System and method for detecting insulation of electric automobile DC charging pile

Abstract

The invention discloses a system and a method for detecting insulation of an electric automobile DC charging pile, and belongs to the field of electric automobile charging piles. The system comprises a bridge-type impedance network, a voltage conditioning circuit, an isolation unit, an A / D sampling unit, a main control unit, a communication unit and a fault alarm unit, wherein the bridge-type impedance network is used for detecting voltage information of the DC charging pile, and the voltage information is processed sequentially through the voltage conditioning circuit, the isolation unit and the A / D sampling unit and then sent to the main control unit; the main control unit calculates the voltage information processed by the A / D sampling unit so as to acquire a positive bus ground insulation resistance value and a negative bus ground insulation resistance value of the DC charging pile, the main control unit controls the fault alarm unit to alarm on the one hand, and on the other hand, the main control unit sends a calculated resistance value to an electric automobile DC charging pile control system through the communication unit. The system and the method disclosed by the invention are simple in circuit structure, reliable, high in precision, high in anti-interference ability and capable of effectively carrying out insulation detection on the electric automobile DC charging pile.

Description

technical field [0001] The invention relates to the technical field of electric vehicle charging piles, in particular to a detection system and a detection method for the ground insulation resistance of DC charging piles. Background technique [0002] With the increasing awareness of global energy saving and environmental protection, the electric vehicle industry in the field of new energy is developing rapidly. At the same time, with the construction and application of a large number of electric vehicle charging piles, their safety has been paid more and more attention by manufacturers and users. Especially the DC charging pile has the characteristics of high power, large volume, high voltage and complex structure. Therefore, in the design of the DC charging pile, higher requirements are put forward for the insulation performance of the output voltage of the DC side to the ground. [0003] Since charging piles are often installed outdoors, the working conditions are relat...

AI Technical Summary

Problems solved by technology

There are many devices on the market for insulation detection based on the balanced bridge method, but they can only qualitatively judge insulation faults, and cannot obtain the value of grounding resistance; It will act; when the positive and negative grounding resistance values ​​are large but the difference is large, the device will falsely alarm

The low-frequency signal injection method is greatly affected by the distributed capacitance of the system to the ground, and the success rate of ground detection and branch circuit search is low; and the injection of low-frequency AC signals increases the voltage ripple of the DC system, which affects the safe operation of the DC system

In addition, the existing insulation detection system is only for the electric vehicle or the power battery pack, but rarely for the DC output side of the DC charging pile.

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