Input-Output Linearization for Power Converter Stability
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Solution Overview
Problem
Existing power converter control methods using trailing-edge modulation result in unstable zero dynamics, limiting stability to a single operating point, especially during startup and transient modes, and fail to account for large signal effects.
Innovation Solution
The implementation of leading-edge modulation combined with input-output linearization to compute the duty ratio of boost or buck-boost converters, providing a stable linear system with open left half-plane zeros, allowing control across a range of operating points without requiring stabilizing gain or specific output trajectories.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If trailing-edge modulation is used to control power converters, then the control implementation is straightforward, but the zero dynamics become unstable and stability is limited to a single operating point
Solution Approach 1:
The patent inverts the conventional trailing-edge modulation approach by using leading-edge modulation instead. This inversion changes the timing relationship between the control signal and the switch operation, which fundamentally alters the zero dynamics characteristics from unstable to stable, while maintaining control effectiveness across multiple operating points
2Stability of the object's composition
If linearization is done through Taylor series expansion at a specific operating point, then the control loop is stabilized at that point, but large signal effects are ignored and the system cannot handle transient modes effectively
Solution Approach 1:
The patent changes the fundamental parameter of the control approach from local linearization (Taylor series at a fixed operating point) to global linearization (input-output linearization valid across the entire operating range). This parameter change enables the system to maintain stability and performance during large signal transients and across multiple operating points, not just at a single nominal point
3Device complexity
If small signal operation assumptions are made for linearization, then the control design is simplified, but the system cannot account for large signal effects during startup and transient modes
Solution Approach 1:
The patent inverts the conventional approach by using leading-edge modulation combined with input-output linearization, which naturally handles large signal effects without requiring small signal assumptions. This inversion maintains control design simplicity while significantly improving reliability during large signal operations such as startup and transient modes
Data Source
AI summary
A system, method and apparatus for controlling boost and buck-boost converters using input-output linearization and leading-edge modulation is provided. The controller includes a summing circuit connected to the converter to create a third voltage representing a difference between the first voltage and the second voltage. A gain circuit is connected to the summing circuit to adjust the third voltage by an appropriate gain. A modulating circuit is connected to the gain circuit, the converter, the first voltage, the second voltage and the second current to create a control signal based on the first voltage, the second voltage, the adjusted third voltage, the fourth voltage and the first current. The control signal is used to control the converter. Typically, the first voltage is a converter output voltage, the second voltage is a reference voltage, the fourth voltage is a converter input voltage, and first current is a converter inductor current.