Protective circuit of vehicle-mounted charger

Abstract

The invention provides a protective circuit of a vehicle-mounted charger. The protective circuit of the vehicle-mounted charger comprises an operational amplifier chip U1, a diode D1, a diode D2, a metal oxide semiconductor (MOS) pipe Q1, a capacitor C1, a capacitor C2, a relay RL1 and a plurality of resistors. According to the protective circuit of the vehicle-mounted charger, a hysteresis comparator is composed of the operational amplifier chip U1 and the resistors, anti-back-charging protection and short-circuit protection are achieved through the hysteresis comparator and the relay, a battery-polarity-reverse protective function is achieved through the resistors and the diodes, therefore short-circuit protection, reverse-polarity protection, battery-back-charging prevention on the vehicle-mounted charger are simultaneously achieved, the system performance of the vehicle-mounted charger is greatly improved, and the service life of the vehicle-mounted charger is greatly prolonged.

Description

technical field [0001] The invention relates to the field of circuit protection, in particular to a protection circuit of a vehicle charger. Background technique [0002] The on-board power battery charger used in electric vehicles is another emerging research field of switching power supply. Generally, the voltage of the on-board power battery is above 200V, and it can reach above 300V after being fully charged. If the charger is connected to the battery in this case, the battery will Charging the capacitor in the charger will instantly generate tens of A or even hundreds of amperes of current, which will easily damage the capacitor and the sampling resistor. Therefore, the reverse charge of this large current will cause great damage to the existing car charger. In addition, for the vehicle power battery charger, if a short circuit occurs at the output of the charger, it is equivalent to a short circuit of the capacitor of the charger, and a large current will be generated ...

AI Technical Summary

Problems solved by technology

In the prior art, in order to avoid the damage of the large current in the charger, there is a technology of sampling with a patch sampling resistor, but because of its small power, it cannot withstand the instantaneous large current, and a diode is often used to solve the instantaneous current, but the diode The conduction voltage drop is generally above 0.2V, which does not have a good effect of protecting the sampling resistor, and cannot realize the function of short circuit protection

In the prior art, there is no technology that realizes the three functions of short circuit protection, reverse connection protection and battery reverse charging protection for the car charger at the same time.

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