CVCC Control Circuit for SMPS Load Regulation
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Solution Overview
Problem
Conventional switch mode power supply (SMPS) systems face challenges in achieving efficient load regulation, particularly under light or no-load conditions, leading to power loss due to the difficulty in integrating opto-couplers and increased circuit volume and cost.
Innovation Solution
A constant voltage constant current (CVCC) circuit for SMPS that includes a voltage feedback circuit, current feedback circuit, control signal generating circuit, and PWM controller, which generates a control signal to manage the main switch, allowing for simplified circuit structure and reduced power loss by turning off the main switch under light or no-load conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional SMPS systems use opto-couplers for feedback control, then output voltage regulation is achieved, but circuit volume and product cost increase
Solution Approach 1:
The patent extracts and eliminates the opto-coupler component from the feedback control circuit. Instead of using optical coupling for feedback, the system employs direct electrical feedback paths through resistive dividers and operational amplifiers, thereby removing the opto-coupler while maintaining regulation functionality
Solution Approach 2:
The patent creates an electrical equivalent of the optical feedback mechanism by using voltage dividers and operational amplifiers to replicate the isolation and feedback function previously performed by opto-couplers, achieving the same control objective through different physical means
2Productivity
If the main switch remains on continuously in SMPS, then power transfer is maintained, but power loss increases under light or no-load conditions
Solution Approach 1:
The patent implements dynamic control of the main switch by introducing a control circuit that adjusts the switch duty cycle based on load conditions. Under light or no-load conditions, the control circuit reduces the duty cycle or turns off the switch completely, dynamically adapting the power transfer to match actual load requirements and minimize energy loss
Solution Approach 2:
The patent employs feedback control where the output voltage is continuously monitored and fed back to the control circuit. This feedback signal enables the control circuit to detect light or no-load conditions and automatically adjust the main switch operation accordingly, creating a closed-loop system that optimizes power transfer efficiency
3Adaptability or versatility
If CVCC control is implemented with traditional circuits, then constant voltage and current output is achieved, but circuit structure becomes complex
Solution Approach 1:
The patent designs a universal control circuit that can operate in multiple modes (constant voltage mode and constant current mode) using the same basic components. By using a single operational amplifier-based control circuit that responds to different feedback conditions, the system achieves dual functionality without requiring separate dedicated circuits for each mode
Solution Approach 2:
The patent merges the constant voltage and constant current control functions into a single integrated control circuit. The control circuit combines voltage feedback and current feedback paths that converge at a common control node, allowing unified control of both output parameters through one circuit structure rather than separate independent circuits
Data Source
AI summary
The present invention discloses CVCC circuits and methods with improved load regulation for an SMPS. In one embodiment, the CVCC can include: a voltage feedback circuit to generate an output voltage feedback signal; a current feedback circuit to generate an output current feedback signal; a control signal generating circuit that receives the output voltage feedback signal and the output current feedback signal, and generates a constant voltage/constant current control signal; a first enable signal generating circuit that compares a first reference voltage and the constant voltage/constant current control signal to generate a first enable signal; and a PWM controller that generates a PWM control signal based on the constant voltage/constant current control signal to control a main switch of the flyback SMPS.