A circuit for preventing battery voltage loss on the output side of a vehicle-mounted dcdc converter

Abstract

The present invention proposes a circuit for preventing battery voltage loss on the output side of a vehicle-mounted DCDC converter. A current anti-backflow unit is set between the output capacitor and the low-voltage battery pack, and the negative input terminal of the comparator applied to the current anti-backflow unit is set. The resistance division formed by the first voltage dividing resistor unit and the second voltage dividing resistor unit to the auxiliary voltage can realize different anti-backflow current values, and set the first self-test unit, the second self-test unit and the third self-test unit unit to realize the high self-test coverage of the safety mechanism, and realize a more flexible, low power consumption, high reliability and high self-test coverage functional safety mechanism applied to the vehicle-mounted DCDC converter to prevent the instantaneous loss of the 12V battery voltage on the output side design.

Description

technical field [0001] The invention relates to the field of power supplies, in particular to a circuit for preventing battery voltage loss at the output side of a vehicle-mounted DC-DC converter. Background technique [0002] With the continuous development of electric vehicle technology, the trend of component integration is becoming more and more obvious. Integrated solutions can not only bring the advantages of function expansion to the vehicle, but also reduce the cost of the vehicle through the sharing of mechanical and electronic components. . The on-board charger is mainly used to draw electric energy from the 220V power grid, and after power conversion, the energy is charged into the high-voltage battery pack of the electric vehicle, while the on-board DCDC converter is used to convert the energy of the high-voltage battery pack of the electric vehicle into, for example, 12V battery energy , The integrated solution of on-board charger (Charger) and on-board DCDC co...

AI Technical Summary

Problems solved by technology

However, considering the failure of the DCDC converter, such as internal short circuit failure, it will cause the current to flow backward from the low-voltage battery pack to the inside of the DCDC converter, resulting in the instantaneous loss of the 12V battery voltage on the output side, which will affect the driving safety of the vehicle.

[0004] In the prior art, the reverse cut-off characteristic of the diode is generally used to prevent the reverse flow of current in the circuit, but when the diode is in the forward conduction state, due to the existence of the forward conduction voltage drop, a certain amount of energy loss will be caused

In addition, electric vehicles have higher and higher requirements for vehicle functional safety, and the traditional diode reverse cut-off scheme can no longer meet the corresponding functional safety requirements. Therefore, it is necessary to design high reliability, low power The circuit (anti-backflow circuit) to prevent the voltage loss of the 12V battery on the output side by checking the coverage has become the demand of the industry

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