CCM Power Converter Control Circuit for Output Current Regulation
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Solution Overview
Problem
Existing power converters operating in discontinuous current mode suffer from lower power efficiency, necessitating the development of a control circuit that can regulate output current in continuous current mode for improved performance.
Innovation Solution
A control circuit that generates a continuous-current signal and a peak-current signal by detecting the switching current of a transformer, using an integration circuit to produce an average-current signal, and a switching control circuit to regulate the output current, with an oscillator determining the switching frequency and a time constant correlated with the switching period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If discontinuous current mode is used, then device count and cost are reduced, but power efficiency deteriorates
Solution Approach 1:
The patent changes the operating parameter from discontinuous current mode to continuous current mode, which fundamentally alters the current waveform characteristics. This parameter change enables higher power efficiency while maintaining cost-effective implementation through the use of standard control circuitry components.
Solution Approach 2:
The patent implements a feedback control mechanism that measures the output current and adjusts the switching duty cycle accordingly. The control circuit continuously monitors the current state and modifies the switching parameters to maintain optimal efficiency, creating a closed-loop system that adapts to varying load conditions.
2Loss of energy
If continuous current mode is implemented, then power efficiency is improved, but control circuit complexity increases
Solution Approach 1:
The control circuit is designed to perform multiple functions: it generates switching signals, measures output current, calculates average current, and regulates duty cycle all within a single integrated controller. This multi-functional approach reduces the need for separate dedicated circuits for each function, thereby limiting the increase in overall system complexity.
Solution Approach 2:
The patent introduces an intermediary integration circuit that simplifies the control process by automatically calculating the average current from the continuous current waveform. This intermediary component acts as a mediator between the current measurement and the duty cycle control, reducing the complexity of direct calculations that would otherwise be required.
Data Source
AI summary
A switching control circuit is provided for measuring and regulating an output current of a power converter. The power converter is operated under continuous current mode. A detection circuit generates a continuous-current signal and a peak-current signal by detecting a switching current of an inductive device. An integration circuit generates an average-current signal in response to the continuous-current signal, the peak-current signal and an off time of a switching signal. The switching control circuit generates the switching signal in response to the average-current signal. The switching signal is coupled to switch the inductive device and regulate the output current of the power converter. A time constant of the integration circuit is correlated to the switching period of the switching signal, therefore the average-current signal will be proportional to the output current.