Non-Inverting Buck-Boost Converter PFM Switch Control
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Solution Overview
Problem
Buck-boost converters operating in pulse frequency modulation (PFM) mode face inefficiencies due to high energy losses from switching and dynamic losses, as well as voltage ripple and overshoots, which are not adequately addressed by existing control methods.
Innovation Solution
A non-inverting buck-boost converter with an efficient PFM switch control system that compares output voltage and inductor current with reference thresholds to optimize switching, minimizing energy losses and voltage overshoots by selectively charging and discharging the inductor based on these comparisons, and employing specific discharging phases for boost and buck modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the converter operates in PFM mode with traditional switching control, then the converter can supply power to the output, but energy losses from switching and dynamic losses are high
Solution Approach 1:
The patent applies dynamics by making the switching control adaptive rather than fixed. The controller dynamically adjusts switching operations based on real-time comparison of inductor current with reference current and output voltage with reference voltage, optimizing the switching timing to minimize both energy losses and maintain power delivery capability
Solution Approach 2:
The patent implements feedback control by continuously monitoring inductor current and output voltage, comparing them against reference values, and using these comparisons to control the switching timing. This closed-loop feedback mechanism enables the system to reduce switching and dynamic losses while maintaining adequate power delivery
2Reliability
If the converter discharges inductor energy packets to maintain output voltage, then the output voltage can be maintained, but voltage ripple and overshoots occur
Solution Approach 1:
The patent applies preliminary anti-action by proactively controlling the switching timing based on predicted voltage thresholds. The controller compares output voltage with reference voltage and adjusts switching operations in advance to prevent voltage overshoots and ripple, rather than reacting after they occur
Solution Approach 2:
The patent implements preliminary action by using reference current and reference voltage thresholds to determine optimal switching timing before voltage excursions occur. The controller proactively initiates or terminates inductor discharge packets based on these pre-established references, preventing voltage ripple and overshoots before they happen
3Reliability
If the converter switches frequently to regulate output voltage, then voltage regulation is maintained, but switching losses increase
Solution Approach 1:
The patent applies partial action by using selective switching based on the degree of voltage deviation. The controller compares output voltage with reference voltage and only initiates switching actions when necessary to correct voltage deviations, avoiding unnecessary frequent switching and reducing associated losses while maintaining adequate voltage regulation
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 significantly reduces energy losses and voltage overshoots, enhancing the efficiency of buck-boost converters by optimizing switching operations and discharging phases, thereby improving overall performance in both boost and buck modes.
Implementation Method 1
The converter may accumulate current energy in the inductor that the converter may then discharge in pulses
Implementation Method 2
The converter may have an output capacitor coupled to the output that stores charge at the output
Data Source
AI summary
Methods, devices, and integrated circuits are disclosed for controlling a buck-boost converter. In one example, a device is configured to compare an output voltage at a voltage output with a low reference voltage and a high reference voltage. The device may compare a current at an inductor with a low threshold current and a high threshold current. The device may, responsive to the output voltage at the voltage output being lower than the low reference voltage, charge the inductor. The device may, responsive to the current at the inductor reaching the high threshold current, couple the inductor to the voltage output to transfer charge from the inductor to the voltage output. The device may, responsive to either the current at the inductor reaching the low threshold current or the output voltage reaching the high reference voltage, stop transferring charge from the inductor to the voltage output.