Active Clamp Flyback Converter Variable Frequency Control
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Solution Overview
Problem
Active clamp flyback converters experience high conduction loss, making them unsuitable for applications requiring ultra-high power density, such as mobile communication terminals.
Innovation Solution
A converter design that includes a transformer with a primary and secondary winding, a first and second switch, and a switching controller that adjusts the turn-on and turn-off times based on load conditions, utilizing an auxiliary winding and diodes to minimize conduction loss by varying switching frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an active clamp flyback converter is used to achieve wide input voltage range and high power density, then the converter can realize zero voltage switching and eliminate voltage overshoot, but the conduction loss increases making it unsuitable for ultra-high power density applications
Solution Approach 1:
The patent applies dynamics by making the switching frequency variable rather than fixed. The controller adjusts the switching frequency based on real-time detection of diode current, transitioning between continuous conduction mode (CCM) and discontinuous conduction mode (DCM). This dynamic adjustment optimizes the balance between zero voltage switching performance and conduction loss across different operating conditions
Solution Approach 2:
The patent changes the operating parameters by detecting the diode current state and adjusting the switching frequency accordingly. When the diode current reaches zero, the controller increases the switching frequency to enter DCM, which reduces the conduction time and thereby reduces conduction loss. This parameter change strategy allows the converter to adapt to different load conditions and minimize energy loss
2Loss of energy
If the switching frequency is increased to reduce conduction loss, then the power density improves, but the switching losses may increase
Solution Approach 1:
The patent applies partial action by selectively increasing the switching frequency only when necessary. Rather than maintaining a constantly high switching frequency, the controller detects when the diode current reaches zero and then increases the frequency. This partial adjustment is sufficient to reduce conduction loss without continuously incurring high switching losses, achieving an optimal balance
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 reduces unnecessary conduction loss by quickening switch times and increasing switching frequency as the load decreases, enhancing efficiency and power density.
Implementation Method 1
a transformer comprising a primary winding and a secondary winding
Implementation Method 2
The first output unit may include a diode connected to the secondary winding
Data Source
AI summary
A converter and a driving method thereof are disclosed. The converter includes a transformer, a main switch, a clamp switch, and a switching controller. Here, the switching controller controls a turn-on time of the main switch and a turn-off time of the clamp switch corresponding to an output load.