Provided is a circuit including a switching transistor having a control terminal configured to receive a control signal and having a current flow path therethrough. The switching transistor becomes conductive in response to the control signal having a first value. The current flow path through the switching transistor provides a current flow line between two nodes. In a non-conductive state, a voltage drop stress is across the switching transistor. The circuit comprises a sense transistor that is coupled to and a scaled replica of the switching transistor. The sense transistor has a sense current therethrough. The sense current is indicative of the current of the switching transistor. The circuit includes coupling circuitry configured to apply the voltage drop stress across the sense transistor in response to the switching transistor being non-conductive. In the non-conductive state, the voltage drop stress is replicated across both the switching transistor and the sense transistor.

According to an embodiment, a capacitor diagnosis device includes a sensor, a frequency spectrum analysis unit, a frequency component extraction unit, and a diagnosis processing unit. The sensor detects a physical quantity that changes with an current flowing through a capacitor in a power conversion unit (PCU) for converting DC power smoothed by the capacitor connected in parallel to DC link(s) into AC power according to a power running operation. The frequency spectrum analysis unit generates a frequency spectrum based on a detection result of the sensor detected during the power running operation of the PCU. The frequency component extraction unit extracts a component of a specific frequency band related to a frequency depending on a configuration of the PCU based on the frequency spectrum. The diagnosis processing unit diagnoses a state of the capacitor based on at least a magnitude of the extracted component of the specific frequency band.

A switching arrangement of an inverter with a filter circuit and a grid relay. For the filter circuit use is made of an equivalent circuit consisting of effective filter inductance, from filter inductance and topology of the filter circuit and effective filter capacitance, from the filter capacitance and topology of the filter circuit. The effective filter inductance and the effective filter capacitance are system parameters. To determine system parameters, a voltage pulse is applied between a first conductor output and a second conductor output when the grid relay is open; the first conductor output and the second conductor output are connected via the switching arrangement to form a closed oscillating circuit a current value of the effective filter inductance and the effective filter capacitance is determined from a current curve and/or voltage curve in the resonant circuit as system parameters for controlling the switching arrangement.

The present disclosure provides an optimization method, a unit, and an electronic device of a shifted frequency (SF)-based electromagnetic transient simulation, comprising: determining a current amplitude and a voltage frequency based on a node voltage and a branch current calculated from a shifted frequency on a basis of a current time step; determining an optimal shifted frequency of the current time step based on the current amplitude and the voltage frequency; and updating the shifted frequency by adopting the optimal shifted frequency of the current time step for calculating a node voltage and a branch current of the next time step. The method, the unit, and the electronic device provided in the present disclosure may gradually update and optimize the shifted frequency in the simulation process so to enable the shifted frequency to reach the best, thus ensuring the accuracy of output current and voltage simulation results.

The present disclosure provides an optimization method, a unit, and an electronic device of a shifted frequency (SF)-based electromagnetic transient simulation, comprising: determining a current amplitude and a voltage frequency based on a node voltage and a branch current calculated from a shifted frequency on a basis of a current time step; determining an optimal shifted frequency of the current time step based on the current amplitude and the voltage frequency; and updating the shifted frequency by adopting the optimal shifted frequency of the current time step for calculating a node voltage and a branch current of the next time step. The method, the unit, and the electronic device provided in the present disclosure may gradually update and optimize the shifted frequency in the simulation process so to enable the shifted frequency to reach the best, thus ensuring the accuracy of output current and voltage simulation results.

A calibration amplifier includes: a plurality of transistors and a variable resistor configured to change in response to clock pulses. During a calibration cycle, one of the plurality of transistors switches on in each calibration step based on a plurality of enable signals, and a gain of the calibration amplifier changes until an output voltage of the calibration amplifier exceeds a reference voltage and is set to a calibrated gain. The calibration amplifier outputs the output voltage by amplifying an input voltage using the calibrated gain.

A calibration amplifier includes: a plurality of transistors and a variable resistor configured to change in response to clock pulses. During a calibration cycle, one of the plurality of transistors switches on in each calibration step based on a plurality of enable signals, and a gain of the calibration amplifier changes until an output voltage of the calibration amplifier exceeds a reference voltage and is set to a calibrated gain. The calibration amplifier outputs the output voltage by amplifying an input voltage using the calibrated gain.

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.

The objective of the present invention is to diagnose an abnormality in the amount of electricity generated by a distributed power source while restricting an increase in the number of sensors. A packet generating unit 200 generates electricity generation amount packet data D2a from electricity generation amount data D1 and identification data D6; an electricity generation feature quantity calculating unit 201 calculates electricity generation feature quantity data D3a, D3b indicating a feature quantity of the amount of electricity generated by each distributed power source, from each item of and a result output unit 203 consolidates abnormalities in the amounts of electricity generated by the distributed power sources, indicated by the determination result data D5, as abnormality diagnosis result data D7, and outputs the same to a display unit 206.

The objective of the present invention is to diagnose an abnormality in the amount of electricity generated by a distributed power source while restricting an increase in the number of sensors. A packet generating unit 200 generates electricity generation amount packet data D2a from electricity generation amount data D1 and identification data D6; an electricity generation feature quantity calculating unit 201 calculates electricity generation feature quantity data D3a, D3b indicating a feature quantity of the amount of electricity generated by each distributed power source, from each item of and a result output unit 203 consolidates abnormalities in the amounts of electricity generated by the distributed power sources, indicated by the determination result data D5, as abnormality diagnosis result data D7, and outputs the same to a display unit 206.