Power supply with a piezoelectric transformer and method for power conversion

• US 8,659,921 B2
• Filed: 08/28/2009
• Issued: 02/25/2014
• Est. Priority Date: 08/28/2009
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Buchwald, Randall Henry, Lyle, David
• Primary Examiner(s): Han, Jessica
• Application Number:
  US12/550,029
• Publication Number:
  US 20110051461A1
• Time in Patent Office: 1,642 Days
• Field of Search: 363 74- 80, 363124-126
• US Class Current: 363/75
• CPC Class Codes: H02M 3/33507 with automatic control of the output voltage or current, e.g. flyback converters H02M3/33561, H02M3/33569 take precedence
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A power supply with a piezoelectric transformer is provided. A method for power conversion is also provided. The power supply includes a piezoelectric transformer and an oscillator circuit connected to the piezoelectric transformer. The oscillator circuit controls a sinusoidal voltage waveform at an input of the piezoelectric transformer to drive the piezoelectric transformer.

Claims

1. A power supply comprising:

a piezoelectric transformer;

a feedback circuit connected to the piezoelectric transformer and configured to control the power supply to operate at a frequency of the piezoelectric transformer;

an oscillator circuit connected to the piezoelectric transformer, the oscillator circuit controlling a sinusoidal voltage waveform at an input of the piezoelectric transformer; and

a phase shift network connected between an output of the piezoelectric transformer and an operational amplifier connected to an input of the piezoelectric transformer.

2. A power supply in accordance with claim 1 further comprising an operational amplifier and phase shift network connected to the oscillator circuit to form a self-oscillating linear DC to DC step-up converter.

3. A power supply in accordance with claim 1 wherein the feedback circuit comprises a phase shifter, and the piezoelectric transformer forms part of the feedback circuit.

4. A power supply in accordance with claim 1 wherein the piezoelectric transformer comprises a piezoceramic material.

5. A power supply in accordance with claim 1 further comprising a voltage multiplier circuit at an output of the piezoelectric transformer generating a rectified and amplified DC signal from the output of the piezoelectric transformer.

6. A power supply in accordance with claim 1 further comprising an operational amplifier connected to the input of the piezoelectric transformer to provide the sinusoidal voltage wave form at a constant voltage and oscillating at a frequency of the piezoelectric transformer.

7. A power supply in accordance with claim 1 further comprising an output voltage controller configured to generate a constant voltage output signal at a set level.

8. A power supply in accordance with claim 1 further comprising an operational amplifier receiving a voltage signal to generate the sinusoidal voltage wave form, wherein the voltage signal is not more than ten volts.

9. A power supply in accordance with claim 1 wherein the oscillator network comprises a pair of clipping diodes.

10. A power supply in accordance with claim 1 further comprising a voltage divider connected to an output of the piezoelectric transformer for generating a feedback signal to control oscillation of the sinusoidal voltage wave form.

11. A low signal mode powered switching system comprising:

a piezoelectric transformer;

a feedback circuit connected to the piezoelectric transformer with the piezoelectric transformer forming part of the feedback circuit;

an operational amplifier and phase shift network connected to an input of the piezoelectric transformer and forming a self-oscillating linear DC to DC step-converter with the feedback circuit such that the piezoelectric transformer receives a sinusoidal voltage wave input; and

a micro-electromechanical system (MEMS) switch connected to an output of the piezoelectric transformer.

12. A low signal mode powered switching system in accordance with claim 11 wherein the operational amplifier receives at an input 10 volts to generate a +/−

5 volts output sinusoidal voltage wave and wherein the piezoelectric transformer generates from the +/−

5 volts output sinusoidal voltage wave a +/−

100 volts sinusoidal voltage wave.

13. A low signal mode powered switching system in accordance with claim 11 further comprising an oscillator circuit controlling a wave shape of the sinusoidal voltage wave input.

14. A low signal mode powered switching system in accordance with claim 11 further comprising an oscillator circuit preventing the wave shape of the sinusoidal voltage wave input from becoming a square wave shape.

15. A low signal mode powered switching system in accordance with claim 11 wherein the piezoelectric transformer comprises a piezoceramic material.

16. A method for power conversion, the method comprising:

generating, from a DC input signal, a sinusoidal drive signal for a piezoelectric transformer;

controlling a frequency of the sinusoidal drive signal to a power source using a feedback signal from the piezoelectric transformer to operate the power source at a frequency of the piezoelectric transformer;

generating a DC output signal from an output of the piezoelectric transformer; and

connecting a phase shift network between an output of the piezoelectric transformer and an operational amplifier connected to an input of the piezoelectric transformer.

17. A method in accordance with claim 16 further comprising rectifying and amplifying the output signal from the piezoelectric transformer.

18. A method in accordance with claim 16 further comprising limiting a voltage level of the output of the piezoelectric transformer.

19. A method in accordance with claim 16 further comprising controlling a waveform of the sinusoidal drive signal to maintain the sinusoidal wave shape of the signal and prevent a square wave shape.