A waveform separator system for determining DC leakage current flowing through an insulating structure in a high voltage direct current power system, wherein the DC leakage current is a composite DC current comprising one or more high magnitude momentary spikes, and having a DC component and an AC component includes: (1) a waveform separator configured to receive the composite DC current flowing through the insulating structure and to separate the composite DC current into corresponding direct current (DC) and alternating current (AC) components wherein the AC component has a first rate of change, and wherein the DC component has a second rate of change, and wherein the first rate of change is greater than the second rate of change; (2) at least one comparator configured to receive the AC component and produce at least one corresponding digital signal; and (3) a processor configured to: (a) receive the at least one corresponding digital signal and the DC component, (b) analyze the at least one corresponding digital signal and the DC component, and; (c) determine a resultant leakage current flowing through the insulating structure.

A device and method for detecting the number of revolutions of a sensorless electric park brake (EPB) motor. The device for detecting the number of revolutions of a sensorless motor includes: an actuator driving motor used to set and release a parking brake of an EPB system; an electronic control module for controlling the motor, a vehicle battery for supplying power to the motor and the electronic control module; and a main processing unit for receiving an output signal of the electronic control module and estimating the number of revolutions of the motor, wherein the electronic control module further includes a ripple measuring unit for receiving an output signal of the motor and measuring a ripple of the motor.

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 test and measurement probe system (100,104), including an input (106) to receive an input signal, the input signal including a low frequency (LF) and/or direct current (DC) component and an alternating current (AC) component, an extractor circuit (110), such as an AC coupling circuit or a LF and/or DC rejection circuit, configured to receive the input signal and to separate the AC component and the LF and/or DC component from the input signal, a first output (118) to output the alternating current component to the test and measurement instrument, and a second output to output the direct current component to the test and measurement instrument. In some embodiments, the LF and/or DC component is digitized prior to being output by the second output.

A method for detecting a contact fault in a photovoltaic system is disclosed. The photovoltaic system includes an inverter and a photovoltaic generator connected to the inverter via DC current lines. The inverter includes a transmitter for coupling a first AC voltage signal having communication frequencies in a first frequency range between 125 kHz and 150 kHz into the DC current lines. A receiver is configured to couple out the first AC voltage signal and is arranged at the photovoltaic generator. A decoupling circuit is configured to decouple the impedance of the photovoltaic generator is arranged between the inverter and the photovoltaic generator, such that the photovoltaic generator is AC decoupled from a transmission path between the inverter and the decoupling circuit. The inverter communicates with the receiver via the first AC voltage signal, and wherein AC currents are measured in the DC current lines and AC voltages are measured between the DC current lines to aid in detection of a contact fault condition.

A circuit for alternating current and direct current leakage detection. The circuit can achieve multiple functions such as direct current leakage detection, alternating current leakage detection, and leakage sampling link self-check. The circuit mainly comprises: an LDO module for converting an externally input power supply voltage into a voltage required for leakage detection; a frequency divider module for performing frequency division on a high-frequency clock signal; a logic control module for driving an MOS transistor and controlling the switching of different working modes; an MOS transistor driving module for driving an external leakage detection coil; a leakage detection coil for inducing alternating current and direct current leakage signals and a leakage self-check signal; a sampling resistor for converting the current signal flowing through the leakage detection coil into a voltage signal; a PGA module for amplifying a sampling signal; a gain control module for controlling a PGA amplification factor; an ADC module for performing digital-to-analog conversion of the signals; a DSP module for processing the alternating current and direct current leakage signals and the leakage self-check signal; and a current limiting module for limiting a loop current.

A method includes obtaining electrical measurements of an input signal of a power system. The electrical measurements are obtained at a sampling frequency and the input signal is indicative of an operating frequency of the power system. The method includes generating an intermediate signal from the input signal. The intermediate signal has a direct current (DC) component indicative of a magnitude and a phase of the input signal. The method includes filtering the intermediate signal using an adjustable length filter to obtain the magnitude and the phase of the input signal. The length of the adjustable length filter varies based at least in part on a period measurement of the power system.

An impedance measurement device of the present disclosure includes: an electrochemical energy device; an amplifier connected to each connection terminal of the electrochemical energy device and configured to amplify a signal introduced into a wiring; and a main board configured to receive the signal from the amplifier and measure an impedance. Accordingly, the present invention has advantages in that high resistance to electromagnetic interference may be achieved by disposing a preamplifier close to a terminal of an electrochemical energy device to amplify only the signal without amplifying a noise introduced into a wiring.

A method for detecting high-frequency AC currents in a DC circuit including a common mode choke with two partial windings includes tapping voltages dropping across the two partial windings due to the AC current, superposing the tapped voltages, and obtaining a superposed AC voltage wherein differential mode portions of the tapped voltages are summed constructively and common mode portions of the voltages are summed destructively; and measuring the superposed AC voltage.

The present invention provides a trip control circuit for a circuit breaker capable of breaking a circuit when a fault current occurs due to a DC current component, as well as an AC current. The trip control circuit comprises a current transformer that has a core allowing a circuit to pass through and a secondary coil for detecting a current flowing on the circuit and providing a current detection signal; an oscillation circuit section that configured to apply an electrical signal to the secondary coil to increase a slope of a hysteresis loop of the current transformer to allow the secondary coil to detect a DC current and an AC current; and a trip determining circuit section that configured to compare a current value indicated by the current detection signal with a predetermined reference current value.