Buck-Boost Converter Frequency Adaptation for Driving Loss Reduction
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Solution Overview
Problem
Buck-boost converters face efficiency issues due to high driving loss and conduction loss, especially when the input voltage is close to the output voltage, and existing control methods either compromise efficiency or result in poor output voltage regulation and noise.
Innovation Solution
A buck-boost converter system operating in five different modes, utilizing two PWM comparators, an error amplifier, and an offset voltage circuit to reduce switching frequency when the input voltage is close to the output voltage, thereby improving efficiency and maintaining regulation performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If all four switches work continuously in buck-boost mode, then the converter can handle both buck and boost operations, but driving loss increases and efficiency decreases
Solution Approach 1:
The patent implements dynamic switching frequency adjustment where the converter operates at full frequency when buck or boost mode is required, but reduces to half frequency when input voltage is close to output voltage. This dynamic frequency adaptation reduces driving loss during light-load conditions while maintaining full adaptability when needed.
Solution Approach 2:
The patent changes the operating frequency parameter based on the voltage difference between input and output. When |Vin - Vout| is small, the switching frequency is halved, which directly reduces the driving loss of switches while maintaining the ability to transition to full frequency when adaptability is needed.
2Loss of energy
If switching frequency is reduced when input voltage is close to output voltage, then driving loss decreases and efficiency improves, but output voltage regulation may be compromised
Solution Approach 1:
The patent incorporates feedback control that continuously monitors the voltage difference between input and output. When |Vin - Vout| exceeds a threshold, the system automatically switches from half-frequency to full-frequency operation, ensuring output voltage regulation is maintained during transitions and load changes while enjoying efficiency benefits during stable light-load conditions.
Solution Approach 2:
The system dynamically adjusts switching frequency based on real-time voltage conditions, transitioning between half-frequency and full-frequency modes. This dynamic adaptation ensures that output voltage regulation is prioritized when voltage differences are significant while maximizing efficiency when voltages are close.
3Power
If inductor current is increased to maintain power transfer, then power delivery is sufficient, but conduction loss increases and efficiency decreases
Solution Approach 1:
The patent uses periodic full-frequency switching bursts interspersed with half-frequency operation. During half-frequency mode, the converter performs sufficient power transfer in each switching cycle, reducing average inductor current and conduction losses while maintaining overall power delivery capability through the periodic full-frequency reinforcement.
Data Source
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AI summary
Systems and methods for providing a buck-boost converter with an improved efficiency are disclosed. The buck-boost converter disclosed operates in 5 different modes, namely in buck mode, half frequency buck mode, half frequency buck-boost mode, half frequency boost mode, and in boost mode. In half frequency buck mode, buck-boost mode, and in half frequency boost mode the switching frequency is halved compared to the switching frequency of buck or boost mode. A simple circuit implementation by adding two offset voltages in ramp signals or PWM comparators enables to halve the switching frequency if required.