# US 2014/0153292 A1 · Primary side sense output current regulation > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0153292 A1 - Document ID: US20140153292A1 - Status: Published application - Kind: A1 - Application number: 13/706,305 - Filed: 2012-12-05 - Published: 2014-06-05 - Earliest claimed: 2012-12-05 - Assignees: iWatt Inc. - Applicants: Iwatt Inc. - Inventors: Liang Yan; John William Kesterson; Xiaoyan Wang; Guang Feng; Clarita Poon - Web page: https://patentgrep.com/patent/US20140153292A1 ## CPC - H02M 3/33507: {with automatic control of the output voltage or current, e.g. flyback converters (H02M3/33561, H02M3/33569 take precedence)} - H02M 3/33523: {with galvanic isolation between input and output of both the power stage and the feedback loop} - H02M 1/0009: {Devices or circuits for detecting current in a converter} - 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 The embodiments disclosed herein describe a method of a controller to maintain a substantially constant average output current at the output of a switching power converter. In one embodiment, the controller uses a regulation voltage that corresponds to the primary peak current regulation level to regulate the average output current. ## Claims ### Claim 1 A switching power converter comprising: a transformer including a primary winding coupled to an input voltage and a secondary winding coupled to an output of the switching power converter; a switch coupled to the primary winding of the transformer, current through the primary winding being generated while the switch is turned on and not being generated while the switch is turned off; and a controller configured to generate a control signal to turn on or turn off the switch at each switching cycle of the switch to maintain a substantially constant average output current at the output of the switching power converter; wherein the controller is configured to generate the control signal by estimating an average output current for each switching cycle of the switch based on a reset time of the transformer calculated from a sensed output voltage from a previous switching cycle and a regulation voltage corresponding to a peak of the current through the primary winding in the previous switching cycle. ### Claim 2 (depends on 1) The switching power converter of claim 1, wherein the controller is further configured to estimate the average output current for each switching cycle of the switch. ### Claim 3 (depends on 1) The switching power converter of claim 1, wherein the controller is further configured to generate the regulation voltage based on a comparison between the average output current and a reference output current. ### Claim 4 (depends on 3) The switching power converter of claim 3, wherein the controller is further configured to generate the regulation voltage by modifying a previously calculated regulation voltage from a prior switching cycle. ### Claim 5 (depends on 1) The switching power converter of claim 1, wherein the controller is further configured to generate the control signal based on a comparison between a sensed peak primary side voltage signal corresponding to the peak current through the primary winding and the regulation voltage. ### Claim 6 (depends on 1) The switching power converter of claim 1, wherein the controller is configured to estimate the average output current by removing high frequency noise from a calculated estimated output current. ### Claim 7 (depends on 1) The switching power converter of claim 1, wherein the controller is further configured to calculate the reset time of the transformer based on the sensed output voltage. ### Claim 8 In a controller, a method of controlling a switching power converter, the switching power converter including a transformer coupled between an input voltage and an output of the switching power converter, the transformer including a primary winding coupled to the input voltage and a secondary winding coupled to the output of the switching power converter, and a switch coupled to the primary winding of the transformer, current through the primary winding being generated while the switch is turned on and not being generated while the switch is turned off, the method comprising: estimating an average output current for each switching cycle of the switch based on a reset time of the transformer from a previous switching cycle calculated from a sensed output voltage and a regulation voltage corresponding to a peak of the current through the primary winding in the previous switching cycle; and generating a control signal to turn on or turn off the switch at each switching cycle of the switch to maintain a substantially constant average output current at the output of the switching power converter based on the estimated average output current. ### Claim 9 (depends on 8) The method of claim 8, wherein the average output current is further estimated for each switching cycle of the switch based on a period of the previous switching cycle, a number of windings of the transformer, and a resistance of a sense resistor coupled to the switch and ground. ### Claim 10 (depends on 8) The method of claim 8, further comprising: comparing the average output current and a reference output current; and generating the regulation voltage based on the comparison. ### Claim 11 (depends on 10) The method of claim 10, wherein generating the regulation voltage comprises: modifying a previously calculated regulation voltage from a prior switching cycle to generate the regulation voltage. ### Claim 12 (depends on 8) The method of claim 8, further comprising: comparing a sensed primary side voltage signal corresponding to the peak current through the primary winding and the regulation voltage; and generating the control signal based on the comparison. ### Claim 13 (depends on 8) The method of claim 8, wherein estimating the average output current comprises: calculating an estimated output current; and removing high frequency noise from the estimated output current to generate the average output current. ### Claim 14 (depends on 8) The method of claim 8, further comprising: calculating the reset time of the transformer based on the sensed output voltage.