Digital Control Power Supply Circuit Ripple Compensation
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Solution Overview
Problem
Digital control power supply circuits face instability in output voltage due to increasing equivalent series resistance (ESR) of output capacitors over time and with temperature changes, leading to increased ripple and reduced average output voltage levels.
Innovation Solution
A digital control power supply circuit with a control circuit that includes an A/D converter sampling feedback voltage at peak or bottom levels, an error detector, a compensator, and a correction unit that adjusts the target voltage based on ripple voltage amplitude, maintaining average output voltage stability by correcting the target data based on the difference between detection and feedback data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If digital control power supply circuit uses conventional feedback control, then control flexibility and design freedom are improved, but output voltage stability deteriorates due to ESR increase and ripple voltage changes
Solution Approach 1:
The patent implements a dual feedback mechanism: conventional feedback control maintains the peak voltage stability, while a separate ripple detection feedback path measures the ripple voltage amplitude and generates correction values. These correction values are fed back to adjust the target voltage dynamically, compensating for ESR changes and maintaining output voltage stability throughout the circuit's operational life.
Solution Approach 2:
The patent dynamically changes the target voltage parameter based on detected ripple voltage amplitude. By measuring the ripple voltage and calculating correction values, the system adjusts the target voltage to compensate for ESR increases, thereby maintaining stable average output voltage despite component aging and temperature variations.
2Temperature
If output capacitor ESR increases over time and temperature, then ripple voltage amplitude increases, but average output voltage level decreases
Solution Approach 1:
The ripple detection circuit continuously monitors ripple voltage amplitude and feeds this information back to the control system. This feedback enables real-time detection of ESR changes caused by temperature variations and aging, allowing the system to compensate for these changes and maintain stable output voltage under varying temperature conditions.
Solution Approach 2:
The system performs self-diagnosis and self-correction by detecting its own ripple voltage characteristics and automatically adjusting the target voltage accordingly. This self-service mechanism compensates for ESR changes without requiring external intervention or manual calibration, maintaining voltage stability throughout the product lifecycle.
3Measurement precision
If feedback control targets peak voltage, then peak voltage stability is improved, but average voltage stability deteriorates due to ripple voltage variations
Solution Approach 1:
The patent segments the feedback control into two independent functions: conventional feedback control maintains peak voltage stability, while a separate ripple detection and correction function maintains average voltage stability. By dividing the control task into these two segments, the system achieves both peak precision and average stability simultaneously.
Solution Approach 2:
The patent introduces an intermediary ripple detection circuit that measures ripple voltage amplitude and generates correction values. This intermediary component bridges the gap between peak voltage control and average voltage stability, allowing the system to maintain both objectives by translating ripple measurements into appropriate target voltage adjustments.
Data Source
AI summary
A control circuit of digital control power supply circuit includes: first filter generating detection voltage having voltage level based on time average of output voltage of the digital control power supply circuit; A/D converter sampling feedback voltage having voltage level based on the output voltage at peak or bottom of the output voltage and converting the sampled feedback voltage into digital feedback data, and converting the detection voltage into digital detection data; error detector generating error data indicating difference between the feedback data and target data indicating target value of the feedback voltage; compensator generating duty command value adjusted to make the error data approximate zero; digital pulse modulator receiving the duty command value and generating pulse signal having duty ratio corresponding to the duty command value; and correction unit correcting the target data based on difference between the detection data and the feedback data.