Biased Quantizer Control for Buck-Boost Ripple Reduction
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Solution Overview
Problem
Buck-boost power converters experience non-linearities and ripple on the output voltage due to transitions between buck and boost modes, which can lead to inefficiencies and discontinuities, especially when output and input voltages are close.
Innovation Solution
A modulator with a biased quantizer is used to generate switching signals for a switching circuit, biasing the control variable to increase the probability of alternating between buck and boost modes within a predetermined range, minimizing the buck-boost 'dead zone' and reducing ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the switching circuit operates in buck-boost mode when output voltage is close to input voltage, then the voltage conversion capability is improved, but non-linearities and ripple on output voltage occur due to mode transitions
Solution Approach 1:
The quantizer applies a bias to the control variable before mode transition to anticipate and prevent excessive switching between buck and boost modes. This preliminary action reduces the frequency of mode transitions and their associated non-linearities and output voltage ripple.
Solution Approach 2:
The invention changes the parameter of the control variable by applying a bias that varies based on the previous switching cycle's operational mode. This dynamic parameter adjustment smooths mode transitions and reduces output voltage ripple while maintaining voltage conversion capability.
2Adaptability or versatility
If the switching circuit frequently transitions between buck and boost modes, then the voltage regulation flexibility is improved, but efficiency decreases due to non-linearities and discontinuities
Solution Approach 1:
By applying a bias to the control variable in advance of mode transitions, the quantizer reduces the frequency of transitions between buck and boost modes. This preliminary action maintains voltage regulation flexibility while improving conversion efficiency by minimizing the energy losses associated with frequent mode switching.
Solution Approach 2:
The bias applied to the control variable is periodic in nature, alternating based on the previous switching cycle's mode. This periodic action creates a rhythm that prevents excessive mode transitions, thereby improving efficiency while preserving regulatory flexibility.
3Stability of the object's composition
If continuous operation in buck-boost mode is implemented, then the mode transition discontinuities are eliminated, but efficiency is negatively impacted
Solution Approach 1:
The quantizer applies a partial bias to the control variable only when necessary, i.e., when the control variable is within a predetermined difference from a boundary between operational modes. This partial action maintains output voltage continuity without the excessive energy consumption that would result from continuous buck-boost mode operation.
Solution Approach 2:
The bias parameter is dynamically adjusted based on the control variable's proximity to mode transition boundaries and the previous switching cycle's mode. This parameter change strategy ensures output voltage continuity while optimizing efficiency by applying bias only when needed.
Data Source
AI summary
A system may include a modulator configured to generate switching signals for a switching circuit based on a control variable, the modulator comprising a quantizer configured to, for a range of values of the control variable within a predetermined difference from a boundary of the control variable between a first operational mode and a second operational mode of the switching circuit, bias the control variable by a bias amount to increase a probability of operating the switching circuit in the first operational mode for a switching cycle if a previous switching cycle of the switching circuit was in the second operational mode; and increase a probability of operating the switching circuit in the second operational mode for the switching cycle if the previous switching cycle of the switching circuit was in the first operational mode.