# US 2018/0323713 A1 · Soft-switching for high-frequency power conversion

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- Number: US 2018/0323713 A1
- Document ID: US20180323713A1
- Status: Published application
- Kind: A1
- Application number: 15/932,746
- Filed: 2018-04-18
- Published: 2018-11-08
- Earliest claimed: 2017-04-18
- Assignees: EMD Technologies Inc.
- Applicants: EMD Technologies Incorporated
- Inventors: Robert Beland; Giampaolo Carli
- Web page: https://patentgrep.com/patent/US20180323713A1

## CPC

- H02M 3/1582: {Buck-boost converters (H02M3/1584 takes precedence)}
- H02M 1/34: Snubber circuits
- H02M 1/0051: {Diode reverse recovery losses}
- 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 1/342: {Active non-dissipative snubbers}
- H02M 3/005: {using Cuk converters}
- H02M 3/1552: {Boost converters exploiting the leakage inductance of a transformer or of an alternator as boost inductor}
- 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 power converter designed for operation at high frequencies includes a soft-switching cell comprising a split inductor, a resonant inductor, a resonant capacitor, two diodes and a controlled semiconductor. Alternatively, the power converter includes a soft-switching cell comprising a transformer having isolated windings, a resonant inductor, a resonant capacitor, two diodes and a controlled semiconductor.

## Claims

### Claim 1

A power converter designed for operation at high frequencies including a soft-switching cell comprising a split inductor, a resonant inductor, a resonant capacitor, two diodes and a controlled semiconductor.

### Claim 2 (depends on 1)

The power converter of claim 1, wherein the resonant inductor and the resonant capacitor form a resonant tank connected to an active circuit that is actuated just prior to the turn-on transition of the main switching device in order to event triggers a half-wavelength resonant voltage transition on the resonant capacitor that causes its voltage to transition from a non-zero value to virtually zero.

### Claim 3 (depends on 1)

The power converter of claim 1, wherein said two diodes include a first clamp diode is connected from ground to one terminal of the split inductor, and a second clamp diode is connected from another terminal of the split inductor to a known DC voltage bus.

### Claim 4 (depends on 3)

The power converter of claim 3, wherein said second clamp diode that is connected from a terminal of the split inductor to a known DC voltage bus is replaced by a zener diode in order to facilitate the demagnetization of said split inductor.

### Claim 5 (depends on 1)

The power converter of claim 1 including a lossless capacitive snubber connecting the controlled semiconductor to the resonant capacitor.

### Claim 6 (depends on 5)

The power converter of claim 5, wherein said lossless snubber includes a diode and a capacitor.

### Claim 7

A power converter designed for operation at high frequencies including a soft-switching cell comprising a transformer having isolated windings, a resonant inductor, a resonant capacitor, two diodes and a controlled semiconductor.

### Claim 8 (depends on 7)

The power converter of claim 7, wherein the resonant inductor and the resonant capacitor form a resonant tank connected to an active circuit that is actuated just prior to the turn-on transition of the main switching device in order to event triggers a half-wavelength resonant voltage transition on the resonant capacitor that causes its voltage to transition from a non-zero value to virtually zero.

### Claim 9 (depends on 7)

The power converter of claim 7, wherein said two diodes include a first clamp diode is connected from ground to one terminal of said transformer and a second clamp diode is connected from another terminal of said transformer to a known DC voltage bus.

### Claim 10 (depends on 9)

The power converter of claim 9, wherein said second clamp diode that is connected from a terminal of said transformer to a known DC voltage bus is replaced by a zener diode in order to facilitate the demagnetization of said transformer.

### Claim 11 (depends on 7)

The power converter of claim 7 including a lossless capacitive snubber connecting the controlled semiconductor to the resonant capacitor.

### Claim 12 (depends on 11)

The power converter of claim 11, wherein said lossless snubber includes a diode and a capacitor.

### Claim 13

A method for controlling operation of a power converter designed for operation at high frequencies includes:
providing a soft-switching cell comprising a transformer with isolated windings, a resonant inductor, a resonant capacitor, two diodes, and an Qaux controlled semiconductor; and
producing a first drive signal for the an Qaux controlled semiconductor and a second drive signal for the an Qmain controlled semiconductor.

### Claim 14 (depends on 13)

The method of claim 13 including terminating said first drive signal upon sensing a voltage transition at any of the windings of the transformer.

### Claim 15 (depends on 13)

The method of claim 13 including terminating said first drive signal after a time that is calculated or estimated using known circuit values and parameters.

### Claim 16 (depends on 13)

The method of claim 13 including initiating said second drive signal upon sensing a transition on the voltage of the resonant capacitor.

### Claim 17 (depends on 16)

The method of claim 16 including terminating said second drive signal by a PWM controller.

### Claim 18 (depends on 16)

The method of claim 16 including terminating said second drive signal by a peak-current mode controller.

### Claim 19 (depends on 13)

The method of claim 13 including initiating said second drive signal upon comparison of the voltage of the resonant capacitor to a set minimum threshold.

### Claim 20 (depends on 19)

The method of claim 19 including terminating said second drive signal by a PWM controller.

### Claim 21 (depends on 19)

The method of claim 19 including terminating said second drive signal by a peak-current mode controller.

### Claim 22 (depends on 11)

The method of claim 11 including initiating said second drive signal upon detection of a decrease of the rate of change of the voltage of the resonant capacitor.

### Claim 23 (depends on 22)

The method of claim 22 including terminating said second drive signal by a PWM controller.

### Claim 24 (depends on 22)

The method of claim 22 including terminating said second drive signal by a peak-current mode controller.

### Claim 25 (depends on 13)

The method of claim 13 including modulating the operational frequency in response to the feedback control loop error signal.