| 摘要 |
PROBLEM TO BE SOLVED: To suppress or remove the DC component of an excitation voltage by providing a piezoelectric transformer connected in parallel with a switching means connected to a DC input power source connected with an inductor, a serial circuit of capacitors, and a switch driving and oscillating means. SOLUTION: The input voltage V1 of a piezoelectric transformer type power converter is 10 V and a serial capacitor 10 has an electrostatic capacitance CR=10 μF (equivalent parallel resistance RPC of 1 GΩ). A piezoelectric transformer 50 has an input electrostatic capacitance CT1 of 110 nF (equivalent parallel resistance RPT of 5 GΩ), and an additional parallel resistor 100 has a resistance value RH of 2 MΩ. The driving frequency of the converter is 58-63 kHz. A half-sine-wave voltage B21 has a waveform containing a DC component and the excitation voltage V22 of the transformer 50 becomes such a waveform that deflects to both the positive and negative sides and the DC component contained in the voltage V22 is almost zero. The half-sine-wave voltage V21 is divided into the excitation voltage V22. In this driving frequency domain, the voltage V21 is divided by the electrostatic capacitance when the voltage V21 is derided as an AC component and the DC component impressed upon the input of the transformer 50 becomes almost zero (about 20 mV), because the impedance of the electrostatic capacitance is sufficiently smaller than the equivalent parallel resistance and additional parallel resistance value. |
