Synchronous Rectifier Bridge Self-Powered Control Module
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Solution Overview
Problem
Existing synchronous rectifiers require an additional power supply and control circuit, and cannot deactivate synchronous rectification when the voltage across the terminals is insufficient, leading to inefficiencies and potential transistor damage in low-voltage applications like automotive alternators.
Innovation Solution
Integration of power components and their control within a single module, utilizing a charge pump to generate supply voltages and an oscillator to control the rectifier bridge, with a standby circuit to deactivate when voltage or frequency is below a threshold, and a shunt circuit for diagnostic purposes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If synchronous rectifiers with switches are used to improve efficiency, then the voltage drop is reduced, but additional power supply and control circuits are required
Solution Approach 1:
The patent combines the power supply circuit and control circuit into a single integrated module with the synchronous rectifier switches. The charge pump circuit generates control voltages from the input voltage itself, and the operational amplifiers are integrated with the power switches, eliminating the need for separate external power supplies and control circuits.
Solution Approach 2:
The synchronous rectifier module is self-powered through a charge pump circuit that generates the necessary control voltages from the input voltage applied to the power terminals. The operational amplifiers use the input voltage and generated voltages to automatically control the switching of the power transistors, making the system self-regulating without external control inputs.
2Loss of energy
If synchronous rectification is always active to maintain efficiency, then energy loss is minimized, but transistor damage may occur when voltage is insufficient
Solution Approach 1:
The operational amplifiers continuously monitor the voltage across the power terminals and the voltage across the body diodes of the transistors. When the input voltage is insufficient or the transistor is in reverse conduction mode, the feedback signals automatically adjust the gate voltages to prevent damage, ensuring safe operation under all voltage conditions.
Solution Approach 2:
The control circuit proactively prevents transistor damage by detecting unfavorable voltage conditions before they can cause harm. The operational amplifiers anticipate potential damage scenarios and adjust the switching control in advance to avoid reverse conduction and excessive voltage stress on the transistors.
3Adaptability or versatility
If the rectifier operates in low-voltage conditions to maintain functionality, then adaptability is improved, but control of transistors becomes unreliable
Solution Approach 1:
The charge pump circuit dynamically adjusts the generated control voltages based on the input voltage level. When input voltage is low, the charge pump generates proportionally lower control voltages that are still sufficient to properly control the transistor gates, maintaining reliable operation across a wide voltage range including automotive low-voltage conditions.
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
Enables efficient operation of synchronous rectifiers without additional power supplies, ensuring correct transistor control and preventing damage from insufficient voltage, while maintaining efficiency and reliability in low-voltage environments.
Implementation Method 1
a charge pump producing at least one of the supply voltages of the first amplifier from the voltages applied to the connection terminals
Implementation Method 2
an oscillator powered by the charge pump itself
Implementation Method 3
at least a first field effect transistor, the first source and the first drain of which are respectively connected to the first and second connection terminals
Implementation Method 4
at least a first operational amplifier comprising a first feedback loop, the first output of which is connected to the first gate of the first transistor
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The member for a synchronous rectifier bridge (14) typically includes at least first and second connection terminals (B+, P), at least one field-effect transistor (15) having source and drain electrodes (16, 17) respectively connected to the first and second terminals (B+, P), and at least one comparator for comparing at least a first voltage source having a predetermined reference voltage and at least a first voltage difference between the voltages applied to the first and second terminals (B+, P) and having an output connected to a gate electrode (21) of the transistor (15). According to the invention, the member (14) further includes at least one load pump (25) providing, from said applied voltages, at least one supply voltage (VH, VL) for supplying said and at least one comparator.