In at least one embodiment an apparatus for diagnosing electronics in an insulation resistance monitoring system is provided. The apparatus includes a controller for being electrically coupled to a plurality of electronics including a plurality of switches that are electrically coupled to a positive branch and to a negative branch in a high voltage network and a low voltage network. The plurality of electronics is configured to perform insulation resistance monitoring in a vehicle. The controller is further configured to at least one of activate and deactivate any number of the plurality of switches to determine an overall voltage of the positive branch and the negative branch. The controller is further configured to detect a fault in at least one of the positive branch and the negative branch that corresponds to a failure of any one of the plurality of electronics based on the overall voltage.

A motor drive device includes: a converter; a power supply; a plurality of inverter units configured to convert DC to AC to drive a plurality of motors by upper arm switching elements connected between a capacitor and motor coils and lower arm switching elements connected between the capacitor and motor coils; a second switch configured to connect the capacitor to the earth; a current detector configured to measure current flowing between the capacitor and the earth; a voltage detector configured to measure the voltage across the capacitor; and, an insulation resistance detector configured to detect insulation resistance of the multiple motors based on the current and voltage measured in a condition that the switching element to which the motor coil to be measured is connected is turned on and the switching elements to which a motor coil other than the target for measurement is connected are turned off.

Electrical bus isolation is detected for an electrified vehicle having a DC power source connected to positive and negative buses. The positive bus is connected to chassis ground, and a resulting first current is sensed that flows through a negative bus leakage resistance and a balanced leakage resistance. The negative bus is connected to chassis ground, and a resulting second current is sensed that flows through a negative bus leakage resistance and a balanced leakage resistance. The positive and negative bus leakage resistances are estimated in response to respective ratios of the first and second currents. An isolation value is compared to a threshold, wherein the isolation value is responsive to a voltage of the DC power source and a smaller one of the positive and negative bus leakage resistances. An atypical isolation is signaled when the isolation value is less than the threshold.

The present invention relates to a system and a method of measuring insulation resistance, which separate a region in which insulation resistance is positioned by installing a device performing a function equivalent to a relay on a path in which insulation resistance of an electric vehicle is measured and measure an insulation resistance value for each region, to recognize a region in which insulation resistance breakdown occurs when breakdown of insulation resistance occurs.

An electric insulation monitoring arrangement (10) for monitoring electric insulation in an electric system (2), in particular of a vehicle, comprising a first conductor (11) and a second conductor (12), the electric insulation monitoring arrangement comprising: an insulation monitoring device (15) comprising a primary measuring unit (13) configured to monitor a first voltage (V.sub.1) between the first conductor and ground, and a second voltage (V2) between the second conductor and ground, the insulation monitoring device being configured to determine an electric insulation of the electric system based on measurement data from the primary measuring unit, at least one secondary measuring unit (14) configured to monitor the first voltage and the second voltage with respect to ground, wherein the at least one secondary measuring unit is provided separately from the insulation monitoring device.

The insulation monitoring device is configured to use measurement data relating to the first voltage and the second voltage received from the at least one secondary measuring unit to verify the determined electric insulation.

An insulation resistance calculation apparatus according to an embodiment of the present disclosure includes a switching unit including a first switch and a second switch that are independently controlled, a first protective resistor and a first reference resistor connected in series between a positive electrode terminal of a battery and a ground when the first switch is turned on, a second protective resistor and a second reference resistor connected in series between a negative electrode terminal of the battery and the ground when the second switch is turned on, a voltage measuring unit configured to measure a first detection voltage applied to the first reference resistor and a second detection voltage applied to the second reference resistor, and a processor configured to determine if a measurement error occurred in measured values of the first detection voltage and measured values of the second detection voltage.

An electric leakage detection apparatus for an electric vehicle including a battery and a chassis, includes a battery voltage sensor; a first series circuit including a first resistor and a first switch connected in series between a first node connected to the battery's negative terminal and a second node connectable to the chassis; a second series circuit including a second resistor and a second switch connected in series between the second node and a third node connected to the positive terminal; a voltage divider connected in parallel to the first series circuit, and including third and fourth resistors connected in series through a fourth node; an analog-digital converter generating a digital signal indicating voltage between the first and fourth nodes; and a control unit determining occurrence of an electric leakage of the battery based on a voltage measured by the analog-digital converter in an electric leakage detection mode.

An insulation resistance measuring apparatus designed to calculate a complex impedance of an ac circuit including a measuring resistor, a coupling capacitor, an insulation resistor installed in a vehicle, and a ground capacitance. The insulation resistance measuring apparatus includes a sine wave current applying device which applies an ac signal to the measuring resistor and measures a voltage change appearing at a junction of the sine wave current applying device and the measuring resistor. The ac signal and the voltage change are used to determine the complex impedance. A resistance value of the insulation resistor is calculated as a function of the complex impedance. This structure enables the circuit to be reduced in size.

A circuit arrangement (20) having an active measuring voltage (U.sub.G) for determining an insulation resistance (R.sub.F) or a complex-valued insulation impedance (Z.sub.F) of an ungrounded power supply system (12) against ground potential (PE), the circuit arrangement (20) having a measuring path (24) which runs between an active conductor (L1, L2) of the power supply system (12) and the ground potential (PE) and includes a measuring-voltage generator (V.sub.G) for generating the measuring voltage (U.sub.G), a measuring resistance (R.sub.M) for capturing a measured voltage (U.sub.M) and a coupling resistance (R.sub.A), the circuit arrangement (20) having a signal evaluation circuit (26) which includes a signal input for evaluating the measured voltage (U.sub.M) and a ground connection (GND). The ground connection (GND) is connected to a ground potential (PE).

Provided is an insulation resistance monitoring device that enables measurement of insulation resistance using a mega tester without removing the insulation resistance monitoring device. The insulation resistance monitoring device that monitors the insulation resistance of an object to be measured such as a motor includes: a current detecting unit that is connected between the power supply line and the ground line of the motor and detects a current flowing through the insulation resistance of the motor: a voltage generating unit connected between the power supply line and the ground line of the motor; and a switch for opening and closing the connection path between the power supply line or the ground line of the motor and the voltage generating unit, wherein the off resistance when the connection path is opened is 100 MΩ or more.