MOS Group Protection Circuit for DC-DC Power-Up Overvoltage
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing DC-DC full-bridge MOS groups in new energy vehicles are prone to damage due to over-voltage or over-current during power-up, leading to increased costs when using higher withstand voltage MOS transistors or inadequate protection with power-up delay strategies.
Innovation Solution
A method and circuit that includes a power supply switch and connection switch controlled by a micro control unit (MCU) to monitor and ensure the voltage conditions are within a preset range before powering the DC-DC chip and MOS group, using under-voltage and over-voltage determination circuits to prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a MOS with higher withstand voltage is selected, then the MOS group is protected from over-voltage damage, but the product cost significantly increases
Solution Approach 1:
The patent implements preliminary voltage detection before the MOS group is powered on. The detection circuit measures the input voltage and compares it with a preset threshold voltage. Only when the voltage is confirmed to be within the safe range does the control circuit enable the MOS group to operate. This preliminary action prevents over-voltage damage without requiring MOS transistors with higher withstand voltage ratings, thereby avoiding increased product costs while maintaining reliability.
2Reliability
If power-up delay control strategy is used, then protection during power-up time is provided, but protection during other procedures is insufficient
Solution Approach 1:
The patent employs a real-time feedback mechanism where the detection circuit continuously monitors the input voltage to the MOS group during all operating conditions, not just during power-up. The detection circuit sends feedback signals to the control circuit, which adjusts the MOS group operation accordingly. This feedback-based approach provides comprehensive protection coverage throughout the entire operational lifecycle, addressing the insufficiency of simple power-up delay strategies.
Solution Approach 2:
The control circuit is configured to detect voltage conditions before enabling the MOS group to operate in any mode. This preliminary voltage verification ensures that the MOS group only operates when voltage conditions are safe, providing protection not only during power-up but also during any subsequent voltage anomalies, thereby expanding protection coverage to all operational procedures.
3Reliability
If voltage monitoring and switch control circuit is added, then MOS group protection is enhanced, but device complexity increases
Solution Approach 1:
The patent designs the detection circuit and control circuit to serve multiple functions. The detection circuit not only monitors voltage for MOS group protection but also provides feedback for overall system voltage management. The control circuit integrates both the power-up control and continuous protection functions in a single unified structure. This multi-functionality reduces the need for separate dedicated circuits, thereby limiting the increase in device complexity while achieving enhanced MOS group protection.
Data Source
AI summary
Provided is a method, a circuit, and a device for protecting a MOS group. The method includes: disconnecting a power supply switch to set a DC-DC chip in an off state; controlling input of a target power supply, and when determining that the voltage signal of the target power supply satisfies the preset condition, determining whether a voltage signal of the target power supply satisfies a preset condition; turning on the power supply switch and supplying, by a chip power supply, power to the DC-DC chip. When the voltage signal of the target power supply satisfies the preset condition, a connection switch is turned on, and the DC-DC chip is connected to a power supply circuit; and when the DC-DC chip is powered on, turning on a target MOS group, and converting a DC voltage signal output by the target power supply into a pulse electrical signal.