DC-DC MOS Group Protection Using Voltage-Gated Power-Up Control
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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 introduces a control circuit as an intermediary between the power supply and the MOS group. This control circuit monitors voltage and current parameters in real-time and controls the switching of MOS transistors to prevent over-voltage and over-current conditions. By using this intermediary control mechanism, the patent protects the MOS group without requiring higher withstand voltage MOS devices, thus avoiding increased product cost while maintaining reliability.
2Reliability
If a power-up delay control strategy is used, then the MOS group is protected during power-up, but the MOS group remains vulnerable to over-voltage or over-current during other procedures
Solution Approach 1:
The patent implements continuous monitoring of voltage and current parameters throughout the entire operation of the MOS group, not just during power-up. The control circuit continuously detects parameter variations and adjusts MOS switching in real-time, ensuring protection coverage during all operational phases including power-up, steady-state operation, and transient conditions. This continuous protection approach eliminates the vulnerability periods present in delay-based strategies.
3Reliability
If real-time voltage monitoring and control switches are added, then the MOS group is protected from over-voltage and over-current, but the circuit complexity increases
Solution Approach 1:
The control circuit in the patent is designed to perform multiple functions: voltage monitoring, current monitoring, MOS switching control, and protection activation. By integrating these functions into a single multi-functional control unit, the patent reduces the overall circuit complexity compared to having separate dedicated circuits for each function. The control circuit serves as a universal protection mechanism that handles various protection scenarios without requiring separate complex circuitry for each case.
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.