SMPS Control Circuit for Efficiency and Transient Response
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Solution Overview
Problem
Existing switched mode power supply (SMPS) control strategies face challenges in maintaining high power efficiency while effectively responding to transients and varying load conditions, often compromising output voltage tolerance and efficiency.
Innovation Solution
A control circuit and method that generate a control signal to adjust the duty cycle of an SMPS based on both input and output voltage levels, allowing for two modes of operation to optimize efficiency and damping of oscillations, enabling improved load regulation and transient response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If output regulated converters use feedback control to compensate for varying load conditions and input voltage changes, then output voltage stability is improved, but power efficiency deteriorates
Solution Approach 1:
The patent implements dynamic control mode switching between regulated and unregulated operation based on real-time operating conditions. The controller dynamically adjusts the duty cycle control strategy: using feedback-regulated control when output voltage stability is critical, and switching to unregulated 100% duty cycle operation when maximum efficiency is the priority, thus adapting the system behavior to current demands
Solution Approach 2:
The patent changes the control parameter (duty cycle control strategy) based on operating conditions. By monitoring input voltage levels and load conditions, the system transitions between different duty cycle control modes: continuous regulation at lower input voltages to maintain stability, and discontinuous conduction mode with 100% duty cycle at higher input voltages to maximize efficiency
2Loss of energy
If fixed ratio converters run with maximised duty cycle to transfer energy almost 100% of the time, then power efficiency is improved, but output voltage tolerance deteriorates
Solution Approach 1:
The system dynamically switches between two operational modes: unregulated mode with 100% duty cycle for maximum efficiency when input voltage is high and load is light, and regulated mode with feedback control when input voltage drops or load increases, thus maintaining output voltage tolerance dynamically based on operating conditions
Solution Approach 2:
The patent segments the operating range into different regions: a high-efficiency unregulated region operating at 100% duty cycle for light loads and high input voltages, and a regulated region using feedback control for heavy loads or low input voltages. This segmentation allows the system to optimize for efficiency in one region while maintaining stability in another
3Stability of the object's composition
If semi-regulated converters compensate for varying input voltage with varying duty cycle, then line regulation is improved, but power efficiency deteriorates
Solution Approach 1:
The patent applies local quality by implementing regulation only where necessary: using feedback control for line regulation when input voltage variations occur, but switching to unregulated 100% duty cycle operation when input voltage is stable and high, thus applying regulation locally rather than globally to minimize efficiency loss
Data Source
AI summary
A control circuit, that controls the duty cycle of a switched mode power supply, comprises a reference voltage generator that, responsive to the input voltage exceeding a threshold value, generates a predetermined reference signal. Responsive to the input voltage not exceeding the threshold value, the reference voltage generator receives a signal indicative of an input voltage of the switched mode power supply and generates a variable reference signal dependent upon the input voltage. The control circuit further comprises an error signal generator that receives a signal indicative of an output voltage of the power supply and generates an error signal based on the reference signal generated by the reference voltage generator and based on the output voltage. The control circuit also includes a duty cycle control signal generator that generates the control signal to control the duty cycle of the power supply in dependence upon the error signal.