PFM Boost Converter Pulse Clustering for Ringing Reduction
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Solution Overview
Problem
Boost converters experience efficiency losses due to ringing on the switching node caused by parasitic capacitance, especially when operating in pulse frequency modulation (PFM) mode, leading to power losses and reduced efficiency, particularly in battery-powered applications.
Innovation Solution
The boost converter employs a control method where current pulses are sourced towards the beginning of a specified time period with no delays between pulses, and no further pulses are sourced after a desired number is reached, minimizing ringing to the end of the period, thus reducing power losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If current pulses are evenly spaced across a specified time period in PFM mode, then the average frequency is maintained, but ringing occurs after each pulse causing power losses
Solution Approach 1:
The patent applies periodic action by clustering current pulses at the beginning of the specified time period rather than spacing them evenly. This creates a periodic pattern where multiple pulses occur in succession without delay, followed by a period with no pulses, thereby maintaining the desired average frequency while reducing ringing-related power losses that occur with evenly spaced pulses
Solution Approach 2:
The patent employs preliminary action by sourcing all current pulses at the beginning of the specified time period before the ringing issue becomes problematic. By completing all necessary pulses early in the period with no delay between them, the system minimizes the occurrence of ringing across multiple cycles while still achieving the required average frequency over the full period
2Loss of energy
If current pulses are sourced with no delay between successive pulses, then ringing is minimized to only after the final pulse, but the timing control complexity increases
Solution Approach 1:
The control circuit implements periodic action by using a specified time period counter that resets after a predetermined number of pulses are sourced. This creates a regular periodic pattern where clusters of pulses with no delay occur at the beginning of each period, making the timing control systematic rather than complex despite the clustered pulse pattern
3Productivity
If pulses are clustered at the beginning of the time period with no spacing, then efficiency is improved by reducing ringing, but the uniformity of pulse distribution is reduced
Solution Approach 1:
The patent resolves this contradiction by implementing periodic action with a specified time period that maintains the desired average frequency. While pulses are clustered at the beginning of each period (reducing uniformity within the period), the periodic repetition ensures that the average frequency remains stable and controlled, achieving efficiency improvement without sacrificing overall frequency stability
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 power losses by limiting ringing to only after the final pulse, maintaining the desired average frequency and enhancing the overall efficiency of the boost converter.
Implementation Method 1
an inductor and a transistor coupled thereto. A control circuit is arranged to control the transistor to cause current pulsed to be sourced through the inductor
Implementation Method 2
A control circuit is arranged to control the transistor to cause current pulsed to be sourced through the inductor
Data Source
AI summary
The present disclosure is directed to a pulse frequency modulation (PFM) control method for a boost converter and apparatus for carrying out the method. A boost converter includes an inductor and a transistor coupled thereto. A control circuit is arranged to control the transistor to cause current pulsed to be sourced through the inductor. When operating in a PFM mode, the control circuit may control the timing of pulses such that, at the beginning of a specified time period, current pulses may be sourced with no spacing between successive pulses. After a desired number of pulses have been sourced, no pulses are sourced for the remainder of the specified time period. Nevertheless, the number of pulses sourced over the time period corresponds to a desired average frequency of pulses.