Switching Converter Frequency Adaptation for Stability
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Solution Overview
Problem
Switching converters face stability issues in certain operating modes, particularly at high input voltage and high output current conditions, where PWM-CCM may not be suitable, leading to potential mode switches to PFM-CCM that can result in stability problems and unwanted RF signal components in the output voltage.
Innovation Solution
A switching converter with a switching circuit, inductor, and oscillator that generates a clock signal based on input voltage, using pulse-width modulation (PWM) with current-mode control, allowing the PWM switching frequency to be adjusted based on input voltage to maintain stable operation in PWM-CCM mode, thereby avoiding unnecessary mode switches to PFM-CCM.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If PWM-CCM mode is used for high input voltage and high output current operation, then power conversion efficiency is improved, but stability problems occur
Solution Approach 1:
The patent applies dynamics by making the switching frequency adjustable rather than fixed. The oscillator frequency is dynamically adapted based on the input voltage level, allowing the system to maintain stable operation across different operating conditions while preserving the efficiency benefits of PWM-CCM mode at high input voltages and currents.
2Stability of the object's composition
If mode switch from PWM-CCM to PFM-CCM is implemented to avoid stability issues, then operational stability is improved, but unwanted RF signal components are generated
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the switching frequency parameter based on input voltage. Instead of switching to PFM-CCM mode which generates RF components, the system modifies the PWM-CCM operating parameters (frequency) to maintain stability, thereby avoiding the harmful RF signal generation while preserving operational stability.
3Ease of operation
If fixed switching frequency is used in PWM-CCM, then control simplicity is maintained, but stable operation cannot be ensured across wide input voltage range
Solution Approach 1:
The patent applies feedback by using the input voltage signal to automatically adjust the oscillator frequency. The switching frequency is proportional to the input voltage, creating a feedback mechanism that maintains stable operation across wide input voltage ranges while keeping the control structure relatively simple through automatic adaptation.
Data Source
AI summary
In accordance with one embodiment, a switching converter includes a switching circuit configured to receive a switching signal and to alternatingly connect an output node of the switching circuit with a supply node and a reference node in accordance with the switching signal. An input voltage is operably applied between the supply node and the reference node. The switching converter further includes an inductor coupled between the output node of the switching circuit and an output node of the switching converter as well as an oscillator configured to generate a clock signal with an oscillator frequency depending on the input voltage. A switching controller is configured to receive the clock signal and to generate the switching signal using pulse-width modulation (PWM), wherein the frequency of the switching signal is set in accordance with the oscillator frequency and a duty cycle of the switching signal is deter-mined using current-mode control.