# US 12,603,574 B2 · Method and system for entering and exiting a frequency clamp mode for variable frequency, offline switch-mode power converters

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- Number: US 12,603,574 B2
- Document ID: US12603574B2
- Status: Granted
- Kind: B2
- Application number: 18/677,768
- Filed: 2024-05-29
- Published: 2024-09-19
- Granted: 2026-04-14
- Earliest claimed: 2020-11-16
- Assignees: Semiconductor Components Industries, LLC
- Applicants: Semiconductor Components Industries, LLC
- Inventors: Anders Lind
- Web page: https://patentgrep.com/patent/US12603574B2

## CPC

- H02M 1/0054: {Transistor switching losses (periodically suspending operation of switching converter in low power mode H02M1/0035)}
- H02M 3/1582: {Buck-boost converters (H02M3/1584 takes precedence)}
- H02M 1/0058: {by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero (using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826)}
- H02M 1/4208: {Arrangements for improving power factor of AC input}
- H02M 1/4233: {using a bridge converter comprising active switches}
- H02M 3/158: including plural semiconductor devices as final control devices for a single load
- 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

A controller for controlling a switching power converter having an input for receiving a periodic input signal and an output for providing a substantially constant output voltage to a load includes a monitor device configured to compare a switching time interval or a switching frequency with a predetermined threshold value to obtain a comparison result and a parameter recorder configured to record an entry criteria in response to the comparison result, wherein the entry criteria indicates a transition of the switching power converter from a variable switching frequency state to a constant switching frequency state.

## Claims

### Claim 1

A method of operating a switching power converter having an input operable to receive a periodic input signal and an output operable to provide a substantially constant output voltage, the method comprising:
measuring a switching time interval or a switching frequency of the switching power converter;
comparing the switching time interval or the switching frequency with a threshold value to obtain a comparison result;
recording an entry criteria in response to the comparison result, wherein the entry criteria indicates a transition of the switching power converter from a variable switching frequency state to a clamped switching frequency state; and
defining an exit criteria based on the entry criteria, wherein the exit criteria is symmetric around a first phase angle value of the periodic input signal.

### Claim 2 (depends on 1)

The method of claim 1, wherein the entry criteria is associated with at least one selected from the group of a time value, a voltage level, and an entry phase angle of the periodic input signal.

### Claim 3 (depends on 1)

The method of claim 1, wherein the first phase angle value is at least one selected from the group of 0 radians, π/2 radians, π radians, and 3π/2 radians.

### Claim 4 (depends on 1)

The method of claim 1, wherein defining the exit criteria comprises:
obtaining an amplitude level of the periodic input signal at which an entry transition occurs; and
determining the exit criteria based on the obtained amplitude level.

### Claim 5 (depends on 4)

The method of claim 4, wherein the exit criteria comprises hysteresis to prevent the switching power converter from oscillating between the clamped switching frequency state and the variable switching frequency state.

### Claim 6 (depends on 4)

The method of claim 4, wherein obtaining the amplitude level of the periodic input signal comprises determining a change direction of the periodic input signal.

### Claim 7 (depends on 1)

The method of claim 1, wherein the exit criteria is defined based on mirroring of the entry criteria with respect to a zero-crossing point of the periodic input signal or with respect to a peak voltage of the periodic input signal.

### Claim 8 (depends on 1)

The method of claim 1, further comprising:
sampling an amplitude of the output voltage at a zero-crossing point of the periodic input signal;
determining a load condition of the switching power converter; and
changing the clamped switching frequency state to the variable switching frequency state in response to the determined load condition.

### Claim 9 (depends on 1)

The method of claim 1 wherein the clamped switching frequency state comprises a clamped switching frequency that is lower than a variable switching frequency of the variable switching frequency state.

### Claim 10 (depends on 1)

The method of claim 1 wherein the clamped switching frequency state is a discontinuous conduction mode and the variable switching frequency state is a critical conduction mode.

### Claim 11 (depends on 1)

The method of claim 1 wherein the switching time interval or the switching frequency of the switching power converter is measured using a monitor device.

### Claim 12

A controller for controlling a switching power converter having an input for receiving a periodic input signal and an output for providing a substantially constant output voltage to a load, the controller comprising:
a monitor device configured to compare a switching time interval or a switching frequency with a threshold value to obtain a comparison result; and
a parameter recorder configured to record an entry criteria in response to the comparison result, wherein:
the entry criteria indicates a transition of the switching power converter from a variable switching frequency state to a clamped switching frequency state;
the parameter recorder is further configured to define an exit criteria based on the entry criteria; and
the exit criteria is symmetric around a first phase angle value of the periodic input signal.

### Claim 13 (depends on 12)

The controller of claim 12, wherein the entry criteria is associated with at least one selected from the group of a time value, a voltage level, and an entry phase angle of the periodic input signal.

### Claim 14 (depends on 12)

The controller of claim 12, wherein the first phase angle value is at least one selected from the group of 0 radians, π/2 radians, π radians, and 3π/2 radians.

### Claim 15 (depends on 12)

The controller of claim 12, wherein the parameter recorder is configured to record the entry criteria after a predetermined number of comparison results indicate the switching time interval is less than the threshold value or after the predetermined number of comparison results indicate the switching frequency is greater than the threshold value.

### Claim 16 (depends on 12)

The controller of claim 12 wherein the entry criteria comprises an amplitude level of the periodic input signal, and the exit criteria comprises the amplitude level of the periodic input signal.

### Claim 17 (depends on 12)

The controller of claim 12, wherein the exit criteria comprises hysteresis to prevent the switching power converter from oscillating between the clamped switching frequency state and the variable switching frequency state.

### Claim 18 (depends on 12)

The controller of claim 12, wherein the exit criteria is defined based on time-value mirroring of the entry criteria with respect to a zero-crossing point of the periodic input signal or with respect to a peak voltage point of the periodic input signal.

### Claim 19 (depends on 12)

The controller of claim 12, wherein the entry criteria is based on a voltage level of the periodic input signal.

### Claim 20 (depends on 12)

The controller of claim 12 further comprising a zero-crossing detector configured to sample an amplitude of the output voltage of the switching power converter in a vicinity of a zero-crossing point of the periodic input signal to determine a load condition of the load, wherein the controller causes the switching power converter to transition from the clamped switching frequency state to the variable switching frequency state in response to the load condition.