SIMO Buck Converter Control Using Inductor Ripple Emulation
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Solution Overview
Problem
Conventional single-inductor multi-output (SIMO) DC-DC buck converters experience severe cross regulation and slow transient response due to rapid changes in output load and fixed cycle control, leading to potential circuit damage and voltage overshoot/undershoot.
Innovation Solution
The SIMO DC-DC buck converter incorporates an inductor current ripple emulator circuit and a control circuit to generate event-triggered control signals based on sensed voltages, stabilizing output voltages by emulating inductor current ripple and using constant on-time control to improve cross regulation and transient response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed cycle PWM control is used, then the control structure is simple, but the transient response is slow and cross regulation performance deteriorates
Solution Approach 1:
The patent transitions from fixed-cycle PWM control to event-triggered control where the switching frequency and duty cycle dynamically adjust based on real-time inductor current ripple measurements. The control cycle adapts to load changes, enabling fast transient response while maintaining manageable control complexity through systematic event-triggering mechanisms.
Solution Approach 2:
The patent implements a feedback mechanism using an inductor current ripple emulator circuit that continuously monitors and feeds back the inductor current ripple information to the control logic. This feedback enables the controller to detect load changes and adjust switching parameters in real-time, resolving the contradiction between simple control structure and fast transient response.
2Device complexity
If fixed cycle control is used, then the control logic is simple, but cross regulation performance deteriorates under rapid load changes
Solution Approach 1:
The inductor current ripple emulator circuit provides continuous feedback about the actual inductor current ripple state to the control logic. This feedback enables the controller to detect load changes and adjust switching parameters in real-time, preventing voltage overshoot/undershoot and improving cross-regulation performance without excessive control logic complexity.
Solution Approach 2:
The patent uses the inductor current ripple emulator to predict upcoming load changes by monitoring ripple characteristics before they fully manifest as output voltage deviations. This preliminary detection allows the control logic to proactively adjust switching parameters, preventing cross-regulation issues before they occur.
3Speed
If event-triggered control is implemented, then transient response improves, but the control mechanism becomes more complex
Solution Approach 1:
The patent introduces an inductor current ripple emulator circuit as an intermediary that simplifies the event-triggered control mechanism. Instead of directly monitoring complex inductor current waveforms, the emulator circuit converts ripple information into a simplified signal that the control logic can easily process, reducing the actual control mechanism complexity while maintaining fast transient response.
Solution Approach 2:
The patent creates a simplified copy of the inductor current ripple behavior through the emulator circuit, which replicates the essential ripple characteristics in a form that is easier to measure and process. This copying approach enables event-triggered control with reduced complexity by working with the emulated signal rather than the original complex current waveform.
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
The solution reduces cross regulation performance issues and enhances transient response speed by stabilizing output voltages and adapting to load changes effectively.
Implementation Method 1
an inductor current ripple emulator circuit coupled to the inductor and configured to generate a sensed voltage according to a first terminal voltage at the ninth terminal and a second terminal voltage at the tenth terminal of the inductor
Data Source
AI summary
A single-inductor multi-output (SIMO) DC-DC buck converter includes a first switch, a second switch, a third switch, a fourth switch, an inductor, an error amplifier circuit, an inductor current ripple emulator circuit, a comparison circuit, and a control circuit. The error amplifier circuit generates a first error signal and a second error signal according to the output voltages of the SIMO DC-DC buck converter. The inductor current ripple emulator circuit generates a sensed voltage according to a first terminal voltage and a second terminal voltage of the inductor. The comparison circuit generates a first comparison result and a second comparison result according to the first error signal, the second error signal, and the sensed voltage. The control circuit generates first to fourth control signals for respectively controlling the first to fourth switches according to the first comparison result and the second comparison result.