Non-contact measuring device and method for direct-current voltage of electric wire

The invention discloses a non-contact measuring device and method for direct-current voltage of a wire, the non-contact measurement of the direct-current voltage of the wire is realized based on a piezoelectric device, the measured direct-current voltage is divided and sampled through a capacitor, the sampled direct-current voltage is applied to two ends of an electrode of the piezoelectric device, and the direct-current voltage is measured according to the inverse piezoelectric effect of the piezoelectric device. The distance between the two polar plates of the piezoelectric device can change along with the magnitude and polarity of the sampling voltage, so that the capacitance of the piezoelectric device is changed. The measurement of the variable capacitance value of the piezoelectric device and the measurement of the sampling capacitance value are realized by combining the locking amplification technology, the sampling voltage can be obtained through the change of the capacitance, and then the measured di