Discrete-Time PFC Converter Control for Stable High-Gain Operation
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Solution Overview
Problem
Existing power factor correction systems face challenges in achieving high gain and frequency while maintaining stability and preserving a minimally acceptable power factor.
Innovation Solution
The implementation of a digital control system for power factor correction that utilizes multi-level, nonlinear control techniques, updating values only at zero-crossings of the input signal, and employing a hybrid control system with different operation levels for small and large signal responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous-time, linear time-invariant control systems are used for power factor correction, then the system maintains stability, but the gain and frequency are limited and the power factor cannot be maintained close to unity under all conditions
Solution Approach 1:
The patent replaces the continuous-time, linear time-invariant control system with a discrete-time, nonlinear control system. This substitution enables the system to achieve high gain and frequency operation while maintaining stability through digital signal processing and adaptive control algorithms that update parameters at zero-crossings of the input signal.
Solution Approach 2:
The patent introduces dynamic operation levels that adapt based on signal conditions. The hybrid control system switches between different operation levels (e.g., small signal response vs. large signal response) to optimize performance across varying operating conditions, enabling high gain and frequency while preserving power factor.
2Productivity
If continuous-time, linear time-invariant control systems are used for power factor correction, then the system operates continuously, but the power factor deviates from unity and control precision is reduced
Solution Approach 1:
The patent employs periodic sampling and updating of control parameters at zero-crossings of the input signal. This periodic action synchronizes with the AC waveform, enabling precise power factor control by resetting and updating control variables at predictable intervals, thereby maintaining power factor close to unity while ensuring continuous operation.
3Measurement precision
If multi-level, nonlinear control techniques are implemented with updates only at zero-crossings, then power factor control precision is improved, but the system complexity increases
Solution Approach 1:
The patent segments the control operation into distinct operation levels (e.g., small signal response, large signal response) and updates control parameters only at specific timing points (zero-crossings). This segmentation reduces the computational burden compared to continuous updates while maintaining high control precision through targeted parameter adjustments at critical moments.
4Adaptability or versatility
If hybrid control system with different operation levels is used, then the system adapts to small and large signal responses, but the device complexity increases
Solution Approach 1:
The patent implements a hybrid control system where a single controller performs multiple functions by switching between different operation levels. The same control architecture handles both small signal responses (for fine regulation) and large signal responses (for gross adjustments), providing universal adaptability without requiring separate dedicated circuits for each function, thereby limiting the increase in device complexity.
Data Source
AI summary
An apparatus for controlling a power converter operable to receive a cyclically varying input signal includes a discrete-time, on-time generator coupled to the power converter and operable to regulate an output voltage of the power converter and a controller operable to compare the output voltage of the power converter against a voltage range or threshold to: obtain a comparison result in synchronization with the cyclically varying input signal and select one of a plurality of operation levels of the discrete-time, on-time generator in response to the comparison result. The plurality of operation levels may include a linear, discrete-time operation level and a nonlinear, discrete-time operation level. The nonlinear, discrete-time operation level may include determining a power deficiency of a bulk capacitor and adjusting a width of an on-time pulse accordingly.