An electric vehicle insulation detection device

Abstract

The invention discloses a novel insulation detection device for electric automobiles.The novel insulation detection device for electric automobiles comprises a low-frequency pulse signal generator, a high-frequency pulse signal generator, a first operational amplifier, a second operational amplifier, a third operational amplifier, a one-out-of-two selective switch, a sampling circuit and a processor unit.The sampling circuit comprises a first branch circuit, a second branch circuit and a fifth resistor, wherein the first branch circuit is formed by connecting a first resistor and a second resistor in series, and the second branch circuit is formed by connecting a third resistor and a fourth resistor in series.An input end of the first operational amplifier is connected to the positive pole or negative pole of a high-voltage battery through the selective switch.An input end of the second operational amplifier is connected to the parallel connection point of the first branch circuit and the second branch circuit.An input end of the third operational amplifier is connected to the connection point of the first resistor and the second resistor.The novel insulation detection device for electric automobiles widens the range of insulation detection of electric automobiles and improves the accuracy of insulation detection of electric automobiles.

Description

technical field [0001] The invention relates to the field of new energy vehicle safety detection, in particular to an electric vehicle insulation detection device. Background technique [0002] At present, the common electric vehicle insulation monitoring equipment on the market mainly uses the bus terminal voltage method and the low frequency signal injection method. Patents CN203422422U, CN101158701A, and CN101603986A all disclose a monitoring system for the insulation resistance of high-voltage systems based on the bus terminal voltage method. Insulation resistance value, bus terminal voltage method can calculate the insulation resistance value of the system by measuring the voltage between the DC bus and the electric chassis before and after the standard resistance is incorporated, but the work is relatively unreliable and has high requirements for high-voltage systems (including voltage value, stability, etc.), and cannot respond to the short-to-ground fault inside the...

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Problems solved by technology

Patents CN203422422U, CN101158701A, and CN101603986A all disclose a monitoring system for the insulation resistance of high-voltage systems based on the bus terminal voltage method. Insulation resistance value, bus terminal voltage method can calculate the insulation resistance value of the system by measuring the voltage between the DC bus and the electric chassis before and after the standard resistance is incorporated, but the work is relatively unreliable and has high requirements for high-voltage systems (including Voltage value, stability, etc.), can not respond to short-to-ground faults inside the high-voltage battery

Patent CN102749562A discloses a measurement method using low-frequency signal method, using low-frequency signal to test parallel insulation resistance value, low-frequency signal injection method injects low-frequency AC signal between the system DC bus and chassis, and the low-frequency signal can automatically adapt to the leakage capacitance and insulation resistance of the system size, high measurement accuracy, high reliability, and low requirements for high-voltage systems, but there are problems such as only testing parallel insulation resistance values, not testing high-voltage voltages, and being unable to locate fault points.

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