The present invention provides an occupant classification apparatus for a vehicle. The occupant classification apparatus for a vehicle includes a sensor mat that is mounted on each seat in the vehicle to sense objects disposed on the seats. An impedance measurer is configured to measure a current based on impedance of the object using the sensor mat A controller is configured to analyze the current measured by the impedance measurer and estimate the object that corresponds to the analyzed result.

A current sensor system for accurately measuring an AC electrical current having frequencies up to 2 kHz, the system comprising: an electrical conductor (e.g. busbar) for conducting said AC current thereby creating a first magnetic field; a magnetic sensor device for measuring a magnetic field component or gradient; an object (e.g. a metal plate) having an electrically conductive surface arranged in the vicinity of said conductor for allowing eddy currents to flow in said surface, thereby creating a second magnetic field which is superimposed with the first magnetic field; wherein the magnetic sensor device is configured for determining the current as a signal or value proportional to the measured component or gradient. The metal plate may have an opening. The current sensor system may further comprise a shielding.

Systems and methods for detecting an arc fault in a circuit breaker use a single-coil current rate of change (di/dt) sensor for monitoring both low frequency alternating current (AC) and broadband high frequency noise on a power line. The di/dt sensor is optimized to amplify any broadband high frequency noise, typically from about 1 MHz to 40 MHz, that may be present on the power line. Low frequency signals representing the current being monitored, typically from about 1 Hz to 10 KHz, is provided to an active integrator circuit with a high gain to enable the single-coil sensitivity. To shorten capacitor charge up time of the active integrator circuit, a charging current is provided to the active integrator circuit upon startup of the circuit breaker.

A device (9) for protecting a direct current electrical system (1) having one or more modules (2) from electric arcs comprises: a first sensor (10) provided with a first ring of ferromagnetic material configured to generate a first signal, representing a oscillating component of a current flowing through a cable inserted into the ring; a conditioning stage (12), having a bandpass filter, for conditioning the first signal; a first threshold comparator (13); a counter (15); a processor (14); a second sensor (19), configured to generate a second signal representing a direct current component of the current flowing through the cable; a second threshold comparator (20).

A method for estimating a fundamental component of an AC voltage includes receiving a timely varying measurement signal of the AC voltage; parametrizing a fundamental component of the AC voltage; and determining parameters of the fundamental component based on minimizing a cost function. The fundamental component has a rated frequency, a variable amplitude and a variable phase shift. The cost function is based on an integral of a norm of a difference between the measurement signal and the parametrized fundamental component via a time horizon. The time horizon starts at an actual time point and goes back via a predefined length. The cost function includes a term based on a norm of the difference between a value of the fundamental component at the actual time point and a value of a previously estimated fundamental component at the actual time point, where the previously estimated fundamental component has been determined for a previous time point.

A method and apparatus to compensate for distortion of a waveform due to the skin effect in a current shunt. The method includes modeling the complex impedance of the shunt as component complex impedances. By designing a filter corresponding to the component complex impedances, the distortion of a waveform across the shunt may be reversed to provide an accurate replica of the undistorted waveform.

A current detector includes: a current sensor that is constructed using a Rogowski coil, detects a current flowing in a measured object, and outputs a detection signal corresponding to a current value of the current; a transfer line that is constructed of a distributed constant line and transfers the detection signal; an impedance converting circuit that is provided between the current sensor and the transfer line and has an input impedance equal or substantially equal to a characteristic impedance of the current sensor; an integrator circuit that integrates the detection signal inputted via the transfer line and outputs an output signal indicating a current value of the current; and a resistance circuit that has a resistance value that is equal or substantially equal to a characteristic impedance of the transfer line and is connected in series between the transfer line and the integrator circuit.

The disclosure relates to a device for measuring electrical current in an electrical conductor (2), the device comprising: a measuring circuit configured to be connected to the electrical conductor, the measuring circuit comprising: a resistor based measuring circuit comprising a resistor (10), a transformer based measuring circuit comprising a current transformer (20) comprising a primary coil (20a), connected in series with the resistor (10) of the resistor based measuring circuit, a first inverter (12) configured to transform a first digital signal using a transfer function being an inverse of a transfer function representing the resistor based measuring circuit; a second inverter (22) configured to transform a second digital signal using a transfer function being an inverse of a transfer function representing the transformer based measuring circuits; and a signal combiner (5) configured to combine the transformed first and second digital signals, thereby providing a digital signal representing the electrical current in the electrical conductor. The disclosure also relates to a method for measuring electrical current in an electrical conductor.

A method and system for measuring alternating-current system quantities through measurement connections producing frequency-dependent errors, in which method the analog signal of at least one measurement channel is sampled at a selected an approximately measured frequency f.sub.m at a multiple frequency f.sub.s, creating a base series depicting a period on each measurement channel, from each base series the fundamental frequency and the magnitude or phase-angle values or both of at least one harmonic frequency component are calculated with the aid of Fourier analysis or similar, each of which is corrected with the aid of a calibrated frequency-dependent function k(f), when the selected quantities are calculated from the calibrated values.

A method may include measuring a physical quantity associated with a load driven by an amplifier, generating a windowing function having a variable length and based on a number of samples of the physical quantity to be processed, applying the windowing function to the physical quantity, performing a transform on the physical quantity as filtered by the windowing function, and determining a characteristic of the load based on the transform.