Synchronous Rectifier Controller Power Supply via Drain Voltage
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Solution Overview
Problem
Existing power conversion apparatuses face challenges in supplying power to synchronous rectifier controllers without increasing cost or overall power consumption, particularly due to high power consumption when using a primary winding and increased transformer costs with auxiliary windings.
Innovation Solution
A power conversion apparatus that includes a transformer, a synchronous rectifier transistor, a capacitor, and a synchronous rectifier controller, where the controller charges the capacitor using the drain voltage of the transistor when it transitions from on to off state and the power supply voltage is below a preset level, thereby providing sufficient power without additional windings or increased consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an auxiliary winding is added to supply power to the synchronous rectifier controller, then the controller can operate, but the transformer cost and winding difficulty increase
Solution Approach 1:
The patent extracts the power supply function from the transformer by using a separate capacitor charged from the primary winding, eliminating the need for an auxiliary winding on the transformer while still providing power to the synchronous rectifier controller
Solution Approach 2:
The patent introduces a capacitor as an intermediary energy storage element between the primary winding and the synchronous rectifier controller, allowing power transfer without direct connection or additional transformer windings
2Reliability
If power is supplied through a rectifier diode and voltage regulating circuit, then the controller can operate, but power consumption increases when primary winding voltage is high
Solution Approach 1:
The patent uses periodic charging of the capacitor during specific intervals (when the synchronous rectifier transistor is off and drain voltage is high) to provide power to the controller, avoiding continuous power draw and reducing overall power consumption
Solution Approach 2:
The patent changes the voltage parameter utilization by charging the capacitor when drain voltage is high (above threshold) and using this stored energy when voltage is low, optimizing power transfer efficiency and reducing losses
3Loss of energy
If a synchronous rectifier transistor is used to replace the rectifier diode, then on-resistance is reduced, but a controller is needed which increases system complexity
Solution Approach 1:
The synchronous rectifier transistor controls itself through drain voltage feedback to the controller, automatically turning on and off based on the voltage conditions without requiring external control signals, simplifying the overall control system
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
This solution reduces the cost of the transformer and prevents increased power consumption by using the capacitor to supply power to the synchronous rectifier controller, ensuring normal operation while avoiding excessive charging and power loss.
Implementation Method 1
a capacitor coupled between a ground terminal and a power supply terminal of the synchronous rectifier controller
Implementation Method 2
a synchronous rectifier transistor with a low on-resistance
Data Source
AI summary
A power conversion apparatus and a charging method of the power conversion apparatus are provided. A synchronous rectifier controller provides a voltage of a drain terminal of a synchronous rectifier transistor to charge a capacitor of a power supply terminal of the synchronous rectifier controller when the synchronous rectifier transistor is turned from an on state to an off state and a voltage of the power supply terminal is less than a preset voltage.