Open-Loop Switch-Mode Boost Converter High Bandwidth
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Solution Overview
Problem
Switch-mode boost power converters typically require a feedback loop due to their non-linear relationship between output voltage and duty-cycle, limiting their signal bandwidth and efficiency compared to switch-mode buck converters which can operate without feedback.
Innovation Solution
A high-speed open-loop switch-mode boost converter is designed with a switching signal generator circuit that produces a switching signal with a non-linear relationship to the input signal amplitude, and a high-order filter circuit to maintain a linear relationship between the input and output signals, eliminating the need for a feedback loop and enhancing bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a feedback loop is used in a switch-mode boost converter to maintain stable output voltage, then output voltage stability is improved, but signal bandwidth is reduced due to the non-linear relationship between duty-cycle and output voltage
Solution Approach 1:
The patent transforms the non-linear relationship between duty-cycle and output voltage into a linear relationship by applying a non-linear transformation to the control signal. The switching signal generator circuit processes the input signal through non-linear functions (including square root and squaring operations) to create a duty-cycle that linearly correlates with the input signal amplitude, enabling open-loop operation with high bandwidth while maintaining stable output through the combined non-linear relationships in the signal path and filter circuit
2Measurement precision
If a feedback loop is implemented in a switch-mode boost converter, then output voltage control is improved, but circuit complexity increases
Solution Approach 1:
The patent removes the feedback loop entirely from the switch-mode boost converter, extracting the control function into the switching signal generator circuit that directly processes the input signal. This eliminates the need for voltage sensing, error amplification, and feedback compensation circuits, significantly reducing component count and circuit complexity while maintaining precise output control through the open-loop non-linear signal processing approach
3Manufacturing precision
If a second-order filter is used in a switch-mode boost converter, then output signal quality is improved, but signal bandwidth is reduced due to filtering of high-frequency components
Solution Approach 1:
The patent employs a dynamic higher-order filter circuit (third-order or higher) that adapts to the signal characteristics and switching frequency. The filter order and characteristics are optimized to pass high-frequency signal components while attenuating switching frequency harmonics, achieving a balance between output signal quality and bandwidth preservation that second-order filters cannot provide
Data Source
AI summary
An open-loop switch-mode boost converter includes a switching signal generator circuit that receives a time-varying input signal and outputs a switching signal. A duty-cycle of the switching signal has a first non-linear relationship to an amplitude of the time-varying input signal. An amplifier receives the switching signal and outputs a time-varying output signal, an amplitude of which has a second non-linear relationship to the duty-cycle of the switching signal. The time-varying output signal has a linear relationship to the time-varying input signal based on the first non-linear relationship and the second non-linear relationship. A filter circuit receives the time-varying output signal and outputs a filtered time-varying output signal which has a maximum frequency component that is substantially the same as a maximum frequency component of the time-varying input signal. The switching signal generator circuit is communicatively isolated from the voltage output node and the filter output node.