Swept sideband PZT driver circuit

• US 8,729,772 B1
• Filed: 12/30/2011
• Issued: 05/20/2014
• Est. Priority Date: 12/30/2010
• Status: Expired due to Fees

• Current Assignee: S&F Sonics Inc.
• Original Assignee: S&F Sonics
• Inventors: Persson, Steve, Arata, David, Pedeflous, Frank
• Primary Examiner(s): ROSENAU, DEREK JOHN
• Application Number:
  US13/341,834
• Time in Patent Office: 872 Days
• Field of Search: 310/314, 310/317
• US Class Current: 310/317
• CPC Class Codes: B06B 1/0276 with simultaneous generation, e.g. with modulation, harmonics
• CPC Class Codes: B06B 1/0284 with consecutive, i.e. sequential generation, e.g. with frequency sweep
• CPC Class Codes: B06B 1/06 operating with piezoelectric effect or with electrostriction piezoelectric or electrostrictive devices per se H10N30/00
• CPC Class Codes: B06B 2201/71 Cleaning in a tank
• CPC Class Codes: H10N 30/802 Drive or control circuitry or methods for piezoelectric or electrostrictive devices not otherwise provided for

Abstract

A swept sideband driver circuit has a boost converter followed by a buck converter obtaining near unity power factor. A full wave bridge powered from the buck converter circuit drives the PZT output load. The output of the buck converter circuit is controlled by a power level control circuit. The analog power level control circuit receives a sample of the output load current and a sample of the output load voltage from which it produces a product. The product signal is compared with manually adjusted pot signal. A difference signal results and used to adjust the output voltage of the buck converter circuit thereby increasing or decreasing the power to the load to drive the error signal to zero. A swept sideband modulation circuit modulates the frequency of the full wave bridge with a harmonic rich signal thereby imposing side bands on the voltage to the PZT load.

Claims

1. A swept side band driver circuit comprising:

A full wave rectifier responsive to voltage from an ac mains source for providing a full wave rectified voltage (FWRV),

a boost converter circuit coupled to the full wave rectified voltage (FWRV) for providing a boosted dc voltage (HVA) and improved power factor,

a buck converter circuit coupled to receive the boosted dc voltage (HVA) for providing a buck output voltage (BOV), and being responsive to an output power control signal (OPCS) for adjusting the value of the buck output voltage (BOV),

a frequency modulating drive circuit for providing a frequency modulated drive signal (FMDS), and

a full wave bridge circuit responsive to the frequency modulated drive signal FMDS) and to the buck output voltage (BOV) for providing a buffered frequency modulated output drive signal (BFMDS),

a power output and load circuit responsive to the buffered frequency modulated output drive signal (BFMDS) for providing a drive signal to a PZT load.

2. The swept sideband driver circuit of claim 1 wherein the power output and load circuit further comprises;

an output voltage measurement circuit that measures the voltage applied to thee PZT load and provides an output voltage measurement signal (OVMS) scaled proportional to the voltage applied to the PZT load (OVMS),

an output current measurement circuit providing an output current measurement signal (OCMS) proportional to the current through the PZT load, and

an output power required circuit for providing an output power required signal (OPRS) scaled to define the power level required at the PZT load,

an output power control circuit coupled to the output power required signal (OPRS) and to the output voltage measurement signal (OVMS) and to the output current measurement signal (OCMS) for providing an output power product signal (OPPS) proportional to the output power delivered to the PZT load, the output power control circuit also having

a summing circuit coupled to receive the output power required signal (OPRS) signal and the output power product signal (OPPS) to provide a difference signal between output power required signal (OPRS) signal and the output power product signal (OPPS) signal and for providing the output power control (OPCS) signal to the buck converter circuit to drive the buck output voltage (BOV) in a direction to drive output power to the PZT to the level commanded by the output power required signal (OPRS).

3. The swept sideband driver circuit of claim 2 wherein the output power required circuit for providing an output power required signal (OPRS) scaled to define the power level required at the PZT load, further comprises;

a variable resistor having a first terminal connected to a bias voltage source, a second terminal connected to a reference return level and a control terminal coupled to a manually positioned tap for sensing a manually selected proportional voltage scaled to represent the output power required signal (OPRS).

4. The swept sideband driver circuit of claim 1 wherein the boost converter circuit (23) further comprises:

a boost modulator (22) coupled to the full wave rectified voltage is controlled by

a boost control circuit, the boost control circuit is coupled to sample the full wave rectified voltage and the boosted dc voltage (HVA) output,

a current sense resistor connected in series with the return circuit from the boosted dc voltage, the return current through the current sense resistor provides a feedback signal to the boost control circuit that is compared to a current command signal within the boost control circuit for power factor correction.

5. The swept sideband driver circuit of claim 1 wherein the boost converter circuit (23) further comprising:

a boost modulator (22) coupled to the full wave rectified voltage is controlled by

a boost control circuit operating as a current mode controller with a fixed duty cycle.

6. The swept sideband driver circuit of claim 1 wherein the load current measurement transformer circuit further comprises:

a primary winding driven by the buffered frequency modulated output drive signal (BFMDS) from the full wave bridge,

a first secondary for impedance matching and for coupling an output voltage to the PZT load, and

a second secondary providing the isolated output voltage measurement signal (OVMS) proportional to the output voltage applied to the PZT load.

7. A swept side band driver circuit comprising:

A full wave rectifier responsive to voltage from an ac mains source for providing

a full wave rectified voltage (FWRV),

a boost converter circuit (23) coupled to the full wave rectified voltage (FWRV) for providing a boosted dc voltage (HVA), the boost converter circuit comprising;

a boost modulator circuit (22) coupled to be powered from the full wave rectified voltage (FWRV) and coupled to be driven by a boost pulse width modulated signal PWMA, the boost modulator circuit providing a boosted dc voltage (HVA) and a switch mode current sense voltage IS, and

a boost control circuit (24) coupled to sample the full wave rectified input dc voltage (FWRV), the switch mode current sense voltage IS for power factor correction and control, and the boosted dc voltage (HVA) for feedback to constantly adjust the duty cycle of the boost pulse width modulated signal PWMA, to maximize the power factor correction of the boost converter circuit and to hold the value of the boosted dc voltage (HVA) within a predetermined boosted dc voltage range,

a buck converter circuit (29) coupled to be powered from the boosted dc voltage (HVA), the buck converter circuit being responsive to an output power control signal (OPCS) for providing a buck output voltage (BOV), and

a full wave bridge circuit (44) responsive to a frequency modulated drive signal FMDS) and to the buck output voltage (BOV) for providing a buffered frequency modulated output drive signal (BFMDS),

a power output and load circuit (48) responsive to and powered by the buffered frequency modulated output drive signal (BFMDS) for providing a drive signal to a PZT load.

8. The swept sideband driver circuit of claim 7 wherein the power output and load circuit further comprising;

a means for providing an output current measurement signal OCMS proportional to the current passing through the PZT load,

a means for providing An output voltage measurement signal OVMS proportional to the voltage applied to the PZT load,

an output power control circuit comprising;

a manually adjusted output power required circuit to provide an output power required signal (OPRS) scaled to define the power level required at the PZT load,

a multiplier circuit for providing the product of the OCMS and the OVMS signals to obtain a signal representing the instantaneous power being dissipated in the PZT (POZT),

a summing circuit for providing the difference between the output power required signal (OPRS) and the instantaneous power being dissipated in the PZT (POZT) and outputting the difference as an error signal,

an integrator circuit for scaling integrating, and buffering the error signal to provide the power control signal (OPCS) to the buck converter circuit (29) to control the value of the buck output voltage (BOV), to drive the error voltage to zero,

whereby the power delivered to the PZT will equal the power level required at the PZT load.

9. The swept sideband driver circuit of claim 7 wherein the output power required circuit for providing an output power required signal (OPRS) scaled to define the power level required at the PZT load, further comprises;

a variable resistor having a first terminal connected to a bias voltage source, a second terminal connected to a reference return level and a control terminal coupled to a manually positioned tap for sensing a manually selected proportional voltage scaled to represent the output power required signal (OPRS).

10. The swept sideband driver circuit of claim 7 wherein the power output and load circuit further comprising;

a load current measurement transformer having a primary winding in series with the PZT load, and an isolated secondary terminated in a current scaling resistor providing a signal voltage proportional to the current passing through the PZT load, and

an output transformer (52) having a primary winding driven by the buffered frequency modulated output drive signal (BFMDS) from the full wave bridge, and

a first secondary for impedance matching and for coupling an output voltage to the PZT load, and

a second secondary providing an isolated output voltage measurement signal (OVMS) proportional to the output voltage applied to the PZT load,

an output current measurement transformer for measuring the output current to the PZT load and for providing an output current measurement signal (OCMS),

an output power required function for providing an output power required signal (OPRS) characterizing the power level required at the PZT load,

an output power control function coupled to the output power required signal (OPRS), the isolated output voltage measurement signal (OVMS), to the output current measurement signal (OCMS) for providing an output power product signal (OPPS), scaled to represent the output power being delivered to the PZT load,

a summing circuit for comparing the output power required signal (OPRS) signal to the output power product signal (OPPS) signal and for providing the output power control (OPCS) signal to the buck converter circuit to drive the output power to the PZT to the level commanded by the output power required signal (OPRS).

11. A swept side band driver circuit comprising:

A full wave rectifier responsive to voltage from an ac mains source for providing a full wave rectified voltage (FWRV),

a boost converter circuit (23) coupled to the full wave rectified voltage (FWRV) for providing a boosted dc voltage (HVA),

a buck converter circuit (29) coupled to receive the boosted dc voltage (HVA) for providing a buck output voltage (BOV), the buck converter circuit being responsive to an output power control signal (OPCS) for adjusting the value of the buck output voltage (BOV),

a frequency modulating drive circuit (60) for providing a frequency modulated drive signal (FMDS), the frequency modulating drive circuit having

a bridge drive circuit (42) coupled to receive a swept sideband modulation signal (SSMS) characterized as being a composite of a nominal sinusoidal frequency modulated by at least a first frequency to provide the modulated drive signal (FMDS), and

a swept sideband modulation circuit (56) having at least

a first function generator providing a first function generator signal (FFGS), and

a resonant mode controller, having an internal oscillator operating at a predetermined nominal frequency (PNF), the predetermined nominal frequency being frequency modulated by the first function generator signal (FFGS) to form the swept sideband modulation signal (SSMS), a composite of a first frequency modulated by a second frequency

the resonant mode controller output swept sideband modulation signal (SSMS) being provided by means of

a complementary pair of resonant mode controller output signals of equal duration separated by a programmed dead time characterizing the frequency modulated by a second frequency (SSMS) to the bridge drive circuit,

the bridge drive circuit (42) being responsive to the complementary pair of resonant mode controller output signal coupled to a transformer (T1) means having isolated first and second secondaries for providing two pairs of isolated FET drive signals that comprise the frequency modulated drive signals (FMDS),

a full wave bridge circuit (44) responsive to a frequency modulated drive signal FMDS) and to the buck output voltage (BOV) for providing a buffered frequency modulated output drive signal (BFMDS),

a power output and load circuit (48) responsive to and powered by the buffered frequency modulated output drive signal (BFMDS) for providing a drive signal to a PZT load.

12. The swept sideband driver circuit of claim 11 wherein the swept sideband modulation circuit (56) having at least

a first function generator providing a first function generator signal (FFGS), and

a resonant mode controller, having an internal oscillator operating at a predetermined nominal frequency (PNF), the predetermined nominal frequency being frequency modulated by the first function generator signal (FFGS) to form the swept sideband modulation signal (SSMS), a composite of a first frequency modulated by a second frequency

further comprising;

a second function generator providing a second function generator signal (SFGS) coupled to the first function generator to modulate the first function generator signal (FFGS)) to form the swept sideband modulation signal (SSMS), a composite of a first frequency modulated by a second frequency that is modulated by a third frequency.

13. The swept sideband driver circuit of claim 11 wherein the power output and load circuit further comprising;

an output transformer (52) having a primary winding driven by the buffered frequency modulated output drive signal (BFMDS) from the full wave bridge (44), and

a first secondary for coupling output voltage to the PZT load.

14. The swept sideband driver circuit of claim 11 wherein the full wave bridge circuit (44) is further characterized as being coupled to the frequency modulated drive signal FMDS) and to the buck output voltage (BOV) to provide a buffered frequency modulated output drive signal (BFMDS), and wherein

the bridge drive circuit (42) outputs a complementary pair of resonant mode controller output signals of equal duration separated by a programmed dead time characterizing the frequency modulated driver signal (FMDS).

15. The swept sideband driver circuit of claim 11 wherein the power output and load circuit further comprising;

an output transformer (52) having a primary winding driven by the buffered frequency modulated output drive signal (BFMDS) from the full wave bridge, and a first secondary for impedance matching and for coupling an output voltage to the PZT load, and

a second secondary providing an isolated output voltage measurement signal (OVMS) proportional to the output voltage applied to the PZT load,

an output current measurement transformer for measuring the output current to the PZT load and for providing an output current measurement signal (OCMS),

an output power required function for providing an output power required signal (OPRS) characterizing the power level required at the PZT load,

an output power control function coupled to the output power required signal (OPRS), the isolated output voltage measurement signal (OVMS), to the output current measurement signal (OCMS) for providing an output power product signal (OPPS), scaled to represent the output power being delivered to the PZT load,

a summing circuit for comparing the output power required signal (OPRS) signal to the output power product signal (OPPS) signal and for providing the output power control (OPCS) signal to the buck converter circuit to drive the output power to the PZT to the level commanded by the output power required signal (OPRS).

16. The swept sideband driver circuit of claim 11 wherein the boost converter circuit coupled to the full wave rectified voltage (FWRV) for providing a boosted dc voltage (HVA), further comprises;

a boost modulator circuit (22) coupled to the full wave rectified input dc voltage (FWRV) and to a first pulse width modulated signal (PWMA), and

a boost control circuit coupled to sample the full wave rectified voltage (FWRV), and the boosted dc voltage (HVA) and to constantly adjust the duty cycle of the first pulse width modulated signal (PWMA), to maximize the power factor correction of the boost converter circuit,

a current sense resistor connected in series with the return circuit from the boosted dc voltage, the return current through the current sense resistor provides a current mode control feedback signal that is compared to a current command signal within the boost control circuit for power factor control.