Voltage sensor (1) comprising a voltage divider (40) for sensing an AC voltage of a HV/MV power conductor (10). For adjusting the common overall impedance of the low-voltage portion of the voltage divider towards a desired impedance, the low-voltage portion (60) comprises one or more low-voltage impedance elements (110), a plurality of adjustment impedance elements (80) and a plurality of switches. In its connect state, each switch electrically connects an adjustment impedance element in parallel to at least one of the one or more low-voltage impedance elements (110). The overall impedance of the high-voltage portion (50) and the overall impedance of the low-voltage portion (60) of the voltage divider (40) are adapted such that, by bringing one or more of the switches (90) into their connect state, the voltage divider (40) has, for an AC voltage of between 5 and 25 kV phase-to-ground and a frequency of between 40 and 70 Hertz, a dividing ratio of 3077, of 6154, of 6769 or of 10 000.

Voltage sensor (1) comprising a voltage divider (40) for sensing an AC voltage of a HV/MV power conductor (10). For adjusting the common overall impedance of the low-voltage portion of the voltage divider towards a desired impedance, the low-voltage portion (60) comprises one or more low-voltage impedance elements (110), a plurality of adjustment impedance elements (80) and a plurality of switches. In its connect state, each switch electrically connects an adjustment impedance element in parallel to at least one of the one or more low-voltage impedance elements (110). The overall impedance of the high-voltage portion (50) and the overall impedance of the low-voltage portion (60) of the voltage divider (40) are adapted such that, by bringing one or more of the switches (90) into their connect state, the voltage divider (40) has, for an AC voltage of between 5 and 25 kV phase-to-ground and a frequency of between 40 and 70 Hertz, a dividing ratio of 3077, of 6154, of 6769 or of 10 000.

Feed forward compensation of parasitic capacitance in a device frontend is provided. A feed forward element is positioned along at least a portion of a length of a first input resistance and a distance away from the first input resistance. In some implementations, the feed forward element has a width that is increasing along the at least a portion of the length of the first input resistance. The feed forward element is operative to introduce an element capacitance that offsets a parasitic capacitance in a volume surrounding the first input resistance.

Feed forward compensation of parasitic capacitance in a device frontend is provided. A feed forward element is positioned along at least a portion of a length of a first input resistance and a distance away from the first input resistance. In some implementations, the feed forward element has a width that is increasing along the at least a portion of the length of the first input resistance. The feed forward element is operative to introduce an element capacitance that offsets a parasitic capacitance in a volume surrounding the first input resistance.

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.

An input-voltage-off detection apparatus includes a voltage adjustment unit, a time delay unit, a voltage clamp unit, an auxiliary voltage discharge switch unit and an isolation notification unit. The voltage adjustment unit receives an input voltage. The time delay unit utilizes the input voltage to generate a direct current voltage. After the input voltage is cut off, the direct current voltage stored in the time delay unit discharges to the voltage adjustment unit. When the direct current voltage reduces to a predetermined voltage, the auxiliary voltage discharge switch unit is turned on, so that an auxiliary voltage winding sends a working voltage to the isolation notification unit. After the isolation notification unit receives the working voltage, the isolation notification unit notifies an electronic apparatus that the input voltage is cut off.

An input-voltage-off detection apparatus includes a voltage adjustment unit, a time delay unit, a voltage clamp unit, an auxiliary voltage discharge switch unit and an isolation notification unit. The voltage adjustment unit receives an input voltage. The time delay unit utilizes the input voltage to generate a direct current voltage. After the input voltage is cut off, the direct current voltage stored in the time delay unit discharges to the voltage adjustment unit. When the direct current voltage reduces to a predetermined voltage, the auxiliary voltage discharge switch unit is turned on, so that an auxiliary voltage winding sends a working voltage to the isolation notification unit. After the isolation notification unit receives the working voltage, the isolation notification unit notifies an electronic apparatus that the input voltage is cut off.

An external power supply and a system connection detection unit applied thereto are provided. For providing DC power, the external power supply separably connects with a positive input terminal and a negative input terminal of a system through a positive output terminal and a negative output terminal respectively. When the positive output terminal and the negative output terminal are respectively connected to the positive input terminal and the negative input terminal, a system detection terminal connects with a system connection terminal of the system, and a connection status signal generated by the system connection detection unit switches the operation of the external power supply from a deep sleeping mode to a normal operation mode. The system connection terminal is electrically connected to one of the positive input terminal and the negative input terminal through at least a first resistive element.

A voltage divider circuit assembly includes resistors, an external electrostatic shield, and internal electrostatic shield(s). The resistors are in series with each other between input terminals that receive an input voltage. An external resistor is disposed between sensing terminals that conduct an output voltage that is the input voltage divided by the resistors in the series. The external shield is conductively coupled with the series of the resistors with the external resistor disposed outside of the external shield and the other resistor(s) inside the external shield. The internal shield(s) are conductively coupled with the resistors and disposed inside the external shield. A first internal resistor is disposed inside the external shield and outside of the internal shield(s). One or more remaining resistors are inside the internal shield(s). The shields divide parasitic capacitances to enable the measurement of dynamically changing high voltage input signals.