# US 10,483,838 B2 · System and method providing over current protection based on duty cycle information for power converter

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

- Number: US 10,483,838 B2
- Document ID: US10483838B2
- Status: Granted
- Kind: B2
- Application number: 15/374,896
- Filed: 2016-12-09
- Published: 2017-07-06
- Granted: 2019-11-19
- Earliest claimed: 2010-12-08
- Assignees: On-Bright Electronics (Shanghai) Co., Ltd.
- Applicants: On-Bright Electronics (Shanghai) Co., Ltd.
- Inventors: Chao Yao; Yunchao Zhang; Yuan Lin; Zhiqiang Sun; Lieyi Fang
- Web page: https://patentgrep.com/patent/US10483838B2

## CPC

- H02M 1/32: Means for protecting converters other than automatic disconnection
- H02H 9/025: {Current limitation using field effect transistors}
- H02M 1/08: Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M 3/156: with automatic control of output voltage or current, e.g. switching regulators
- H02M 3/33507: {with automatic control of the output voltage or current, e.g. flyback converters (H02M3/33561, H02M3/33569 take precedence)}
- H02M 3/33515: {with digital control}
- H02M 1/0009: {Devices or circuits for detecting current in a converter}
- 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)
- H02H: EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS (indicating or signalling undesired working conditions G01R, e.g. G01R31/00, G08B; locating faults along lines G01R31/08; emergency protective devices H01H)

## Abstract

System and method for protecting a power converter. An example system controller for protecting a power converter includes a signal generator, a comparator, and a modulation and drive component. The signal generator is configured to generate a threshold signal. The comparator is configured to receive the threshold signal and a current sensing signal and generate a comparison signal based on at least information associated with the threshold signal and the current sensing signal, the current sensing signal indicating a magnitude of a primary current flowing through a primary winding of a power converter. The modulation and drive component is coupled to the signal generator.

## Claims

### Claim 1

A signal generator for protecting a power converter, the signal generator comprising:
a modulation and drive component configured to generate a modulation signal to output a drive signal to a switch in order to affect a primary current flowing through a primary winding of a power converter, the modulation signal including an on-time period, the switch being closed during the on-time period;
a ramping-signal generator configured to receive the modulation signal and generate a ramping signal based on at least information associated with the modulation signal;
a sampling-signal generator configured to receive the modulation signal and generate a sampling signal including a pulse in response to a falling edge of the modulation signal; and
a sample-and-hold component configured to receive the sampling signal and the ramping signal and output a sampled-and-held signal associated with a magnitude of the ramping signal corresponding to the pulse of the sampling signal;
wherein:
the falling edge of the modulation signal is at a first time;
the pulse of the sampling signal starts at a second time and ends at a third time;
the first time and the second time are the same; and
the on-time period ends at the first time.

### Claim 2 (depends on 1)

The signal generator of claim 1 wherein the modulation signal is a pulse-width-modulation signal.

### Claim 3 (depends on 1)

The signal generator of claim 1 wherein the modulation signal is the drive signal.

### Claim 4 (depends on 1)

The signal generator of claim 1 wherein the modulation signal is not the drive signal.

### Claim 5 (depends on 1)

The signal generator of claim 1 wherein the modulation and drive component includes:
a modulation component configured to generate the modulation signal; and
a gate drive component configured to receive the modulation signal and output the drive signal based on at least information associated with the modulation signal.

### Claim 6 (depends on 1)

The signal generator of claim 1 wherein the modulation and drive component includes:
a modulation component configured to generate a first signal; and
a gate drive component configured to receive the first signal, generate the modulation signal based on at least information associated with the first signal, and output the modulation signal as the drive signal.

### Claim 7 (depends on 1)

The signal generator of claim 1, and further comprising:
a comparator configured to receive a threshold signal associated with the sampled-and-held signal and a current sensing signal associated with the primary current and output a comparison signal to the modulation and drive component based on at least information associated with the sampled-and-held signal and the current sensing signal.

### Claim 8 (depends on 7)

The signal generator of claim 7, and further comprising a low-pass filter configured to receive the sampled-and-held signal and output the threshold signal based on at least information associated with the sampled-and-held signal.

### Claim 9 (depends on 8)

The signal generator of claim 8 wherein the sample-and-hold component and the low-pass filter share at least one capacitor.

### Claim 10 (depends on 8)

The signal generator of claim 8 wherein the sample-and-hold component includes:
a first switch configured to be closed and open in response to the sampling signal; and
a first capacitor configured to be charged in response to the ramping signal when the first switch is closed.

### Claim 11 (depends on 1)

The signal generator of claim 1 wherein the ramping-signal generator includes, a capacitor configured to be charged in response to the modulation signal being at a first logic level and output the ramping signal.

### Claim 12 (depends on 1)

The signal generator of claim 1, and further comprising:
a threshold-signal generator configured to receive the sampled-and-held signal and generate a threshold signal based on at least information associated with the sampled-and-held signal, the modulation signal being associated with one or more first switching periods and a second switching period following the one or more first switching periods, the one or more first switching periods corresponding to one or more first duty cycles, the second switching period including an on-time period and an off-time period;
wherein the threshold-signal generator is further configured to:
determine a first threshold signal value based on at least information associated with the one or more first duty cycles;
set a time to zero at a beginning of the on-time period of the second switching period; and
if the time satisfies one or more first predetermined conditions, generate the threshold signal so that the threshold signal decreases, from the determined first threshold signal value, with the increasing time in magnitude.

### Claim 13

A signal generator for protecting a power converter, the signal generator comprising:
a modulation and drive component configured to generate a modulation signal to output a drive signal to a switch in order to affect a primary current flowing through a primary winding of a power converter;
a ramping-signal generator configured to receive the modulation signal and generate a ramping signal based on at least information associated with the modulation signal;
a sampling-signal generator configured to receive the modulation signal and generate a sampling signal including a pulse in response to a falling edge of the modulation signal;
a sample-and-hold component configured to receive the sampling signal and the ramping signal and output a sampled-and-held signal associated with a magnitude of the ramping signal corresponding to the pulse of the sampling signal;
a comparator configured to receive a threshold signal associated with the sampled-and-held signal and a current sensing signal associated with the primary current and output a comparison signal to the modulation and drive component based on at least information associated with the sampled-and-held signal and the current sensing signal; and
a low-pass filter configured to receive the sampled-and-held signal and output the threshold signal based on at least information associated with the sampled-and-held signal;
wherein the sample-and-hold component includes:
a first switch configured to be closed and open in response to the sampling signal; and
a first capacitor configured to be charged in response to the ramping signal when the first switch is closed;
wherein the low-pass filter includes:
a first resistor including a first resistor terminal and a second resistor terminal, the first resistor terminal being coupled to the first switch; and
a second capacitor coupled to the second resistor terminal;
wherein:
the falling edge of the modulation signal is at a first time;
the pulse of the sampling signal starts at a second time and ends at a third time; and
the first time and the second time are the same.

### Claim 14

A signal generator for protecting a power converter, the signal generator comprising:
a modulation and drive component configured to generate a modulation signal to output a drive signal to a switch in order to affect a primary current flowing through a primary winding of a power converter;
a ramping-signal generator configured to receive the modulation signal and generate a ramping signal based on at least information associated with the modulation signal;
a sample-and-hold component configured to receive the ramping signal and the modulation signal and output a sampled-and-held signal associated with a magnitude of the ramping signal in response to the modulation signal;
a filter-signal generator configured to receive the modulation signal and generate a filter signal based on at least information associated with the modulation signal; and
a low-pass filter configured to receive the filter signal and the sampled-and-held signal and, in response to the filter signal, generate a first signal based on at least information associated with the sampled-and-held signal;
wherein the filter-signal generator is further configured to change the filter signal from a first logic level to a second logic level in response to the modulation signal changing from a third logic level to a fourth logic level.

### Claim 15 (depends on 14)

The signal generator of claim 14 wherein the modulation signal is the drive signal.

### Claim 16 (depends on 14)

The signal generator of claim 14 wherein the modulation signal is not the drive signal.

### Claim 17 (depends on 14)

The signal generator of claim 14 wherein the sample-and-hold component and the low-pass filter share at least one capacitor.

### Claim 18 (depends on 14)

The signal generator of claim 14 wherein the modulation and drive component includes:
a modulation component configured to generate the modulation signal; and
a gate drive component configured to receive the modulation signal and output the drive signal based on at least information associated with the modulation signal.

### Claim 19 (depends on 14)

The signal generator of claim 14, and further comprising a comparator configured to receive the first signal as a threshold signal and a current sensing signal associated with the primary current and output a comparison signal to the modulation and drive component based on at least information associated with the sampled-and-held signal and the current sensing signal.

### Claim 20 (depends on 14)

The signal generator of claim 14 wherein the sample-and-hold component includes:
a first switch configured to be closed and open in response to a sampling signal; and
a first capacitor configured to be charged in response to the ramping signal when the first switch is closed.

### Claim 21 (depends on 20)

The signal generator of claim 20 wherein the low-pass filter includes:
a second switch configured to be closed and open in response to the filter signal; and
a second capacitor configured to be charged when the second switch is closed.

### Claim 22 (depends on 14)

The signal generator of claim 14 wherein the ramping-signal generator includes, a capacitor configured to be charged in response to the modulation signal being at a first logic level and output the ramping signal.

### Claim 23 (depends on 14)

The signal generator of claim 14 wherein the modulation signal is a pulse-width-modulation signal.

### Claim 24 (depends on 14)

The signal generator of claim 14 wherein the modulation and drive component includes:
a modulation component configured to generate the modulation signal; and
a gate drive component configured to receive the modulation signal and output the drive signal based on at least information associated with the modulation signal.

### Claim 25 (depends on 14)

The signal generator of claim 14 wherein the modulation and drive component includes:
a modulation component configured to generate a second signal; and
a gate drive component configured to receive the second signal, generate the modulation signal based on at least information associated with the second signal, and output the modulation signal as the drive signal.

### Claim 26 (depends on 14)

The signal generator of claim 14 wherein the filter-signal generator includes a NOT gate.

### Claim 27 (depends on 26)

The signal generator of claim 26 wherein:
the NOT gate includes a first terminal and a second terminal; and
the first terminal is configured to receive the modulation signal.

### Claim 28 (depends on 27)

The signal generator of claim 27 wherein the second terminal of the NOT gate is configured to output the filter signal.

### Claim 29

A method for generating a signal for protecting a power converter, the method comprising:
generating a modulation signal to output a drive signal to a switch in order to affect a primary current flowing through a primary winding of a power converter, the modulation signal including an on-time period, the switch being closed during the on-time period;
receiving the modulation signal;
processing information associated with the modulation signal;
generating a ramping signal based on at least information associated with the modulation signal;
generating a sampling signal including a pulse in response to a falling edge of the modulation signal;
receiving the sampling signal and the ramping signal; and
outputting a sampled-and-held signal associated with a magnitude of the ramping signal corresponding to the pulse of the sampling signal;
wherein:
the falling edge of the modulation signal is at a first time;
the pulse of the sampling signal starts at a second time and ends at a third time;
the first time and the second time are the same; and
the on-time period ends at the first time.

### Claim 30

A method for generating a signal for protecting a power converter, the method comprising:
generating a modulation signal to output a drive signal to a switch in order to affect a primary current flowing through a primary winding of a power converter;
receiving the modulation signal;
processing information associated with the modulation signal;
generating a ramping signal based on at least information associated with the modulation signal;
generating a filter signal based on at least information associated with the modulation signal;
receiving the ramping signal and the modulation signal;
outputting a sampled-and-held signal associated with a magnitude of the ramping signal in response to the modulation signal;
receiving the filter signal and the sampled-and-held signal; and
generating, in response to the filter signal, a first signal based on at least information associated with the sampled-and-held signal;
wherein the generating a filter signal based on at least information associated with the modulation signal includes:
changing the filter signal from a first logic level to a second logic level in response to the modulation signal changing from a third logic level to a fourth logic level.

### Claim 31 (depends on 30)

The method of claim 30 wherein the generating a filter signal based on at least information associated with the modulation signal further includes:
receiving a second signal; and
generating a third signal;
wherein the third signal is an inverted signal of the second signal.