Charging and discharging protection circuit of lithium iron phosphate battery for electric automobile

Abstract

The invention discloses a charging and discharging protection circuit of a lithium iron phosphate battery for an electric automobile. The charging and discharging protection circuit is connected to the positive direct-current output end and the negative direct-current output end of a charger, and is characterized by being provided with an electrically-controlled mechanical switch consisting of a first contactor, a second contactor and a control circuit, wherein the positive and the negative control input ends of the control circuit of the electrically-controlled mechanical switch are connected with the positive and the negative ends of the lithium iron phosphate battery respectively; the normally closed contact of the first contactor and an IGBT1 (Insulated Gate Bipolar Translator 1) constitute a first parallel connection group; the normally closed contact of the second contactor and an IGBT2 constitute a second parallel connection group; reverse fly-wheel diodes are arranged in the IGBT1 and the IGBT2; and the first parallel connection group and the second parallel connection group are connected in series to constitute a combined protection switch. Normal switch-on of a charging and discharging loop is ensured, and arcing caused by switch-off of the normally-closed contacts of the first contactor and the second contactor is avoided. The combined protection switch can be used for separately controlling an overcharging loop and an over-discharging loop, and is particularly suitable for performing charging and discharging protection on the lithium iron phosphate battery of the electric automobile.

Description

technical field [0001] The invention relates to charging and discharging of batteries, in particular to a charging and discharging protection circuit for lithium iron phosphate batteries for electric vehicles. Background technique [0002] The lithium iron phosphate battery used in the existing electric vehicle power battery is a lithium ion battery using lithium iron phosphate as the positive electrode material, and the outlet of the existing battery pack is not provided with a battery protection circuit. Instead, the battery is protected by controlling other circuits. Because other links are usually not controlled, or the user does not use it according to the operating procedures, the battery is actually not protected often and damaged. The charging and discharging protection device of lithium iron phosphate battery requires disconnecting from the charging rectifier after fully charged to avoid shortening the battery cycle life caused by long-term floating charging or over...

AI Technical Summary

Problems solved by technology

[0002] The lithium iron phosphate battery used in the existing electric vehicle power battery is a lithium ion battery using lithium iron phosphate as the positive electrode material, and the outlet of the existing battery pack is not equipped with a battery protection circuit

Instead, the battery is protected by controlling other circuits. Because other links are usually not controlled, or the user does not use it according to the operating procedures, the battery is actually not protected often and is damaged.

The charging and discharging protection device of lithium iron phosphate battery requires disconnecting from the charging rectifier after fully charged to avoid shortening the battery cycle life caused by long-term floating charging or overcharging. After discharging to the low-voltage protection point, it is required to disconnect from the load connected to avoid shortening the battery cycle life due to over-discharge

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