLC converter is configured to operate at frequency of at least one MHz.
19. The system of claim 13 , wherein the LLC converter is configured for high voltage direct current (DC) to alternating current (AC) conversion.