A power converting device includes a DC-DC converting circuit, a DC-AC converting circuit, and an insulation detecting circuit. The DC-DC converting circuit is configured to convert a DC input voltage to a DC bus voltage. The DC-AC converting circuit is electrically coupled to the DC-DC converting circuit and configured to convert the DC bus voltage to an AC voltage. The insulation detecting circuit is electrically coupled between the DC-DC converting circuit and the DC-AC converting circuit. The insulation detecting circuit is configured to detect a ground impedance value of the power converting device according to the DC bus voltage.

A power monitor includes a detecting circuit, a processing circuit, and a warning circuit. The detecting circuit detects a first abnormal condition of a primary side circuit and a second abnormal condition of a secondary side circuit. The processing circuit calculates a first class and a first occurring number of the first abnormal condition, and calculates a second class and a second occurring number of the second abnormal condition. The processing circuit determines whether the first occurring number is larger than a first predetermined number corresponding to the first class; if it is, the processing circuit outputs a first abnormal signal. The processing circuit determines whether the second occurring number is larger than a second predetermined number corresponding to the second class; if it is, the processing circuit outputs a second abnormal signal. The warning circuit outputs a warning signal according to the first or the second abnormal signal.

The present disclosure relates to a method for estimating parameters of a junction of a power semi-conductor element comprising: •—Detecting at least one stable on-line operating condition through measurements (2, 3, 4) of Von, Ion, Tc on a semi-conductor module (1) where Ion is a current for which the on-state voltage Von of the semi-conductor is sensitive to the temperature and Tc is the temperature of the casing of said semi-conductor element; •—Measuring and storing at least one parameter set Von, Ion, Tc of said at least one stable operating condition; •—in a calculating unit (52), providing calculations for minimizing the error between a junction temperature estimation Tj of an electrical model Tj=F(Von, Ion, θelec) comprising a first set of unknown parameters θelec and another junction temperature estimation Tjmod of a loss/thermal model Tj=G(lon, Tc, θ mod) comprising a second set of unknown parameters θ mod and obtaining at least one set of parameters θelec and at least one parameter θ mod providing minimization of said error; •—providing the calculated value of Tj with at least one of the calculated parameters sets θelec and/or θ mod and the measured Von, Ion, Tc; •—Storing the at least one parameters set θelec and/or θ mod and/or Tj.

A ground-fault detecting device includes: a first detecting module, having a first input terminal, a second input terminal, and a third input terminal coupled to a first-phase electric power, a second-phase electric power, and a third-phase electric power on an AC side of a photovoltaic power generating system respectively, for sampling voltages of the first-phase electric power, the second-phase electric power, and the third-phase electric power to generate a first sampled voltage, a second sampled voltage, and a third sampled voltage respectively; and a controller, coupled to the first detecting module, for determining if a ground-fault occurs in the AC side before the photovoltaic power generating system is connected to a grid according to the first sampled voltage, the second sampled voltage, and the third sampled voltage; wherein the controller generates an alarm signal when the ground-fault occurs in the AC side.

A method of detecting a serial arc fault in a DC-power circuit includes injecting an RF-signal with a narrow band-width into the DC-power circuit and measuring a response signal related to the injected RF-signal in the DC-power circuit. The method further includes determining a time derivative of the response signal, analyzing the time derivative, and signaling an occurrence of a serial arc fault in the power circuit based on the results of the analysis. A system for detecting an arc fault is configured to perform a method as described before.

A method of detecting a serial arc fault in a DC-power circuit includes injecting an RF-signal with a narrow band-width into the DC-power circuit and measuring a response signal related to the injected RF-signal in the DC-power circuit. The method further includes determining a time derivative of the response signal, analyzing the time derivative, and signaling an occurrence of a serial arc fault in the power circuit based on the results of the analysis. A system for detecting an arc fault is configured to perform a method as described before.

The present description concerns a circuit (5) for monitoring the operation of a component (1) associated with equipment (3), comprising: at least one device (100) for measuring one or a plurality of physical quantities associated with the operation of the component; and a circuit for calculating a value representative of a remaining lifetime of a component, said monitoring circuit (5) being linked to the equipment.

A current measurement apparatus for a three-phase inverter, according to one embodiment of the present invention, comprises: a current detection element connected to a lower end of one of three lower switches constituting the inverter; a current measurement unit measuring currents by using the current detection element and the two lower switches that are not connected to the current detection element; and a current correction unit for correcting, on the basis of the relationship between a first current value measured by means of the current detection element and second and third current values measured by means of the two lower switches, the second and third current values.

A method and apparatus for performing an on-system built-in self-test of a converter are provided. In the method, a controller generates a test signal and outputs the test signal to the converter. The controller receives a response signal from the converter and determines a plurality of bin powers of a plurality of bins, respectively, of a frequency domain signal representative of the response signal. The controller determines a figure of merit for the converter based on a first bin power of a first bin of the plurality of bin powers, where the first bin corresponds to a frequency of the test signal.

A method and apparatus for performing an on-system built-in self-test of a converter are provided. In the method, a controller generates a test signal and outputs the test signal to the converter. The controller receives a response signal from the converter and determines a plurality of bin powers of a plurality of bins, respectively, of a frequency domain signal representative of the response signal. The controller determines a figure of merit for the converter based on a first bin power of a first bin of the plurality of bin powers, where the first bin corresponds to a frequency of the test signal.