Switched-Mode Power Supply Mode Switching Without Transition Oscillation
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Solution Overview
Problem
Existing switched-mode power supplies experience oscillations and inefficiencies during transitions between pulse skipping and continuous conduction modes, particularly when dealing with medium output loads, and there is a need for improved energy efficiency in these transitions.
Innovation Solution
Implementing a comparator that compares the output voltage with a reference voltage during a controlled portion of the conduction phase, and transitioning between modes based on this comparison, without considering zero-current detection during the conduction phase of the first switch, to minimize oscillations and enhance energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If zero-current detection is used to determine mode transitions, then accurate detection of current state is achieved, but oscillations occur during transitions between PSK and CCM modes
Solution Approach 1:
The conduction phase is divided into two distinct periods: a first period where zero-current detection is active and a second period where voltage comparison is active. This segmentation allows the system to use different detection methods at different times, avoiding the oscillation problem while maintaining accurate detection throughout the cycle.
Solution Approach 2:
The detection mechanism dynamically switches between zero-current detection and voltage comparison based on the timing within the conduction phase. This dynamic adaptation allows the system to optimize detection accuracy while preventing oscillations during mode transitions.
2Speed
If mode transition occurs immediately when voltage comparison indicates switching condition, then response speed is improved, but energy is wasted due to unnecessary coil recharging
Solution Approach 1:
The system performs preliminary detection during the first period of the conduction phase using zero-current detection. This preliminary action prepares the system for potential mode transition without immediately executing it, allowing energy-efficient decision-making before committing to the transition.
Solution Approach 2:
The system uses feedback from both zero-current detection and voltage comparison to determine the optimal timing for mode transition. This dual-feedback mechanism ensures that transitions occur at the most energy-efficient moment while maintaining fast response capability.
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 approach reduces oscillations and enhances energy efficiency by allowing seamless transitions between modes, particularly by avoiding unnecessary recharging of the coil, thus saving energy during mode changes.
Implementation Method 1
a comparator adapted to comparing the second output voltage with a third comparison voltage
Implementation Method 2
a coil coupling the first switch to the second output node
Data Source
AI summary
A switched-mode power supply is provided. An example switched-mode power supply includes: a first switch coupling a first node receiving a first power supply voltage to a second node supplying a second output voltage; and a comparator adapted to comparing the second output voltage with a third comparison voltage. When the switched-mode power supply is operating in a pulse skipping mode, the comparator is adapted to indicating that the second output voltage is higher than the third comparison voltage during part of the conduction phase of the first switch.