# US 12,184,188 B2 · Determining synchronous rectification on-time of CLLC converter

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 12,184,188 B2
- Document ID: US12184188B2
- Status: Granted
- Kind: B2
- Application number: 18/570,265
- Filed: 2021-06-17
- Published: 2024-08-15
- Granted: 2024-12-31
- Earliest claimed: 2021-06-17
- Assignees: Siemens Aktiengesellschaft
- Applicants: Siemens Aktiengesellschaft
- Inventors: Hua Liao
- Web page: https://patentgrep.com/patent/US12184188B2

## CPC

- H02M 3/33573: {Full-bridge at primary side of an isolation transformer}
- H02M 3/33592: {having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer}
- H02M 1/0009: {Devices or circuits for detecting current in a converter}
- H02M 3/01: {Resonant DC/DC converters}
- H02M 3/33584: {Bidirectional converters}
- Y02B 70/10: Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
- H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P)
- Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS

## Abstract

An example method may include: determining a transformer turns ratio and resonant frequency of a converter; determining datasets of peak current and output current of a secondary side diode, an excitation current of a primary excitation inductor when the secondary side diode is off, and an excitation current of the primary excitation inductor when a primary side driving signal is off; measuring a operating frequency and output current of the converter; determining coefficients equal to a ratio of the output current to the peak current multiplied by π 2 , and a ratio of an excitation current of the primary excitation inductor when the secondary side diode is off to an excitation current of the primary excitation inductor when the primary side driving signal is off; measuring a resonant current initial value of a primary resonant inductor; and based on all these, calculating a diode on-time.

## Claims

### Claim 1

A method for determining a synchronous rectification on-time of a CLLC (capacitor-inductor-inductor-capacitor) converter operating in an under-resonant mode, the method comprising:
determining a transformer turns ratio and resonant frequency of the CLLC converter;
using a simulation method, determining datasets of a peak current and output current of a secondary side diode, as well as an excitation current of a primary excitation inductor when the secondary side diode is off, and an excitation current of the primary excitation inductor when a primary side driving signal is off;
measuring a current operating frequency and current output current of the CLLC converter;
based on the operating frequency and the output current, calculating a first coefficient and a second coefficient by means of a linear interpolation method, wherein the first coefficient is equal to a ratio of the output current to the peak current then multiplied by
π
2
,
and the second coefficient is equal to a ratio of the excitation current of the primary excitation inductor when the secondary side diode is off to an excitation current of the primary excitation inductor when the primary side driving signal is off;
measuring a resonant current initial value of a primary resonant inductor; and
based on the transformer turns ratio, the resonant frequency, the resonant current initial value, the current output current, the first coefficient and the second coefficient, calculating a diode on-time.

### Claim 2 (depends on 1)

The method as claimed in claim 1, further comprising using the calculated diode on-time to configure a timing register in a controller of the converter.

### Claim 3 (depends on 1)

The method as claimed in claim 1, wherein the method includes determining a diode on-time of each switching cycle of the CLLC converter.

### Claim 4 (depends on 1)

The method as claimed in claim 1, wherein the value of the diode on-time is calculated using:
1
2
*
resonant
⁢
frequency
·
1
1
+
turns
⁢
ratio
π
·
resonant
⁢
current
⁢
initial
⁢
value
output
⁢
current
·
first
⁢
coefficient
⁢
(
1
-
second
⁢
coefficient
)
.