Switching Converter Zero-Current Offset Control for Light-Load Ripple

Solution Overview

Problem

Existing switching converters face efficiency issues in no load and light load regions due to excessive negative inductor current and increased inductor current ripple, particularly in discontinuous conduction mode (DCM) operations, which affect applications sensitive to output ripple and transient response.

Innovation Solution

Implementing a negative current tracking control function that adjusts the offset of a zero current detector to minimize negative inductor current and reduce inductor current ripple by varying the offset based on input/output voltage conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a fixed negative inductor current is allowed in DCM operation, then regulation is maintained in no load and light load regions, but efficiency decreases due to excessive negative inductor current and increased inductor current ripple

Engineering Contradiction:

Improveregulation maintenanceVSAvoidconverter efficiency

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies dynamics by transitioning from a fixed negative inductor current approach to a variable negative inductor current approach. The controller dynamically adjusts the negative inductor current based on real-time detection of actual inductor current zero-crossing points, ensuring the negative current adapts to varying load conditions and input/output voltages, thereby maintaining regulation while minimizing unnecessary current and reducing losses

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements feedback through a zero-current detector that continuously monitors the inductor current and provides feedback to the controller. This feedback mechanism enables the controller to detect actual zero-crossing points and adjust the negative inductor current accordingly, creating a closed-loop system that optimizes efficiency while maintaining regulation in no-load and light-load conditions

Inventive Principle:

Principle #23Feedback

2Reliability

If a fixed negative inductor current is allowed in DCM operation, then regulation is maintained, but inductor current ripple increases causing efficiency reduction

Engineering Contradiction:

Improveregulation maintenanceVSAvoidinductor current ripple

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies dynamics by transitioning from a fixed negative inductor current approach to a variable negative inductor current approach. The controller dynamically adjusts the negative inductor current based on real-time detection of actual inductor current zero-crossing points, ensuring the negative current adapts to varying load conditions and input/output voltages, thereby maintaining regulation while minimizing unnecessary current and reducing losses

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements feedback through a zero-current detector that continuously monitors the inductor current and provides feedback to the controller. This feedback mechanism enables the controller to detect actual zero-crossing points and adjust the negative inductor current accordingly, creating a closed-loop system that optimizes efficiency while maintaining regulation in no-load and light-load conditions

Inventive Principle:

Principle #23Feedback

3Loss of energy

If pulse skip method is used in no load and light load regions, then efficiency can be improved, but transient response characteristics deteriorate making it unsuitable for ripple-sensitive applications

Engineering Contradiction:

Improveconverter efficiencyVSAvoidtransient response characteristics

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent implements feedback through a zero-current detector that continuously monitors the inductor current and provides feedback to the controller. This feedback mechanism enables the controller to detect actual zero-crossing points and adjust the negative inductor current accordingly, creating a closed-loop system that optimizes efficiency while maintaining regulation in no-load and light-load conditions

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent applies periodic action by utilizing the natural periodic switching behavior of the converter in DCM operation. By synchronizing the negative inductor current adjustment with the periodic zero-crossing events detected by the zero-current detector, the system maintains continuous regulation without the need for pulse skipping, thereby preserving transient response characteristics while improving efficiency

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS12580475B2Switching converter equipped with negative current tracking control function

Publication Date: 2026.03.17 SILICON MITUS

AI summary

The switching converter equipped with negative current tracking control includes a switching transistor whose drain is connected to an input power supply, a rectifying transistor whose drain is connected to a source of the switching transistor and whose source is connected to a ground, an inductor having one end connected to the source of the switching transistor and the drain of the rectifying transistor, an output capacitor having a first end connected to the other end of the inductor and a second end connected to a ground, a PWM controller that outputs a PWM control signal to a gate of the switching transistor and a gate of the rectifying transistor, a zero current detector that detects zero crossing of an inductor current flowing through the inductor, and a negative current tracking controller that variably adjusts an offset of the zero current detector.