Active Clamp Power Supply With Dual Capacitors for Current Limiting
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Solution Overview
Problem
Existing switching power supplies with active clamp circuits face issues of excessive current in the output diode and clamp switch, leading to potential damage and reduced efficiency due to premature shutdown of synchronous rectifiers.
Innovation Solution
Incorporating a path guiding module within the active clamp circuit that utilizes two clamp capacitors connected to different positions on the transformer's primary side, allowing them to obtain and discharge energy independently, thereby reducing excessive current and minimizing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If an existing active clamp circuit with a single clamp capacitor is used, then the leakage inductance energy can be stored and returned to the transformer, but excessive current in the output diode and clamp switch occurs causing damage and reduced efficiency
Solution Approach 1:
The single clamp capacitor is segmented into two separate clamp capacitors (C1 and C2), each connected to different leakage inductances (L1 and L2) on the primary side of the transformer. This segmentation distributes the energy storage function across multiple components, preventing excessive current concentration in any single component and thereby improving reliability while maintaining energy recovery capability.
Solution Approach 2:
The path guiding module acts as an intermediary that controls the charging and discharging paths of the two clamp capacitors. It ensures that C1 and C2 charge from different leakage inductances separately and discharge in parallel through the clamp switch, mediating the energy flow to prevent current overload while enabling efficient energy recovery.
2Device complexity
If a single clamp capacitor is used in the active clamp circuit, then the circuit structure remains simple, but the capacitor must withstand high voltage and handle excessive current leading to potential damage
Solution Approach 1:
The single high-stress clamp capacitor is divided into two capacitors (C1 and C2) that each handle lower voltage and current stress individually. By segmenting the capacitor function, the harmful factors of excessive current and voltage are distributed and reduced per component, preventing damage while maintaining relatively simple circuit structure through the use of standard dual-capacitor configuration.
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 configuration effectively limits current during discharge, reduces the risk of device damage, and simplifies the selection of clamp capacitors by allowing them to operate at lower voltages, enhancing the overall efficiency and reliability of the switching power supply.
Implementation Method 1
guide the first clamp capacitor and the second clamp capacitor to obtain an electric energy from different positions on the primary side of the transformer
Implementation Method 2
guide the first clamp capacitor to discharge the primary side of the transformer after being connected in parallel with the second clamp capacitor
Data Source
AI summary
The invention provides a switching power supply and an electronic device, comprising an active clamp circuit and a transformer, the active clamp circuit including a first clamp capacitor, a second clamp capacitor, and a path guiding module that is connected at two terminals of the first clamp capacitor and two terminals of the second clamp capacitor respectively; the path guiding module, the first and the second clamp capacitors are all directly or indirectly connected to a primary side of the transformer; the path guiding module is configured to guide the first and the second clamp capacitors to obtain an electric energy from different positions on the primary side of the transformer in a first time period, and to guide the first and the second clamp capacitors to discharge the primary side of the transformer after being connected in parallel with each other in a second time period.