Synchronous Rectification DC-DC Converter Backflow Detection
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Solution Overview
Problem
Existing synchronous rectification DC-DC converters have complex circuit configurations due to the need for a current monitor circuit, which can lead to inaccurate backflow detection and insufficient reduction of backflow, particularly when used with power storage devices, risking overcharge.
Innovation Solution
A simplified circuit configuration that includes a voltage detection circuit and a converter controller comparing detected voltage with a reference voltage to maintain a constant output voltage, eliminating the need for a current monitor circuit and reducing backflow by setting the reference voltage equal to the detected voltage when the target voltage is lower.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a current monitor circuit is provided to detect backflow current, then backflow detection accuracy is improved, but circuit configuration becomes complicated
Solution Approach 1:
The patent extracts the backflow detection function from a separate current monitor circuit and integrates it into the existing voltage detection circuit. By detecting backflow through voltage changes across the switching element rather than direct current measurement, the system achieves accurate backflow detection without adding circuit complexity
Solution Approach 2:
The voltage detection circuit is given a dual function: it simultaneously monitors the switching element voltage for both normal operation control and backflow detection. This multi-functionality eliminates the need for a dedicated current monitor circuit while maintaining detection accuracy
2Reliability
If a current monitor circuit is provided to detect backflow current, then backflow detection capability is improved, but circuit configuration becomes complicated
Solution Approach 1:
The patent extracts backflow detection capability from a separate current monitoring system and implements it through voltage detection across the switching element. This approach ensures reliable backflow detection and prevention without complicating the circuit configuration
Solution Approach 2:
The control unit continuously monitors the voltage across the switching element and provides feedback control. When backflow is detected through voltage changes, the control unit immediately adjusts the switching element state to prevent further backflow, ensuring reliable protection without additional circuitry
3Device complexity
If response characteristics of current monitor circuit are insufficient, then circuit configuration is simplified, but backflow detection accuracy is degraded
Solution Approach 1:
The patent replaces direct current measurement (analogous to mechanical measurement) with voltage detection across the switching element. This substitution leverages the faster response characteristics of voltage detection circuits, achieving both simplified configuration and high detection accuracy
4Device complexity
If backflow is not sufficiently reduced, then circuit configuration is simplified, but power storage device may be overcharged
Solution Approach 1:
The control unit implements continuous feedback monitoring of the switching element voltage to detect backflow conditions. When backflow is detected, the control unit immediately takes corrective action to prevent power storage device overcharge, ensuring reliable protection without complicating the circuit
Solution Approach 2:
The system takes preliminary anti-action by detecting backflow trends through voltage changes before significant backflow current can damage the power storage device. The control unit proactively prevents overcharge conditions rather than reacting after damage occurs
Data Source
AI summary
A DC-DC converter includes a synchronous rectification converter that converts electric power, a voltage detection circuit that detects a voltage proportional to an output voltage of the converter, a converter controller that compares a detection voltage detected by the voltage detection circuit with a reference voltage and controls an operation of the converter to provide a constant or substantially constant voltage of the detection voltage, and a command processor that sets, in a case where a target voltage command value input from an ECU is lower than a voltage value of the output voltage of the converter, a voltage value of the reference voltage to be equal or substantially equal to a voltage value of the detection voltage.