SIMO Power Converter Peak-Current Threshold Control
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Solution Overview
Problem
Single-inductor multiple-output (SIMO) DC-DC converters face inefficiencies in continuous conduction mode (CCM) due to energy wastage and regulation challenges, particularly in managing peak inductor current and freewheeling states, which affect the overall power conversion efficiency and reliability.
Innovation Solution
A SIMO power converter system with a state machine and analog control circuit that adjusts the peak-current threshold based on total output voltage errors and freewheeling states, using a peak-current threshold control circuit with an error amplifier, low-pass filter, and freewheeling circuit to optimize inductor current management during charging and discharging cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the inductor is charged to a high peak current to ensure sufficient energy for regulating each output during a cycle, then the energy availability for output regulation is improved, but energy is wasted due to excessive charging
Solution Approach 1:
The patent implements dynamic adjustment of the peak-current threshold based on the freewheeling state duration. The control circuit monitors whether the converter operates in CCM or DCM and adjusts the threshold accordingly, transforming the static threshold into a dynamic parameter that adapts to operating conditions, thereby optimizing energy utilization and reducing waste
Solution Approach 2:
The patent employs feedback mechanisms where the control circuit continuously monitors the freewheeling state and uses this information to adjust the peak-current threshold for subsequent cycles. This closed-loop control ensures that the inductor is charged to the appropriate level needed for output regulation without excessive energy storage
2Loss of energy
If the peak-current threshold is reduced to minimize energy loss during freewheeling state, then energy efficiency is improved, but the risk of entering discontinuous current mode increases
Solution Approach 1:
The patent dynamically adjusts the peak-current threshold based on real-time detection of the freewheeling state. When the freewheeling state is detected, the threshold is reduced to minimize energy loss; when not detected, the threshold is maintained at a level that ensures continuous current mode operation, thus adapting to conditions to balance efficiency and reliability
Solution Approach 2:
The patent changes the peak-current threshold parameter based on operating conditions. By monitoring the freewheeling state and adjusting the threshold parameter accordingly, the system optimizes the balance between energy efficiency and maintaining reliable CCM operation
3Device complexity
If a fixed peak-current threshold is used to simplify control circuit design, then device complexity is reduced, but energy efficiency deteriorates due to inability to adapt to freewheeling states
Solution Approach 1:
The control circuit automatically detects the freewheeling state and adjusts the peak-current threshold without external intervention. The system serves itself by monitoring its own operating state and making appropriate parameter adjustments, achieving adaptive control with minimal additional complexity
Solution Approach 2:
The control circuit is designed to perform multiple functions: monitoring the freewheeling state, determining the operating mode (CCM or DCM), and adjusting the peak-current threshold. This multi-functional approach achieves adaptive energy optimization without proportionally increasing circuit complexity
Data Source
AI summary
A circuit to control the peak current of a single inductor multiple output (SIMO) power converter operating in continuous current mode (CCM) is disclosed. The circuit generates a peak-current threshold signal that can be raised or lowered based on an error signal generated by comparing output voltages to their respective regulated levels. Additionally, the circuit can lower the peak-current threshold signal when an energy storage element of the SIMO power converter is in a freewheeling state. The lowering can occur at a rate that continues as long at the freewheeling state persists. The disclosed circuits and methods allow the peak-current threshold to converge on a level that facilitates the sufficient charging of the energy storage element to provide enough energy to the outputs but not excessive charging so as to increase ohmic loss associated with the freewheeling state.