Systems and methods that provide a portable, verified voltage source that allows safe testing of separate contact and non-contact voltage measurement devices. A proving unit of the present disclosure selectively provides a known or specified direct current (DC) voltage, a contact alternating current (AC) voltage, and a non-contact AC voltage, which voltages may be fixed or may be user-selectable. The proving unit may include a visual indicator and/or an audible indicator that provides the user with an indication confirming that the proving unit is supplying the selected output voltage within the specifications of the proving unit, so the user will know that the proving unit is operating normally and is ready for testing the operation of a contact or non-contact voltage measurement device. If the proving unit cannot provide the specified voltage output, the indicator(s) provides a signal to the user that the proving unit is currently non-functional.

A current detecting apparatus measures an input current or an output current of an electronic apparatus. The current detecting apparatus includes a current detecting module, a direct-current measurement module and a current detecting module. The current detecting module includes a coil configured to electromagnetically couple to a path of an input or a path of an output of the electronic apparatus to obtain a first voltage signal. The direct-current measurement module measures the path of the input or the path of the output to obtain a second voltage signal. The current detecting module converts the first voltage signal into a first current command, and converts the second voltage signal into a second current command. The first current command is an alternating-current component of the input current or the output current. The second current command is a direct-current component of the input current or the output current.

A current detecting apparatus measures an input current or an output current of an electronic apparatus. The current detecting apparatus includes a current detecting module, a direct-current measurement module and a current detecting module. The current detecting module includes a coil configured to electromagnetically couple to a path of an input or a path of an output of the electronic apparatus to obtain a first voltage signal. The direct-current measurement module measures the path of the input or the path of the output to obtain a second voltage signal. The current detecting module converts the first voltage signal into a first current command, and converts the second voltage signal into a second current command. The first current command is an alternating-current component of the input current or the output current. The second current command is a direct-current component of the input current or the output current.

An estimation system includes a battery, an inverter, a motor, a U-phase current sensor, and an ECU. The inverter includes U-phase upper and lower arm circuits, V-phase upper and lower arm circuits, and W-phase upper and lower arm circuits. A mode of the inverter includes a first mode in which the U-phase upper arm circuit, the V-phase lower arm circuit, and the W-phase lower arm circuit are on and a second mode in which the U-phase lower arm circuit, the V-phase upper arm circuit, and the W-phase upper arm circuit are on. The ECU performs estimation processing for estimating a current value of the battery. The estimation processing includes first processing for estimating the current value in accordance with a detection value from the U-phase current sensor when the mode of the inverter is set to the first mode or the second mode.

An estimation system includes a battery, an inverter, a motor, a U-phase current sensor, and an ECU. The inverter includes U-phase upper and lower arm circuits, V-phase upper and lower arm circuits, and W-phase upper and lower arm circuits. A mode of the inverter includes a first mode in which the U-phase upper arm circuit, the V-phase lower arm circuit, and the W-phase lower arm circuit are on and a second mode in which the U-phase lower arm circuit, the V-phase upper arm circuit, and the W-phase upper arm circuit are on. The ECU performs estimation processing for estimating a current value of the battery. The estimation processing includes first processing for estimating the current value in accordance with a detection value from the U-phase current sensor when the mode of the inverter is set to the first mode or the second mode.

Systems and methods for measuring alternating current (AC) voltage of an insulated conductor (e.g., insulated wire) are provided, without requiring a galvanic connection between the conductor and a test electrode or probe. A non-galvanic contact (or non-contact) voltage measurement system includes a conductive sensor, an internal ground guard and a reference shield. A common mode reference voltage source is electrically coupled between the internal ground guard and the reference shield to generate an AC reference voltage which causes a reference current to pass through the conductive sensor. At least one processor receives a signal indicative of current flowing through the conductive sensor due to the AC reference voltage and the AC voltage in the insulated conductor, and determines the AC voltage in the insulated conductor based at least in part on the received signal.

In some examples, a method of performing measurement of a device under test (DUT) coupled to a connector includes determining a first voltage signal representative of a current of the DUT, the current flowing through the connector. The method also includes determining a second voltage signal representative of a voltage of the DUT, as provided at the connector. The method also includes determining a calibration current according to the first voltage signal. The method also includes modifying measurement of the DUT according to the calibration current.

In some examples, a method of performing measurement of a device under test (DUT) coupled to a connector includes determining a first voltage signal representative of a current of the DUT, the current flowing through the connector. The method also includes determining a second voltage signal representative of a voltage of the DUT, as provided at the connector. The method also includes determining a calibration current according to the first voltage signal. The method also includes modifying measurement of the DUT according to the calibration current.

An absence of voltage indicator has an isolation circuit, an FM modulator attached to the isolation circuit, a reference oscillator, and a mixer attached to the reference oscillator and the FM modulator, wherein the output of the mixer is the difference of the two signals. In one embodiment, the FM modulator includes a variable capacitor which varies in response to a voltage in parallel to a fixed capacitor and an inductor in parallel to the capacitors.

An absence of voltage indicator has an isolation circuit, an FM modulator attached to the isolation circuit, a reference oscillator, and a mixer attached to the reference oscillator and the FM modulator, wherein the output of the mixer is the difference of the two signals. In one embodiment, the FM modulator includes a variable capacitor which varies in response to a voltage in parallel to a fixed capacitor and an inductor in parallel to the capacitors.