Buck-Boost Converter Feed-Forward Control for Seamless Ripple Compensation
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Solution Overview
Problem
Buck-boost converters face challenges in seamlessly compensating for output ripple at the boundary between buck and boost modes, requiring effective feed-forward compensation to maintain stable voltage conversion.
Innovation Solution
The implementation of a buck-boost converter with a controller that generates a ramp signal with delayed reset timing and compensates for inductor current using pulses with emulated duty ratios, ensuring uniform compensation voltage regardless of input voltage changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feed-forward compensation is applied in buck-boost converter, then output ripple compensation is improved, but the compensation ratio varies depending on operation mode causing instability at mode boundaries
Solution Approach 1:
The patent dynamically adjusts the reset timing of the ramp signal based on the operation mode (buck, boost, or buck-boost) to maintain consistent feed-forward compensation ratio across all modes. The controller determines the operation mode by comparing input and output voltages, then selectively resets the ramp signal at appropriate timings to ensure stable output ripple compensation regardless of mode transitions
Solution Approach 2:
The patent changes the timing parameter of the ramp signal reset based on operation mode. By adjusting when the ramp signal is reset (earlier for buck mode, later for boost mode, and selectively for buck-boost mode), the system maintains optimal feed-forward compensation across different operating conditions without requiring separate compensation circuits for each mode
2Stability of the object's composition
If ramp signal reset timing is adjusted for different operation modes, then output voltage stability is improved, but complex control logic is required to determine optimal reset timing
Solution Approach 1:
The patent uses feedback from voltage comparison to simplify control logic. The controller compares input voltage (Vin) and output voltage (Vout) to determine operation mode, then automatically selects the appropriate ramp signal reset timing. This feedback mechanism eliminates the need for complex external control circuits while maintaining output voltage stability across mode transitions
Data Source
AI summary
An electronic circuit includes a buck-boost converter and controller. The converter includes an inductive element, a plurality of switches and a plurality of drivers therein, and is configured to generate an output voltage in response to an input voltage. The controller configured to: (i) generate a ramp signal having a reset timing that is delayed as the input voltage decreases, (ii) generate a sensing voltage having a magnitude that is a function of a magnitude of an inductor current in the inductive element, (iii) generate a feedback voltage having a magnitude that is a function of a magnitude of the output voltage, (iv) generate a compensation voltage in response to the feedback voltage and a reference voltage, and (v) uniformly maintain the compensation voltage based on the ramp signal and the sensing voltage, and independent of any change in the input voltage.