# US 11,305,047 B2 · Systems and methods for driving negative pressure sources in negative pressure therapy systems > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,305,047 B2 - Document ID: US11305047B2 - Status: Granted - Kind: B2 - Application number: 16/098,604 - Filed: 2017-05-03 - Published: 2019-05-02 - Granted: 2022-04-19 - Earliest claimed: 2016-05-03 - Assignees: Smith & Nephew, Inc. - Applicants: Smith & Nephew PLC - Inventors: Ben Alan Askem; Victoria Beadle; John Philip Gowans; Mark Hesketh; Allan Kenneth Frazer Grugeon Hunt; William Kelbie; Damyn Musgrave; Joseph William Robinson - Web page: https://patentgrep.com/patent/US11305047B2 ## CPC - A61M 1/962: {having pumping means on the suction site, e.g. miniature pump on dressing or dressing capable of exerting suction} - A61M 1/74: {Suction control (underwater drainage A61M1/61)} - A61M 1/96: {Suction control thereof} - A61M 1/966: {having a pressure sensor on or near the dressing} - A61M 2205/0294: Piezoelectric materials - A61M 2205/106: reciprocating - A61M 2205/33: Controlling, regulating or measuring - A61M 2205/3331: Pressure; Flow - A61M 2205/502: User interfaces, e.g. screens or keyboards - A61M 2205/8212: with means or measures taken for minimising energy consumption - A61M: DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY (introducing media into or onto the bodies of animals A61D7/00; means for inserting tampons A61F13/26; devices for administering food or medicines orally A61J; containers for collecting, storing or administering blood or medical fluids A61J1/05); DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY (surgery A61B; chemical aspects of surgical articles A61L); DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR {(Electrotherapy, e.g. producing anaesthesia by the use of alternating or intermittent currents A61N1/36021)} ## Abstract Embodiments of negative pressure wound therapy systems and methods are disclosed. In one embodiment, an apparatus includes a source of negative pressure, a coupling circuit, a driving circuit, and a controller. The driving circuit supplies a driving signal to the source of negative pressure via the coupling circuit to cause the source of negative pressure to provide negative pressure to a wound dressing. The coupling circuit includes an inductive reactance that limits a rate of change over time of the driving signal. The controller controls the driving signal supplied by the driving circuit. ## Claims ### Claim 1 An apparatus for applying negative pressure to a wound, the apparatus comprising: a source of negative pressure configured to provide negative pressure via a fluid flow path to a wound dressing placed over a wound of a patient, the source of negative pressure comprising an actuator configured to convert an electrical energy to a mechanical energy; a coupling circuit including an inductive reactance; a driving circuit configured to supply a driving signal to the actuator via the coupling circuit to cause the source of negative pressure to provide negative pressure; and a controller configured to control the driving signal supplied by the driving circuit, wherein the coupling circuit comprises an inductor electrically coupled in series between a first output of the driving circuit and a first input of the actuator and an electrical short electrically coupled in series between a second output of the driving circuit and a second input of the actuator. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein the actuator is configured to generate negative pressure by converting the electrical energy to the mechanical energy without converting the electrical energy to a magnetic energy. ### Claim 3 (depends on 1) The apparatus of claim 1, wherein the source of negative pressure comprises a piezoelectric pump, and the actuator comprises a piezoelectric transducer. ### Claim 4 (depends on 1) The apparatus of claim 1, wherein the source of negative pressure comprises a micropump. ### Claim 5 (depends on 1) The apparatus of claim 1, further comprising the wound dressing, the source of negative pressure being disposed on or within the wound dressing. ### Claim 6 (depends on 1) The apparatus of claim 1, wherein the coupling circuit is configured to limit a rate of change over time of the driving signal supplied from the driving circuit to the actuator. ### Claim 7 (depends on 1) The apparatus of claim 1, wherein the inductive reactance is greater than 5 mΩ at an operating frequency of 1 kHz. ### Claim 8 (depends on 1) The apparatus of claim 1, wherein the inductor has an inductance between 1 μH and 100 μH. ### Claim 9 (depends on 8) The apparatus of claim 8, wherein the inductor has a maximum current rating of at least 1 A. ### Claim 10 (depends on 1) The apparatus of claim 1, wherein the driving circuit comprises an H-bridge circuit. ### Claim 11 (depends on 1) The apparatus of claim 1, wherein the controller is further configured to provide a control signal to the driving circuit, and the controller is configured to control the driving signal by adjusting a pulse width modulation of the control signal. ### Claim 12 (depends on 1) The apparatus of claim 1, wherein a magnitude of the driving signal is less than 50 V. ### Claim 13 (depends on 1) The apparatus of claim 1, wherein the driving circuit comprises a boost converter and an H-bridge. ### Claim 14 (depends on 1) A method of treating a wound on a patient, the method comprising: by a negative wound therapy apparatus of claim 1: generating and outputting a control signal; activating a plurality of switches of the driving circuit responsive to the control signal; supplying the driving signal to the actuator of the source of negative pressure via the plurality of switches; limiting a rate of change over time of the driving signal; and supplying negative pressure with the source of negative pressure to the wound dressing responsive to the driving signal. ### Claim 15 (depends on 14) The method of claim 14, wherein said limiting the rate of change over time comprises limiting the rate of change over time using the coupling circuit. ### Claim 16 (depends on 14) The method of claim 14, wherein said supplying negative pressure is performed by converting the electrical energy to the mechanical energy without converting the electrical energy to a magnetic energy. ### Claim 17 (depends on 14) The method of claim 14, wherein said activating the plurality of switches comprises activating pairs of the plurality of switches responsive to the control signal. ### Claim 18 (depends on 14) The method of claim 14, wherein the control signal comprises a square waveform having a duty cycle of 50%.