U.S. patent application number 17/148530 was filed with the patent office on 2022-02-24 for control circuit and control method for power converter.
The applicant listed for this patent is National Taiwan University of Science and Technology. Invention is credited to HUANG-JEN CHIU, Chien-Chun Huang.
Application Number | 20220060100 17/148530 |
Document ID | / |
Family ID | |
Filed Date | 2022-02-24 |
United States Patent
Application |
20220060100 |
Kind Code |
A1 |
Huang; Chien-Chun ; et
al. |
February 24, 2022 |
CONTROL CIRCUIT AND CONTROL METHOD FOR POWER CONVERTER
Abstract
A control circuit and a control method for a power converter are
provided. The power converter includes a plurality of resonant
tanks and a plurality of switches disposed between an input
terminal and an output terminal. The switches correspond to a first
mode and a second mode, respectively, and the control circuit
includes a first switch control circuit, a first zero current
detection circuit, a second zero current detection circuit, a first
switch off detector, a modulation time calculation module, a second
switch control circuit, a third zero current detection circuit, a
fourth zero current detection circuit, and a second switch off
detector. The control circuit uses a plurality of zero current
detection circuits to perform time modulations on a plurality of
rectifier switches in the switches.
Inventors: |
Huang; Chien-Chun; (Taoyuan
City, TW) ; CHIU; HUANG-JEN; (New Taipei City,
TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
National Taiwan University of Science and Technology |
Taipei City |
|
TW |
|
|
Appl. No.: |
17/148530 |
Filed: |
January 13, 2021 |
International
Class: |
H02M 1/08 20060101
H02M001/08; H02M 7/217 20060101 H02M007/217 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 21, 2020 |
TW |
109128519 |
Claims
1. A control method for a power converter including a plurality of
resonant tanks and a plurality of switches arranged between an
input terminal and an output terminal, the plurality of switches
corresponding to a first mode and a second mode, respectively, the
input terminal receiving an input voltage, and the control method
comprising: configuring a first switch control circuit to control
the plurality of switches corresponding to the first mode to be
turned on in the first mode, so as to form a first resonant current
along a first resonant path and a second resonant current along a
second resonant path through the plurality of resonant tanks,
respectively, wherein the plurality of switches include a first
rectifier switch located on the first resonant path and a second
rectifier switch located on the second resonant path; configuring a
first zero current detection circuit to detect the first resonant
current on the first rectifier switch, and output, in response to
detecting that the first resonant current reaches zero amp, a first
zero current signal to enable the first switch control circuit to
control the first rectifier switch to be turned off; configuring a
second zero current detection circuit to detect the second resonant
current on the second rectifier switch, and output, in response to
detecting that the second resonant current reaches zero amp, a
second zero current signal to enable the first switch control
circuit to control the second rectifier switch to be turned off;
configuring a first switch off detector to detect whether or not
the first rectifier switch and the second rectifier switch are both
turned off, and output, in response to the first rectifier switch
and the second rectifier switch being both turned off, a first
turn-off confirmation signal; configuring a modulation time
calculation module to calculate a first modulation time according
to a feedback voltage from the output terminal; configuring the
modulation time calculation module to, in response to receiving the
first turn-off confirmation signal, output a second mode activation
signal after the first rectifier switch and the second rectifier
switch are turned off and the first modulation time has elapsed;
configuring a second switch control circuit to, in response to
receiving the second mode activation signal, control the plurality
of switches corresponding to the second mode to be turned on, so as
to form a third resonant current along a third resonant path and a
fourth resonant current along a fourth resonant path through the
plurality of resonant tanks, respectively, wherein the plurality of
switches include a third rectifier switch located on the third
resonant path and a fourth rectifier switch located on the fourth
resonant path; configuring a third zero current detection circuit
to detect the third resonant current on the third rectifier switch,
and output, in response to detecting that the third resonant
current reaches zero amp, a third zero current signal to enable the
second switch control circuit to control the third rectifier switch
to be turned off; configuring a fourth zero current detection
circuit to detect the fourth resonant current on the fourth
rectifier switch, and output, in response to detecting that the
fourth resonant current reaches zero amp, a fourth zero current
signal to enable the second switch control circuit to control the
fourth rectifier switch to be turned off; configuring a second
switch off detector to detect whether or not the third rectifier
switch and the fourth rectifier switch are both turned off, and
output, in response to the third rectifier switch and the fourth
rectifier switch being both turned off, a second turn-off
confirmation signal; configuring the modulation time calculation
module to calculate a second modulation time according to the
feedback voltage from the output terminal; and configuring the
modulation time calculation module to, in response to receiving the
second turn-off confirmation signal, output a first mode activation
signal after the third rectifier switch and the fourth rectifier
switch are turned off and the second modulation time has
elapsed.
2. The control method according to claim 1, further comprising:
configuring the first switch control circuit to, in response to
receiving the first turn-off confirmation signal, control the
switches other than the first rectifier switch and the second
rectifier switch among the plurality of switches corresponding to
the first mode to be turned off within the first modulation time
after the first rectifier switch and the second rectifier switch
are turned off.
3. The control method according to claim 1, further comprising:
configuring the second switch control circuit to, in response to
receiving the second turn-off confirmation signal, control the
switches other than the third rectifier switch and the fourth
rectifier switch among the plurality of switches corresponding to
the second mode to be turned off within the second modulation time
after the third rectifier switch and the fourth rectifier switch
are turned off.
4. The control method according to claim 1, wherein the modulation
time calculation module includes a first calculation unit and a
second calculation unit, and the control method further comprises:
configuring the first calculation unit to calculate the first
modulation time according to the feedback voltage, and output, in
response to receiving the first turn-off confirmation signal, the
second mode activation signal after the first rectifier switch and
the second rectifier switch are turned off and the first modulation
time has elapsed; and configuring the second calculation unit to
calculate the second modulation time according to the feedback
voltage, and output, in response to receiving the second turn-off
confirmation signal, the first mode activation signal after the
third rectifier switch and the fourth rectifier switch are turned
off and the second modulation time has elapsed.
5. The control method according to claim 1, wherein the modulation
time calculation module includes a third calculation unit and a
phase shifter, and the control method further comprises:
configuring the third calculation unit to: continuously calculate
and update a total modulation time based on the feedback voltage;
and sample the total modulation time calculated when the switches
corresponding to the first mode are turned on, take one-half of the
total modulation time as a time point at which the switches
corresponding to the second mode are turned on, take the total
modulation time as a time point at which the switches corresponding
to the first mode are turned on to enter the first mode of a next
cycle, and correspondingly generate a time modulation signal;
configuring the phase shifter to, in response to receiving the time
modulation signal, generate a phase shifted control signal
according to one-half of the total modulation time as the second
mode activation signal, to turn on the switches corresponding to
the second mode after the switches corresponding to the first mode
are turned on and the half of the total modulation time elapses,
and after the third calculation unit receives the first turn-off
confirmation signal; and configuring the third calculation unit to
use the time modulation signal as the first mode activation signal
after the switches corresponding to the switches corresponding to
the first mode are turned on and the total modulation time elapses,
and after the third calculation unit receives the second turn-off
confirmation signal, to turn on the switches corresponding to the
first mode to enter the first mode of the next cycle.
6. A control circuit for a power converter including a plurality of
resonant tanks and a plurality of switches arranged between an
input terminal and an output terminal, the plurality of switches
corresponding to a first mode and a second mode, respectively, the
input terminal receiving an input voltage, and the control circuit
comprising: a first switch control circuit configured to control
the plurality of switches corresponding to the first mode to be
turned on in the first mode, so as to form a first resonant current
along a first resonant path and a second resonant current along a
second resonant path through the plurality of resonant tanks,
respectively, wherein the plurality of switches include a first
rectifier switch located on the first resonant path and a second
rectifier switch located on the second resonant path; a first zero
current detection circuit configured to detect the first resonant
current on the first rectifier switch, and output, in response to
detecting that the first resonant current reaches zero amp, a first
zero current signal to enable the first switch control circuit to
control the first rectifier switch to be turned off; a second zero
current detection circuit configured to detect the second resonant
current on the second rectifier switch, and output, in response to
detecting that the second resonant current reaches zero amp, a
second zero current signal to enable the first switch control
circuit to control the second rectifier switch to be turned off; a
first switch off detector configured to detect whether or not the
first rectifier switch and the second rectifier switch are both
turned off, and output, in response to the first rectifier switch
and the second rectifier switch being both turned off, a first
turn-off confirmation signal; a modulation time calculation module
configured to calculate a first modulation time according to a
feedback voltage from the output terminal, and output, in response
to receiving the first turn-off confirmation signal, a second mode
activation signal after the first rectifier switch and the second
rectifier switch are turned off and the first modulation time has
elapsed; a second switch control circuit configured to, in response
to receiving the second mode activation signal, control the
plurality of switches corresponding to the second mode to be turned
on, so as to form a third resonant current along a third resonant
path and a fourth resonant current along a fourth resonant path
through the plurality of resonant tanks, respectively, wherein the
plurality of switches include a third rectifier switch located on
the third resonant path and a fourth rectifier switch located on
the fourth resonant path; a third zero current detection circuit
configured to detect the third resonant current on the third
rectifier switch, and output, in response to detecting that the
third resonant current reaches zero amp, a third zero current
signal to enable the second switch control circuit to control the
third rectifier switch to be turned off; a fourth zero current
detection circuit configured to detect the fourth resonant current
on the fourth rectifier switch, and output, in response to
detecting that the second resonant current reaches zero amp, a
fourth zero current signal to enable the second switch control
circuit to control the fourth rectifier switch to be turned off;
and a second switch off detector configured to detect whether or
not the third rectifier switch and the fourth rectifier switch are
both turned off, and output, in response to the third rectifier
switch and the fourth rectifier switch being both turned off, a
second turn-off confirmation signal; wherein the modulation time
calculation module configured to calculate a second modulation time
according to the feedback voltage from the output terminal, and
output, in response to receiving the second turn-off confirmation
signal, a first mode activation signal after the third rectifier
switch and the fourth rectifier switch are turned off and the
second modulation time has elapsed.
7. The control circuit according to claim 6, wherein the first
switch control circuit is further configured to, in response to
receiving the first turn-off confirmation signal, control the
switches other than the first rectifier switch and the second
rectifier switch among the plurality of switches corresponding to
the first mode to be turned off within the first modulation time
after the first rectifier switch and the second rectifier switch
are turned off.
8. The control circuit according to claim 6, wherein the second
switch control circuit is further configured to, in response to
receiving the second turn-off confirmation signal, control the
switches other than the third rectifier switch and the fourth
rectifier switch among the plurality of switches corresponding to
the second mode to be turned off within the second modulation time
after the third rectifier switch and the fourth rectifier switch
are turned off.
9. The control circuit according to claim 6, wherein the modulation
time calculation module includes a first calculation unit and a
second calculation unit, and the first calculation unit is
configured to calculate the first modulation time according to the
feedback voltage, and output, in response to receiving the first
turn-off confirmation signal, the second mode activation signal
after the first rectifier switch and the second rectifier switch
are turned off and the first modulation time has elapsed; wherein
the second calculation unit is configured to calculate the second
modulation time according to the feedback voltage, and output, in
response to receiving the second turn-off confirmation signal, the
first mode activation signal after the third rectifier switch and
the fourth rectifier switch are turned off and the second
modulation time has elapsed.
10. The control circuit according to claim 6, wherein the
modulation time calculation module includes a third calculation
unit and a phase shifter, and the third calculation unit is
configured to continuously calculate and update a total modulation
time based on the feedback voltage, sample the total modulation
time calculated when the switches corresponding to the first mode
are turned on, take one-half of the total modulation time as a time
point at which the switches corresponding to the second mode are
turned on, take the total modulation time as a time point at which
the switches corresponding to the first mode are turned on to enter
the first mode of a next cycle, and correspondingly generate a time
modulation signal; wherein the phase shifter is configured to, in
response to receiving the time modulation signal, generate a phase
shifted control signal according to one-half of the total
modulation time as the second mode activation signal, to turn on
the switches corresponding to the second mode after the switches
corresponding to the first mode are turned on and the half of the
total modulation time elapses, and after the third calculation unit
receives the first turn-off confirmation signal, and wherein the
third calculation unit is further configured to use the time
modulation signal as the first mode activation signal after the
switches corresponding to the switches corresponding to the first
mode are turned on and the total modulation time elapses, and after
the third calculation unit receives the second turn-off
confirmation signal, to turn on the switches corresponding to the
first mode to enter the first mode of the next cycle.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATION
[0001] This application claims the benefit of priority to Taiwan
Patent Application No. 109128519, filed on Aug. 21, 2020. The
entire content of the above identified application is incorporated
herein by reference.
[0002] Some references, which may include patents, patent
applications and various publications, may be cited and discussed
in the description of this disclosure. The citation and/or
discussion of such references is provided merely to clarify the
description of the present disclosure and is not an admission that
any such reference is "prior art" to the disclosure described
herein. All references cited and discussed in this specification
are incorporated herein by reference in their entireties and to the
same extent as if each reference was individually incorporated by
reference.
FIELD OF THE DISCLOSURE
[0003] The present disclosure relates to a control circuit and a
control method, and more particularly to a control circuit and a
control method for a power converter.
BACKGROUND OF THE DISCLOSURE
[0004] In the existing switching resonant tank converter circuit,
it has only been proposed to automatically adjust on-times to
individually control the off timing of rectifier switches, to
achieve optimal efficiency. However, in parallel applications, no
solution is proposed for the current sharing between multiple sets
of converters.
[0005] Therefore, one of the important issues in the art is how to
improve a control mechanism to retain existing automatic adjustment
of on-time control, such that an overall converter can be optimized
in terms of efficiency, with the output voltage and output
impedance being adjustable, and parallel outputs can be
balanced.
SUMMARY OF THE DISCLOSURE
[0006] In response to the above-referenced technical inadequacies,
the present disclosure provides a control circuit and a control
method for a power converter.
[0007] In one aspect, the present disclosure provides a control
method for a power converter including a plurality of resonant
tanks and a plurality of switches arranged between an input
terminal and an output terminal. The plurality of switches
correspond to a first mode and a second mode, respectively, and the
input terminal receives an input voltage. The control method
includes: configuring a first switch control circuit to control the
plurality of switches corresponding to the first mode to be turned
on in the first mode, to respectively form a first resonant current
along a first resonant path and a second resonant current along a
second resonant path through the plurality of resonant tanks, in
which the plurality of switches include a first rectifier switch
located on the first resonant path and a second rectifier switch
located on the second resonant path; configuring a first zero
current detection circuit to detect the first resonant current on
the first rectifier switch, and output, in response to detecting
that the first resonant current reaches zero amp, a first zero
current signal to enable the first switch control circuit to
control the first rectifier switch to be turned off; configuring a
second zero current detection circuit to detect the second resonant
current on the second rectifier switch, and output, in response to
detecting that the second resonant current reaches zero amp, a
second zero current signal to enable the first switch control
circuit to control the second rectifier switch to be turned off;
configuring a first switch off detector to detect whether or not
the first rectifier switch and the second rectifier switch are both
turned off, and output, in response to the first rectifier switch
and the second rectifier switch being both turned off, a first
turn-off confirmation signal; configuring a modulation time
calculation module to calculate a first modulation time according
to a feedback voltage from the output terminal, and output, in
response to receiving the first turn-off confirmation signal, a
second mode activation signal after the first rectifier switch and
the second rectifier switch are turned off and the first modulation
time has elapsed; configuring a second switch control circuit to,
in response to receiving the second mode activation signal, control
the plurality of switches corresponding to the second mode to be
turned on, to respectively form a third resonant current along a
third resonant path and a fourth resonant current along a fourth
resonant path through the plurality of resonant tanks, in which the
plurality of switches include a third rectifier switch located on
the third resonant path and a fourth rectifier switch located on
the fourth resonant path; configuring a third zero current
detection circuit to detect the third resonant current on the third
rectifier switch, and output, in response to detecting that the
third resonant current reaches zero amp, a third zero current
signal to enable the second switch control circuit to control the
first rectifier switch to be turned off; configuring a fourth zero
current detection circuit to detect the fourth resonant current on
the fourth rectifier switch, and output, in response to detecting
that the second resonant current reaches zero amp, a fourth zero
current signal to enable the second switch control circuit to
control the fourth rectifier switch to be turned off; configuring a
second switch off detector to detect whether or not the third
rectifier switch and the fourth rectifier switch are both turned
off, and output, in response to the third rectifier switch and the
fourth rectifier switch being both turned off, a second turn-off
confirmation signal; and configuring the modulation time
calculation module to calculate a second modulation time according
to the feedback voltage from the output terminal, and output, in
response to receiving the second turn-off confirmation signal, a
first mode activation signal after the third rectifier switch and
the fourth rectifier switch are turned off and the second
modulation time has elapsed.
[0008] In certain embodiments, the control method further includes
configuring the first switch control circuit to, in response to
receiving the first turn-off confirmation signal, control the
switches other than the first rectifier switch and the second
rectifier switch among the plurality of switches corresponding to
the first mode to be turned off within the first modulation time
after the first rectifier switch and the second rectifier switch
are turned off
[0009] In certain embodiments, the control method further includes
configuring the second switch control circuit to, in response to
receiving the second turn-off confirmation signal, control the
switches other than the third rectifier switch and the fourth
rectifier switch among the plurality of switches corresponding to
the second mode to be turned off within the second modulation time
after the third rectifier switch and the fourth rectifier switch
are turned off.
[0010] In certain embodiments, the modulation time calculation
module includes a first calculation unit and a second calculation
unit. The control method further includes: configuring the first
calculation unit to calculate the first modulation time according
to the feedback voltage, and output, in response to receiving the
first turn-off confirmation signal, the second mode activation
signal after the first rectifier switch and the second rectifier
switch are turned off and the first modulation time has elapsed;
and configuring the second calculation unit to calculate the second
modulation time according to the feedback voltage, and output, in
response to receiving the second turn-off confirmation signal, the
first mode activation signal after the third rectifier switch and
the fourth rectifier switch are turned off and the second
modulation time has elapsed.
[0011] In certain embodiments, the modulation time calculation
module includes a third calculation unit and a phase shifter. The
control method further includes: configuring the third calculation
unit to calculate a total modulation time according to the feedback
voltage, correspondingly generate a time modulation signal, and
output, in response to receiving the first turn-off confirmation
signal or the second turn-off confirmation signal, the time
modulation signal with the calculated total modulation time; and
configuring the phase shifter to, in response to receiving the time
modulation signal, phase-shift the time modulation signal according
to one-half of the total modulation time to generate a
phase-shifted time modulation signal, and use the time modulation
signal and the phase-shifted time modulation signal as the second
mode activation signal and the first mode activation signal to be
output, respectively.
[0012] In another aspect, the present disclosure provides a control
circuit for a power converter including a plurality of resonant
tanks and a plurality of switches arranged between an input
terminal and an output terminal. The plurality of switches
correspond to a first mode and a second mode, respectively, and the
input terminal receives an input voltage. The control circuit
includes a first switch control circuit, a first zero current
detection circuit, a second zero current detection circuit, a first
switch off detector, a modulation time calculation module, a second
switch control circuit, a third zero current detection circuit, a
fourth zero current detection circuit, and a second switch off
detector. The first switch control circuit is configured to control
the plurality of switches corresponding to the first mode to be
turned on in the first mode, to respectively form a first resonant
current along a first resonant path and a second resonant current
along a second resonant path through the plurality of resonant
tanks. The plurality of switches include a first rectifier switch
located on the first resonant path and a second rectifier switch
located on the second resonant path. The first zero current
detection circuit is configured to detect the first resonant
current on the first rectifier switch, and output, in response to
detecting that the first resonant current reaches zero amp, a first
zero current signal to enable the first switch control circuit to
control the first rectifier switch to be turned off The second zero
current detection circuit is configured to detect the second
resonant current on the second rectifier switch, and output, in
response to detecting that the second resonant current reaches zero
amp, a second zero current signal to enable the first switch
control circuit to control the second rectifier switch to be turned
off The first switch off detector is configured to detect whether
or not the first rectifier switch and the second rectifier switch
are both turned off, and output, in response to the first rectifier
switch and the second rectifier switch being both turned off, a
first turn-off confirmation signal. The modulation time calculation
module is configured to calculate a first modulation time according
to a feedback voltage from the output terminal, and output, in
response to receiving the first turn-off confirmation signal, a
second mode activation signal after the first rectifier switch and
the second rectifier switch are turned off and the first modulation
time has elapsed. The second switch control circuit is configured
to, in response to receiving the second mode activation signal,
control the plurality of switches corresponding to the second mode
to be turned on, to respectively form a third resonant current
along a third resonant path and a fourth resonant current along a
fourth resonant path through the plurality of resonant tanks. The
plurality of switches include a third rectifier switch located on
the third resonant path and a fourth rectifier switch located on
the fourth resonant path. The third zero current detection circuit
is configured to detect the third resonant current on the third
rectifier switch, and output, in response to detecting that the
third resonant current reaches zero amp, a third zero current
signal to enable the second switch control circuit to control the
third rectifier switch to be turned off The fourth zero current
detection circuit is configured to detect the fourth resonant
current on the fourth rectifier switch, and output, in response to
detecting that the second resonant current reaches zero amp, a
fourth zero current signal to enable the second switch control
circuit to control the fourth rectifier switch to be turned off The
second switch off detector is configured to detect whether or not
the third rectifier switch and the fourth rectifier switch are both
turned off, and output, in response to the third rectifier switch
and the fourth rectifier switch being both turned off, a second
turn-off confirmation signal. The modulation time calculation
module is configured to calculate a second modulation time
according to the feedback voltage from the output terminal, and
output, in response to receiving the second turn-off confirmation
signal, a first mode activation signal after the third rectifier
switch and the fourth rectifier switch are turned off and the
second modulation time has elapsed.
[0013] Therefore, the control circuit and the control method for
the power converter provided by the present disclosure can enable
rectifier switches of a power converter that has multiple sets of
rectification paths to determine on-times individually through the
zero current detection circuits. The control circuit and the
control method provided by the present disclosure can not only
overcome differences in on-times of the rectifier switches caused
by the component error of each individual rectifier loop, but can
also achieve functions of zero voltage turned on and zero current
turned off for each of the rectifier components, thereby optimizing
an overall efficiency of the power converter.
[0014] In addition, after ensuring that all rectification paths of
the power converter have completed zero current turn-off, trigger
timings of the switching signals of the power converter are
adjusted to achieve modulation of the converter output impedance,
thereby achieving functions of output voltage adjustment and
current-sharing for parallel output.
[0015] These and other aspects of the present disclosure will
become apparent from the following description of the embodiment
taken in conjunction with the following drawings and their
captions, although variations and modifications therein may be
affected without departing from the spirit and scope of the novel
concepts of the disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] The present disclosure will become more fully understood
from the following detailed description and accompanying drawings
in which:
[0017] FIG. 1 is a functional block diagram of a control circuit
for a power converter according to a first embodiment of the
present disclosure.
[0018] FIG. 2 is a circuit layout of the power converter according
to the first embodiment of the present disclosure.
[0019] FIG. 3 is a switch timing diagram according to the first
embodiment of the present disclosure.
[0020] FIG. 4 is a functional block diagram of a control circuit
for a power converter according to a second embodiment of the
present disclosure.
[0021] FIG. 5 is a circuit layout of the power converter according
to the second embodiment of the present disclosure.
[0022] FIG. 6 is a switch timing diagram according to the second
embodiment of the present disclosure.
DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
[0023] The present disclosure is more particularly described in the
following examples that are intended as illustrative only since
numerous modifications and variations therein will be apparent to
those skilled in the art. Like numbers in the drawings indicate
like components throughout the views. As used in the description
herein and throughout the claims that follow, unless the context
clearly dictates otherwise, the meaning of "a", "an", and "the"
includes plural reference, and the meaning of "in" includes "in"
and "on". Titles or subtitles can be used herein for the
convenience of a reader, which shall have no influence on the scope
of the present disclosure.
[0024] The terms used herein generally have their ordinary meanings
in the art. In the case of conflict, the present document,
including any definitions given herein, will prevail. The same
thing can be expressed in more than one way. Alternative language
and synonyms can be used for any term(s) discussed herein, and no
special significance is to be placed upon whether a term is
elaborated or discussed herein. A recital of one or more synonyms
does not exclude the use of other synonyms. The use of examples
anywhere in this specification including examples of any terms is
illustrative only, and in no way limits the scope and meaning of
the present disclosure or of any exemplified term. Likewise, the
present disclosure is not limited to various embodiments given
herein. Numbering terms such as "first", "second" or "third" can be
used to describe various components, signals or the like, which are
for distinguishing one component/signal from another one only, and
are not intended to, nor should be construed to impose any
substantive limitations on the components, signals or the like.
First Embodiment
[0025] FIG. 1 is a functional block diagram of a control circuit
for a power converter according to a first embodiment of the
present disclosure. Referring to FIG. 1, the first embodiment of
the present disclosure provides a control circuit for a power
converter, and further reference can be made to FIG. 2, which is a
circuit layout of the power converter according to the first
embodiment of the present disclosure. As shown in FIG. 2, the power
converter can be a switched tank converter (STC), which includes
resonant tanks RS1 and RS2 and switches Q1 to Q12 provided between
an input terminal Vin and an output terminal Vout. The switches Q1
to Q12 can respectively correspond to a first mode .PHI.1 and a
second mode .PHI.2, and the input terminal Vin receives an input
voltage. The resonant tank RS1 can include a resonant capacitor CR1
and a resonant inductor LR1. The resonant tank RS2 can include a
resonant capacitor CR2 and a resonant inductor LR2. A non-resonant
capacitor CF1 is separate from the resonant tanks RS1 and RS2, and
is a capacitor that does not contribute to characteristic resonant
frequencies of the resonant tanks RS1 and RS2 themselves. In this
embodiment, only one non-resonant capacitor CF1 is included in the
circuit. However, depending on topology of the STC circuit, more
than one non-resonant capacitor can be used. In a specific
switching state, depending on the circuit topology and application,
each resonant tank RS1 and RS2 can be connected in series or in
parallel with a specific non-resonant capacitor.
[0026] Each of the plurality of switches Q1 to Q12 has a first
terminal, a second terminal, a control terminal, and a
corresponding body diode. The control terminal can receive a
control signal so that the switch is in off or on state. In the
embodiment of FIG. 1, N-channel MOSFET switches are utilized.
However, other types of switches can also be used. Among the
switches Q1 to Q12, the switches Q1, Q4, Q5, Q7, Q10, and Q11
correspond to the first mode .PHI.1, and the switches Q2, Q3, Q6,
Q8, Q9, and Q12 correspond to the second mode .PHI.2.
[0027] The control circuit 1 of the present disclosure is further
described. As shown in FIG. 1, the control circuit 1 includes a
first switch control circuit SW1, a first zero current detection
circuit ZCD1, a second zero current detection circuit ZCD2, a first
switch off detector OFFC1, a modulation time calculation module
TMC, a second switch control circuit SW2, a third zero current
detection circuit ZCD3, a fourth zero current detection circuit
ZCD4, and a second switch off detector OFFC2.
[0028] The details of each part of the control circuit 1 will be
described hereinafter based on FIG. 3. Reference is made to FIG. 3,
which is a switch timing diagram according to the first embodiment
of the present disclosure.
[0029] As shown in FIG. 3, the first mode .PHI.1 starts at time t0,
and the first switch control circuit SW1 is configured to control
the plurality of switches corresponding to the first mode .PHI.1 to
be turned on in the first mode .PHI.1. For example, the switches
Q1, Q4, Q5, Q7, Q10, and Q11 are controlled by switching signals
VGS1, VGS4, VGS5, VGS7, VGS10, and VGS11, respectively, and the
switches Q2, Q3, Q6, Q8, Q9 and Q12 corresponding to the second
mode .PHI.2 are controlled by switching signals VGS2, VGS3, VGS6,
VGS8, VGS9 and VGS12. In this case, a first resonant current i1
along the first resonant path L1 and a second resonant current i2
along the second resonant path L2 can be formed by the resonant
tanks RS1 and RS2, respectively.
[0030] The switches Q1, Q4, Q5, Q7, Q10, and Q11 include a first
rectifier switch located on the first resonance path L1, and a
second rectifier switch located on the second resonance path L2.
For example, it can be seen from FIG. 3 that the body diodes of the
switches Q11 and Q7 follow a direction of the current, and
therefore have a rectifying function, which can be used as the
aforementioned first rectifier switch and second rectifier switch,
respectively. In the first resonance path L1, the switch Q10 can
also be used as the first rectifier switch, but the switch Q11 is
used here in this embodiment.
[0031] Next, the first zero current detection circuit ZCD1 is
configured to detect the first resonant current i1 on the first
rectifier switch (the switch Q11 at this time), that is, to detect
a switch current ISD11 on the switch Q11. In response to the first
resonant current i1 (i.e., the switch current ISD11) being detected
to reach zero amp, the first zero current detection circuit ZCD1
outputs a first zero current signal to enable the first switch
control circuit SW1 to control the first rectifier switch (switch
Q11) to be turned off, which is at time t1.
[0032] At the same time, when the second resonant path L2 is
generated, the second zero current detection circuit ZCD2 is also
configured to detect the second resonant current i2 on the second
rectifier switch (in this case, the switch Q7), in other words, to
detect a switch current ISD7 on the switch Q7. In response to the
second resonant current i2 being detected to reach zero amp, the
second zero current detection circuit ZCD2 outputs a second zero
current signal to enable the first switch control circuit SW1 to
control the second rectifier switch (switch Q7) to be turned off,
and it is at time t2.
[0033] The reason for using the first zero current detection
circuit ZCD1 and the second zero current detection circuit ZCD2 for
detection is that the resonance tanks RS1 and RS2 of the power
converter may not match with each other, resulting in different
resonance frequencies. Therefore, in order for the first resonant
path L1 and the second resonant path L2 to individually operate at
the resonant frequency, the most efficient manner is to configure
the first zero-current detection circuit ZCD1 and the second
zero-current detection circuit ZCD2 to detect on-times respectively
required by the switches Q11 and Q7, and then control the first
switch control circuit SW1.
[0034] Further, the first switch off detector OFFC1 is configured
to detect whether or not the first rectifier switch and the second
rectifier switch are both turned off At time t2, when it is
detected that both the first rectifier switch (switch Q11) and the
second rectifier switch (switch Q7) are turned off, the first
turn-off confirmation signal is outputted.
[0035] Next, the modulation time calculation module TMC is
configured to calculate the first modulation time MT1 based on a
feedback voltage from the output terminal Vout. For example, the
output terminal Vout can be connected to a feedback circuit FB to
transmit the feedback voltage of the output terminal Vout to the
modulation time calculation module TMC. If the output voltage is
too high, a longer first modulation time MT1 will be calculated and
used to decrease the output voltage, and if the output voltage is
too low, a shorter first modulation time MT1 is calculated to
increase the output voltage. In this embodiment, the feedback
voltage can be compared with a predetermined voltage, and an error
between the two can be converted into a length of the first
modulation time MT1 through a compensator. During the first
modulation time MT1, the first rectifier switch (switch Q11) and
the second rectifier switch (switch Q7) are both in the off
state.
[0036] For the switches Q1, Q4, Q5, Q10 other than the first
rectifier switch (switch Q11) and the second rectifier switch
(switch Q7) among the switches Q1, Q4, Q5, Q7, Q10, and Q11
corresponding to the first mode .PHI.1, the first switch control
circuit SW1 can be controlled by a fixed control method. The first
switch control circuit SW1 can be configured to, in response to
receiving the first turn-off confirmation signal, control the
switches Q1, Q4, Q5, and Q10 to be turned off within the first
modulation time MT1 after the first rectifier switch (switch Q11)
and the second rectifier switch (switch Q7) are turned off
[0037] In addition, in response to receiving the first turn-off
confirmation signal, after the first rectifier switch (switch Q11)
and the second rectifier switch (switch Q7) are turned off, and
after the first modulation time MT1 has elapsed, the modulation
time calculation module TMC can output a second mode activation
signal, and it is at time t3.
[0038] At time t3, the second switch control circuit SW2 is
configured to, in response to receiving the second mode activation
signal, control the switches Q2, Q3, Q6, Q8, Q9, and Q12
corresponding to the second mode .PHI.2 to be turned on, to
respectively form a third resonance current i3 along a third
resonance path L3 and a fourth resonance current i4 along a fourth
resonance path L4 through the resonant tanks RS1 and RS2.
Similarly, switches Q2, Q3, Q6, Q8, Q9, and Q12 include a third
rectifier switch (in this case, switch Q9) located on the third
resonant path L3 and a fourth rectifier switch located on the
fourth resonant path L4 (in this case, switch Q12).
[0039] Next, the third zero current detection circuit ZCD3 is
configured to detect the third resonant current i3 on the third
rectifier switch (the switch Q9), in other words, to detect a
switch current ISD9 on the switch Q9. In response to the third
resonant current i3 (i.e., the switch current ISD9) being detected
to reach zero amp, the third zero current detection circuit ZCD3
outputs a third zero current signal to enable the second switch
control circuit SW2 to control the third rectifier switch (switch
Q9) to be turned off, and it is at time t4.
[0040] At the same time, when the fourth resonant path L4 is
generated, the fourth zero current detection circuit ZCD4 is
configured to detect a fourth resonant current i4 (that is, the
switch current ISD12) on the fourth rectifier switch (switch Q12).
In response to the fourth resonant current i4 (switching current
ISD12) being detected to reach zero amp, the fourth zero current
detection circuit ZCD4 outputs a fourth zero current signal to
enable the second switch control circuit SW2 to control the fourth
rectifier switch (switch Q12) to be turned off, and it is at time
t5. Similarly, the most efficient manner is to configure the third
zero current detection circuit ZCD3 and the fourth zero current
detection circuit ZCD4 to detect the on-times of the switches Q9
and Q12 individually required to control the second switch control
circuit SW2.
[0041] Further, the second switch off detector OFFC2 is configured
to detect whether or not the third rectifier switch and the fourth
rectifier switch are both turned off When the third rectifier
switch and the fourth rectifier switch are both turned off, a
second turn-off confirmation signal is outputted. At time t5, when
it is detected that both the third rectifier switch (switch Q9) and
the fourth rectifier switch (switch Q12) are turned off, the second
turn-off confirmation signal is output.
[0042] Next, the modulation time calculation module TMC is further
configured to calculate the second modulation time MT2 based on the
feedback voltage from the output terminal Vout. For example, the
output terminal Vout can be connected to the feedback circuit FB to
transmit the feedback voltage of the output terminal Vout to the
modulation time calculation module TMC. If the output voltage is
too high, a longer second modulation time MT2 will be calculated
and used to decrease the output voltage, and if the output voltage
is too low, a shorter second modulation time MT2 is calculated to
increase the output voltage. In this embodiment, the feedback
voltage can be compared with a predetermined voltage, and an error
between the two can be converted into a length of the second
modulation time MT2 through the compensator. During the second
modulation time MT2, the third rectifier switch (switch Q9) and the
fourth rectifier switch (switch Q12) are both in the off state.
[0043] In addition, in response to receiving the second turn-off
confirmation signal, after the third rectifier switch (switch Q9)
and the fourth rectifier switch (switch Q12) are turned off, and
after the second modulation time MT2 has elapsed, the modulation
time calculation module TMC can output the first mode activation
signal, and the power converter circuit is periodically driven in
the manner of the aforementioned first mode.
[0044] For the switches Q2, Q3, Q6, and Q8 other than the third
rectifier switch (switch Q9) and the fourth rectifier switch
(switch Q12) among the switches Q2, Q3, Q6, Q8, Q9, and Q12
corresponding to the second mode .PHI.2, the second switch control
circuit SW2 can be controlled by a fixed control method. The second
switch control circuit SW2 can be configured to, in response to
receiving the first turn-off confirmation signal, control the
switches Q2, Q3, Q6, and Q8 to be turned off within the second
modulation time MT2 after the third rectifier switch (switch Q9)
and the fourth rectifier switch (switch Q12) are turned off
[0045] In this embodiment, the modulation time calculation module
TMC can include a first calculation unit CU1 and a second
calculation unit CU2 to calculate the required modulation time in
the first mode .PHI.1 and the second mode .PHI.2, respectively. The
first calculation unit CU1 is configured to calculate the first
modulation time MT1 according to the feedback voltage, and output,
in response to receiving the first turn-off confirmation signal,
the second mode activation signal after the first rectifier switch
(switch Q11) and the second rectifier switch (switch Q7) are turned
off and the first modulation time MT1 has elapsed.
[0046] Similarly, the second calculation unit CU2 is configured to
calculate the second modulation time MT2 according to the feedback
voltage, and output, in response to receiving the second turn-off
confirmation signal, the first mode activation signal after the
third rectifier switch (switch Q9) and the fourth rectifier switch
(switch Q12) are turned off and the second modulation time MT2 has
elapsed.
Second Embodiment
[0047] Reference is further made to FIG. 4, which is a functional
block diagram of a control circuit for a power converter according
to a second embodiment of the present disclosure. As shown in FIG.
4, the elements of this embodiment are basically similar to those
of FIG. 1, so that part of the repeated description will be
omitted. The difference is that the modulation time calculation
module TMC of this embodiment includes a third calculation unit CU3
and a phase shifter PS. The following is a description with
reference to FIGS. 5 and 6. FIG. 5 is a circuit layout of a power
converter according to the second embodiment of the present
disclosure, and FIG. 6 is a switch timing diagram according to the
second embodiment of the present disclosure.
[0048] As shown in FIG. 5, the power converter can be a resonant
switched capacitor converter (ReSC), which includes a two-stage
resonant tank and switches Q1' to Q8' arranged between an input
terminal Vin and an output terminal Vout, and an output capacitor
Cout and an output resistor Rout connected to the output terminal
Vout. The switches Qi' to Q8' can respectively correspond to the
first mode .PHI.1 and the second mode .PHI.2, and the input
terminal Vin receives an input voltage. The first-stage resonant
tank can include a resonant capacitor C1 and a resonant inductor
L01. The second-stage resonant tank can include a resonant
capacitor C2 and a resonant inductor L02. A non-resonant capacitor
Cm1 is separate from the two-stage resonant tank, and is a
capacitor that does not contribute to characteristic resonant
frequencies. In this embodiment, only one non-resonant capacitor
Cm1 is included in the circuit. However, depending on topology of
the ReSC circuit, more than one non-resonant capacitor can be
used.
[0049] Among the switches Q1' to Q8', the switches Q2', Q3', Q6',
and Q7' correspond to the first mode .PHI.1, and the switches Q1',
Q4', Q5', and Q8' correspond to the second mode .PHI.2.
[0050] As shown in FIG. 6, the first mode .PHI.1 starts at time t0,
and the first switch control circuit SW1 is configured to control
the plurality of switches corresponding to the first mode .PHI.1 to
be turned on in the first mode .PHI.1. For example, the switches
Q2', Q3', Q6', and Q7' are respectively controlled by the switch
signals VGS2', VGS3', VGS6', and VGS7', and the switches Q1', Q4',
Q5' and Q8' corresponding to the second mode .PHI.2 are controlled
by switch signals VGS1', VGS4', VGS5', and VGS8'. In this case, the
first resonant current i1 along the first resonant path L1 and the
second resonant current i2 along the second resonant path L2 can be
respectively formed by the two-stage resonant tank.
[0051] The switches Q2', Q3', Q6', and Q7' include a first
rectifier switch located on the first resonance path L1, and a
second rectifier switch located on the second resonance path L2.
For example, it can be seen from FIG. 6 that the body diodes of the
switches Q7' and Q3' follow a direction of the current, which
therefore have rectification functions and can be used as the
aforementioned first rectifier switch and second rectifier switch,
respectively.
[0052] Next, the first zero current detection circuit ZCD1 is
configured to detect the first resonant current i2 on the first
rectifier switch (the switch Q3' at this time), in other words, to
detect a switch current ISD3' on the switch Q3'. In response to the
first resonant current i2 (i.e., the switch current ISD3') being
detected to reach zero amp, the first zero current detection
circuit ZCD1 outputs a first zero current signal to enable the
first switch control circuit SW1 to control the first rectifier
switch (switch Q3') to be turned off, and it is at time t1.
[0053] At the same time, when the second resonant path L1 is
generated, the second zero current detection circuit ZCD2 is also
configured to detect the second resonant current i1 on the second
rectifier switch (in this case, the switch Q7'), in other words, to
detect a switch current ISD7' on the switch Q7'. In response to the
second resonant current i1 being detected to reach zero amp, the
second zero current detection circuit ZCD2 outputs a second zero
current signal to enable the first switch control circuit SW1 to
control the second rectifier switch (switch Q7') to be turned off,
and it is at time t2.
[0054] Further, the first switch off detector OFFC1 is configured
to detect whether or not the first rectifier switch and the second
rectifier switch are both turned off At time t2, when it is
detected that both the first rectifier switch (switch Q7') and the
second rectifier switch (switch Q3') are turned off, the first
turn-off confirmation signal is outputted.
[0055] As shown in FIG. 4, the third calculation unit CU3 is
respectively connected to the first switch control circuit SW1, the
feedback circuit FB, the first switch off detector OFFC1, and the
second switch off detector OFFC2. The phase shifter PS is connected
between the third calculation unit CU3 and the second switch
control circuit SW2.
[0056] The third calculation unit CU3 can be used to receive the
first turn-off confirmation signal and the second turn-off
confirmation signal. The third calculation unit CU3 is configured
to calculate a total modulation time TMT according to the feedback
voltage.
[0057] In more detail, the third calculation unit CU3 continuously
calculates and updates the total modulation time TMT according to
the feedback voltage, and samples the total modulation time TMT
calculated at the time when the switches Q2', Q3', Q6', and Q7'
corresponding to the first mode .PHI.1 are turned on, take one half
of the total modulation time TMT as a time point at which the
switches Q1', Q4', Q5', and Q8' corresponding to the second mode
.PHI.2 are turned on, take the total modulation time TMT as a time
point at which the switches Q2', Q3', Q6', and Q7 corresponding to
the first mode .PHI.1 are turned on to enter the first mode .PHI.1
of the next cycle, and correspondingly generate a time modulation
signal.
[0058] The phase shifter PS is configured to, in response to
receiving the time modulation signal, generate a phase shifted
control signal according to one-half of the total modulation time
(for example, phase amount Phase as shown in FIG. 6) as the second
mode activation signal, to turn on the switches Q1', Q4', Q5', and
Q8' corresponding to the second mode .PHI.2 after the switches Q2',
Q3', Q6', and Q7 corresponding to the first mode .PHI.1 are turned
on and the half of the total modulation time elapses, and after the
third calculation unit CU3 receives the first turn-off confirmation
signal.
[0059] Further, the phase shifter PS is configured to, in response
to receiving the time modulation signal, phase-shift the time
modulation signal according to one-half of the total modulation
time TMT, for example, a phase shift amount Phase as shown in the
FIG. 6, to generate a phase shifted time modulation signal, and use
the time modulation signal and the phase shifted time modulation
signal to be output as the second mode activation signal and the
first mode activation signal, respectively.
[0060] In other words, different from the foregoing embodiment, a
start time of the second mode .PHI.2 is essentially controlled by
the phase shifter PS, that is, a switching cycle time of the first
mode .PHI.1 (that is, the first mode activation signal) is phased
shifted by 180 degrees. Therefore, at time t3, the switches Q1',
Q4', Q5', and Q8' corresponding to the second mode .PHI.2 can be
triggered by outputting the second mode activation signal.
[0061] In the second mode .PHI.2, the second switch control circuit
SW2 is configured to, in response to receiving the second mode
activation signal, control the switches Q1', Q4', Q5', and Q8'
corresponding to the second mode D2 to be turned on, to
respectively form the third resonance current i3 along the third
resonance path L3 and the fourth resonance current i4 along the
fourth resonance path L4 through the resonant tanks. Similarly, the
switches Q1', Q4', Q5', and Q8' include a third rectifier switch
(in this case, switch Q1') located on the third resonant path L3
and a fourth rectifier switch (switch Q5' at this time) located on
the fourth resonant path L4.
[0062] Next, the third zero current detection circuit ZCD3 is
configured to detect the third resonant current i3 on the third
rectifier switch (the switch Q1'), in other words, to detect a
switch current ISD1' on the switch Q1'. In response to the third
resonant current i3 (i.e., the switch current ISD1') being detected
to reach zero amp, the third zero current detection circuit ZCD3
outputs a third zero current signal to enable the second switch
control circuit SW2 to control the third rectifier switch (switch
Q1') to be turned off, and it is at time t4.
[0063] At the same time, when the fourth resonant path L4 is
generated, the fourth zero current detection circuit ZCD4 is
configured to detect a fourth resonant current i4 (that is, the
switch current ISD5') on the fourth rectifier switch (switch Q5').
In response to the fourth resonant current i4 (switching current
ISD5') being detected to reach zero amp, the fourth zero current
detection circuit ZCD4 outputs a fourth zero current signal to
enable the second switch control circuit SW2 to control the fourth
rectifier switch (switch Q5') to be turned off, and it is at time
t5.
[0064] The second switch off detector OFFC2 is configured to detect
whether or not the third rectifier switch and the fourth rectifier
switch are both turned off When the third rectifier switch and the
fourth rectifier switch are both turned off, a second turn-off
confirmation signal is outputted. At time t5, when it is detected
that both the third rectifier switch (switch Q1') and the fourth
rectifier switch (switch Q5') are turned off, the second turn-off
confirmation signal is outputted.
[0065] Next, the third calculation unit CU3 is further configured
to use the time modulation signal as the first mode activation
signal after the switches corresponding to the switches Q2', Q3',
Q6', and Q7 corresponding to the first mode .PHI.1 are turned on
and the total modulation time TMT elapses, and after the third
calculation unit CU3 receives the second turn-off confirmation
signal, to turn on the switches Q2', Q3', Q6', and Q7 corresponding
to the first mode .PHI.1 to enter the first mode of the next cycle
(for example, at time t6).
Beneficial Effects of the Embodiments
[0066] In conclusion, the control circuit and the control method
for the power converter provided by the present disclosure can
enable rectifier switches of a power converter with multiple sets
of rectification paths to determine on-times individually through
the zero current detection circuits. The control circuit and the
control method provided by the present disclosure can not only
overcome difference in on-times of the rectifier switches caused by
the component error of individual rectifier loop, but can also
achieve functions of zero voltage turned on and zero current turned
off for each of the rectifier components, thereby optimizing an
overall efficiency of the power converter.
[0067] In addition, after ensuring that all rectification paths of
the power converter have completed zero current turn-off, trigger
timings of the switching signals of the power converter are
adjusted to achieve modulation of the converter output impedance,
thereby providing functions of output voltage adjustment and
current-sharing for parallel output.
[0068] The foregoing description of the exemplary embodiments of
the disclosure has been presented only for the purposes of
illustration and description and is not intended to be exhaustive
or to limit the disclosure to the precise forms disclosed. Many
modifications and variations are possible in light of the above
teaching.
[0069] The embodiments were chosen and described in order to
explain the principles of the disclosure and their practical
application so as to enable others skilled in the art to utilize
the disclosure and various embodiments and with various
modifications as are suited to the particular use contemplated.
Alternative embodiments will become apparent to those skilled in
the art to which the present disclosure pertains without departing
from its spirit and scope.
* * * * *