Power Converter Asynchronous Synchronous Control for Backflow Prevention
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Solution Overview
Problem
Vehicle-mounted DC-DC converters face challenges in preventing current backflow from the low-voltage side to the high-voltage side, leading to excessive consumption and wear of the low-voltage battery, while synchronous switching improves responsiveness and efficiency but risks current backflow, and asynchronous switching prevents backflow but degrades responsiveness and efficiency.
Innovation Solution
A power conversion device with a transformer, high-voltage and low-voltage side switching circuits, and a surge voltage-suppressing capacitor, where the controller controls the switching states asynchronously until the capacitor is fully charged and then synchronously, optimizing duty ratios to prevent backflow and ensure high responsiveness and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If synchronous switching operation is performed to improve current responsiveness and power conversion efficiency, then current responsiveness and efficiency are improved, but current backflow occurs from the low-voltage side to the high-voltage side
Solution Approach 1:
The patent applies dynamics by making the switching operation mode changeable from asynchronous to synchronous based on the charge state of the surge voltage-suppressing capacitor. The controller dynamically selects the appropriate switching mode: asynchronous switching when the capacitor is uncharged (to prevent backflow) and synchronous switching when the capacitor is charged (to improve efficiency and responsiveness). This resolves the contradiction by making the system adaptable rather than fixed.
Solution Approach 2:
The patent changes the operational parameter (switching mode) based on the capacitor's charge state. By monitoring the voltage across the surge voltage-suppressing capacitor and switching between asynchronous and synchronous modes, the system optimizes performance while preventing harmful current backflow. This parameter change approach allows the system to achieve high efficiency only when safe to do so.
2Reliability
If asynchronous switching operation is performed to prevent current backflow, then current backflow is prevented, but current responsiveness and power conversion efficiency are significantly degraded
Solution Approach 1:
The system dynamically transitions from asynchronous to synchronous switching based on capacitor charge state. Initially operating in asynchronous mode for reliability, then switching to synchronous mode for optimal performance once the capacitor is charged. This dynamic adaptation resolves the contradiction between reliability and productivity.
Solution Approach 2:
The patent implements periodic switching between operational modes based on the charging cycle of the capacitor. The system alternates between asynchronous operation (when capacitor needs charging) and synchronous operation (when capacitor is charged), creating a periodic action pattern that balances reliability and efficiency requirements.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively suppresses current backflow while enhancing current responsiveness and power conversion efficiency by dynamically switching between asynchronous and synchronous control modes based on the capacitor's charge state.
Implementation Method 1
a transformer including a primary winding and a secondary winding
Implementation Method 2
a surge voltage-suppressing capacitor electrically connected in parallel with the low-voltage switching circuit
Data Source
AI summary
A power conversion device capable of suppressing current backflow while also improving current responsiveness and power conversion efficiency is achieved. A snubber capacitor capable of absorbing switching surge is connected to a low-voltage side switching circuit that includes switching elements. Until a predetermined time elapses from when a request to start switching is received, a controller determines that the snubber capacitor has not reached full charge or near-full charge, and asynchronously controls the low-voltage side switching circuit and a high-voltage side switching circuit that includes switching elements. After the predetermined time elapses, the controller synchronously controls the low-voltage side switching circuit and the high-voltage side switching circuit, and also controls a duty ratio of the low-voltage side switching circuit and the high-voltage side switching circuit such that current does not flow back from the low-voltage side switching circuit to the high-voltage side switching circuit.