Isolated resonant conversion control method, apparatus and system, and readable storage medium based on switching frequency of input-side switch transistor

Patent metadata

Field	Value
Publication number	US-12368368-B2
Application number	US-202318295925-A
Country	US
Kind code	B2
Filing date	Apr 5, 2023
Priority date	Dec 24, 2020
Publication date	Jul 22, 2025
Grant date	Jul 22, 2025

Abstract

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.

First claim

The invention claimed is:

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

Assignees

• Contemporary Amperex Technology Hong Kong Ltd

Inventors

• Gao Jinfeng
• He Weichen
• Yao Yuan
• Yan Yu

Classifications

• H02M3/01 Primary

  Resonant DC/DC converters · CPC title

• H02M1/0009

  Devices or circuits for detecting current in a converter · CPC title

• H02M1/0032

  Control circuits allowing low power mode operation, e.g. in standby mode · CPC title

• H02M1/0054 Primary

  Transistor switching losses (periodically suspending operation of switching converter in low power mode H02M1/0035) · CPC title

• H02M1/0048

  Circuits or arrangements for reducing losses (using snubbers H02M1/34) · CPC title