Adaptive Ramp Signal Generator for Power Regulator Stability
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Solution Overview
Problem
Power regulator systems using ripple-based control, such as buck converters, experience delays in inductor current sensing due to certain ESR components, leading to sub-harmonic oscillations of the output current.
Innovation Solution
A power regulator system with an adaptive ramp signal generator, comprising a switch control stage, a feedback stage, and a ramp generator stage, where the ramp signal is generated based on the output voltage and activation signals, using an adjustable resistor-capacitor (RC) circuit and an adaptive ripple controller to adjust the RC time constant and reference voltage, thereby controlling the PWM signal and mitigating sub-harmonic oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If ESR components are used for current sensing in ripple-based control, then the power regulator system can implement PWM control, but delay in inductor current sensing occurs leading to sub-harmonic oscillations
Solution Approach 1:
The patent introduces an artificial ramp signal as an intermediary element that mediates between the delayed current sensing and the PWM control. This ramp signal, generated by the ramp generator stage, compensates for the sensing delay by providing a predictable timing reference that prevents sub-harmonic oscillations while maintaining the ease of current sensing using ESR components.
Solution Approach 2:
The patent dynamically adjusts the ramp signal parameters (slope, amplitude, timing) based on the detected switching frequency and operating conditions. By changing these parameters adaptively, the system maintains stable PWM control across different load conditions while compensating for the inherent delays in ESR-based current sensing.
2Reliability
If external ramp generation circuitry is used, then the power regulator system can achieve stable control, but device complexity and component count increase
Solution Approach 1:
The patent merges the ramp generation function with the existing power regulator control circuitry. The ramp generator stage is integrated into the feedback control loop, sharing common components such as the comparator and control logic. This integration achieves stable control through artificial ramp signaling while minimizing additional external circuitry by combining functions within the existing system architecture.
3Ease of manufacture
If fixed ramp signal parameters are used, then the circuit design is simplified, but the system cannot adapt to varying output voltage and switching frequency conditions
Solution Approach 1:
The patent implements dynamic adaptation of ramp signal parameters based on real-time detection of switching frequency and output voltage conditions. The system automatically adjusts the ramp signal characteristics (slope, amplitude, phase) to match varying operating conditions, maintaining optimal control performance across different load and line conditions while preserving relatively simple circuit implementation through automated adaptation.
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
The system internally generates an adaptive ramp signal, reducing the need for external ramp generation circuitry, enhancing stability and eliminating the risk of sub-harmonic oscillations by dynamically adjusting the ramp signal characteristics based on output voltage and switching frequency, thus providing a more compact and efficient power supply solution.
Implementation Method 1
a ramp generator stage comprising a resistor-capacitor (RC) circuit that is configured to generate the ramp signal, the RC circuit having an RC time constant
Data Source
AI summary
One embodiment includes a power regulator system. The system includes a switch control stage configured to generate at least one activation signal based on a pulse-width modulation (PWM) signal and to control a respective at least one switch to generate an output voltage. The system also includes a feedback stage configured to generate the PWM signal based on a ramp signal and a feedback voltage that is based on the output voltage. The system further includes a ramp generator stage configured to adaptively generate the ramp signal based on the output voltage and based on the at least one activation signal.