# US 11,310,883 B2 · Electrolytic capacitorless, selectively dimmable LED driver > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,310,883 B2 - Document ID: US11310883B2 - Status: Granted - Kind: B2 - Application number: 17/321,057 - Filed: 2021-05-14 - Published: 2021-09-02 - Granted: 2022-04-19 - Earliest claimed: 2019-05-20 - Assignees: The Research Foundation for The State University of New York - Applicants: The Research Foundation for The State University of New York - Inventors: Pritam Das - Web page: https://patentgrep.com/patent/US11310883B2 ## CPC - H02M 1/14: Arrangements for reducing ripples from DC input or output - H02M 1/083: {for the ignition at the zero crossing of the voltage or the current} - H02M 3/33569: {having several active switching elements (H02M3/3353 takes precedence)} - H02M 3/33571: {Half-bridge at primary side of an isolation transformer} - H02M 3/33576: {having at least one active switching element at the secondary side of an isolation transformer} - H05B 45/10: Controlling the intensity of the light - H05B 45/325: Pulse-width modulation [PWM] - H05B 45/355: Power factor correction [PFC]; Reactive power compensation - H05B 45/38: using boost topology - H05B 45/382: with galvanic isolation between input and output - H05B 45/385: using flyback topology - H02M 1/008: {Plural converter units for generating at two or more independent and non-parallel outputs, e.g. systems with plural point of load switching regulators} - H02M 1/4208: {Arrangements for improving power factor of AC input} - 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) - H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL ## Abstract An apparatus method for driving light emitting diodes (LEDs), comprising: receiving an alternating current input; producing a DC current having a voltage with an AC-DC boost power-factor correction stage, having a variable-frequency operation, and a set of switches controlled in dependence on the voltage to limit a peak LED current; and producing an LED drive current with a DC-DC power conversion stage having a set of switches to selectively pulse-width modulate the LEDs to control a brightness, wherein the set of switches in the AC-DC boost power-factor correction stage and the set of switches in the DC-DC power conversion stage are each controlled to switch at zero current. ## Claims ### Claim 1 An electronic driver circuit, comprising: an input configured to receive an alternating current input; an AC-DC boost stage, having a first set of switches, the AC-DC boost stage producing a load-dependent instantaneous ripple voltage; a DC-DC power conversion stage, having a second set of switches; a coupling device configured to transfer power from the AC-DC boost stage to the DC-DC power conversion stage; and a controller configured to control: the first set of switches in the AC-DC boost stage, to transfer power to the DC-DC power conversion stage, while limiting a peak current, and the second set of switches in the DC-DC power conversion stage, to selectively pulse-width modulate an average current, a pulse width modulation frequency of the DC-DC power conversion stage being dependent on the load and the instantaneous ripple voltage, wherein the first set of switches in the AC-DC boost stage and the second set of switches in the DC-DC power conversion stage are each controlled to switch at zero voltage; and an output configured to supply the pulse width modulated current. ### Claim 2 (depends on 1) The electronic driver circuit according to claim 1, wherein the pulse width modulated current is adapted to control a dimming of an LED light source. ### Claim 3 (depends on 1) The electronic driver circuit according to claim 1, wherein the coupling device comprises an AC coupling device which couples the AC-DC boost stage to the DC-DC power conversion stage by passing an alternating current through a capacitor. ### Claim 4 (depends on 1) The electronic driver circuit according to claim 1, wherein the coupling device comprises a non-electrolytic film capacitor. ### Claim 5 (depends on 1) The electronic driver circuit according to claim 1, wherein the limited peak current comprises a limited peak LED current of a set of LEDs powered by the pulse width modulated current. ### Claim 6 (depends on 1) The electronic driver circuit according to claim 1, wherein the DC-DC power conversion stage comprises a plurality of DC-DC power conversion substages sharing a common AC-DC boost stage, wherein each of the plurality of DC-DC power conversion substages is controlled to have an independent pulse width modulation. ### Claim 7 (depends on 1) The electronic driver circuit according to claim 1, wherein the DC-DC power conversion stage is non-resonant. ### Claim 8 (depends on 1) The electronic driver circuit according to claim 1, wherein the coupling device comprises a capacitor, and the DC-DC power conversion stage comprises a symmetric half-bridge non-resonant DC-DC converter, a high frequency transformer, and a symmetric voltage multiplier output rectifier with purely capacitive output through the capacitor. ### Claim 9 (depends on 1) The electronic driver circuit according to claim 1, wherein the DC-DC power conversion stage is substantially without an electrolytic capacitor passing a load current. ### Claim 10 (depends on 1) The electronic driver circuit according to claim 1, wherein the AC-DC boost stage has a frequency of operation which is varied in dependence on at least a DC bus voltage, and the DC-DC power conversion stage receives power from a DC bus at the DC bus voltage. ### Claim 11 (depends on 1) The electronic driver circuit according to claim 1, wherein the controller is further configured to implement a cycle-by-cycle peak current mode control, with time multiplexing, to control both the peak current and the average current. ### Claim 12 (depends on 1) The electronic driver circuit according to claim 1, wherein the controller is further configured to control the first switches of the AC-DC boost stage to correct a power factor. ### Claim 13 (depends on 1) The electronic driver circuit according to claim 1, the second set of switches in the DC-DC power conversion stage are controlled to short a transformer. ### Claim 14 A method for driving a load, comprising: receiving an alternating current input; producing a DC current having an average voltage and a load-dependent instantaneous ripple voltage with an AC-DC boost stage, having a frequency operation and a maximum load, and a first set of switches controlled in dependence on the average voltage to limit a peak load current; and producing a pulse width modulated output current to drive the load with a DC-DC power conversion stage coupled to the AC-DC boost stage through a coupling device, the DC-DC power conversion stage having a second set of switches to control a pulse-width modulation frequency of the pulse width modulated output current dependent on the pulse width modulated output current supplied to the load and the instantaneous ripple voltage, wherein the first set of switches in the AC-DC boost stage and the second set of switches in the DC-DC power conversion stage are each controlled to switch at zero voltage. ### Claim 15 (depends on 14) The method according to claim 14, wherein the load comprises a series of LEDs, which have a brightness controlled by the pulse width modulated output current. ### Claim 16 (depends on 14) The method according to claim 14, wherein the coupling device comprises a non-electrolytic capacitor. ### Claim 17 (depends on 14) The method according to claim 14, wherein the DC-DC power conversion stage comprises a plurality of DC-DC power conversion substages sharing a common AC-DC boost stage, wherein each DC-DC power conversion substage is controlled to have an independent pulse width modulation. ### Claim 18 (depends on 14) The method according to claim 14, wherein: the coupling device comprises a non-electrolytic capacitor, and an input AC power source supplies the output current operating substantially without an electrolytic capacitor passing a load current; the DC-DC power conversion stage comprises a symmetric half-bridge non-resonant DC-DC converter, a high frequency transformer, and a symmetric voltage multiplier output rectifier with purely capacitive output; the DC-DC power conversion stage receives power from the DC bus at a DC bus voltage; and the pulse width modulation frequency is varied in dependence on at least the DC bus voltage. ### Claim 19 (depends on 14) The method according to claim 14, wherein the controller is configured to implement cycle-by-cycle peak current mode control, with time multiplexing, to control both the peak and the average currents to the LED, and to correct a power factor. ### Claim 20 A driver circuit, comprising: an AC-DC boost stage, having a first set of switches; a DC-DC power conversion stage having a second set of switches; a controller configured to control the first set of switches to provide power to the DC-DC power conversion stage by non-resonant operation at a frequency above a resonant frequency, while limiting a peak output current of the DC-DC power conversion stage, and to control and the second set of switches to selectively pulse-width modulate the output current of the DC-DC power conversion stage at a pulse width modulation frequency by shorting a transformer current, wherein the first set of switches and the second set of switches are each controlled to switch at zero voltage, and the pulse width modulation frequency is different from the frequency above the resonant frequency of operation of the AC-DC boost stage.