Dual-Constant-Time Buck-Boost Regulator Control
Solution Overview
Problem
Existing buck-boost switching regulators face issues with stability, high power consumption, and complex control mechanisms due to the need for multiple conversion modes and fixed frequency operation, which results in slower transient response and increased switching losses.
Innovation Solution
A constant time buck-boost switching regulator is developed, featuring a control circuit that generates two sets of constant times - a constant OFF time for the buck circuit and a constant ON time for the boost circuit, allowing operation in pure buck and boost modes without the need for buck-boost or transient modes, thus reducing switching losses and enabling Pulse Frequency Modulation without additional circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the regulator operates in buck-boost conversion mode with all four switches switching in one cycle period, then the operation range is extended, but the switching loss and power consumption increase
Solution Approach 1:
The patent divides the conversion process into two separate constant time intervals: a first constant time for buck conversion and a second constant time for boost conversion. This segmentation allows the regulator to handle different conversion modes independently, avoiding the need for all four switches to operate simultaneously, thereby reducing switching losses while maintaining extended operation range.
Solution Approach 2:
The patent implements periodic switching action with fixed time intervals for different conversion modes. By using constant time periods for buck and boost conversions separately, the system achieves regular switching patterns that reduce overlapping switch operations, thus lowering power consumption while maintaining adaptability across different voltage ranges.
2Device complexity
If the regulator uses fixed frequency operation, then the control mechanism is simplified, but the transient response becomes slower
Solution Approach 1:
The patent changes the control parameter from fixed frequency to constant time intervals. By using constant time periods for buck and boost conversions rather than fixed switching frequency, the system achieves faster transient response while keeping the control mechanism relatively simple. This parameter change allows the regulator to adapt more quickly to load changes without significantly increasing control complexity.
3Adaptability or versatility
If the regulator implements multiple conversion modes (pure buck, pure boost, and buck-boost), then the adaptability is improved, but the device complexity increases
Solution Approach 1:
The patent segments the control of different conversion modes into separate constant time generators: a first constant time generator for buck mode and a second constant time generator for boost mode. This segmentation simplifies the overall control circuit by avoiding the need for complex mode-detection and switching logic, while still providing all three conversion modes through selective activation of the appropriate constant time interval.
4Stability of the object's composition
If the regulator requires slope compensation circuitry for stability, then the stability is improved, but the device complexity increases
Solution Approach 1:
The patent employs constant time control intervals that inherently provide the necessary stability without requiring external slope compensation circuitry. The fixed time periods for buck and boost conversions create natural stability margins, allowing the regulator to maintain stable operation through its own control mechanism rather than requiring additional compensating circuits.
Data Source
AI summary
The present invention provides a dual constant time buck-boost switching regulator, and a control circuit and a method thereof. The buck-boost switching regulator converts an input voltage to an output voltage and it includes a buck circuit and a boost circuit. The buck circuit includes an inductor, a buck power switch and a buck power device. The boost circuit includes the inductor, a boost power switch and a boost power device. The present invention controls the buck power switch to be OFF by a constant OFF time in the buck conversion mode, and controls the boost power switch to be ON by a constant ON time in the boost conversion mode. An offset signal ensures that the buck-boost regulator operates only in pure buck conversion mode and pure boost conversion mode, but does not need to operate in a buck-boost conversion mode.