A motor driving device includes: a rectifier circuit for rectifying an AC input voltage supplied from an AC power supply to a DC voltage; a smoothing capacitor for smoothing the rectified DC voltage; a relay that outputs a contact signal when the input voltage is input to the rectifier circuit from the AC power supply; an input voltage detector for detecting the input voltage; a capacitor voltage detector for detecting the capacitor voltage; a volatile first storage; a nonvolatile second storage; and a backup start determiner for determining whether or not to start a backup operation of transferring the information stored in the first storage to the second storage, based on at least one of the contact signal, the input voltage and the capacitor voltage.

The subject disclosure describes a structure and method that generates the average of two or more reference quantities (e.g., reference voltage potentials) and monitors the integrity of the voltage reference potentials. The subject technology produces a reference with improved accuracy and more accurate monitoring compared to traditional techniques. For example, the subject technology provides for a fault circuit that includes a monitoring circuit, and an averaging circuit configured to receive a plurality of reference signals and to produce an averaged reference signal based on the received plurality of reference signals. In some examples, the monitoring circuit is configured to receive the averaged reference signal from the averaging circuit, compare the averaged reference signal to each of the plurality of reference signals, and generate a fault signal when the averaged reference signal deviates from at least one of the plurality of reference signals by at least a threshold value.

A measurement circuit may include a transistor having a first terminal, a second terminal, and a third terminal, wherein the first terminal is coupled to a first reference voltage. The measurement circuit may further include a first operational amplifier including a first input coupled to the second terminal of the transistor and an output coupled to the third terminal of the transistor. The first operational amplifier may further include a second input configured to receive a second reference voltage. The measurement circuit may also include a first unity-gain voltage follower including a second operational amplifier having a first input coupled to the first input of the first operational amplifier. Methods of measuring a threshold voltage, semiconductor devices, and electronic systems are also described.

A converter operable to convert an input voltage at an input node to an output voltage at an output node coupled to a load by switching on and off a transistor at a switching frequency, the converter comprising: an error amplifier circuit having a first input coupled to a reference voltage, a second input coupled to the output node through a resistive divider, a first output operable to output a control current and a second output operable to output a current equivalent to the control current; a peak current comparator circuit having a first input coupled to the second output of the error amplifier circuit, a second input and an output, the second input is coupled to the input node through an inductor; an off-time timer circuit having an input coupled to the first output of the error amplifier circuit and an output, the off-time timer circuit operable to set the switching frequency based on the control current; and a control circuit having a first input coupled to the output of the peak current comparator circuit, a second input coupled to the output of the off-time timer circuit and an output coupled to a control terminal of the transistor.

Transmission-line voltage measurements in a digital-electricity power system are validated by acquiring a series of transmission-line voltage measurements during a sample period when a transmitter-disconnect device is in a non-conducting state. A numerical analysis is performed to determine a point in time at which AC components in the transmission line have diminished and at which the primary change in the transmission-line voltage measurement values is due to DC decay. A receiver acquires a series of receiver-voltage measurements during the same sample period; and a numerical analysis is performed on the receiver-voltage measurements to determine the point in time at which the AC components have diminished and where the primary change in the transmission-line voltage measurement values is due to DC decay. The transmitter-disconnect device is then placed in a non-conducting state based on an evaluation of those measurements.

A method for extracting a characteristic signal from a power frequency signal includes steps of: S1, detecting a voltage half-wave zero-crossing area in a single voltage cycle in the power frequency signal by a signal; superimposing a voltage modulation signal on the voltage half-wave zero-crossing area, and superimposing an instantaneous pulse on a current cycle in the power frequency signal corresponding to the voltage half-wave zero-crossing area; generating the characteristic signal with current cycles and voltage cycles; S2, demodulating whether there is the voltage modulation signal in the power frequency signal, if so, executing step S3; and S3, demodulating the characteristic signal to obtain the current modulation signal and the voltage modulation signal respectively; and determining whether data corresponding to the current modulation signal and date corresponding to the voltage modulation signal are predetermined data, wherein if so, the characteristic signal exists. The method has strong anti-interference ability.

The earth leakage circuit breaker of the present disclosure includes a leakage current detection unit outputting a leakage current detection signal; a conversion unit outputting the leakage current magnitude of a fundamental wave component, a ratio of a third harmonic component, and a ratio of a positive pole peak current value to a negative pole peak current value; and a control unit comparing the leakage current magnitude of a fundamental wave component, the ratio of a third harmonic component, and the ratio of a positive pole peak current value to a negative pole peak current value with predetermined reference values to determine whether a leakage current of the alternating current component is generated or a leakage current of the direct current component is generated and to thereby output a trip control signal when it is determined that the leakage current of the direct current or alternating current component is generated.

A method and a system for detecting and processing one or more deviations from an acceptable electrical behavior at a point of interest in an electrical network, the system comprising a voltage sensor and/or a current sensor, a measurement-processor configured to process measurements received from the at least one of a voltage sensor and a current sensor, at least one storage for storing one or more acceptable values related to the electrical behavior at the point of interest, and a deviation-processor, the deviation processor is configured to receive one or more detected values related to the electrical behavior at a point in time at the point of interest and detect one or more deviations between the one or more acceptable values and the one or more detected values, and analyze one or more deviations between the one or more acceptable values and the one or more detected values.

A power conversion device including an intermediate capacitor that carries out a charging and discharging operation and a voltage sensor that detects a voltage of the intermediate capacitor, and including a current sensor that detects a current flowing in a reactor, and an abnormality determining unit that determines that there is an abnormality of the voltage sensor using a current value calculated based on a detected value from the current sensor, wherein a gain error, an offset error, and a sticking error of the voltage sensor can be detected.

A method includes selecting at least one first voltage that defines subsets of DC voltages from among an ordered set of DC voltages, comparing the first voltage with a DC reference voltage, selecting one of the subsets based on a result of the comparing, and comparing each voltage of the selected subset with the reference voltage.