Buck Converter PWM Control for Adaptive Pull-Up Switching Frequency
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Solution Overview
Problem
Existing small-sized buck converters face challenges in maintaining high stability and low energy consumption, particularly under heavy load conditions where inductance drops significantly, leading to excessive ripples and performance issues.
Innovation Solution
A new buck converter design that senses the current of its power transformation component and adjusts the turn-on frequency of the pull-up transistor, using a PWM control signal generator to regulate the output voltage and mitigate inductance drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a small-sized inductor is used in the buck converter, then the device size is reduced, but the inductance drops significantly under heavy load causing excessive ripples and performance degradation
Solution Approach 1:
The patent implements dynamic frequency adjustment of the pull-up transistor based on sensed current levels. Under heavy load conditions, the switching frequency is increased to compensate for the small inductor's inductance drop, maintaining stable output voltage and current ripple performance while enabling compact converter design
2Reliability
If a large-sized inductor is adopted to avoid excessive inductance changes, then the conversion performance stability is improved, but the device size becomes unsuitable for portable applications
Solution Approach 1:
The patent changes the operating frequency parameter dynamically based on load conditions. By sensing the current and adjusting the pull-up transistor's switching frequency, the system compensates for the small inductor's characteristics under heavy load, achieving stable performance without requiring a large inductor
3Object-generated harmful factors
If the buck converter operates at constant high frequency to reduce RMS current, then the current ripple is reduced, but switching loss increases considerably
Solution Approach 1:
The patent implements dynamic frequency modulation where the pull-up transistor's switching frequency varies with load conditions. Under heavy load, frequency increases to control current ripple; under light load, frequency decreases to minimize switching losses, optimizing both performance and efficiency
4Reliability
If the turn-on frequency of the pull-up transistor is increased to compensate for inductance drop, then the conversion performance stability is improved, but switching loss increases
Solution Approach 1:
The patent uses current sensing feedback to dynamically adjust the pull-up transistor's switching frequency. The sensed current information triggers frequency increases only when needed under heavy load conditions, maintaining output stability while avoiding unnecessary switching losses during normal or light load operation
Data Source
AI summary
A buck converter with an adaptive turn-on frequency of a pull-up transistor is shown. The buck converter uses a pulse-width modulation (PWM) control signal generator to generate a PWM control signal that drives a power transistor driver to generate PWM signals driving the pull-up transistor and pull-down transistor of the buck converter. Especially, the PWM control signal generator generates the PWM control signal based on feedback of an output voltage of the buck converter as well as feedback of a sensed current about a power transformation component of the buck converter, to modify a turn-on frequency of the pull-up transistor in response to a change in the sensed current.