A soft start circuit, soft start method and DC charging pile

Abstract

The invention provides a soft starting circuit, a soft starting method and a DC charging pile. The soft starting circuit comprises a controller, a rectifying module, a first switch, a second switch and a backflow prevention diode, wherein the controller acquires measured values of three detection points in real time, and obtains charging voltage and current information of a battery pack from a vehicle battery management system BMS; the first detection point detects voltage between a positive output end and a negative output end of the rectifying module, the second detection point detects voltage between output positive and negative ends of the charging pile, and the third detection point detects output current of the charging pile and the rectifying module; and the controller adjusts the output voltage and current of the rectifying module and controls the on-off time sequence of the first switch and the second switch, so as to avoid the occurrence of surge current in the process of starting the charging. The soft starting circuit, the soft starting method and the DC charging pile effectively suppress the surge current at the time of starting the charging, avoid the damage to electrical devices caused by the impact of the surge current, and avoid the adhesion of contacts of the switching devices through controlling the time sequence of the switching devices.

Description

technical field [0001] The invention relates to the technical field of new energy vehicle charging, in particular to a soft start circuit, a corresponding soft start method, and a DC charging pile using the soft start circuit and method. Background technique [0002] The commonly used starting charging scheme in DC charging piles is mainly to communicate with the battery pack management system (BMS) through the controller, and obtain the current voltage of the battery pack, the maximum allowable charging voltage and the initial charging current (usually the maximum charging current of the battery pack), The controller uses this as the voltage and current target values ​​when the rectifier module starts. When the rectifier module starts up, the output voltage rises rapidly. When the output voltage exceeds the battery pack voltage, the current also rises rapidly due to the very small current limiting resistance of the charging circuit. Before reaching the current limit value, ...

AI Technical Summary

Problems solved by technology

When the rectifier module starts up, the output voltage rises rapidly. When the output voltage exceeds the battery pack voltage, the current also rises rapidly due to the very small current limiting resistance of the charging circuit. Before reaching the current limit value, the output voltage of the rectifier module continues to rise rapidly. , resulting in an inrush current; this inrush current will be exacerbated if the switch closure time is improper

It can be seen that this method simply relies on the current limiting speed and accuracy of the rectifier module, it is difficult to effectively suppress or eliminate the inrush current, and it is easy to shorten the life of each component of the charging circuit or damage it.

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