The present disclosure relates to an insulation resistance measuring device and method, including a parameter resistance connected to a negative electrode terminal of a battery; a shunt resistance connectable to the parameter resistance; a current detection circuit including an operational amplifier configured to detect and output voltage between both ends of the shunt resistance; and a control unit configured to determine the insulation resistance of the battery using a switch control terminal configured to control a switch connected between the parameter resistance and the shunt resistance to an ON or OFF state, a detection signal output terminal configured to selectively apply a first high voltage signal and a first low voltage signal to the shunt resistance, a control signal output terminal configured to apply a control voltage signal to the operational amplifier to adjust an output voltage of the operational amplifier within a predetermined range, an ADC connected to an output terminal of the operational amplifier, and a predefined insulation resistance formula that includes, as a parameter, a first voltage change amount with respect to the output voltage of the operational amplifier being measured through the ADC when the first high voltage signal and the first low voltage signal are applied to the shunt resistance.

The present application provides an insulation detection circuit, a method and a battery management system. The circuit includes: a first voltage dividing module, where, one end of the first voltage dividing module is connected to a positive electrode of a power battery to be detected, and the other end of the first voltage dividing module is connected to a first isolation module and a second voltage dividing module respectively; the second voltage dividing module, connected to a negative electrode of the power battery to be detected; the first isolation module, connected to one end of a sampling module; the sampling module, where, the other end of the sampling module is connected to one end of a signal generating module; the signal generating module, where, the other end of the signal generating module is connected to power ground; and the processing module.

Methods and devices are provided for testing the function of a standard insulation monitoring device, installed in an ungrounded power supply system, during operation. The basic concept of the invention rests upon adding a testing apparatus to the ungrounded power supply system, which is being monitored using an insulation monitoring device according to regulations, between the active conductors of an ungrounded power supply system and ground, said testing apparatus systematically changing an insulation resistance of the ungrounded power supply system and observing the reaction of the insulation monitoring device in a fully automated manner in perpetually repetitive testing cycles. The power supply system is monitored perpetually during its operation. In the method, the current operating state (insulation level, load state) of the power supply system is detected via network parameters, such as insulation resistance and system leakage capacity, and consulted for assessing the functionality of the insulation monitoring device.

The invention relates to a circuit assembly (10) for fault detection in an ungrounded high-voltage system (20) having a connected inverter (4) and having at least one resistor (5) between a high-voltage potential (7a, 7b) of the high-voltage system (20) and a reference potential (8), the circuit assembly (10) comprising: a sensing circuit (1), which is designed to tap a voltage from the resistor (5), to generate a first measurement value therefrom and to provide the first measurement value at an output (1c, 1d); and an evaluation device (2), which is connected to the output (1c, 1d) of the sensing circuit (1), the evaluation device (2) being designed to compare the first measurement value with a first limit value and to output a first signal if the first measurement value exceeds the first limit value.

An abnormality detection device includes: a coupling-capacitor having a first-end and a second-end coupled with a high-voltage circuit; a signal output unit; a signal extraction unit; and a signal input unit. The signal output unit is coupled with the first-end of the coupling-capacitor via a detection-resistor, and outputs an alternating-current inspection-signal. The signal extraction unit extracts the inspection-signal, as an extraction-signal, output between the detection-resistor and the coupling-capacitor. The signal input unit detects abnormality of insulation resistance of the high-voltage circuit based on a level of the inputted extraction-signal. The signal extraction unit includes a signal removing filter and a subtraction circuit. The filter removes a signal equal in frequency to the inspection-signal and passes low-frequency noises lower in frequency than the inspection-signal. The subtraction circuit outputs a differential signal, as the extraction-signal, between a signal having passed through the filter and a signal not having passed through the filter.

A detection circuit includes: a first switch, a second switch, a first detection resistor and a second detection resistor, wherein the first switch and the first detection resistor are coupled in series to form a first branch, a first end of the first branch is electrically connected with a positive bus of the photovoltaic inverter and a second end of the first branch is electrically connected with a ground; and the second switch and the second detection resistor are coupled in series to form a second branch, a first end of the second branch is electrically connected with a negative bus of the photovoltaic inverter and a second end of the second branch is electrically connected with the ground.

A detection circuit includes: a first switch, a second switch, a first detection resistor and a second detection resistor, wherein the first switch and the first detection resistor are coupled in series to form a first branch, a first end of the first branch is electrically connected with a positive bus of the photovoltaic inverter and a second end of the first branch is electrically connected with a ground; and the second switch and the second detection resistor are coupled in series to form a second branch, a first end of the second branch is electrically connected with a negative bus of the photovoltaic inverter and a second end of the second branch is electrically connected with the ground.

Method and apparatus for determining a ground fault impedance. In one embodiment the apparatus comprises a voltage divider and a ground fault detection module for (i) determining a first voltage based on at least one voltage measurement of the voltage divider while the voltage divider is coupled between the first AC line and the DC line; (ii) determining a second voltage based on at least one voltage measurement of the voltage divider while the voltage divider is coupled between the second AC line and the DC line; (iii) determining a differential voltage based on at least one voltage measurement between the first AC line and the second AC line; and (iv) computing the ground fault impedance based on the first voltage, the second voltage, and the differential voltage.

Method and apparatus for determining a ground fault impedance. In one embodiment the apparatus comprises a voltage divider and a ground fault detection module for (i) determining a first voltage based on at least one voltage measurement of the voltage divider while the voltage divider is coupled between the first AC line and the DC line; (ii) determining a second voltage based on at least one voltage measurement of the voltage divider while the voltage divider is coupled between the second AC line and the DC line; (iii) determining a differential voltage based on at least one voltage measurement between the first AC line and the second AC line; and (iv) computing the ground fault impedance based on the first voltage, the second voltage, and the differential voltage.

Implementations of ground fault circuit interrupter (GFCI) self-test circuits may include: a current transformer coupled to a controller, a silicon controlled rectifier (SCR) test loop coupled to the controller, a ground fault test loop coupled to the controller, and a solenoid coupled to the controller. The SCR test loop may be configured to conduct an SCR self-test during a first half wave portion of a phase and the ground fault test loop may be configured to conduct a ground fault self-test during a second half wave portion of a phase. An SCR may be configured to activate the solenoid to deny power to a load upon one of the SCR self-test or the ground fault self-test being identified as failing.