Buck Converter Feedforward PID Control for Fast Line Response
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Solution Overview
Problem
Existing methods for implementing line feedforward in buck converters with time-based control face challenges in efficiency, size, and design complexity, while maintaining transient response to input voltage variations.
Innovation Solution
A DC-DC converter circuit employing a feedback-PID structure with fast injection and fine correction circuits, along with a low-pass filter and proportional-integral circuit, to implement line feedforward, optimizing response to input voltage variations and noise across different frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If additional circuitry is used for line feedforward in time-based control, then transient response to input voltage variations is improved, but chip area and power consumption increase significantly
Solution Approach 1:
The VCO and VCDL circuits are designed to perform multiple functions: they serve both as the core time-based control mechanism and as the line feedforward path. By making these existing circuits multi-functional, the patent eliminates the need for separate dedicated feedforward circuitry, thereby maintaining fast transient response while avoiding additional chip area consumption
Solution Approach 2:
The patent merges the line feedforward function with the existing time-based control circuits (VCO and VCDL). Instead of implementing feedforward as a separate additional circuit, the invention combines both functions into the same circuitry, allowing the VCO frequency adjustments to simultaneously achieve both control and feedforward objectives
2Speed
If additional circuitry is used for line feedforward, then transient response is improved, but power consumption increases
Solution Approach 1:
The VCO and VCDL circuits are designed to perform multiple functions: they serve both as the core time-based control mechanism and as the line feedforward path. By making these existing circuits multi-functional, the patent eliminates the need for separate dedicated feedforward circuitry, thereby maintaining fast transient response while avoiding additional power consumption
Solution Approach 2:
The patent merges the line feedforward function with the existing time-based control circuits (VCO and VCDL). Instead of implementing feedforward as a separate additional circuit, the invention combines both functions into the same circuitry, allowing the VCO frequency adjustments to simultaneously achieve both control and feedforward objectives without extra power cost
3Speed
If line feedforward circuitry is added, then transient response improves, but control loop complexity and stability risks increase
Solution Approach 1:
The VCO and VCDL circuits are designed to perform multiple functions: they serve both as the core time-based control mechanism and as the line feedforward path. By making these existing circuits multi-functional, the patent eliminates the need for separate dedicated feedforward circuitry, thereby maintaining fast transient response while avoiding additional control loop complexity
Solution Approach 2:
The patent merges the line feedforward function with the existing time-based control circuits (VCO and VCDL). Instead of implementing feedforward as a separate additional circuit, the invention combines both functions into the same circuitry, simplifying the overall control architecture while maintaining performance
4Measurement precision
If traditional PWM comparator and error amplifier are used, then control precision is maintained, but power consumption and chip area increase
Solution Approach 1:
The patent extracts and eliminates the PWM comparator and error amplifier from the control architecture by replacing them with time-based control elements (VCO and VCDL). This extraction removes the power-hungry components while maintaining control functionality through phase-domain processing, significantly reducing power consumption without sacrificing control precision
Solution Approach 2:
The patent replaces the traditional voltage-based control mechanism (PWM comparator and error amplifier) with a time-based control mechanism (VCO and VCDL). This substitution transitions from voltage-domain processing to time-domain processing, eliminating the need for power-intensive analog components while achieving equivalent or superior control performance
Data Source
AI summary
This disclosure describes a DC-DC converter with improved response to input voltage variations. The converter employs a feedback-PID structure with a fast injection circuit and fine correction circuit to regulate output voltage. The fast injection circuit produces rapid duty cycle adjustments in response to input voltage changes, implementing a feedforward path. The fine correction circuit works with the fast injection circuit to provide integral action. A low-pass filter and the fine correction circuit create a bandpass filtering. The control loop includes a proportional-integral and a phase detection circuit to generate the final driving signal. A multiplier circuit tracks the input voltage and produces a control current proportional to the steady-state duty cycle. This approach enables fast response to input variations and precise long-term regulation while effectively managing noise across different frequency ranges.