# US 6,297,976 B1 · Thin, cascade-connected direct current source circuit > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,297,976 B1 - Document ID: US6297976B1 - Status: Granted - Kind: B1 - Application number: 09/557,181 - Filed: 2000-04-21 - Granted: 2001-10-02 - Earliest claimed: 1999-04-23 - Assignees: LG Electronics Inc. - Inventors: Katsuo Isono - Web page: https://patentgrep.com/patent/US6297976B1 ## CPC - H02M 3/33553: {with galvanic isolation between input and output of both the power stage and the feedback loop} - 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 1/008: {Plural converter units for generating at two or more independent and non-parallel outputs, e.g. systems with plural point of load switching regulators} - 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 The present invention relates to a power supply having a plurality of converters which is capable of easily setting a load share of each converter and simplifying the construction of the circuit, thereby reducing the cost. A DC source circuit having such a power supply includes a plurality of converters (each having a transformer, switches for interrupting a DC input and supplying the same to a first side of the transformer and a rectifier circuit for rectifying a voltage outputted from a second side of the transformer), an output circuit which cascade-connects each output voltage of the plurality of converters and thereby obtains a composite output voltage Vout, and a common control circuit for feedback-controlling the plurality of switches as a function of the composite output voltage, e.g., according to the difference between the composite output voltage and the reference voltage. A load of each converter is shared according to each set output voltage. In addition, the cost of the power supply can be reduced by commonly using the control circuit. ## Claims ### Claim 1 A direct current source circuit, comprising: a plurality of converters each having a transformer, switches for interrupting a DC input and supplying the same to a first side of the transformer and a rectifier circuit for rectifying an AC voltage outputted from a second side of the transformer; an output circuit which cascade-connects each output voltage of the plurality of converters and thereby obtains a composite output voltage; and a common feedback control circuit for controlling the plurality of switches as a function of the composite output voltage. ### Claim 2 (depends on 1) The circuit according to claim 1, wherein the plurality of converters comprise at least one or more than one of a current resonance converter, a forward converter, a RCC converter and a flyback converter. ### Claim 3 (depends on 1) The circuit according to claim 1, wherein the control circuit makes transistors turn on/off at a lower frequency when the output voltage of the power supply is decreased, and said circuit makes the transistors turn on/off at a higher frequency when the output voltage of the power supply is increased. ### Claim 4 (depends on 1) The circuit according to claim 1, wherein the output voltage of the power supply is divided and detected by a plurality of resistors to thereby be inputted to an output voltage comparater. ### Claim 5 (depends on 1) The circuit of claim 1, wherein the first side of each transformer has a first connection point and a second connection point, and wherein the first connection points are connected in parallel and the second connection points are connected in parallel. ### Claim 6 (depends on 5) The circuit of claim 5, wherein an inductor is connected between each first connection point and a first end of a first winding in each transformer. ### Claim 7 (depends on 5) The circuit of claim 5, wherein a condenser is connected between each second connection point and a second end of a first winding in each transformer. ### Claim 8 (depends on 7) The circuit of claim 7, wherein the second end of each transformer is connected together in parallel. ### Claim 9 (depends on 5) The circuit of claim 5, wherein a second side of each transformer is also connected together in parallel. ### Claim 10 (depends on 5) The circuit of claim 5, wherein for each transformer, the first connection point is connected to the second connection point by a smoothing condenser. ### Claim 11 (depends on 1) The direct current source circuit of claim 1 wherein the common control circuit further switches the plurality of switches at a frequency corresponding to a difference between the composite output voltage and a reference voltage.