Isolated resonant conversion control method, apparatus and system, and readable storage medium based on switching frequency of input-side switch transistor
An isolated resonant conversion control apparatus includes a voltage and current obtaining unit configured to obtain an output voltage and an output current of an output-side switch transistor of an isolated resonant conversion unit, and a processing unit configured to calculate a switching frequency of an input-side switch transistor of the isolated resonant conversion unit based on the output voltage and the output current, obtain a turn-on offset time and a turn-off offset time of the output-side switch transistor relative to the input-side switch transistor based on the switching frequency of the input-side switch transistor, obtain a duty ratio of a second driving signal based on a duty ratio of a first driving signal, the turn-on offset time, and the turn-off offset time, and generate the second driving signal based on the switching frequency and the duty ratio of the second driving signal.
1. An isolated resonant conversion control apparatus, comprising:
a voltage and current obtaining unit configured to obtain an output voltage and an output current of an output-side switch transistor of an isolated resonant conversion unit; and
a processing unit configured to:
calculate a switching frequency of an input-side switch transistor of the isolated resonant conversion unit based on the output voltage and the output current;
in response to the output current being greater than a synchronization start threshold current, obtain, based on the switching frequency of the input-side switch transistor, a turn-on offset time and a turn-off offset time of the output-side switch transistor relative to the input-side switch transistor;
obtain, based on a duty ratio of a first driving signal, the turn-on offset time, and the turn-off offset time, a duty ratio of a second driving signal;
generate the second driving signal based on the switching frequency of the input-side switch transistor and the duty ratio of the second driving signal; and
drive the output-side switch transistor by using the second driving signal;
wherein the first driving signal is used to drive the input-side switch transistor.
2. The isolated resonant conversion control apparatus of claim 1 , wherein the processing unit is further configured to:
obtain a turn-on time point and a turn-off time point for the first driving signal based on the duty ratio of the first driving signal;
obtain a turn-on time point for the second driving signal based on the turn-on time point of the first driving signal and the turn-on offset time;
obtain a turn-off time point for the second driving signal based on the turn-off time point of the first driving signal and the turn-off offset time; and
obtain the duty ratio of the second driving signal based on the turn-on time point of the second driving signal and the turn-off time point of the second driving signal.
3. The isolated resonant conversion control apparatus of claim 1 , wherein the processing unit is further configured to:
calculate the switching frequency of the input-side switch transistor based on the output voltage and the output current by means of proportional-integral feedback control.
4. The isolated resonant conversion control apparatus of claim 1 , wherein the processing unit is further configured to:
determine the synchronization start threshold current based on an on loss of a body diode connected in parallel with the output-side switch transistor and a switching loss of the output-side switch transistor.
5. The isolated resonant conversion control apparatus of claim 4 , wherein the processing unit is further configured to:
obtain I d at a condition of P 1 =P 2 , and use I d as the synchronization start threshold current, wherein P 1 and P 2 are respectively the on loss of the body diode and the switching loss of the output-side switch transistor,
P
1
=
1
T
t
∫
0
dT
t
I
d
2
d
t
×
R
o
n
,
and P 2 =½×T s ×V d ×I d ×f,
wherein T t is an on time of the body diode, R on is a forward on resistance of the body diode, I d is a current flowing through the output-side switch transistor, T g is a time at which the body diode and the output-side switch transistor are simultaneously on, V d is an on voltage of the output-side switch transistor, and f is a switching frequency of the output-side switch transistor.
6. The isolated resonant conversion control apparatus of claim 1 , wherein the processing unit is further configured to:
in response to the output current being less than a synchronization end threshold current, stop driving the output-side switch transistor of the isolated resonant conversion unit, wherein the synchronization end threshold current is less than the synchronization start threshold current.
7. An isolated resonant conversion control system, comprising:
an isolated resonant conversion unit, comprising an input-side switch transistor and an output-side switch transistor; and
an isolated resonant conversion control apparatus configured to drive the input-side switch transistor and the output-side switch transistor, the isolated resonant conversion control apparatus comprising:
a voltage and current obtaining unit configured to obtain an output voltage and an output current of the output-side switch transistor; and
a processing unit configured to:
calculate a switching frequency of the input-side switch transistor based on the output voltage and the output current;
in response to the output current being greater than a synchronization start threshold current, obtain, based on the switching frequency of the input-side switch transistor, a turn-on offset time and a turn-off offset time of the output-side switch transistor relative to the input-side switch transistor;
obtain, based on a duty ratio of a first driving signal, the turn-on offset time, and the turn-off offset time, a duty ratio of a second driving signal;
generate the second driving signal based on the switching frequency of the input-side switch transistor and the duty ratio of the second driving signal; and
drive the output-side switch transistor by using the second driving signal;
wherein the first driving signal is used to drive the input-side switch transistor.
8. An isolated resonant conversion control method, comprising:
obtaining an output voltage and an output current of an output-side switch transistor of an isolated resonant conversion unit;
calculating a switching frequency of an input-side switch transistor of the isolated resonant conversion unit based on the output voltage and the output current;
in response to the output current being greater than a synchronization start threshold current, obtaining, based on the switching frequency of the input-side switch transistor, a turn-on offset time and a turn-off offset time of the output-side switch transistor relative to the input-side switch transistor;
obtaining, based on a duty ratio of a first driving signal, the turn-on offset time, and the turn-off offset time, a duty ratio of a second driving signal, wherein the first driving signal is used to drive the input-side switch transistor;
generating the second driving signal based on the switching frequency of the input-side switch transistor and the duty ratio of the second driving signal; and
driving the output-side switch transistor of the isolated resonant conversion unit by using the second driving signal.
9. The isolated resonant conversion control method of claim 8 , wherein obtaining the duty ratio of the second driving signal based on the duty ratio of the first driving signal, the turn-on offset time, and the turn-off offset time comprises:
obtaining a turn-on time point and a turn-off time point for the first driving signal based on the duty ratio of the first driving signal;
obtaining a turn-on time point for the second driving signal based on the turn-on time point of the first driving signal and the turn-on offset time;
obtaining a turn-off time point for the second driving signal based on the turn-off time point of the first driving signal and the turn-off offset time; and
obtaining the duty ratio of the second driving signal based on the turn-on time point of the second driving signal and the turn-off time point of the second driving signal.
10. The isolated resonant conversion control method of claim 8 , wherein calculating the switching frequency of the input-side switch transistor based on the output voltage and the output current comprises:
calculating the switching frequency of the input-side switch transistor based on the output voltage and the output current by means of proportional-integral feedback control.
11. The isolated resonant conversion control method of claim 8 , further comprising:
determining the synchronization start threshold current based on an on loss of a body diode connected in parallel with the output-side switch transistor and a switching loss of the output-side switch transistor.
12. The isolated resonant conversion control method of claim 11 , wherein determining the synchronization start threshold current based on the on loss of the body diode connected in parallel with the output-side switch transistor and the switching loss of the output-side switch transistor comprises:
obtaining I d at a condition of P 1 =P 2 , and using I d as the synchronization start threshold current, wherein P 1 and P 2 are respectively the on loss of the body diode and the switching loss of the output-side switch transistor,
P
1
=
1
T
t
∫
0
dT
t
I
d
2
d
t
×
R
o
n
,
and P 2 =½×T s ×V d ×I d ×f,
wherein T t is an on time of the body diode, R on is a forward on resistance of the body diode, I d is a current flowing through the output-side switch transistor, T g is a time at which the body diode and the output-side switch transistor are simultaneously on, V d is an on voltage of the output-side switch transistor, and f is a switching frequency of the output-side switch transistor.
13. The isolated resonant conversion control method of claim 8 , further comprising:
in response to the output current being less than a synchronization end threshold current, stopping driving the output-side switch transistor of the isolated resonant conversion unit, wherein the synchronization end threshold current is less than the synchronization start threshold current.
14. A non-transitory computer-readable storage medium, storing instructions that, when executed by a processor, cause the processor to implement the isolated resonant conversion control method according to claim 8 .