Piezoelectric devices and methods and circuits for driving same

• US 7,287,965 B2
• Filed: 04/02/2004
• Issued: 10/30/2007
• Est. Priority Date: 04/02/2004
• Status: Expired due to Fees

• Current Assignee: Par Technology Corporation
• Original Assignee: Adaptivenergy, LLC
• Inventors: Vogeley, James, Jones, Sanford, Schemmann, Marcel F. C.
• Primary Examiner(s): Rodriguez; William H.
• Application Number:
  US10/816,000
• Publication Number:
  US 20050225202A1
• Time in Patent Office: 1,306 Days
• Field of Search: 417/322, 417/413.2
• US Class Current: 417/413.2
• CPC Class Codes: F04B 43/046 with piezoelectric drive
• CPC Class Codes: H10N 30/802 Drive or control circuitry or methods for piezoelectric or electrostrictive devices not otherwise provided for

Abstract

A drive circuit (18) produces a drive signal for a pump (10) having a piezoelectric actuator (14), with the piezoelectric actuator (14) forming a part of the drive circuit (18) and serving to shape a waveform of the drive signal. The drive circuit (18) comprises a pulse generator (100) which generates pulses; a converter circuit (102) which receives the pulses and produces charge packets at a rate which equals a desired drive frequency; and, the piezoelectric actuator (14). The piezoelectric actuator (14) receives the charge packets and, by its capacitive nature, integrates the charge packets to shape the waveform of the drive signal. Preferably, the piezoelectric actuator (14) integrates the charge packets to yield a drive field that approximates a sine wave. In one non-limiting example embodiment, the pulse generator (100) comprises a microcontroller-based pulsed width modulator (PWM) circuit (116) and the converter circuit (102) comprises a flyback circuit.

Claims

1. A pump comprising:

a pump body configured to at least partially define a pumping chamber;

a piezoelectric actuator situated in the pump body and responsive to a drive signal for pumping fluid in the pumping chamber;

a drive circuit configured to apply the drive signal to the piezoelectric actuator as a series of high voltage charge packets configured to dynamically shape a waveform for the piezoelectric actuator as the actuator operates in the pump; and

wherein the drive circuit further comprises;

a pulse generator configured to generate digital pulses, wherein the pulse generator comprises a pulsed width modulator (PWM) circuit;

a converter circuit configured to use the digital pulses generated by the pulse generator to produce the series of high voltage charge packets.

2. The pump of claim 1, wherein the drive circuit further comprises the piezoelectric actuator, and wherein the piezoelectric actuator, by a capacitive nature of the piezoelectric actuator, integrates the charge packets to shape the waveform of the drive signal.

3. The pump of claim 1, wherein the pulsed width modulator (PWM) circuit comprises a microcontroller.

4. The pump of claim 1, wherein the pulses generated by the pulsed width modulator (PWM) circuit have a pulse width chosen to produce a desired amplitude for the drive signal.

5. A method of operating a piezoelectric pump having a piezoelectric actuator situated in a pump body and responsive to a drive signal for pumping fluid, the method comprising:

(1) generating digital pulses and a pulse width modulator circuit for modulating a pulse width of the digital pulses in accordance with a desired waveform for the drive signal;

(2) using the digital pulses of act (1) to produce a series of high voltage charge packets configured to dynamically shape a waveform for the piezoelectric actuator as the actuator operates in the pump;

applying the series of high voltage charge packets as the drive signal to the piezoelectric actuator;

operating the piezoelectric actuator in the pump in response to the drive signal.

6. The pump of claim 5, further comprising using the piezoelectric actuator to integrate the charge packets and thereby shape the waveform of the drive signal.

7. A pump comprising:

a pump body configured to at least partially define a pumping chamber;

a piezoelectric actuator situated in the pump body and responsive to a drive signal for pumping fluid in the pumping chamber; and

a drive circuit configured to produce the drive signal, the piezoelectric actuator forming a part of the drive circuit, wherein the drive circuit comprises;

a pulse generator configured to generate digital pulses;

a converter circuit configured to use the digital pulses generated by the pulse generator to produce high voltage charge packets configured to dynamically shape a waveform for the piezoelectric actuator as the actuator operates in the pump; and

wherein the piezeolectric is configured, by a capacitive nature of the piezoelectric actuator, to integrate the charge packets to shape the waveform of the drive signal;

wherein the pulse generator comprises a pulsed width modulator (PWM) circuit.

8. The pump of claim 7, wherein the pulsed width modulator (PWM) circuit comprises a microcontroller.

9. The pump of claim 7, wherein the digital pulses generated by the pulsed width modulator (PWM) circuit have a pulse width chosen to produced a desired amplitude for the drive signal.

10. A pump comprising:

a pump body configured to at least partially define a pumping chamber;

a piezoelectric actuator situated in the pump body and responsive to a drive signal for pumping fluid in the pumping chamber; and

a drive circuit configured to product the drive signal, the piezoelectric actuator forming a part of the drive circuit, wherein the drive circuit comprises;

a pulse generator configured to generate digital pulses;

a converter circuit configured to use the digital pulses generated by the pulse generator to produce high voltage charge packets configured to dynamically shape a waveform for the piezoelectric actuator as the actuator operates in the pump; and

wherein the piezoelectric is configured, by a captive nature of the piezoelectric actuator, to integrate the charge packets to shape the waveform of the drive signal;

wherein the converter circuit comprises a flyback circuit.

11. The pump of claim 10, wherein the flyback circuit produces potentials that are bipolar with respect to an electrical ground.

12. A pump comprising:

a pump body configured to at least partially define a pumping chamber;

a piezoelectric actuator situated in the pump body and responsive to a drive signal for pumping fluid in the pumping chamber; and

a drive circuit configured to product the drive signal, the piezoelectric actuator forming a part of the drive circuit, wherein the drive circuit comprises;

a pulse generator configured to generate digital pulses;

a converter circuit configured to use the digital pulses generated by the pulse generator to produce high voltage charge packets configured to dynamically shape a waveform for the piezoelectric actuator as the actuator operates in the pump; and

wherein the piezoelectric is configured, by a captive nature of the piezoelectric actuator, to integrate the charge packets to shape the waveform of the drive signal;

a filter configured to filter components of the charge packets produced by the converter circuit.

13. A pump comprising:

a pump body configured to at least partially define a pumping chamber;

a piezoelectric actuator situated in the pump body and responsive to a drive signal for pumping fluid in the pumping chamber; and

a drive circuit configured to product the drive signal, the piezoelectric actuator forming a part of the drive circuit, wherein the drive circuit comprises;

a pulse generator configured to generate digital pulses;

a converter circuit configured to use the digital pulses generated by the pulse generator to produce high voltage charge packets configured to dynamically shape a waveform for the piezoelectric actuator as the actuator operates in the pump; and

wherein the piezoelectric is configured, by a captive nature of the piezoelectric actuator, to integrate the charge packets to shape the waveform of the drive signal;

wherein a frequency of the pulses produced by the converter circuit is greater than an ability of the piezoelectric actuator to mechanically respond.

14. The pump of claim 13, wherein the frequency of the charge packets produced by the converter circuit is chosen to be greater than an ability of the piezoelectric actuator to mechanically respond so that the charge packets produced by the converter circuit do not contribute to one of mechanical inefficiency and noise in the piezoelectric actuator.

15. A pump comprising:

a pump body configured to at least partially define a pumping chamber;

a piezoelectric actuator situated in the pump body and responsive to a drive signal for pumping fluid in the pumping chamber; and

a drive circuit configured to product the drive signal, the piezoelectric actuator forming a part of the drive circuit, wherein the drive circuit comprises;

a pulse generator configured to generate digital pulses;

a converter circuit configured to use the digital pulses generated by the pulse generator to produce high voltage charge packets configured to dynamically shape a waveform for the piezoelectric actuator as the actuator operates in the pump; and

wherein the piezoelectric is configured, by a captive nature of the piezoelectric actuator, to integrate the charge packets to shape the waveform of the drive signal;

wherein the charge packets comprise positive pulses and negative pulses, and wherein the piezoelectric actuator integrates the positive pulses and the negative pulses to yield a drive field that approximates a sine wave.

16. A pump comprising:

a pump body configured to at least partially define a pumping chamber;

a piezoelectric actuator situated in the pump body and responsive to a drive signal for pumping fluid in the pumping chamber; and

a drive circuit configured to product the drive signal, the piezoelectric actuator forming a part of the drive circuit, wherein the drive circuit comprises;

a pulse generator configured to generate digital pulses;

a converter circuit configured to use the digital pulses generated by the pulse generator to produce high voltage charge packets configured to dynamically shape a waveform for the piezoelectric actuator as the actuator operates in the pump; and

wherein the piezoelectric is configured, by a captive nature of the piezoelectric actuator, to integrate the charge packets to shape the waveform of the drive signal;

wherein neither a bridge switching circuit nor a charge storage circuit are connected between the converter circuit and the piezoelectric actuator.

17. A pump comprising:

a pump body configured to at least partially define a pumping chamber;

a piezoelectric actuator situated in the pump body and responsive to a drive signal for pumping fluid in the pumping chamber;

a power supply; and

a drive circuit which is powered by the power supply and which is configured to produce the drive signal, wherein the drive circuit comprises;

a pulse generator configured to generate digital pulse, the pulse generator comprising a pulsed width modulator (PWM) circuit;

a converter circuit configured to use the digital pulses generated by the pulse generator to produce high voltage charge packets; and

wherein the piezoelectric actuator, by a capacitive nature of the piezoelectric actuator, integrates the charge packets to dynamically shape a waveform for the piezoelectric actuator as the actuator operates in the pump.

18. The pump of claim 17, wherein the charge packets comprise positive pulses and negative pulses, and wherein the piezoelectric actuator integrates the positive pulses and the negative pulses to yield a drive field that approximates a sine wave.

19. The pump of claim 17, wherein the digital pulses generated by the pulsed width modulator (PWM) circuit have a pulse width chosen to produced a desired amplitude for the drive signal.

20. A pump comprising:

a pump body configured to at least partially define a pumping chamber;

a piezoelectric actuator situated in the pump body and responsive to a drive signal for pumping fluid in the pumping chamber; and

a drive circuit configured to apply the drive signal to the piezoelectric actuator as a series of digital pulses, wherein the drive circuit comprises;

a source of digital pulses;

a transformer;

a power switching element configured to receive the digital pulses and to selectively apply current to the transformer;

means for using an electromotive force generated by parasitic capacitance of the transformer to provide a high voltage bipolar output to the piezoelectric actuator.

21. The apparatus of claim 20, wherein the transformer is has only one secondary winding with no taps.

22. The apparatus of claim 20, wherein the source produces a single PWM pulse train.

23. The apparatus of claim 20, wherein the source produces a unipolar, low frequency, low potential control signal to the means for using an electromotive force.

24. The apparatus of claim 20, further comprising a second transformer connected in parallel to the transformer.