A semiconductor device includes a transistor, a diode, a first detection circuit, a second detection circuit, a calculation circuit, and a determination circuit. The diode is connected in reverse parallel with the transistor. The first detection circuit is configured to detect a change rate of a gate voltage of the transistor with respect to time. The second detection circuit is configured to detect a gate current of the transistor. The calculation circuit is configured to calculate a gate capacitance based on the change rate of the gate voltage with respect to time, and the gate current. The determination circuit is configured to determine, based on a determination result of the gate capacitance when a charge is injected to a gate of the transistor, whether a current flows to the diode or to the transistor.

An isolator includes: a transmission circuit that generates an alternating current transmission signal in which a first potential is set to be a reference potential; a first insulating element to which the alternating current transmission signal is supplied; a second insulating element that generates an alternating current reception signal in which a second potential is set to be a reference potential by being alternating current-coupled to the first insulating element through an insulating film; a reception circuit that reproduces reception data based on the alternating current reception signal; an impedance control unit that controls an impedance of the first or the second insulating element to be higher than an impedance before the control; and a leakage current detection unit that detects a leakage current flowing between the first and the second insulating elements through the first or the second insulating element in which the impedance has been controlled.

A motor driving device includes: a rectifier that rectifies an AC current and outputs a DC current to a DC link; an inverter unit that converts the DC current to an AC current for a motor; an initial charging unit that initially charges a smoothing capacitor with the DC current that flows through a charging resistor; a storage unit that stores a load capability of the charging resistor; a power calculation unit that calculates an amount of power generated in the charging resistor in response to the DC current flowing therethrough; and an opening/closing unit that shuts off the DC current from flowing in the smoothing capacitor when the amount of power reaches the load capability during an initial charging period and allows the DC current to flow in the smoothing capacitor after the shutoff when the amount of power is smaller than or equal to a threshold value.

A system and method for detecting deteriorated junctions within an electrical circuit includes a voltage channel circuit, a load circuit, and a microcontroller. The voltage channel circuit is connectable to the electrical circuit and includes a multiplier circuit, a peak detector circuit, and a filter circuit. The multiplier circuit is configured to square a line voltage of the electrical circuit. The peak detector circuit is configured to detect peak voltages of the line voltage based on an output of the multiplier circuit. A DC output voltage is provided from the filter circuit based on the output of the multiplier circuit. The load circuit is connectable to the electrical circuit and includes a plurality of resistors and a plurality of switches controlled by the microcontroller to enable current flow through the plurality of resistors to control the line voltage. The microcontroller is configured to detect deteriorated junctions based upon comparison of an output of the peak detector circuit and the DC output voltage.

A system and method are described for determining if power lines have been damaged. A virtual circuit is established between a control unit and a remote response unit. A signal is transmitted from the remote response unit responsive to a prior signal transmitted by the control unit. Based on a comparison of measurements of the response signal to expected values, a determination is made as to whether or not the line has been damaged.

An electric arc detection apparatus includes: a current sensor; a first filter; a second filter; an FFT processing portion that generates a high-frequency power spectrum and a low-frequency power spectrum; an electric arc detection portion that detects an electric arc by using the high-frequency power spectrum; a pseudo electric arc mask portion that determines a pseudo electric arc by using the low-frequency power spectrum; and an electric arc presence/absence determining portion.

An arc fault detection unit is disclosed for a low-voltage electrical circuit. The arc fault detection unit includes at least one voltage sensor, for periodically determining electrical voltage values of the electrical circuit, connected to an evaluation unit. The evaluation unit is designed such that a first half of a first number of voltage values is continuously summed to form a first partial sum and the second half of the voltage values is continuously summed to form a second partial sum and a difference of the two partial sums is calculated. Either as one alternative the difference or the amplitude of the difference is compared with a first threshold value and if the value is exceeded, an arc fault detection signal is output; or as a second alternative the difference is compared with a second threshold value and if the value is undershot, an arc fault detection signal is output.

An embodiment relates to an arc fault detection unit for an electrical low-voltage circuit including, connected to an evaluation unit, a voltage sensor assigned to the circuit, for periodically determining electrical voltage values of the circuit; and a current sensor assigned to the circuit, for periodically determining electrical current values. They are embodied such that pairs of a voltage and a current value are determined continuously at a point in time. In each case, a first value pair of a voltage and of a current value is present at a first point in time, a second value pair is present at a second point in time, and a third value pair is present at a third point in time. An arc voltage, which is compared to a threshold value, is calculated from the three value pairs. If the threshold value is exceeded, an arc fault detection signal is output.

An arc fault detection unit for an electrical low-voltage circuit, includes at least one voltage sensor assigned to the circuit, for periodically determining electrical voltage values of the circuit, and at least one current sensor assigned to the circuit, for periodically determining electrical current magnitudes of the circuit, both of which are connected to an evaluation unit. The sensors being embodied such that value pairs, having a voltage value and a current magnitude are determined continuously, a value set including a plurality of value pairs. Further, an arc voltage, compared to a first threshold value, is calculated from three value sets and in response to the first threshold value being exceeded, an arc fault detection signal is output.

A switching power converter is provided that communicates with a mobile device to receive a value of a load detection current. The switching power converter adjusts the cycling of a power switch until a constant current mode of operation is entered with a known output current driving the mobile device. The switching power converter subtracts the load current from the output current to measure a soft-short circuit current.