Flyback Converter Standby Control with Periodic Photocoupler Sampling
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Solution Overview
Problem
Flyback converters in battery chargers for portable electronic devices continue to consume power in standby mode due to the active feedback loop, particularly when using a photocoupler, which constitutes a significant portion of standby power.
Innovation Solution
Implement a power converter with a primary-side and secondary-side controller that transitions to a standby mode upon detecting load disconnection, where the secondary-side controller sends a no-load message, and the primary-side controller monitors compensation signals to periodically switch the power switch, reducing power consumption by disabling or minimizing the operation of the feedback loop components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the feedback loop remains active in standby mode to stabilize output voltage, then output voltage stability is maintained, but power consumption increases significantly due to photocoupler operation
Solution Approach 1:
The patent implements periodic sampling of the compensation signal instead of continuous monitoring. The controller samples the compensation signal at specific intervals (e.g., every N switching cycles) rather than continuously, which significantly reduces the duty cycle of the photocoupler while still maintaining adequate voltage regulation. This periodic action allows the system to maintain reliability while dramatically reducing standby power consumption.
Solution Approach 2:
The patent dynamically adjusts the operation mode of the feedback loop based on load conditions. When light load or no-load condition is detected, the system transitions from continuous feedback loop operation to periodic sampling mode. This dynamic adaptation allows the system to optimize between voltage stability and power consumption based on actual operating conditions.
2Use of energy by moving object
If the photocoupler is turned OFF in standby mode to reduce power consumption, then standby power is reduced, but output voltage regulation capability is compromised
Solution Approach 1:
Instead of completely turning off the photocoupler, the system uses periodic sampling where the photocoupler is activated only at specific intervals to sample the compensation signal. This maintains the regulation capability while minimizing power consumption during standby mode.
Solution Approach 2:
The system uses the existing compensation signal that is already generated by the error amplifier to provide feedback information during standby mode. By sampling this existing signal periodically rather than continuously, the system maintains regulation capability using minimal additional power.
3Use of energy by moving object
If functional blocks within the IC are turned OFF in standby mode to reduce current consumption, then IC power consumption is reduced, but the feedback loop cannot remain active to monitor and control output voltage
Solution Approach 1:
The patent segments the feedback loop operation into essential and non-essential functional blocks. The error amplifier and compensation signal generation are maintained in a reduced-power state, while continuous operation of all functional blocks is eliminated. This segmentation allows selective power management that maintains critical functions while reducing overall consumption.
Solution Approach 2:
The system uses periodic sampling of the compensation signal to maintain feedback loop functionality with minimal active components. By sampling rather than continuously processing the feedback signal, the system can keep essential blocks active at minimal power while turning off non-essential processing functions during standby mode.
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
Significantly reduces power consumption in standby mode by minimizing the operation of the feedback loop, particularly the photocoupler, while maintaining output voltage stability through periodic switching, thus conserving energy.
Implementation Method 1
the feedback loop generates the compensation signal through an photocoupler
Implementation Method 2
a flyback converter is often used as the fundamental architecture for battery chargers
Data Source
AI summary
An embodiment of the invention discloses a method for powering down a power converter with a photo coupler. Responsive to disconnection of a load from the power converter, the power converter is placed into a standby mode, during which a LED current flowing through the LED of the photo coupler is switched a predetermined number of times at each predetermined period, where the predetermined number is at least once.