Power Converter Control Circuit Light-Load Regulation
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Solution Overview
Problem
Existing power converters face challenges in reducing output voltage and current at light load and no load conditions while maintaining safety and efficiency, often requiring costly and bulky opto-couplers and secondary-side regulators.
Innovation Solution
A control circuit for power converters that includes an input circuit, amplifier, PWM circuit, and power management circuit, which generates a feedback signal to regulate output voltage by sampling reflected transformer voltages, eliminating the need for opto-couplers and secondary-side regulators, thereby reducing size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional power converter design with opto-coupler and secondary-side regulator is used, then galvanic isolation and output voltage regulation are achieved, but device size and manufacturing cost increase
Solution Approach 1:
The patent extracts and eliminates the opto-coupler and secondary-side regulator from the traditional power converter architecture. By using primary-side regulation with reflected voltage sensing, the design removes these isolated components while maintaining galvanic isolation through the transformer itself, thereby reducing device size and complexity.
Solution Approach 2:
The transformer serves multiple functions: power transfer, galvanic isolation, and voltage sensing through reflected voltage. The control circuit integrates multiple functions (regulation, sensing, and control) into a single primary-side architecture, eliminating the need for separate secondary-side regulation components.
2Reliability
If traditional power converter design with opto-coupler and secondary-side regulator is used, then output voltage regulation is achieved, but manufacturing cost increases
Solution Approach 1:
The patent removes expensive components (opto-coupler, secondary-side regulator) from the design. The reflected voltage sensing method uses existing transformer windings and simple voltage division networks, significantly reducing component count and manufacturing cost while maintaining regulation capability.
Solution Approach 2:
The patent uses voltage copying through the transformer's reflected voltage to sense output conditions without direct electrical connection. This allows regulation control to be implemented on the primary side using inexpensive voltage sensing circuits rather than expensive isolation components.
3Reliability
If output voltage is maintained at full load level during light load operation, then voltage regulation is maintained, but power consumption increases
Solution Approach 1:
The patent implements dynamic output voltage adjustment based on load conditions. The control circuit monitors load current and adjusts the output voltage reference accordingly, lowering the voltage during light load periods to reduce power consumption while maintaining adequate regulation for the actual load requirements.
Solution Approach 2:
The patent changes the operating parameters (output voltage level) based on load conditions. By adjusting the voltage reference and control parameters dynamically, the system optimizes power efficiency during light load operation while maintaining sufficient voltage regulation performance.
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 solution effectively reduces output voltage during light load conditions, conserving power and minimizing converter size and cost by using a feedback loop to adjust switching signals and reference signals without requiring opto-couplers or secondary-side regulators.
Implementation Method 1
an off-line power converter must provide galvanic isolation between its primary side and secondary side
Implementation Method 2
generating a feedback signal through sampling a reflected voltage of a transformer
Implementation Method 3
The PWM circuit generates a switching signal according to the feedback signal for switching the transformer and regulating the output voltage
Data Source
AI summary
A control circuit of a power converter and a method therefore are provided. The control circuit comprises an input circuit, an amplifier, a PWM circuit, and a power management circuit. The input circuit is coupled to a transformer to generate a sensing signal related to an output voltage of the power converter. The amplifier generates a feedback signal according to the sensing signal and a reference signal. The PWM circuit generates a switching signal according to the feedback signal for switching the transformer and regulating the output voltage of the power converter. The power management circuit controls the reference signal according to the feedback signal. The power management circuit includes a timer for determining a period, and the output voltage of the power converter decreases while an output power of the power converter is lower than a light-load threshold. A method for controlling the control circuit is also disclosed.