Systems and methods for driving negative pressure sources in negative pressure therapy systems
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.
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.
2. 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.
3. The apparatus of claim 1 , wherein the source of negative pressure comprises a piezoelectric pump, and the actuator comprises a piezoelectric transducer.
4. The apparatus of claim 1 , wherein the source of negative pressure comprises a micropump.
5. The apparatus of claim 1 , further comprising the wound dressing, the source of negative pressure being disposed on or within the wound dressing.
6. 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.
7. The apparatus of claim 1 , wherein the inductive reactance is greater than 5 mΩ at an operating frequency of 1 kHz.
8. The apparatus of claim 1 , wherein the inductor has an inductance between 1 μH and 100 μH.
9. The apparatus of claim 8 , wherein the inductor has a maximum current rating of at least 1 A.
10. The apparatus of claim 1 , wherein the driving circuit comprises an H-bridge circuit.
11. 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.
12. The apparatus of claim 1 , wherein a magnitude of the driving signal is less than 50 V.
13. The apparatus of claim 1 , wherein the driving circuit comprises a boost converter and an H-bridge.
14. 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.
15. 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.
16. 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.
17. 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.
18. The method of claim 14 , wherein the control signal comprises a square waveform having a duty cycle of 50%.