# US 8,569,963 B2 · Cascade boost and inverting buck converter with independent control > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,569,963 B2 - Document ID: US8569963B2 - Status: Granted - Kind: B2 - Application number: 13/291,377 - Filed: 2011-11-08 - Published: 2012-12-20 - Granted: 2013-10-29 - Earliest claimed: 2011-06-17 - Assignees: Intersil Americas Inc. - Applicants: Michael M. Walters - Inventors: Michael M. Walters - Web page: https://patentgrep.com/patent/US8569963B2 ## CPC - H02M 3/1582: {Buck-boost converters (H02M3/1584 takes precedence)} - H05B 45/327: Burst dimming - H05B 45/355: Power factor correction [PFC]; Reactive power compensation - H05B 45/375: using buck topology - H05B 45/38: using boost topology - H02M 1/007: {Plural converter units in cascade (push-pull DC/DC converters with pre-regulator H02M3/3374; DC-AC converters following a DC-DC stage including a high frequency transformer H02M7/4807; DC-AC converters following a DC-DC conversion stage generating periodically varying voltages H02M7/4826)} - H05B 45/3725: Switched mode power supply [SMPS] - H05B 45/385: using flyback topology - Y02B 20/30: Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED] - 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 - Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS ## Abstract A converter system including a cascade boost converter and inverting buck converter and controller for converting a rectified AC voltage to a DC output current. The system uses inductors and is configured to use a common reference voltage. The controller is configured to control switching of the converters in an independent manner to decouple operation from each other. For example, control pulses for the boost converter may be wider than pulses for the buck converter. The controller may control the boost converter based on constant on-time control and may control the inverting buck converter based on peak current control. The rectified AC voltage may be an AC conductive angle modulated voltage, where the controller may inhibit switching of the inverted buck converter at a dimming frequency having a duty cycle based on a phase angle of the AC conductive angle modulated voltage. ## Claims ### Claim 1 A converter system, comprising: a cascade boost converter and inverting buck converter for converting a rectified AC voltage to a DC output current; a controller having input and output control signals referenced to a common voltage, wherein said controller is configured to control switching of said boost converter and switching of said inverting buck converter in an independent manner to decouple operation of said inverting buck converter from operation of said boost converter; and wherein said controller is configured to control said boost converter with a plurality of boost pulses on a boost pulse signal referenced to said common voltage, wherein said controller is configured to control said inverting buck converter with a plurality of buck pulses on a buck pulse signal referenced to said common voltage, and wherein each of said plurality of boost pulses is wider than a corresponding one of said plurality of buck pulses. ### Claim 2 (depends on 1) The converter system of claim 1, wherein said boost converter comprises a first switch, wherein said inverting buck converter comprises a second switch, and wherein said controller is configured to initiate each of said plurality of boost pulses by turning on either one of said first and second switches. ### Claim 3 (depends on 1) The converter system of claim 1, wherein said controller is configured to control said boost converter based on constant on-time control and to control said inverting buck converter based on peak current control. ### Claim 4 (depends on 1) The converter system of claim 1, wherein: said controller is configured to control said boost converter based on constant on-time control using a fixed time period; wherein said boost converter has an output coupled to a capacitor which is coupled to an input of said inverting buck converter; wherein said controller comprises a voltage sensor configured to determine voltage across said capacitor and to provide a sense signal indicative thereof referenced to said common voltage; and wherein said controller periodically adjusts said fixed time period based on said sense signal. ### Claim 5 (depends on 1) The converter system of claim 1, wherein: said rectified AC voltage comprises an AC conductive angle modulated voltage; and wherein said controller inhibits switching of said inverting buck converter during a portion of each cycle of a dimming frequency, wherein said portion is based on a phase angle of said AC conductive angle modulated voltage. ### Claim 6 (depends on 1) The converter system of claim 1, wherein: said boost converter comprises: a first inductor having a first end receiving said rectified AC voltage and having a second end; a first switch having a first current terminal coupled to said second end of said inductor, having a second current terminal coupled to said common voltage, and having a control terminal receiving a first control signal referenced to said common voltage from said controller; a first diode having an anode coupled to said second end of said inductor and having a cathode; and a first capacitor having a first end coupled to said cathode of said first diode and having a second end; and wherein said inverting buck converter comprises: a second switch having a first current terminal coupled to said cathode of said first diode, having a second current terminal coupled to said common voltage, and having a control terminal receiving a second control signal referenced to said common voltage from said controller; a second diode having an anode coupled to said second end of said first capacitor and having a cathode coupled to said common voltage; a second inductor having a first end coupled to said second end of said first capacitor and having a second end coupled to an output node; and a second capacitor coupled between said output node and said common voltage. ### Claim 7 (depends on 6) The converter system of claim 6, wherein said controller comprises: a constant on-time generator which asserts said first control signal to turn on said first switch upon initiation of each cycle of a clock signal and to turn off said first switch after a predetermined time period during said each cycle of said clock signal; a current sensor which senses current through said second inductor; and a peak current controller which asserts said second control signal to turn on said second switch upon said initiation of each cycle of said clock signal and to turn off said second switch during said each cycle of said clock signal when said current through said second inductor reaches a peak value. ### Claim 8 (depends on 7) The converter system of claim 7, wherein said rectified AC voltage comprises an AC conductive angle modulated voltage, and wherein said controller further comprises: a phase angle sensor which senses a phase angle of said AC conductive angle modulated voltage and provides a phase signal indicative thereof; a dimming controller which generates an inhibit signal which toggles between first and second levels at a dimming frequency and with a duty cycle based on said phase signal; and wherein said peak current controller inhibits switching of said second switch while said inhibit signal is at said first level. ### Claim 9 (depends on 1) The converter system of claim 1, further comprising a DC load coupled to an output of said inverting buck converter and receiving said DC output current. ### Claim 10 (depends on 9) The converter system of claim 9, wherein said DC load comprises a least one light emitting diode. ### Claim 11 A controller for controlling a cascade boost converter and an inverting buck converter for converting a rectified AC voltage to a DC output current, comprising: a boost controller configured to provide at least one first control signal referenced to a common voltage for controlling switching of the boost converter; a buck controller configured to provide at least one second control signal referenced to the common voltage for controlling switching of the inverting buck converter in an independent manner to decouple operation of the inverting buck converter from operation of the boost converter; and wherein said boost controller is configured to generate a plurality of boost pulses on said first control signal; wherein said buck controller is configured to generate a corresponding plurality of buck pulses on said second control signal; and wherein each of said plurality of boost pulses is wider than a corresponding one of said plurality of buck pulses. ### Claim 12 (depends on 11) The controller of claim 11, wherein the boost converter includes a first switch and the inverting buck converter includes a second switch, said controller further comprising: a constant on-time generator for turning on the first switch upon initiation of each cycle of a clock signal and for turning off the first switch after a predetermined time period during said each cycle of said clock signal; a current sense input for sensing current through the buck converter and for providing a current sense signal indicative thereof referenced to the common voltage; and a peak current controller for turning on the second switch upon initiation of each cycle of said clock signal and for turning off the second switch when said current sense signal indicates a peak current level. ### Claim 13 (depends on 12) The controller of claim 12, wherein a capacitor is coupled between the boost converter and the inverting buck converter, wherein said controller further comprises: a voltage sense input referenced to the common voltage for sensing voltage across the capacitor and for providing a voltage sense signal indicative thereof; and wherein said constant on-time generator is configured to adjust said predetermined time period based on said voltage sense signal. ### Claim 14 (depends on 11) The controller of claim 11, wherein the rectified AC voltage comprises an AC conductive angle modulated voltage, wherein said controller further comprises: a phase angle sensor which senses a phase angle of the AC conductive angle modulated voltage and provides a phase signal indicative thereof; a dimming controller which generates an inhibit signal which toggles between first and second levels at a dimming frequency and with a duty cycle based on said phase signal; and wherein said buck controller is configured to inhibit switching of the inverting buck converter while said inhibit signal is at said first level. ### Claim 15 A method of controlling a cascade boost converter and inverting buck converter for converting a rectified AC voltage to a DC output current, comprising: generating a plurality of boost pulses on a boost pulse signal referenced to a common voltage for controlling switching of the boost converter; generating a plurality of buck pulses on a buck pulse signal referenced to the common voltage for controlling switching of the inverting buck converter in an independent manner to decouple operation of the inverting buck converter from operation of the boost converter; and wherein said generating a plurality of boost pulses and said generating a plurality of buck pulses comprises generating each boost pulse to be wider than a corresponding buck pulse. ### Claim 16 (depends on 15) The method of claim 15, wherein the boost converter comprises a first switch and wherein the inverting buck converter comprises a second switch, and wherein said generating a plurality of boost pulses comprises turning on either one of the first and second switches. ### Claim 17 (depends on 15) The method of claim 15, wherein the boost converter comprises a first switch and wherein the inverting buck converter comprises a second switch, said method further comprising: turning the first and second switches on upon initiation of each cycle of a clock signal; monitoring current through the inverting buck converter; turning off the second switch when the current through the inverting buck converter reaches a peak level; and turning off the first switch after a constant time period during each cycle of the clock signal. ### Claim 18 (depends on 17) The method of claim 17, further comprising: providing a capacitor between the boost converter and inverting buck converter; monitoring voltage across the capacitor and providing a sense signal; and periodically adjusting the constant time period based on the sense signal. ### Claim 19 (depends on 15) The method of claim 15, wherein the rectified AC voltage comprises an AC conductive angle modulated voltage, further comprising: sensing a phase angle of the AC conductive angle modulated voltage and providing a phase signal indicative thereof; generating an inhibit signal which toggles between first and second levels at a dimming frequency and with a duty cycle based on the phase signal; and inhibiting switching of the inverting buck converter while the inhibit signal is at the second level.