Operating parameter power conversion method and power converter
Disclosed is a method for operating a rectifier circuit, a control circuit for operating a rectifier circuit, and a power converter. The method includes operating the rectifier circuit ( 2 ) in a PFC mode, wherein operating the rectifier circuit ( 2 ) in the PFC mode includes regulating an output voltage (Udc) of the rectifier circuit ( 2 ). Regulating the output voltage (Udc) includes operating a switch ( 26 ) of the rectifier circuit ( 2 ) at a fixed switching frequency (fsw), and regulating the output voltage (Udc) includes regulating the output voltage (Udc) dependent on at least one operating parameter of the rectifier circuit ( 2 ) such that the switch ( 26 ) is operated under ZVS conditions.
1. A method comprising:
operating a rectifier circuit in a PFC (Power Factor Correction) mode, wherein operating the rectifier circuit in the PFC mode comprises: regulating an output voltage of the rectifier circuit, wherein regulating the output voltage comprises switching a switch of the rectifier circuit at a fixed switching frequency; and
wherein regulating the output voltage further comprises, during operation of switching the switch of the rectifier circuit at the fixed switching frequency, regulating the output voltage with respect to an output voltage reference, the output voltage reference derived from at least one operating parameter of the rectifier circuit such that the switch is operated under ZVS (Zero Voltage Switching) conditions.
2. The method as in claim 1 , wherein regulating the output voltage comprises:
adjusting a magnitude of the output voltage reference dependent on the at least one operating parameter of the rectifier circuit; and
regulating the output voltage of the rectifier circuit such that a magnitude of the output voltage is generated with respect to the adjusted output voltage reference.
3. The method according to claim 2 , wherein the rectifier circuit includes an inductor having an inductance; and
wherein adjusting the output voltage reference further comprises adjusting the output voltage reference dependent on a magnitude of the inductance and a magnitude of the fixed switching frequency.
4. The method according to claim 3 , wherein operating the switch under ZVS conditions comprises adjusting a duty-cycle of controlling the switch such that a magnitude of current through the inductor crosses a zero reference multiple times in each drive cycle of controlling the switch ON and OFF at the fixed switching frequency to convert an alternating input voltage inputted to the rectifier circuit into the output voltage.
5. The method according to claim 1 , wherein the at least one operating parameter comprises an RMS (Root Mean Square) value of an alternating input voltage supplied to the rectifier circuit;
wherein the rectifier circuit is operative to convert the alternating input voltage into the output voltage; and
wherein the output voltage is a DC output voltage.
6. The method according to claim 5 , wherein the at least one operating parameter further includes a metric indicating an average input power supplied by the alternating input voltage to the rectifier circuit; and
wherein the output voltage reference is derived based on a combination of a magnitude the RMS value of the alternating input voltage and a magnitude of the average input power.
7. The method according to claim 5 , wherein the at least one operating parameter includes an output power of the rectifier circuit.
8. The method according to claim 1 , wherein the rectifier circuit includes two rectifier stages connected in parallel; and
wherein regulating the output voltage comprises operating a respective switch in each of the rectifier stages at a same fixed switching frequency.
9. The method according to claim 1 further comprising:
converting the output voltage of the rectifier circuit into a fixed output voltage or a fixed output current via a DC-DC converter coupled to the rectifier circuit.
10. The method according to claim 9 , wherein the DC-DC converter comprises a first converter stage and a second converter stage,
wherein the first converter stage is a regulated converter stage and the second converter stage is a non-regulated converter stage.
11. The method of claim 1 , wherein a RMS (Root Mean Square) value of an alternating input voltage inputted to the rectifier circuit ranges between 90 Volts RMS and 265 Volts RMS, the rectifier circuit operative to convert the alternating input voltage into the output voltage.
12. The method of claim 1 , wherein the output voltage reference is adjusted to be within 210V and 400V.
13. The method as in claim 1 , wherein Udc represents the output voltage;
wherein Udc* represents the output voltage reference, the method further comprising:
adjusting the output voltage reference (Udc*) as follows:
U
d
c
*
(
U
a
c
r
m
s
)
=
Uac
rm
s
3
·
2
Uac
rm
s
2
-
P
max
·
2
·
fsw
·
L
,
where Pmax denotes a maximum output power of the rectifier circuit, where Uac rms denotes an RMS value of an input voltage supplied to the rectifier circuit, where fsw denotes a magnitude of the switching frequency, and L′ denotes an inductance of an inductor in the rectifier circuit; and
when the rectifier circuit is operative to convert the input voltage into the output voltage.
14. The method as in claim 1 , wherein the output voltage reference is represented by Udc*;
wherein Uac represents an input voltage supplied to the rectifier circuit, the rectifier circuit operative to convert the input voltage into the output voltage;
the method further comprising: adjusting the output voltage reference Udc* dependent on an RMS (Root Mean Square) setting of the input voltage as follows:
U
d
c
*
(
U
a
c
r
m
s
)
=
p
·
Uac
rm
s
3
·
2
Uac
rm
s
2
-
P
max
·
2
·
fsw
·
L
,
where Pmax denotes a maximum input power of the rectifier circuit, Uac rms denotes an RMS setting of the input voltage Uac, fsw denotes a magnitude of the switching frequency, L′ denotes an inductance of an inductor in the rectifier circuit, and p denotes a proportionality factor, wherein 1<p<1.2.
15. A PFC (Power Factor Correction) control circuit configured to operate a rectifier circuit in a PFC mode, wherein, to operate the rectifier circuit in the PFC mode, the control circuit is-operative to:
adjust an output voltage reference dependent on at least one operating parameter of the rectifier circuit;
convert an input voltage received by the rectifier circuit into an output voltage;
regulate a magnitude of the output voltage of the rectifier circuit with respect to the adjusted output voltage reference; and
wherein the control circuit, to regulate the output voltage, is configured to operate a switch of the rectifier circuit at a fixed switching frequency.
16. A power converter circuit comprising:
the PFC control circuit according to claim 15 ; and
the rectifier circuit controlled by the PFC control circuit.
17. The power converter circuit according to claim 16 further comprising:
a DC-DC converter connected to the PFC rectifier, the DC-DC converter operative to receive the output voltage from the PFC rectifier.
18. The power converter circuit according to claim 16 , wherein the DC-DC converter comprises a first converter stage and a second converter stage,
wherein the first converter stage is a regulated converter stage and the second converter stage is a non-regulated converter stage.
19. An apparatus comprising:
a PFC (Power Factor Correction) control circuit operative to:
monitor operation of a rectifier circuit, the rectifier circuit operative to convert an input voltage into an output voltage based on an output voltage reference;
adjust the output voltage reference depending on the monitored operation of the rectifier circuit; and
via the rectifier circuit, regulate the output voltage with respect to the adjusted output voltage reference, regulation of the output voltage including switching of a switch in the rectifier circuit at a fixed switching frequency, wherein switching of the switch at the fixed switching frequency is operative to convert the input voltage into the output voltage.
20. The apparatus as in claim 19 , wherein the PFC control circuit is further operative to:
via the monitored operation of the rectifier circuit, receive input indicating a magnitude of the input voltage inputted to the rectifier circuit, the input voltage being an alternating voltage; and
adjust a magnitude of the output voltage reference based on the magnitude of the input voltage.
21. The apparatus as in claim 20 , wherein the PFC control circuit is further operative to:
via the regulation of the output voltage, adjust a duty cycle of switching the switch in the rectifier circuit between ON and OFF states.
22. The apparatus as in claim 19 , wherein the PFC control circuit is further operative to:
via the monitored operation of the rectifier circuit: i) receive first input indicating a magnitude of the input voltage inputted to the rectifier circuit, the input voltage being an alternating voltage, and ii) receive second input indicating a magnitude of power supplied by the input voltage to the rectifier circuit; and
adjust a magnitude of the output voltage reference based on a combination of the magnitude of the input voltage and the magnitude of the power supplied by the input voltage.
23. The apparatus as in claim 22 , wherein the PFC control circuit is further operative to:
during the regulation of the output voltage, adjust a duty cycle of switching the switch in the rectifier circuit between ON and OFF states based on a magnitude of the output voltage with respect to the magnitude of the output voltage reference, the adjusted duty cycle of switching the switch operative to control a magnitude of input current supplied by the input voltage to the rectifier circuit, the controlled magnitude of the input current operative to maintain the magnitude of the output voltage with respect to the output voltage reference.
24. The apparatus as in claim 23 , wherein the switch is controlled via zero voltage switching with respect to the magnitude of the input current to the rectifier circuit as supplied from the input voltage, where a magnitude of the input voltage crosses a zero threshold twice during each control cycle of switching the switch at the fixed frequency.
25. The apparatus as in claim 19 , wherein the PFC control circuit is operative to control the rectifier circuit such that an average input current supplied from the input voltage to the rectifier circuit is in phase with a magnitude the input voltage.