Non-isolated DCDC resonant conversion control circuit and control method
According to a non-isolated DCDC resonant conversion control circuit provided in embodiments of this application, an inductor and a capacitor that are resonant are connected in series, so that a current flowing through the inductor is a sine waveform. A waveform coefficient of the sine wave is small, and a conduction loss of the sine wave is low. Therefore, the circuit provided in embodiments of this application can significantly reduce a circuit loss. According to the non-isolated DCDC resonant conversion control method provided in embodiments of this application, not only a phase shift angle can be adjusted to enable a switching transistor to implement zero voltage switching (ZVS) on, but switching frequency can also be adjusted. Therefore, ranges in which a voltage and power of an output interface can be adjusted are large, so that non-isolated wide-range DCDC resonant conversion is implemented.
1. A non-isolated DC-DC resonant conversion control circuit, comprising an input interface, a first switching transistor, a second switching transistor, a third switching transistor, a fourth switching transistor, an inductor, a capacitor, and an output interface, wherein
the first switching transistor and the second switching transistor, that are connected in series with each other, are coupled to the input interface in series;
the third switching transistor and the fourth switching transistor, that are connected in series with each other, are coupled to the output interface in series;
the inductor and the capacitor, that are connected in series with each other, are coupled between an end A that is a node on which the first switching transistor and the second switching transistor are connected in series and an end B that is a node on which the third switching transistor and the fourth switching transistor are connected in series; and
a negative electrode of the input interface is coupled to a negative electrode of the output interface, or a positive electrode of the input interface is coupled to a positive electrode of the output interface, wherein:
a phase shift angle θ of a voltage between the input interface and the output interface satisfies
θ
=
cos
-
1
(
V
out
V
i
n
)
when
V
o
u
t
V
i
n
≤
1
,
and
θ
=
cos
-
1
(
V
i
n
V
out
)
when
V
i
n
V
o
u
t
≤
1
,
V in is a voltage of the input interface, and V out is a voltage of the output interface; and/or
output power P 0 of the output interface is
P
o
=
2
*
V
i
n
*
V
o
u
t
π
2
*
(
2
π
f
s
*
L
-
1
2
π
f
s
*
C
)
*
sin
θ
,
V in is the voltage of the input interface, V out is the voltage of the output interface, f s is a switching frequency, L is an inductance value of the inductor, and C is a capacitance value of the capacitor.
2. The non-isolated DC-DC resonant conversion control circuit according to claim 1 , wherein the phase shift angle θ of the voltage between the input interface and the output interface satisfies:
θ
=
cos
-
1
(
V
out
V
i
n
)
when
V
out
V
i
n
≤
1
,
and
θ
=
cos
-
1
(
V
i
n
V
out
)
when
V
i
n
V
out
≤
1
,
wherein
V in is the voltage of the input interface, and V out is the voltage of the output interface.
3. The non-isolated DC-DC resonant conversion control circuit according to claim 1 , wherein the output power P 0 of the output interface is:
P
o
=
2
*
V
i
n
*
V
out
π
2
*
(
2
π
f
s
*
L
-
1
2
π
f
s
*
C
)
*
sin
θ
,
wherein
V in is the voltage of the input interface, V out is the voltage of the output interface, f s is the switching frequency, L is the inductance value of the inductor, Cis a capacitance value of the capacitor, and θ is the phase shift angle of the voltage between the input interface and the output interface.
4. The non-isolated DC-DC resonant conversion control circuit according to claim 1 , wherein
when the first switching transistor is on, the second switching transistor is off;
when the first switching transistor is off, the second switching transistor is on;
when the third switching transistor is on, the fourth switching transistor is off; and
when the third switching transistor is off, the fourth switching transistor is on.
5. The non-isolated DC-DC resonant conversion control circuit according to claim 1 , further comprising a control unit, wherein
the control unit is coupled to the first switching transistor, the second switching transistor, the third switching transistor, and the fourth switching transistor, and is configured to control setting on and off of the first switching transistor, the second switching transistor, the third switching transistor, and the fourth switching transistor.
6. The non-isolated DC-DC resonant conversion control circuit according to claim 1 , further comprising a phase shift angle adjustment unit configured to determine the phase shift angle θ of the voltage between the input interface and the output interface based on the voltage of the input interface and a target voltage of the output interface.
7. The non-isolated DC-DC resonant conversion control circuit according to claim 1 , further comprising a frequency adjustment unit configured to determine a switching frequency of the first switching transistor in the control circuit based on the phase shift angle θ and a first target power or a first target current of the output interface.
8. The non-isolated DC-DC resonant conversion control circuit according to claim 7 , wherein
the frequency adjustment unit is further configured to adjust the switching frequency based on the phase shift angle θ and a second target power or a second target current of the output interface.
9. A power supply system, comprising a power supply module and the non-isolated DC-DC resonant conversion control circuit according to claim 1 , wherein
the power supply module is connected to the input interface of the non-isolated DC-DC resonant conversion control circuit.
10. The power supply system according to claim 9 , wherein the power supply module is a lithium battery or a photovoltaic power supply.
11. A non-isolated DC-DC resonant conversion control method comprising:
determining a phase shift angle θ of a voltage between an input interface and an output interface of a control circuit based on a voltage of the input interface and a target voltage of the output interface;
determining a switching frequency of a first switching transistor in the control circuit based on the phase shift angle θ and a first target power or a first target current of the output interface; and
controlling, based on the phase shift angle θ and the switching frequency, the first switching transistor, a second switching transistor, a third switching transistor, and a fourth switching transistor in the control circuit to be on or off,
wherein in the control circuit:
the first switching transistor and the second switching transistor, that are connected in series with each other, are coupled to the input interface in series;
the third switching transistor and the fourth switching transistor, that are connected in series with each other, are coupled to the output interface in series;
the inductor and the capacitor, that are connected in series with each other, are coupled between an end A that is a node on which the first switching transistor and the second switching transistor are connected in series and an end B that is a node on which the third switching transistor and the fourth switching transistor are connected in series; and
a negative electrode of the input interface is coupled to a negative electrode of the output interface, or a positive electrode of the input interface is coupled to a positive electrode of the output interface; wherein:
the determining a phase shift angle θ based on a voltage of the input interface and a target voltage of the output interface comprises determining the phase shift angle θ based on the voltage of the input interface and the target voltage of the output interface by using a phase shift angle calculation formula, the phase shift angle calculation formula is
θ
=
cos
-
1
(
V
out
V
i
n
)
when
V
out
V
i
n
≤
1
,
and
θ
=
cos
-
1
(
V
i
n
V
out
)
when
V
i
n
V
out
≤
1
,
V in is the voltage of the input interface, and V out is the target voltage of the output interface; and/or
the determining a switching frequency based on the phase shift angle θ and first target power or a first target current of the output interface comprises determining the switching frequency based on an output power calculation formula, the phase shift angle θ, and the first target power or the first target current of the output interface, the output power calculation formula is
P
o
=
2
*
V
i
n
*
V
out
π
2
*
(
2
π
f
s
*
L
-
1
2
π
f
s
*
C
)
*
sin
θ
,
P 0 is the first target power of the output interface, V in is the voltage of the input interface, V out is the target voltage of the output interface, f s is the switching frequency, Lis an inductance value of an inductor, C is a capacitance value of a capacitor.
12. The control method according to claim 11 , wherein the determining a phase shift angle θ based on a voltage of the input interface and a target voltage of the output interface comprises:
determining the phase shift angle θ based on the voltage of the input interface and the target voltage of the output interface by using the phase shift angle calculation formula.
13. The control method according to claim 11 , wherein the determining a switching frequency based on the phase shift angle θ and first target power or a first target current of the output interface comprises:
determining the switching frequency based on the output power calculation formula, the phase shift angle θ, and the first target power or the first target current of the output interface.
14. The control method according to claim 13 , wherein after the determining the switching frequency based on an output power calculation formula, the phase shift angle θ, and the first target power or the first target current of the output interface, the method further comprises:
adjusting the switching frequency, and calculating power of the output interface by using the output power calculation formula until the power of the output interface reaches second target power of the output interface.
15. The control method according to claim 13 , wherein the determining the switching frequency based on an output power calculation formula, the phase shift angle θ, and the first target power or the first target current of the output interface comprises:
obtaining the first target power of the output interface through calculation by using a target current of the output interface and the target voltage of the output interface; and
determining the switching frequency based on the output power calculation formula, the phase shift angle θ, and the first target power or the first target current of the output interface.
16. The control method according to claim 11 , wherein the controlling, based on the phase shift angle θ and the switching frequency, the first switching transistor, a second switching transistor, a third switching transistor, and a fourth switching transistor in the control circuit to be on or off comprises:
when the first switching transistor is controlled to be on, controlling the second switching transistor to be off;
when the first switching transistor is controlled to be off, controlling the second switching transistor to be on;
when the third switching transistor is controlled to be on, controlling the fourth switching transistor to be off; and
when the third switching transistor is controlled to be off, controlling the fourth switching transistor to be on.