A voltage measurement device for pulse-width modulation (PWM) signals is provided, which includes a conversion circuit and a processing circuit. The conversion circuit receives a first PWM signal and a second PWM signal from a motor driving device, and converts the first PWM signal and the second PWM signal into the absolute value signal and the polarity signal of the line-to-line voltage signal between the first PWM signal and the second PWM signal. The processing circuit converts the polarity signal and the absolute value signal into a first integral signal and a second integral signal, and reconstructs the line-to-line voltage signal according to the first integral signal and the second integral signal so as to obtain the reconstructed voltage signal of the line-to-line voltage signal.

A voltage measurement device for pulse-width modulation (PWM) signals is provided, which includes a conversion circuit and a processing circuit. The conversion circuit receives a first PWM signal and a second PWM signal from a motor driving device, and converts the first PWM signal and the second PWM signal into the absolute value signal and the polarity signal of the line-to-line voltage signal between the first PWM signal and the second PWM signal. The processing circuit converts the polarity signal and the absolute value signal into a first integral signal and a second integral signal, and reconstructs the line-to-line voltage signal according to the first integral signal and the second integral signal so as to obtain the reconstructed voltage signal of the line-to-line voltage signal.

To easily measure a voltage to ground of electromagnetic interference waves generated on a cable. A capacitance-to-ground measurement mechanism 10 includes a first electrode 11 and a second electrode 12 positioned at equal altitudes to be opposed to the earth, and a first voltage measurement device 15 to measure a voltage generated in a first resistance 14 connected between the first electrode 11 and the second electrode 12 by an output signal from an oscillation circuit 13. A voltage-to-ground measurement mechanism 30 includes a GND electrode 31 positioned at an altitude equal to that of the first electrode 11 and the second electrode 12 to be opposed to the earth, and a second voltage measurement device 33 to measure a voltage generated in a second resistance 32 connected between the GND electrode 31 and a probe 34 that is brought into contact with a cable core 106 as a measurement target. A computation mechanism 50 includes a computation device 51 to calculate a voltage to ground of electromagnetic interference waves generated on a cable based on data of respective voltages measured by the capacitance-to-ground measurement mechanism 10 and the voltage-to-ground measurement mechanism 30.

To easily measure a voltage to ground of electromagnetic interference waves generated on a cable. A capacitance-to-ground measurement mechanism 10 includes a first electrode 11 and a second electrode 12 positioned at equal altitudes to be opposed to the earth, and a first voltage measurement device 15 to measure a voltage generated in a first resistance 14 connected between the first electrode 11 and the second electrode 12 by an output signal from an oscillation circuit 13. A voltage-to-ground measurement mechanism 30 includes a GND electrode 31 positioned at an altitude equal to that of the first electrode 11 and the second electrode 12 to be opposed to the earth, and a second voltage measurement device 33 to measure a voltage generated in a second resistance 32 connected between the GND electrode 31 and a probe 34 that is brought into contact with a cable core 106 as a measurement target. A computation mechanism 50 includes a computation device 51 to calculate a voltage to ground of electromagnetic interference waves generated on a cable based on data of respective voltages measured by the capacitance-to-ground measurement mechanism 10 and the voltage-to-ground measurement mechanism 30.

It is described an attenuation measurement device (100), comprising:

i) a detector unit (110) having a coupling capacitance (120), and an input capacitance (130), wherein the detector unit (110) is configured to produce a detector output signal (112a,b) in reply to an input signal received at the coupling capacitance (120) and/or at the input capacitance (130);
ii) a test unit (140), coupled to the detector unit (110), and configured to provide a test signal (141) with at least one known signal property as a first input signal to the coupling capacitance (120);
iii) a calibration unit (150), coupled to the detector unit (110), and configured to provide a calibration signal (151) as a second input signal to the input capacitance (130); and
iv) a control unit configured to
a) determine a first detector output signal (112a) produced by the detector unit (110) in response to the test signal (141),
b) identify a specific calibration signal (151) that yields a second detector output signal (112b) that is comparable to the first detector output signal (112a), and
c) derive a capacitance-indicative information based on the identified specific calibration signal (151).

An electrosurgical generator which outputs high-frequency AC voltage for an electrosurgical instrument includes a leakage current detecting device for the connected electrosurgical instrument. The leakage current detecting device is embodied as a voltage measuring device, the inputs of which are connected in each case via a capacitive coupling to an active and a neutral line of the output line and which has a bipolar voltage divider having a predetermined fixed ratio. An asymmetry detector connected via a capacitive coupling compares upper and lower voltage at the voltage divider, and outputs a fault signal for leakage current in the case of deviation of the ratio of upper to lower voltage from the predetermined fixed ratio.

An electrosurgical generator which outputs high-frequency AC voltage for an electrosurgical instrument includes a leakage current detecting device for the connected electrosurgical instrument. The leakage current detecting device is embodied as a voltage measuring device, the inputs of which are connected in each case via a capacitive coupling to an active and a neutral line of the output line and which has a bipolar voltage divider having a predetermined fixed ratio. An asymmetry detector connected via a capacitive coupling compares upper and lower voltage at the voltage divider, and outputs a fault signal for leakage current in the case of deviation of the ratio of upper to lower voltage from the predetermined fixed ratio.

The present application provides method and circuit for monitoring a power supply, which firstly obtains an auxiliary side voltage from a switching power supply and then adopts a divided voltage circuit to obtain a divided voltage from the auxiliary side voltage, for detecting the divided voltage and a detected current flowed in the detection circuit with adopting a first detection circuit and a second detection circuit in an switch circuit to correspondingly generate a first and a second detection signals, which is corresponding to an ambient temperature and an output voltage of the power supply. Hereby, the power supply is monitored.

Controlling a switching element in accordance with a voltage output from a signal amplifying circuit enables adjusting a voltage to be received by a current calculation circuit. Even when a range of a air volume to be used is wide and a range of output of a DC motor is wide, or a current flowing through the DC motor has a wide range, a resistance value of a shunt resistor and an amplification factor of a signal amplifying circuit are not required to be reduced, and thus current detection accuracy of the DC motor can be improved.

Controlling a switching element in accordance with a voltage output from a signal amplifying circuit enables adjusting a voltage to be received by a current calculation circuit. Even when a range of a air volume to be used is wide and a range of output of a DC motor is wide, or a current flowing through the DC motor has a wide range, a resistance value of a shunt resistor and an amplification factor of a signal amplifying circuit are not required to be reduced, and thus current detection accuracy of the DC motor can be improved.