Charging pile insulation monitoring device designed using special bridge method

Abstract

A charging pile insulation monitoring device designed using a special bridge method comprises a balanced bridge module, an unbalanced bridge module, a voltage conversion module, a voltage isolation module, a signal processing module and a communication module, which are connected in sequence. The balanced bridge module is composed of a pair of resistors of positive power-ground and a pair of resistors of negative power-ground. The voltage collected by the voltage conversion module is taken from partial voltages of the two pairs of resistors. The voltage isolation module is used for converting an input voltage into a low voltage signal. The signal processing module digitally transforms the input voltage, and calculates the value of grounding resistance. The communication module is used for sending the calculation result to a system host. With the device, the fault type of charging pile grounding can be inferred, and the value of grounding resistance can be calculated accurately. The charging pile insulation monitoring device based on the monitoring method can stably and reliably monitor the grounding fault of a DC charging pile and the size of grounding resistance. The monitoring method is relatively advantageous in the field at present.

Description

technical field [0001] The invention relates to insulation monitoring of charging piles, in particular to a safety monitoring device for grounding faults of DC charging piles. Background technique [0002] With the massive construction and application of electric vehicle charging stations and charging piles, their safety has been paid more and more attention. In particular, DC charging piles have high power, large volume, and high voltage, and are often equipped with batteries for energy storage, so the structure is complex. When the insulation of the charging pile output DC side is not good, it will cause equipment damage, fire, and personal electric shock. Since the leakage fault on the DC output side cannot activate the leakage protector on the AC side, it is particularly important to add insulation monitoring and ground fault protection devices on the DC side. [0003] The current charging pile insulation monitoring methods mainly include the bridge balance principle a...

AI Technical Summary

Problems solved by technology

The insulation monitoring device based on the bridge balance principle is widely used, but it cannot monitor the situation when the positive and negative insulation of the charging pile is equally reduced; even if the insulation monitoring device alarms, it cannot directly obtain the insulation resistance of the system to the ground

Using low-frequency detection principle to monitor ground fault is a new method adopted in recent years, but the ground resistance it can monitor is restricted by the distributed capacitance of charging piles to ground, and low-frequency AC signals are easily interfered by the outside world, and the injected low-frequency The AC signal increases the voltage ripple coefficient of the charging pile

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