A ground fault detection device compatible with Y capacitors of various capacities without increasing the capacitance of a detection capacitor is provided. The ground fault detection device includes a first detection capacitor that operates as a flying capacitor, a second detection capacitor that operates as a flying capacitor, a control unit measures the charging voltage of the first detection capacitor and the second detection capacitor, a switching unit that switches between a state using a first measurement system in which the first detection capacitor is charged with the high voltage battery and the charging voltage of the first detection capacitor is measured by the control unit, and a state using a second measurement system in which the second detection capacitor is charged with the high voltage battery and the charging voltage of the second detection capacitor is measured by the control unit.

A ground fault detection device compatible with Y capacitors of various capacities without increasing the capacitance of a detection capacitor is provided. The ground fault detection device includes a first detection capacitor that operates as a flying capacitor, a second detection capacitor that operates as a flying capacitor, a control unit measures the charging voltage of the first detection capacitor and the second detection capacitor, a switching unit that switches between a state using a first measurement system in which the first detection capacitor is charged with the high voltage battery and the charging voltage of the first detection capacitor is measured by the control unit, and a state using a second measurement system in which the second detection capacitor is charged with the high voltage battery and the charging voltage of the second detection capacitor is measured by the control unit.

A monitoring system includes an array of optical sensors disposed within a transformer tank. Each optical sensor is configured to have an optical output that changes in response to a temperature within the transformer tank. An analyzer is coupled to the array of optical sensors. The analyzer is configured to determine a sensed temperature distribution based on the sensed temperature. The sensed temperature distribution is compared to an expected distribution. Exterior contamination of the transformer tank is detected based on the comparison.

A monitoring system includes an array of optical sensors disposed within a transformer tank. Each optical sensor is configured to have an optical output that changes in response to a temperature within the transformer tank. An analyzer is coupled to the array of optical sensors. The analyzer is configured to determine a sensed temperature distribution based on the sensed temperature. The sensed temperature distribution is compared to an expected distribution. Exterior contamination of the transformer tank is detected based on the comparison.

A driver device includes: a voltage terminal; a ground terminal; an output terminal; a first nMOS power transistor having a drain electrically connected to the voltage terminal, a source electrically connected to the output terminal, and a gate; an overvoltage protection circuit configured to limit a gate-to-source voltage of the first nMOS power transistor in a normal operating mode for the driver device; a pulldown circuit configured to force the first nMOS power transistor off in a stress test mode for the driver device; and a blocking circuit configured to block current flow from the output terminal to the ground terminal through the overvoltage protection circuit and the pulldown circuit in the stress test mode. A method of stress testing the driver device is also described.

A driver device includes: a voltage terminal; a ground terminal; an output terminal; a first nMOS power transistor having a drain electrically connected to the voltage terminal, a source electrically connected to the output terminal, and a gate; an overvoltage protection circuit configured to limit a gate-to-source voltage of the first nMOS power transistor in a normal operating mode for the driver device; a pulldown circuit configured to force the first nMOS power transistor off in a stress test mode for the driver device; and a blocking circuit configured to block current flow from the output terminal to the ground terminal through the overvoltage protection circuit and the pulldown circuit in the stress test mode. A method of stress testing the driver device is also described.

The proposed mechanism for weld detection, uses isolation monitoring circuits (which is used for measurement of the leakage current between battery positive and negative to the chassis ground (on pack or link side) and checks the health status of the contactors. The mechanism connects isolation monitoring circuit between two points on the battery pack (between two sides of the high current contactors) and measures the resistance of two points, therefore checking the continuity of the contactors in the system. Since it can measure a range of resistance, it can also check if a contactor is completely welded or it has been partially welded. This would be important because in case of partial weld, the car can fix the problem and remove the partial weld by activating and deactivating the contactors for several time, with or without inserting high current in the coil of the contactors. Since the proposed mechanism is using available measurement circuits of the isolation monitoring unit and these circuits are designed with high reliability (which is required for the electrical vehicles), the proposed mechanism is going to lower the cost of the entire vehicle while keeping the passenger safe.

The invention relates to a method for ascertaining an earth fault and the earth-fault direction in a three-phase network which is operated in a compensated manner or in an insulated manner. Value pairs of a zero voltage and a zero current are measured, the active or reactive energy is calculated, and a voltage flag and a current flag are combined by a Boolean link, wherein the presence of a earth fault is ascertained depending on the result, and a decision is made as to whether the earth-fault direction is signalled as “forward” or “reverse” at least on the basis of the sign of the active or reactive energy.

A system includes a monitoring and/or protection system that includes an insulation derivation circuit. The insulation derivation circuit is configured to derive a first temperature compensation curve based on a first temperature and a first current, and the monitoring and/or protection system is configured to communicatively couple to a first current sensor configured to sense the first current traversing a first phase of a stator winding of a motor, a generator, or a combination thereof. The insulation derivation circuit is also configured to communicatively couple to a first temperature sensor configured to sense the first temperature of the stator when the stator is energized, and the temperature compensation curve is configured to map a temperature to a leakage dissipation factor.

Systems, methods, and computer-readable media are disclosed for high impedance detection in electric distribution systems. An example method may include calculating, by a processor, a relative randomness of a signal, wherein the relative randomness is a derivative of a first scale wavelet transform divided by an energy of the signal. The example method may also include calculating, by the processor, one or more scales of a wavelet transform of the signal. The example method may also include calculating, by the processor, one or more energy ratios between energy of the wavelet transform in the one or more scales. The example method may also include calculating, by the processor, a zero-crossing phase difference between a third harmonic and a fundamental component of the signal. The example method may also include determining, by the processor, that a high impedance fault occurs based on at least one of: the relative randomness, a comparison between the one or more scales of the wavelet transform, and the zero-crossing phase difference.