System and methods for high accuracy, non-intrusive current sensing are provided. A system may include two magnetic field sensors configured for differential sensing. The system may further include frontend circuitry configured to remove direct current (DC) offset of the magnetic field sensors, upconvert the outputs of the magnetic field sensors, and filter out at least one frequency component from the up-converted signals. The system may receive output signals from the front-end circuitry corresponding to each sensor. The system may further calculate a differential signal based on the output signals. The system may apply optimal detection based on the differential signal and a reference signal to calculate a measurement of current flow. The system may determine a phase angle measurement between the differential signal and the reference signal to calculate a direction of the current flow in the conductor and output various measurement information related to the detected current.

A signal processing circuit for a measurement instrument is described. The signal processing circuit includes an analysis circuit, a measurement input, and at least two parallel measurement channels. The parallel measurement channels are configured to process the input signal, thereby generating first and second complex-valued measurement signals. The analysis circuit is configured to determine first and second error quantities associated with the first and second complex-valued measurement signals, respectively. The analysis circuit is configured to determine a complex-valued average signal corresponding to a combined average of the first and second complex-valued measurement signals. The analysis circuit is configured to determine a combined error quantity based on the complex-valued average signal. The analysis circuit is configured to determine a comparison quantity based on the combined error quantity as well as based on the first error quantity and/or the second error quantity.

A lossless exciting current sampling circuit for an isolated converter includes first and second voltage sampling circuits and a subtraction circuit formed by an operational amplifier. The two sampling circuits sample voltages of the primary winding of an isolation transformer, with outputs fed into the subtracter. The subtracter output is the circuit's output. RC low-pass filters with large time constants are used as primary voltage sampling circuits, realizing integration of voltage differences between the exciting inductance terminals, enabling lossless current sampling without resistors or transformers. The current sampling result is utilized for volt-second balance control, realized along with a hold circuit and comparator which compares the sampling hold result with the current sampling result to generate a control signal.

An insulation monitoring device, according to various embodiment of the present application, comprising an impedance formed between a power line and a ground of a system comprises, a signal generation circuit for applying a triangular wave signal to the power line through a signal measurement circuit, the signal measurement circuit for measuring a voltage difference across the detection resistor of the signal measurement circuit or a current flowing through the detection resistor when the triangular wave signal is applied to the impedance, a control circuit for obtaining an impedance value of the impedance based on at least one of the voltage difference and the current, and monitoring the impedance value.

A sensor device includes an electrically conductive carrier and a magnetic field sensor mounted on the electrically conductive carrier. The magnetic field sensor includes a first pair of first sensing elements configured to provide a first differential signal representative of a magnetic field generated by an electrical current through an electrical conductor and by eddy currents generated in the electrically conductive carrier. The magnetic field sensor further includes a second pair of second sensing elements configured to provide a second differential signal representative of a magnetic field generated by the eddy currents and independent of a magnetic field generated by the electrical current through the electrical conductor. The sensor device further includes a unit configured to provide an output signal based on a difference or a sum including the first differential signal and the second differential signal.

A current detection circuit includes a first resistor and a second resistor identical in current path and equal in resistance value, a first and second signal transmission units which transmit respectively a signal representing the potential of the first resistor, a third and fourth signal transmission units which transmit respectively a signal representing the potential of the second resistor, a first difference operation unit which calculates the difference between the respective signals from the first and second signal transmission units, a second difference operation unit which calculates the difference between the respective signals from the third and fourth signal transmission units, and a summing unit which sums the signals output from the first and second difference operation units. The first signal transmission unit and the fourth signal transmission unit, and the second signal transmission unit and the third signal transmission unit are disposed in proximity to each other.

Ripple detection device and seat device are provided that can optimally control variable filter passband in accordance with motor driving state by using linear relational expression for deriving ripple current frequency based on ripple current and motor terminal-to-terminal voltage, and can detect ripple pulses with high accuracy. Ripple detection device includes ripple current detector for detecting ripple current generated when motor is driven, motor voltage detector for detecting motor terminal-to-terminal voltage, variable filter for passing a component, of the ripple current detected by ripple current detector, that is in predetermined frequency band, and frequency adjuster for adjusting predetermined frequency band of variable filter to include ripple current frequency derived using linear relational expression for deriving ripple current frequency based on ripple current detected by ripple current detector and motor terminal-to-terminal voltage detected by motor voltage detector.

The present invention provides an information acquisition device and method for a pulsating voltage. The device uses a signal isolation circuit to receive a switch-controlling voltage of a motor driver and outputs a logic voltage. When a signal processing module receives the logic voltage from the signal isolation circuit, the signal processing module starts a counter and determines whether a rising or falling edge is present in the logic voltage. When determining that a first rising edge, a first falling edge, and a second rising edge are respectively present in the logic voltage, the signal processing module respectively stores a value of the counter as a first counter value, a second counter value, and a third counter value, and proceeds to calculate a voltage duty cycle of a motor-switching period based on the counter values. The present invention calculates the voltage duty cycle with improved accuracy.

A detector circuit for a measurement instrument is described. The detector circuit includes a first signal input, a second signal input, and an averaging sub-circuit. The first signal input is configured to receive a first complex-valued measurement signal associated with an input signal received from a device under test. The second signal input is configured to receive a second complex-valued measurement signal associated with the input signal received from the device under test. The averaging sub-circuit is configured to determine an average of the first complex-valued measurement signal and of a complex conjugate of the second complex-valued measurement signal over a predetermined number of samples, thereby obtaining a complex-valued average signal. The averaging sub-circuit is configured to generate an output signal based on the complex-valued average signal. Further, a signal processing circuit and a measurement instrument are described.

The present application relates to current sensing circuitry (100) that comprises a differential amplifier (110) comprising first and second inputs configured to sense a current across a sense resistance, and an output configured to output a current sense signal. The circuitry (100) further comprises a first current source, a second current source and a switch network operable in: a first phase in which the first current source is connected to the first input and disconnected from the output, and the second current source is connected to the output and disconnected from the first input; and a second phase in which the first current source is connected to the output and disconnected from the first input, and the second current source is connected to the first input and disconnected from the output.