Unified Buck-Boost Regulator Control for Low Output Ripple
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Solution Overview
Problem
Existing switching voltage regulators using Buck-Boost mode experience high ripple in output voltage due to independent and separate operation of Buck and Boost control loops, which is undesirable for stability and efficiency.
Innovation Solution
A control device for a switching voltage regulator that integrates a Buck modulator and a Boost modulator with a selection circuit, enabling seamless transitions between Buck, Boost, and Buck-Boost modes by adjusting duty cycles based on input and output voltage ratios, using a single control loop to minimize ripple and enhance efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If independent Buck and Boost control loops are used, then the regulator can operate in both Buck and Boost modes, but output voltage ripple increases
Solution Approach 1:
The patent combines the Buck and Boost control loops into a single integrated control structure with unified PWM generation. The control device uses a single error amplifier and integrator that simultaneously control both half-bridges, eliminating the independent operation that causes ripple. The triangular signal generator and PWM modulator are shared resources that coordinate both modes seamlessly.
Solution Approach 2:
The control device is designed as a universal controller that handles both Buck and Boost operations through the same control pathway. The error amplifier, integrator, and PWM modulator serve dual purposes for both operating modes, allowing the system to adapt to different voltage conversion needs while maintaining consistent control characteristics and minimizing ripple through unified regulation.
2Adaptability or versatility
If separate Buck and Boost control loops operate independently, then mode transitions are possible, but transient time increases
Solution Approach 1:
The unified control structure ensures continuous regulation action during mode transitions. The error amplifier and integrator maintain continuous operation, providing uninterrupted control signals to both half-bridges. This continuous control action eliminates the gaps and adjustments that occur with separate control loops, thereby reducing transient time when switching between Buck and Boost modes.
Solution Approach 2:
The control system dynamically adapts to mode transitions through a single flexible control pathway. The PWM modulator and triangular signal generator can seamlessly adjust their operation to accommodate transitions between Buck and Boost modes without requiring reconfiguration of separate control loops, enabling faster and smoother mode changes.
3Adaptability or versatility
If independent Buck and Boost control loops are used, then each mode can be optimized separately, but device complexity increases
Solution Approach 1:
The patent employs a universal control device that performs both Buck and Boost regulation through a single integrated pathway. The error amplifier, integrator, and PWM modulator are designed to handle both operating modes simultaneously, eliminating the need for separate control loop hardware and reducing overall device complexity while maintaining full functionality.
Solution Approach 2:
The control architecture merges the Buck and Boost control functions into a single unified structure. By combining the error amplification, integration, and PWM generation functions into shared components that serve both modes, the patent reduces the total number of control elements required compared to having independent control loops for each mode.
Data Source
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AI summary
A control circuit and method, wherein an error signal is generated representative of a difference between an output voltage of a switching circuit and a nominal signal; a single control signal is generated, representative of an average error of the error signal; the single control signal is compared with a first periodic reference signal and a second periodic reference signal; a first pulse width modulated signal is generated by a Buck modulator; a second pulse width modulated signal is generated by a Boost modulator. The first and second periodic reference signals have a same period T, same amplitude range, same phase and different maximum and minimum values, the maximum value of the first periodic reference signal is lower than the single control signal in a Boost control mode, the minimum value of the second periodic reference signal is higher than the single control signal in a Buck control mode, the maximum value of the first periodic reference signal and the minimum value of the second periodic reference signal is higher, respectively lower than the single control signal in a transient control mode, between the Buck control mode and the Boost control mode.