Peak-Value Current Mode Control Circuit for Power Converters
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Solution Overview
Problem
Conventional power converter control circuits require a compensation capacitor to stabilize the compensation signal, increasing the size and cost of the converter and complicating integration, as they struggle to manage the ripple of the current effectively.
Innovation Solution
A control circuit operating in peak-value current mode that controls the power switch based on inductor current detection signals, eliminating the need for a compensation signal by adjusting the maximum on-time to maintain a constant output current, thereby simplifying the circuit structure and reducing components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a compensation capacitor is introduced in the feedback loop to obtain a stable compensation signal, then the stability of the compensation signal is improved, but the size and cost of the power converter increase
Solution Approach 1:
The patent extracts and eliminates the compensation capacitor from the feedback loop by adopting peak-value current mode control. The control circuit directly compares the inductor current detection signal with a peak current reference signal, removing the need for compensation components while maintaining stable output current control.
Solution Approach 2:
The inductor current detection signal itself serves the dual purpose of both current sensing and compensation function. By using the peak value of the inductor current as the control reference, the system achieves self-regulation without external compensation components, reducing circuit complexity and size.
2Stability of the object's composition
If a compensation capacitor is introduced in the feedback loop, then the stability of the compensation signal is improved, but the number of peripheral components and chip pins increases
Solution Approach 1:
The patent removes the compensation capacitor and associated peripheral components from the circuit by implementing peak-value current mode control. The control circuit integrates all necessary functions within the chip, eliminating external compensation components and reducing the number of required chip pins.
Solution Approach 2:
The inductor current detection signal performs multiple functions simultaneously: it serves as the current sensing signal, the compensation signal, and the reference for peak current mode control. This multi-functionality eliminates the need for separate compensation components and reduces overall circuit complexity.
3Stability of the object's composition
If conventional control method with compensation capacitor is used, then the compensation signal stability is improved, but the circuit integration is complicated
Solution Approach 1:
The patent extracts the compensation function from the traditional feedback loop and integrates it directly into the peak-value current mode control circuitry. This eliminates the need for external compensation capacitors and simplifies the manufacturing process by reducing the number of external components required.
Solution Approach 2:
The patent merges the compensation function with the peak current mode control function into a single integrated circuit. By combining these functions, the control circuit achieves both stable compensation signal generation and simplified circuit integration without requiring external components.
Data Source
AI summary
The disclosure relates to a control circuit and a control method for a power converter. The power converter comprises a power switch and an inductor being coupled to the power switch. The control circuit controls operation of the power switch to charge and discharge the inductor for generating an inductor current and providing an output current. The control circuit controls the power switch to be turned on when or after an inductor current detection signal is zero, and controls the power switch to be turned off when the inductor current detection signal reaches a peak reference signal or when the power switch has been turned on for a maximum on time. The control circuit also adjusts the maximum on time in accordance with the inductor current detection signal, so that the power converter provides a constant output current to a load. The control circuit operates at a peak-value current mode and maintains the current of the power converter nearly stable without obtaining a compensation signal. The circuit structure is simplified and the number of peripheral components is reduced.