A measurement system includes: a first voltage measurement unit, which measures a first voltage as a line voltage between first and second phases of a three-phase power line configured by three phases including the first, second, and a third phase; a first current measurement unit, which measures a first current as a current of the first phase; a third current measurement unit, which measures a third current as a current of the third phase; a determination unit, which determines a direction of rotation of the three phases based on the first voltage and the first current; and a computation unit which, based on at least the determination of the direction of rotation by the determination unit, computes a change in a current phase due to a load device in each of the first, third, and a second current as a current of the second phase.

A measurement system includes: a first voltage measurement unit, which measures a first voltage as a line voltage between first and second phases of a three-phase power line configured by three phases including the first, second, and a third phase; a first current measurement unit, which measures a first current as a current of the first phase; a third current measurement unit, which measures a third current as a current of the third phase; a determination unit, which determines a direction of rotation of the three phases based on the first voltage and the first current; and a computation unit which, based on at least the determination of the direction of rotation by the determination unit, computes a change in a current phase due to a load device in each of the first, third, and a second current as a current of the second phase.

According to one embodiment, a sensor includes an element part, and a control circuit part. The element part includes first and second elements. Each of the first and second elements includes a first magnetic element and a first conductive member. The control circuit part includes a first current circuit, a differential circuit, and a phase detection circuit. The first current circuit is configured to supply a first current to the first conductive member. The differential circuit is configured to output a differential signal corresponding to a difference of a first signal and a second signal. The first signal corresponds to a change in a first electrical resistance of the first magnetic element of the first element, The second signal corresponds to a change in a second electrical resistance of the first magnetic element of the second element. The phase detection circuit is configured to perform a phase detection of the differential signal.

According to one embodiment, a sensor includes an element part, and a control circuit part. The element part includes first and second elements. Each of the first and second elements includes a first magnetic element and a first conductive member. The control circuit part includes a first current circuit, a differential circuit, and a phase detection circuit. The first current circuit is configured to supply a first current to the first conductive member. The differential circuit is configured to output a differential signal corresponding to a difference of a first signal and a second signal. The first signal corresponds to a change in a first electrical resistance of the first magnetic element of the first element, The second signal corresponds to a change in a second electrical resistance of the first magnetic element of the second element. The phase detection circuit is configured to perform a phase detection of the differential signal.

Filter circuitry is constituted by transversal filters which are connected in parallel to each other. The transversal filters change amplitude and a phase of an input digital signal X.sub.in[n.Math.T.sub.s] and output different digital signals X.sub.1[n.Math.T.sub.s], X.sub.2[n.Math.T.sub.s], and X.sub.3[n.Math.T.sub.s] as respective resulting digital signals whose amplitude and phase have been changed. A phase frequency computer computes a phase θ.sub.X[n.Math.T.sub.s] and a frequency f.sub.X[n.Math.T.sub.s] of the input digital signal X.sub.in[n.Math.T.sub.s] by performing phase computation and frequency computation using the digital signals X.sub.1[n.Math.T.sub.s], X.sub.2[n.Math.T.sub.s], and X.sub.3[n.Math.T.sub.s] output by the transversal filters.

According to one embodiment, a voltage converting device includes a DC power source; an inverter generating AC power; an AC component detector configured to detect an AC component of current flowing through a first terminal or a second terminal of the inverter in the DC power source side; and a phase estimator configured to estimate a phase relation between a phase of voltage of the AC power and a phase of current of the AC power based on an amplitude of a specific frequency component contained in a first absolute value signal of the AC component. The AC power generated by the inverter is supplied to a loading device, and an impedance of the loading device at a fundamental of a driving frequency of the inverter is smaller than an impedance of the loading device at an odd-order harmonic of the driving frequency.

According to one embodiment, a voltage converting device includes a DC power source; an inverter generating AC power; an AC component detector configured to detect an AC component of current flowing through a first terminal or a second terminal of the inverter in the DC power source side; and a phase estimator configured to estimate a phase relation between a phase of voltage of the AC power and a phase of current of the AC power based on an amplitude of a specific frequency component contained in a first absolute value signal of the AC component. The AC power generated by the inverter is supplied to a loading device, and an impedance of the loading device at a fundamental of a driving frequency of the inverter is smaller than an impedance of the loading device at an odd-order harmonic of the driving frequency.

Methods for determining a line fault of a power system. The methods include obtaining sampled values of voltages and currents of phases of a power line in the power system, determining a phase compensation voltage of a first phase and an interphase compensation voltage of an interphase loop between a second phase and a third phase, and detecting the line fault in the first phase and/or the interphase loop by comparing the phase compensation voltage and the interphase compensation voltage.

A method for generating an electrochemical impedance spectrum for a battery includes: collecting, in a discharge state of a battery, battery discharge information of the battery periodically according to a preset collection interval, where the battery discharge information includes collection time, and current information and voltage information associated with the collection time; performing Fourier transform according to the collection interval and battery discharge information, to obtain multiple frequency-based first battery signals; determining a second battery signal from the multiple first battery signals, where the second battery signal includes a voltage signal greater than or equal to a preset voltage threshold; and determining an electrochemical impedance at a corresponding frequency according to the second battery signal, and constructing an electrochemical impedance spectrum according to all the electrochemical impedance.

A method for generating an electrochemical impedance spectrum for a battery includes: collecting, in a discharge state of a battery, battery discharge information of the battery periodically according to a preset collection interval, where the battery discharge information includes collection time, and current information and voltage information associated with the collection time; performing Fourier transform according to the collection interval and battery discharge information, to obtain multiple frequency-based first battery signals; determining a second battery signal from the multiple first battery signals, where the second battery signal includes a voltage signal greater than or equal to a preset voltage threshold; and determining an electrochemical impedance at a corresponding frequency according to the second battery signal, and constructing an electrochemical impedance spectrum according to all the electrochemical impedance.