Relay state detection method and device of electric vehicle high-voltage system

Abstract

The invention provides a relay state detection method of an electric vehicle high-voltage system. The method comprises the step of determining whether a relay is in a normal work state or in a fault state based on the voltages at both ends of the relay and / or the coil current of the relay according to the switch-on and switch-off time sequences of the relay in the electric vehicle high-voltage system. Correspondingly, a relay state detection device is provided. The method and the device can be used for monitoring the relay state to clearly determine whether the relay is in the work state or in the fault state, thereby well controlling the output of high-voltage power and ensuring the personal safety as well as the safety of electric vehicles.

Description

technical field [0001] The invention relates to the technical field of electric vehicles, in particular to a method and device for detecting the state of a relay in a high-voltage system of an electric vehicle. Background technique [0002] Vehicles utilizing gasoline internal combustion engines or diesel internal combustion engines have caused severe air pollution. Accordingly, various recent efforts to develop electric vehicles or hybrid vehicles have focused on reducing air pollution. [0003] In current hybrid vehicles and pure electric vehicles, the high-voltage power source is usually composed of several battery packs in series, and the output voltage is as high as hundreds of volts, which is far beyond the safe voltage that the human body can bear. The output and cut-off of the high-voltage power of the battery pack is usually realized by the battery management system (BMS) controlling the closing and opening of the relay. The relay is equivalent to a safety switch ...

AI Technical Summary

Problems solved by technology

[0004] At present, the method of detecting the relay is mainly to collect the current in the relay coil as the re-inspection signal of the relay, but this method can only detect whether the BMS has controlled the relay, but cannot effectively monitor the status of the relay, that is, it cannot be clearly judged Whether the relay is in a working state or a fault state, and faults such as relay sticking cannot be detected

For example, when the relay contacts are 'sticking' (the so-called relay sticking is the phenomenon that the relay contacts pull out the arc before contacting at the moment when the high voltage of the battery is connected, the high-temperature arc burns the contacts, and the contacts cannot be disconnected normally. ), if the relay is disconnected through the BMS control, the staff will hypothetically think that the relay has cut off the high voltage of the power battery.

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