Method and apparatus for driving piezoelectric transformer
US5923542A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 13, 1998 |
| Grant date | Jul 13, 1999 |
| Priority date | — |
| Expiry date | Oct 13, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02M7/48
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A combination of two control methods are used, one of which is a method to control the boosting ratio of the piezoelectric transformer and another is a method to control the driving waveform of the piezoelectric transformer. The threshold values for switching the control methods are set with a hysteresis characteristic in order to avoid instability in the driving frequency at the time of switching and also to avoid driving at a natural frequency. When the source voltage is fixed, the driving frequency is increased by changing the resistance of the detection resistor 16 until the driving frequency reaches the natural frequency causing problems. When the driving frequency reaches the natural frequency, the power supply to the driving circuit is reduced to reduce the amplitude of the driving wave for reducing the driving frequency without changing the output voltage. At this state when the amplitude is small, the minimum output voltage is obtained by increasing the driving frequency to the natural frequency. This method and apparatus provide a wider range of output voltages and reliable output characteristics of the piezoelectric transformer.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.