Power Converter Dual-Loop Voltage Control for Low Ripple Loads
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Solution Overview
Problem
Existing power converter systems face challenges in effectively regulating output voltage with minimal ripple in the presence of time-varying current and power load, particularly in personal audio devices like wireless telephones and media players.
Innovation Solution
The implementation of a dual-loop control system for power converters, utilizing an outer hysteretic control loop and an inner continuous control loop, which measures the time duration for output voltage to cross voltage thresholds to determine current load and set peak and valley current thresholds, along with a switch controller using comparators for hysteretic or continuous control modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single control loop is used for voltage regulation, then the control system is simple, but the output voltage ripple is large under time-varying loads
Solution Approach 1:
The control system is segmented into two independent control loops: an outer hysteretic control loop that provides coarse voltage regulation and an inner continuous control loop that minimizes voltage ripple. Each loop operates with its own voltage thresholds and control parameters, allowing them to function independently while collectively achieving superior voltage regulation performance compared to a single loop system.
2Speed
If hysteretic control is used for fast response, then the response speed is fast, but the output voltage ripple increases
Solution Approach 1:
The hysteretic control function is isolated to the outer loop which handles fast response requirements, while the inner continuous control loop is dedicated to ripple minimization. This segmentation allows each control mode to optimize for its specific function without compromising the other, achieving both fast response and low ripple simultaneously.
Solution Approach 2:
The inner continuous control loop acts as an intermediary between the outer hysteretic loop and the power converter. It smooths the control signal from the outer loop and provides fine-grained current control that reduces voltage ripple while maintaining the fast response capability of the outer hysteretic loop.
3Object-generated harmful factors
If continuous control is used for smooth regulation, then the output voltage ripple is reduced, but the response speed to load changes decreases
Solution Approach 1:
The continuous control function is assigned to the inner loop which handles ripple reduction, while the outer hysteretic loop handles fast response to load changes. This segmentation allows the continuous control to operate at higher frequencies for ripple minimization while the hysteretic loop provides rapid response to external disturbances.
Solution Approach 2:
The control loops are nested with the inner continuous control loop embedded within the outer hysteretic control loop. The inner loop operates at a higher frequency and provides fine control, while the outer loop operates at a lower frequency and provides coarse control with fast response. This nested structure allows both control modes to work together effectively, with the inner loop smoothing the output of the outer loop.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces ripple and enhances efficiency in voltage regulation, minimizing voltage droop and maintaining stable output voltage across varying loads, thereby improving the performance of power converters in electronic devices.
Implementation Method 1
the plurality of comparators are used for controlling the inductive power converter in one or both of a hysteretic control mode and a continuous control mode, each comparator having a respective reference voltage to which the output voltage is compared
Data Source
AI summary
A system may include a power converter configured to receive an input voltage and generate an output voltage and a controller configured to control operation of the power converter based on a comparison of the output voltage with at least one output voltage threshold and set the at least one output voltage threshold based on the input voltage.