DC-DC Converter Burst Mode for Low Power Efficiency
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Solution Overview
Problem
Switching power supplies face challenges in maintaining efficiency and regulation at low load power levels, often resulting in increased switching losses and audible noise, as they struggle to achieve suitable duty cycles and power factor correction.
Innovation Solution
The implementation of a DC-DC switching power converter that operates in series of converter cycles with a duration of 1% or less of the pulse duration, varying the duration of the operating interval based on the power level, and adjusting the current envelope to approximate the pulse waveform, while using a controller to maintain the output voltage within a predetermined range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous high-frequency switching is used to maintain power factor correction and output voltage regulation, then power factor correction and voltage stability are improved, but switching losses increase and efficiency deteriorates at low power levels
Solution Approach 1:
The patent applies periodic action by operating the power converter in discrete bursts rather than continuous operation. The converter is enabled during selected intervals (when instantaneous power exceeds a threshold) and disabled during other intervals, creating a periodic on-off pattern that reduces average switching losses while maintaining voltage regulation through energy storage in capacitors during enabled periods.
Solution Approach 2:
The patent implements dynamics by making the converter operation adaptive to instantaneous power conditions. The control system dynamically adjusts the enabled/disabled state based on real-time power level detection, transitioning between continuous operation at high power and burst mode at low power, thereby optimizing efficiency across varying load conditions.
2Loss of energy
If the power converter is disabled during low power operation to reduce switching losses, then energy efficiency is improved, but output voltage regulation deteriorates
Solution Approach 1:
The patent applies beforehand cushioning by using energy storage capacitors to accumulate energy during enabled intervals before the converter is disabled. This pre-stored energy cushions the output during disabled periods, maintaining voltage regulation without requiring continuous switching operation, thus reducing losses while preserving reliability.
Solution Approach 2:
The patent introduces energy storage capacitors as intermediaries between the power converter and the load. These capacitors mediate the transfer of energy, allowing the converter to operate discontinuously while still providing continuous regulated output voltage to the load, thereby resolving the contradiction between reduced switching and maintained regulation.
3Loss of energy
If burst mode operation is implemented to reduce power consumption, then energy efficiency is improved, but audible noise may increase due to fixed frequency bursts
Solution Approach 1:
The patent applies dynamics by making the burst frequency adaptive rather than fixed. The converter operates in burst mode with variable frequency determined by instantaneous power conditions, allowing the system to optimize between efficiency and noise reduction by adjusting burst timing dynamically rather than operating at a fixed audible frequency.
Solution Approach 2:
The patent implements parameter changes by varying the operational parameters (enabled/disabled timing, burst frequency, duration) based on power level conditions. This allows the system to transition smoothly between different operational characteristics, reducing power consumption while minimizing audible noise through parameter optimization rather than fixed-frequency operation.
4Reliability
If power factor correction is maintained at all power levels, then power quality is improved, but device complexity increases due to continuous control requirements
Solution Approach 1:
The patent applies dynamics by implementing adaptive power factor correction that activates continuously only when instantaneous power exceeds a predetermined threshold. Below this threshold, the system transitions to a simpler burst mode operation, dynamically adjusting the control strategy based on power level to maintain power quality when needed while reducing complexity when not required.
Solution Approach 2:
The patent applies segmentation by dividing the operational range into distinct segments: a high-power segment where continuous power factor correction is maintained, and a low-power segment where simplified burst mode operation is used. This segmentation allows the system to apply appropriate control complexity only where necessary, maintaining power quality at high power while reducing overall device complexity.
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 enables efficient operation across a range of power levels, reducing switching losses and audible noise, and allows for continuous variable operation from full power factor correction mode to standby mode without invoking different operating modes.
Implementation Method 1
a first DC-DC switching power converter for converting power received from the unipolar input for delivery to a first load via a first output at a first DC output voltage
Data Source
AI summary
A method and apparatus for efficiently converting power from an AC line is disclosed. The power converter supplies power to the load, performing power factor correction at nominal and high loads, i.e. above a predetermined output power threshold, and operating in an on-demand burst mode at low loads, i.e. below a predetermined output power threshold, e.g. to supply power in a green mode to supervisory circuitry during a powered off state. The duration of an operating interval during which power conversion takes place may be reduced and varied at low loads as a function of the output power demands to increase overall conversion efficiency. The operating interval may be centered about a peak in the input voltage waveshape for operating intervals that are less than a full rectification period. For operating intervals that are less than a full rectification period a modified power factor correction may be used, in which the input current waveshape approximates the input voltage waveshape during the operating interval.