# US RE48,368 E1 · Smart matching step-down circuits and travel-use power conversion devices > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US RE48,368 E1 - Document ID: USRE48368E1 - Status: Granted - Kind: E1 - Application number: 16/412,444 - Filed: 2019-05-15 - Granted: 2020-12-22 - Earliest claimed: 2014-09-30 - Assignees: Guangdong Bestek Medical Devices Co., Ltd. - Applicants: Guangdong BESTEK Medical Devices Co., Ltd. - Inventors: Xinhua Xu - Web page: https://patentgrep.com/patent/USRE48368E1 ## CPC - H02M 5/458: using semiconductor devices only - H02M 1/08: Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters - H02M 1/10: Arrangements incorporating converting means for enabling loads to be operated at will from different kinds of power supplies, e.g. from AC or DC - H02M 3/156: with automatic control of output voltage or current, e.g. switching regulators - H02M 1/32: Means for protecting converters other than automatic disconnection - 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) ## Abstract Provided is a smart matching step-down circuit, comprising an alternating current input terminal (10), a rectifier filter circuit (20), a switching circuit (30), a high voltage BUCK control step-down circuit (40), a floating zero potential control circuit (41), a voltage detection and feedback circuit (50), a PWM controller (52), a full-bridge DC/AC converter circuit (60), an alternating current output terminal (70), an output voltage detection circuit (62), and a conversion controller (80); the high voltage BUCK control step-down circuit comprises a step-down inductor (L1) and a step-down capacitor (C18); the first end of the step-down inductor is connected to the output terminal of the switching circuit; the second end of the step-down inductor is connected to the positive electrode of the step-down filter capacitor, and is used for stepping down and filtering the pulse voltage, then outputting a second current; the floating zero potential control circuit comprises a flyback diode (D11, D12); the cathode of the flyback diode is connected to the circuit ground, together with the first end of the step-down inductor; the anode of the flyback diode is connected to the floating ground (GND), together with the negative electrode of the step-down filter capacitor; the smart matching step-down circuit can step down a wide voltage, and is broadly adaptable. ## Claims ### Claim 1 A smart matching step-down circuit, comprising: an alternating current (AC) input terminal connects to an external power supply to input a first AC within a predetermined voltage range; a rectifier filter circuit connects to the AC input terminal for rectifying and filtering waveforms of the first AC to form a first direct current (DC); an input end of a switching circuit connects to the rectifier filter circuit, and in response to control signals, the switching circuit is turned on or off to output a pulse voltage; a high voltage BUCK control step-down circuit comprises a voltage step-down inductor, and a voltage step-down filter capacitor, wherein a first end of the voltage step-down inductor connects to an output end of the switching circuit, and a second end of the voltage step-down inductor connects to a positive pole of the voltage step-down filter capacitor for performing a voltage step-down process and a filtering process toward the pulse voltage so as to output a second DC; a floating zero potential control circuit comprises fly-back diodes, a cathode of the fly-back diodes and the first end of the voltage step-down inductor cooperatively connect to a floating ground; a voltage detection and feedback circuit comprises an input end connecting to the second end of the voltage step-down inductor to detect the second DC so as to generate a feedback message; a PWM controller comprises a feedback end connecting to an output end of the voltage detection and feedback circuit, and a control end connecting to a controlled end of the switching circuit, in response to the feedback message, the PWM controller is configured to output control signals controlling a pulse width of the pulse voltage; a full-bridge DC/AC converter circuit comprises an input end connecting to a positive pole of the voltage step-down filter capacitor to convert the second DC to the second AC; an AC output end connects to the output end of the full-bridge DC/AC converter circuit to output the second AC; an output voltage detection circuit connects to the AC output end to sample voltages of the second AC from the AC output end so as to generate a first sampling voltage; and a conversion controller connecting to the output voltage detection circuit and the full-bridge DC/AC converter circuit, the conversion controller is configured to controlling a duty cycle ratio of outputted waveform of the full-bridge DC/AC converter circuit in accordance with the first sampling voltage so as to stabilize the second AC. ### Claim 2 (depends on 1) The smart matching step-down circuit as claimed in claim 1, wherein the smart matching step-down circuit further comprises an output current detection circuit connecting to current detection ends of the AC output terminal and the conversion controller, and the output current detection circuit is configured to sample current of the second AC from the AC output terminal to generate a sampling current; the conversion controller controls the duty cycle ratio of the outputted waveforms of the full-bridge DC/AC converter circuit in accordance with the first sampling voltage and the sampling current to stabilize the second AC. ### Claim 3 (depends on 1) The smart matching step-down circuit as claimed in claim 1, wherein the switching circuit comprises a MOS transistor and a switch driving circuit, a drain of the MOS transistor is the input end of the switching circuit, a gate of the MOS transistor is a controlled end of the switching circuit, and a source of the MOS transistor is the output end of the switching circuit. ### Claim 4 (depends on 1) The small matching step-down circuit as claimed in claim 1, wherein the voltage detection and feedback circuit comprises an optoelectronic coupler, a reference stabilized source, and a voltage sampling circuit, a positive end of at least one light emitting diode (LED) of the optoelectronic coupler connects to a second end of the voltage step-down inductor via a power supply circuit, and a negative end of the LED of the optoelectronic coupler connects to a cathode of the reference stabilized source, an anode of the reference stabilized source is grounded, and a reference pole of the reference stabilized source connects to the second end of the voltage step-down inductor via the voltage sampling circuit, and a photo-triode of the optoelectronic coupler connects to the feedback end of the PWM controller. ### Claim 5 (depends on 1) The smart matching step-down circuit as claimed in claim 1, wherein the full-bridge DC/AC converter circuit comprises an inverter-bridge having a first MOS transistor, a second MOS transistor, a third MOS transistor, and a fourth MOS transistor, gates of the first MOS transistor, the second MOS transistor, the third MOS transistor, and the fourth MOS transistor respectively connects to one MOS driving circuit, and the MOS driving circuit connects to the corresponding PWM control end of the conversion controller; a source of the second MOS transistor is a fire-wire end of the AC output terminal, and a source of the fourth MOS transistor is a zero-line end of the AC output terminal. ### Claim 6 (depends on 5) The smart matching step-down circuit as claimed in claim 5, wherein the output current detection circuit comprises a thirty-third resistor, a thirty-fourth resistor, and a thirty-fifth resistor, ends of the thirty-third resistor, the thirty-fourth resistor, and the thirty-fifth resistor connect to a source of the fourth MOS transistor and the voltage detection end of the conversion controller, and the other ends of the thirty-third resistor, the thirty-fourth resistor, and the thirty-fifth resistor connect to the floating ground. ### Claim 7 (depends on 5) The smart matching step-down circuit as claimed in claim 5, wherein the output voltage detection circuit comprises a rectifying bridge, an AC L pin connects to the source of the first MOS transistor and a L pin of the conversion controller, an AC N pin connects to the source of the fourth MOS transistor and the N pin of the conversion controller, a DC positive pole pin of the rectifying bridge connects to the floating ground via a twenty-first capacitor, an DC positive pole pin further connects to a VB pin of the conversion controller, and the DC negative pole pin connects to the floating ground. ### Claim 8 (depends on 1) The smart matching step-down circuit as claimed in claim 1, wherein the smart matching step-down circuit further comprises an over-current detection circuit, the over-current detection circuit comprises a twenty-ninth resistor and a twenty-second resistor, one end of the twenty-ninth resistor connects to the output end of the switching circuit, and the other end of the twenty-ninth resistor is grounded, one end of the twenty-second resistor connects to the output end of the switching circuit, and the other end of the twenty-second resistor connects to a current detection end of the PWM controller. ### Claim 9 A travel-use power conversion device comprises a smart matching step-down circuit, the smart matching step-down circuit comprising: an alternating current (AC) input terminal connects to an external power supply to input a first AC within a predetermined voltage range; a rectifier filter circuit connects to the AC input terminal for rectifying and filtering waveforms of the first AC to form a first direct current (DC); an input end of a switching circuit connects to the rectifier filter circuit, and M response to control signals, the switching circuit is turned on or off to output a pulse voltage; a high voltage BUCK control step-down circuit comprises a voltage step-down inductor, and a voltage step-down filter capacitor, wherein a first end of the voltage step-down inductor connects to an output end of the switching circuit, and a second end of the voltage step-down inductor connects to a positive pole of the voltage step-down filter capacitor for performing a voltage step-down process and a filtering process toward the pulse voltage so as to output a second DC; a floating zero potential control circuit comprises fly-back diodes, a cathode of the fly-back diodes and the first end of the voltage step-down inductor cooperatively connect to a floating ground; a voltage detection and feedback circuit comprises an input end connecting to the second end of the voltage step-down inductor to detect the second DC so as to generate a feedback message; a PWM controller comprises a feedback end connecting to an output end of the voltage detection and feedback circuit, and a control end connecting to a controlled end of the switching circuit, in response to the feedback message, the PWM controller is configured to output control signals controlling a pulse width of the pulse voltage; a full-bridge DC/AC converter circuit comprises an input end connecting to a positive pole of the voltage step-down filter capacitor to convert the second DC to the second AC; an AC output end connects to the output end of the full-bridge DC/AC converter circuit to output the second AC; an output voltage detection circuit connects to the AC output end to sample voltages of the second AC from the AC output end so as to generate a first sampling voltage; and a conversion controller connecting to the output voltage detection circuit and the full-bridge DC/AC converter circuit, the conversion controller is configured to controlling a duty cycle ratio of outputted waveform of the full-bridge DC/AC converter circuit in accordance with the first sampling voltage so as to stabilize the second AC. ### Claim 10 (depends on 9) The travel-use power conversion device as claimed in claim 9, wherein the smart matching step-down circuit further comprises an output current detection circuit connecting to current detection ends of the AC output terminal and the conversion controller, and the output current detection circuit is configured to sample current of the second AC from the AC output terminal to generate a sampling current; the conversion controller controls the duty cycle ratio of the outputted waveforms of the full-bridge DC/AC converter circuit in accordance with the first sampling voltage and the sampling current to stabilize the second AC. ### Claim 11 (depends on 9) The travel-use power conversion device as claimed in claim 9, wherein the switching circuit comprises a MOS transistor and a switch driving circuit, a drain of the MOS transistor is the input end of the switching circuit, a gate of the MOS transistor is a controlled end of the switching circuit, and a source of the MOS transistor is the output end of the switching circuit. ### Claim 12 (depends on 9) The travel-use power conversion device as claimed in claim 9, wherein the voltage detection and feedback circuit comprises an optoelectronic coupler, a reference stabilized source, and a voltage sampling circuit, a positive end of at least one light emitting diode (LED) of the optoelectronic coupler connects to a second end of the voltage step-down inductor via a power supply circuit, and a negative end of the LED of the optoelectronic coupler connects to a cathode of the reference stabilized source, an anode of the reference stabilized source is grounded, and a reference pole of the reference stabilized source connects to the second end of the voltage step-down inductor via the voltage sampling circuit, and a photo-triode of the optoelectronic coupler connects to the feedback end of the PWM controller. ### Claim 13 (depends on 9) The travel-use power conversion device as claimed in claim 9, wherein the full-bridge DC/AC converter circuit comprises an inverter-bridge having a first MOS transistor, a second MOS transistor, a third MOS transistor, and a fourth MOS transistor, gates of the first MOS transistor, the second MOS transistor, the third MOS transistor, and the fourth MOS transistor respectively connects to one MOS driving circuit, and the MOS driving circuit connects to the corresponding PWM control end of the conversion controller; a source of the second MOS transistor is a fire-wire end of the AC output terminal, and a source of the fourth MOS transistor is a zero-line end of the AC output terminal. ### Claim 14 (depends on 13) The travel-use power conversion device as claimed in claim 13, wherein the output current detection circuit comprises a thirty-third resistor, a thirty-fourth resistor, and a thirty-fifth resistor, ends of the thirty-third resistor, the thirty-fourth resistor, and the thirty-fifth resistor connect to a source of the fourth MOS transistor and the voltage detection end of the conversion controller, and the other ends of the thirty-third resistor, the thirty-fourth resistor, and the thirty-fifth resistor connect to the floating ground. ### Claim 15 (depends on 13) The travel-use power conversion device as claimed in claim 13, wherein the output voltage detection circuit comprises a rectifying bridge, an AC L pin connects to the source of the first MOS transistor and a L pin of the conversion controller, an AC N pin connects to the source of the fourth MOS transistor and the N pin of the conversion controller, a DC positive pole pin of the rectifying bridge connects to the floating ground via a twenty-first capacitor, an DC positive pole pin further connects to a VB pin of the conversion controller, and the DC negative pole pin connects to the floating ground. ### Claim 16 (depends on 9) The travel-use power conversion device as claimed in claim 9, wherein the smart matching step-down circuit further comprises an over-current detection circuit, the over-current detection circuit comprises a twenty-ninth resistor and a twenty-second resistor, one end of the twenty-ninth resistor connects to the output end of the switching circuit, and the other end of the twenty-ninth resistor is grounded, one end of the twenty-second resistor connects to the output end of the switching circuit, and the other end of the twenty-second resistor connects to a current detection end of the PWM controller. ### Claim 17 A smart matching step-down circuit, comprising: an alternating current (AC) input terminal connects to an external power supply to input a first AC within a predetermined voltage range; a rectifier filter circuit connects to the AC input terminal for rectifying and filtering waveforms of the first AC to form a first direct current (DC); a high voltage BUCK control step-down circuit connected to the rectifier filter circuit for performing a voltage step-down process and a filtering process toward the first DC so as to output a second DC; a full-bridge DC/AC converter circuit connected to the high voltage BUCK control step-down circuit to convert the second DC to a second AC; an AC output end connected to the full-bridge DC/AC converter circuit to output the second AC; and a switching circuit having an input end connecting to the rectifier filter circuit, and in response to control signals so that the switching circuit is turned on or off to output a pulse voltage. ### Claim 18 (depends on 17) The smart matching step-down circuit as claimed in claim 17, wherein the high voltage BUCK control step-down circuit comprises a voltage step-down inductor, and a voltage step-down filter capacitor, wherein a first end of the voltage step-down inductor connects to an output end of the switching circuit, and a second end of the voltage step-down inductor connects to a positive pole of the voltage step-down filter capacitor for performing a voltage step-down process and a filtering process toward the pulse voltage so as to output the second DC. ### Claim 19 (depends on 18) The smart matching step-down circuit as claimed in claim 18, wherein the smart matching step-down circuit further comprises a voltage detection and feedback circuit comprising an input end connecting to the second end of the voltage step-down inductor to detect the second DC so as to generate a feedback message. ### Claim 20 (depends on 19) The smart matching step-down circuit as claimed in claim 19, wherein the smart matching step-down circuit further comprises a PWM controller comprising a feedback end connecting to an output end of the voltage detection and feedback circuit, and a control end connecting to a controlled end of the switching circuit, in response to the feedback message, the PWM controller is configured to output control signals controlling a pulse width of the pulse voltage. ### Claim 21 (depends on 20) The smart matching step-down circuit as claimed in claim 20, wherein the smart matching step-down circuit further comprises an over-current detection circuit comprising a twenty-ninth resistor and a twenty-second resistor, one end of the twenty-ninth resistor connects to the output end of the switching circuit, and the other end of the twenty-ninth resistor is grounded, one end of the twenty-second resistor connects to the output end of the switching circuit, and the other end of the twenty-second resistor connects to a current detection end of the PWM controller. ### Claim 22 (depends on 17) The smart matching step-down circuit as claimed in claim 17, wherein the smart matching step-down circuit further comprises a floating zero potential control circuit connected to the high voltage BUCK control step-down circuit and configured to control the second DC in a floating manner. ### Claim 23 (depends on 22) The smart matching step-down circuit as claimed in claim 22, wherein the floating zero potential control circuit comprises fly-back diodes, a cathode of the fly-back diodes and the first end of the voltage step-down inductor cooperatively connect to a circuit ground, an anode of the fly-back diodes and a negative pole of the voltage step-down filter capacitor cooperatively connect to a floating ground. ### Claim 24 (depends on 17) The smart matching step-down circuit as claimed in claim 17, wherein the smart matching step-down circuit further comprises a voltage control circuit connected to the full-bridge DC/AC converter circuit and configured to control the full-bridge DC/AC converter circuit so as to stably output the second AC. ### Claim 25 (depends on 24) The smart matching step-down circuit as claimed in claim 24, wherein the voltage control circuit comprises an output voltage detection circuit connected to the AC output end to sample voltages of the second AC from the AC output end so as to generate a first sampling voltage. ### Claim 26 (depends on 25) The smart matching step-down circuit as claimed in claim 25, wherein the voltage control circuit further comprises a conversion controller connecting to the output voltage detection circuit and the full-bridge DC/AC converter circuit, the conversion controller is configured to controlling a duty cycle ratio of outputted waveform of the full-bridge DC/AC converter circuit in accordance with the first sampling voltage so as to stabilize the second AC. ### Claim 27 (depends on 26) The smart matching step-down circuit as claimed in claim 26, wherein the full-bridge DC/AC converter circuit comprises an inverter-bridge having a first MOS transistor, a second MOS transistor, a third MOS transistor, and a fourth MOS transistor, gates of the first MOS transistor, the second MOS transistor, the third MOS transistor, and the fourth MOS transistor respectively connects to one MOS driving circuit, and the MOS driving circuit connects to the corresponding PWM control end of the conversion controller; a source of the second MOS transistor is a fire-wire end of the AC output terminal, and a source of the fourth MOS transistor is a zero-line end of the AC output terminal. ### Claim 28 (depends on 27) The smart matching step-down circuit as claimed in claim 27, wherein the smart matching step-down circuit further comprises an output current detection circuit comprising a thirty-third resistor, a thirty-fourth resistor, and a thirty-fifth resistor, ends of the thirty-third resistor, the thirty-fourth resistor, and the thirty-fifth resistor connect to a source of the fourth MOS transistor and the voltage detection end of the conversion controller, and the other ends of the thirty-third resistor, the thirty-fourth resistor, and the thirty-fifth resistor connect to a floating ground. ### Claim 29 (depends on 27) The smart matching step-down circuit as claimed in claim 27, wherein the output voltage detection circuit comprises a rectifying bridge, an AC L pin connects to the source of the first MOS transistor and an L pin of the conversion controller, an AC N pin connects to the source of the fourth MOS transistor and the N pin of the conversion controller, a DC positive pole pin of the rectifying bridge connects to a floating ground via a twenty-first capacitor, an DC positive pole pin further connects to a VB pin of the conversion controller, and the DC negative pole pin connects to the floating ground. ### Claim 30 (depends on 17) The smart matching step-down circuit as claimed in claim 17, wherein the switching circuit comprises a MOS transistor and a switch driving circuit, a drain of the MOS transistor is the input end of the switching circuit, a gate of the MOS transistor is the controlled end of the switching circuit, and a source of the MOS transistor is the output end of the switching circuit. ### Claim 31 (depends on 19) The smart matching step-down circuit as claimed in claim 19, wherein the voltage detection and feedback circuit comprises an optoelectronic coupler, a reference stabilized source, and a voltage sampling circuit, a positive end of an LED of the optoelectronic coupler connects to the second end of the voltage step-down inductor within the high voltage BUCK control step-down circuit via a power supply circuit, and a negative end of the LED of the optoelectronic coupler connects to a cathode of the reference stabilized source, an anode of the reference stabilized source is grounded, and a reference pole of the reference stabilized source connects to the second end of the voltage step-down inductor within the high voltage BUCK control step-down circuit via the voltage sampling circuit, and a photo-triode of the optoelectronic coupler connects to a feedback end of the PWM controller.